CN1910008A - Manufacture of a heat transfer system - Google Patents

Abstract

A method of making an evaporator includes orienting a vapor barrier wall, orienting a liquid barrier wall, and positioning a wick between the vapor barrier wall and the liquid barrier wall. The vapor barrier wall is oriented such that a heat-absorbing surface of the vapor barrier wall defines at least a portion of an exterior surface of the evaporator. The exterior surface is configured to receive heat. The liquid barrier wall is oriented adjacent the vapor barrier wall. The liquid barrier wall has a surface configured to confine liquid. A vapor removal channel is defined at an interface between the wick and the vapor barrier wall. A liquid flow channel is defined between the liquid barrier wall and the primary wick.

Description

Manufacturing of heat transfer systems

Cross References to Related Applications

This application claims priority to US Provisional Application No. 60/514,670, filed October 28,2003. This application is a continuation-in-part of US Application No. 10/676265, filed October 2, 2003, which claims priority from US Application No. 60/415,424, filed October 2, 2002. This application is also a continuation-in-part of U.S. Application No. 10/694387, filed October 28, 2003, which claims priority to U.S. Provisional Application No. 60/421,737, filed October 28, 2002 . This application is also a continuation-in-part of U.S. Application No. 10/602022, filed June 24, 2003, which claims priority to U.S. Provisional Application No. 60/391006, filed June 24, 2002 And is a continuation-in-part of US Application No. 09/896561, filed June 29, 2001, which claims priority to US Provisional Application No. 60/215,588, filed June 30, 2000. All of these applications are hereby incorporated by reference.

technical field

The specification relates to heat transfer systems and methods of making the same.

Background technique

Heat transfer systems are used to transfer heat from one location (heat source) to another (heat sink). The heat transfer system can be used in terrestrial or extraterrestrial applications. For example, heat transfer systems are incorporated on satellite equipment operating in sub-zero or low-gravity environments. As another example, heat transfer systems can be used in electronic equipment that often requires cooling during operation.

Loop heat pipes (LHP) and capillary pumped loops (CPL) are passive two-phase heat transfer systems. Each includes an evaporator thermally coupled to a heat source, a condenser thermally coupled to a heat sink, a fluid flowing between the evaporator and condenser, and a fluid reservoir for fluid expansion. The fluid within the heat transfer system can be referred to as the working fluid. The evaporator includes a main core and a core including fluid flow channels. The heat obtained by the evaporator is transferred to and discharged by the condenser. These systems exploit the capillary pressure generated in the fine pore wick within the evaporator in order to facilitate the circulation of the working fluid from the evaporator to the condenser and back to the evaporator. The main distinguishing feature between LHP and CPL is the location of the circuit reservoir, which is used to store excess fluid diverted from the circuit during operation. Typically, the CPL's reservoir is located away from the evaporator, while the LHP's reservoir is co-located with the evaporator.

Contents of the invention

In one general aspect, a method of making an evaporator includes orienting a vapor barrier wall, orienting a liquid barrier wall, and positioning a wick between the vapor barrier wall and the liquid barrier wall. The vapor barrier wall is oriented such that the heat absorbing surface of the vapor barrier wall defines at least a portion of the outer surface of the evaporator. The outer surface is configured to receive heat. Orienting the liquid barrier wall adjacent to the vapor barrier wall. The liquid barrier wall has a surface configured to confine liquid. At least one of orienting the vapor barrier wall, orienting the liquid barrier wall, and positioning the core includes defining a vapor removal channel at an interface between the core and the vapor barrier wall. At least one of the directional vapor barrier wall, the directional liquid barrier wall and the positioning core includes defining a liquid flow channel between the liquid barrier wall and the main core.

Embodiments may include one or more of the following aspects. For example, the method may also include forming a vapor barrier wall and forming a liquid barrier wall. Forming the vapor barrier wall may include forming the vapor barrier wall into a planar shape and forming the liquid barrier wall may include forming the liquid barrier wall into a planar shape. Forming the vapor barrier wall may include forming the vapor barrier wall into an annular shape and forming the liquid barrier wall may include forming the liquid barrier wall into an annular shape.

Positioning the core includes heat shrinking the core on the vapor barrier wall. Positioning the core includes heat shrinking the liquid barrier wall over the core.

Positioning may include positioning the wick between the vapor barrier wall and the liquid confining surface of the liquid barrier wall.

The method may include orienting the subcooler proximate to the liquid barrier wall. Orienting the subcooler may include heat shrinking the subcooler onto the liquid barrier wall.

The method may include electroetching, machining or photoetching the vapor removal channels into the vapor barrier wall. The method may include embedding the vapor removal channels within the core.

The method may also include forming the vapor barrier wall by rolling the vapor barrier material into a cylindrical shape and sealing mating edges of the vapor barrier material. The method may include forming the liquid barrier wall by rolling the liquid barrier material into a cylindrical shape and sealing mating edges of the liquid barrier material.

Orienting the liquid barrier walls may include heat shrinking the liquid barrier walls.

The method may include forming a liquid blocking wall, and photoetching a liquid flow channel into the liquid blocking wall.

In another general aspect, a method of making an evaporator includes orienting a liquid barrier wall having an annular shape, orienting a vapor barrier wall having an annular shape coaxial with the liquid barrier wall, and positioning a wick between the liquid barrier wall and the vapor barrier wall, The core is coaxial with the liquid barrier wall.

Embodiments may include one or more of the following aspects. For example, the method may also include forming a vapor barrier wall and forming a liquid barrier wall.

Positioning the core may include heat shrinking the core on the vapor barrier wall. Positioning the core may include heat shrinking the liquid barrier wall over the core. Positioning may include positioning the wick between the vapor barrier wall and the liquid confining surface of the liquid barrier wall.

The method may include orienting the subcooler proximate to the liquid barrier wall. Orienting the subcooler may include heat shrinking the subcooler onto the liquid barrier wall.

The method may include electroetching, machining or photoetching the vapor removal channels into the vapor barrier wall. The method may include embedding the vapor removal channels within the core.

The method may also include forming the vapor barrier wall by rolling the vapor barrier material into a cylindrical shape and sealing mating edges of the vapor barrier material. The method may further include forming the liquid barrier wall by rolling the liquid barrier material into a cylindrical shape and sealing mating edges of the liquid barrier material.

Orienting the liquid barrier walls may include heat shrinking the liquid barrier walls.

Other features and advantages will be apparent from the description, drawings, and claims.

Description of drawings

Figure 1 is a schematic diagram of a heat transfer system.

FIG. 2 is a diagram of an embodiment of the heat transport system schematically shown in FIG. 1 .

3 is a flowchart of a process for transferring heat using a heat transfer system.

FIG. 4 is a graph showing temperature profiles of various components of the heat transfer system in the process flow of FIG. 3 .

5A is a diagram of a three-port main evaporator shown in the heat transfer system of FIG. 1 .

5B is a cross-sectional view of the main evaporator taken along 5B-5B of FIG. 5A.

6 is a diagram of a four port main evaporator that can be incorporated into the heat transfer system shown in FIG. 1 .

7 is a schematic diagram of an embodiment of a heat transport system.

8A, 8B, 9A and 9B are perspective views of an application using a heat transfer system.

8C is a cross-sectional view of the fluid line taken along 8C-8C of FIG. 8A.

8D and 9C are schematic illustrations of embodiments of the heat transport system of FIGS. 8A and 9A, respectively.

Fig. 10 is a cross-sectional view of a planar evaporator.

Fig. 11 is an axial cross-sectional view of an annular evaporator.

FIG. 12 is a radial cross-sectional view of the annular evaporator of FIG. 11 .

FIG. 13 is an enlarged view of a portion of the radial cross-sectional view of the annular evaporator of FIG. 12 .

14A is a perspective view of the annular evaporator of FIG. 11 .

14B is a top and partial cross-sectional view of the annular evaporator of FIG. 14A.

14C is an enlarged cross-sectional view of a portion of the annular evaporator of FIG. 14B.

14D is a cross-sectional view of the annular evaporator of FIG. 14B taken along line 14D-14D.

14E and 14F are enlarged views of portions of the annular evaporator of FIG. 14D.

14G is a perspective cutaway view of the annular evaporator of FIG. 14A.

Figure 14H is a detailed perspective cutaway view of the annular evaporator of Figure 14G.

15A is a plan detail view of a vapor barrier wall formed into a barrel segment assembly of the annular evaporator of FIG. 14A.

15B is a cross-sectional view of the vapor barrier wall of FIG. 15A taken along line 15B-15B.

Figure 16A is a perspective view of the main wick of the annular evaporator of Figure 14A.

Figure 16B is a top view of the primary core of Figure 16A.

16C is a cross-sectional view of the main core of FIG. 16B taken along line 16C-16C.

Figure 16D is an enlarged view of a portion of the main core of Figure 16C.

17A is a perspective view of a liquid barrier wall formed into an annular ring of the annular evaporator of FIG. 14A.

Figure 17B is a top view of the vapor barrier wall of Figure 17A.

Figure 17C is a cross-sectional view of the vapor barrier wall of Figure 17B taken along line 17C-17C.

Figure 17D is an enlarged view of a portion of the vapor barrier wall of Figure 17C.

18A is a perspective view of a ring separating the liquid barrier wall of FIG. 17A from the vapor barrier wall of FIG. 15A.

Figure 18B is a top view of Figure 18A.

Figure 18C is a cross-sectional view of the loop of Figure 18B taken along line 18C-18C.

Figure 18D is an enlarged view of a portion of the circle of Figure 18C.

19A is a perspective view of a ring of the annular evaporator of FIG. 14A.

Fig. 19B is a top view of Fig. 19A.

Figure 19C is a cross-sectional view of the ring of Figure 19B taken along line 19C-19C.

Figure 19D is an enlarged view of a portion of the circle of Figure 19C.

Figure 20 is a perspective view of a cyclic heat exchange system capable of cooling using a heat transfer system.

21 is a cross-sectional view of a cyclic heat exchange system such as the cyclic heat exchange system of FIG. 20 .

22 is a side view of a cyclic heat exchange system such as the cyclic heat exchange system of FIG. 20 .

23 is a schematic diagram of a first embodiment of a thermodynamic system including a cyclic heat exchange system and a heat transfer system.

24 is a schematic diagram of a second embodiment of a thermodynamic system including a cyclic heat exchange system and a heat transfer system.

Fig. 25 is a schematic diagram of a heat transfer system using an evaporator designed according to the principles of Figs. 10-13.

FIG. 26 is a functional exploded view of the heat transfer system of FIG. 25 .

27 is a detailed view in partial cross-section of an evaporator used in the heat transfer system of FIG. 25 .

FIG. 28 is a perspective view of a heat exchanger used in the heat transfer system of FIG. 25 .

29 is a graph of the temperature of the heat source of the cyclic heat exchange system versus the surface area of the interface between the heat transfer system and the heat source of the cyclic heat exchange system.

Figure 30 is a top plan view of a heat transfer system packaged around a portion of a cyclic heat exchange system.

31 is a partial cross-sectional elevation view (taken along line 31 - 31 ) of a heat transfer system packaged around the cyclic heat exchange system of FIG. 30 .

32 is a partial cross-sectional elevation view (taken at detail 3200 ) of the interface between the heat transfer system and the cyclic heat exchange system of FIG. 30 .

Figure 33 is an upper perspective view of the heat transfer system mounted to the cyclic heat exchange system.

34 is a lower perspective view of the heat transfer system mounted to the cyclic heat exchange system of FIG. 33 .

35 is a partial cross-sectional view of the interface between the evaporator of the heat transfer system and the cyclic heat exchange system with the evaporator clamped to the cyclic heat exchange system.

36 is a side view of a clamp for clamping the evaporator to the cyclic heat exchange system of FIG. 35 .

37 is a partial cross-sectional view of the interface between the evaporator of the heat transfer system and the cyclic heat exchange system, wherein the interface is formed by an interference fit between the evaporator and the cyclic heat exchange system.

38 is a partial cross-sectional view of the interface between the evaporator of the heat transfer system and the cyclic heat exchange system, where the interface is formed by integrally forming the evaporator with the cyclic heat exchange system.

Figure 39 is a top plan view of the condenser of the heat transfer system.

40 is a partial cross-sectional view of the condenser of FIG. 39 taken along line 40-40.

41-43 are detailed cross-sectional views of condensers having a stacked configuration.

Figure 44 is a detailed cross-sectional view of a condenser in an extruded configuration.

Figure 45 is a perspective detail and cross-sectional view of a condenser with an extruded configuration.

Figure 46 is a cross-sectional view of one side of the heat transfer system packaged around the cyclic heat exchange system.

47 is a perspective view of a thermodynamic system including a cyclic heat exchange system and a heat transfer system.

48 is a schematic diagram of a portion of the heat transfer system of FIG. 47. FIG.

49 is a perspective view of a portion of the heat transfer system of FIG. 47. FIG.

FIG. 50 is a side perspective view of the thermodynamic system of FIG. 47 .

FIG. 51 is a schematic diagram of a portion of the thermodynamic system of FIG. 47 .

52 is a perspective view of the thermodynamic system of FIG. 47. FIG.

53A is a perspective view of a wick subassembly that is part of the evaporator of the heat transfer system of FIG. 47 .

Figure 53B is a perspective view of a portion of the core subassembly of Figure 53A.

53C is a perspective view of a liquid barrier wall that is part of the evaporator of the heat transfer system of FIG. 47 .

53D is a perspective view of a subcooler that is part of the evaporator of the heat transfer system of FIG. 47 .

53E is a perspective view of the evaporator of the heat transfer system of FIG. 47 .

FIG. 54 is a flowchart of a process for fabricating the thermodynamic system of FIG. 47 including a process for fabricating the heat transfer system of FIG. 47 .

Figure 55 is a flowchart of a process for preparing the core subassembly of Figures 53A and 53B.

56A-56E are perspective views illustrating steps in the process of FIG. 55 .

Figure 57 is a flowchart of a process for preparing the liquid barrier wall of Figure 53C.

58A-58E are perspective views illustrating steps in the process of FIG. 57 .

59 is a flowchart of a procedure for preparing the outer subassembly of the evaporator of the heat transfer system of FIG. 47. FIG.

60A-60G are perspective views illustrating steps in the process of FIG. 59 .

61 is a flowchart of a procedure for integrating an outer subassembly with a wick subassembly of an evaporator of the heat transfer system of FIG. 47. FIG.

62A-62E are perspective views illustrating steps in the process of FIG. 61 .

63 is a flowchart of a process for completing the vaporizer body formed during the process of FIG. 61 .

64A is a side cross-sectional view of the evaporator body showing a step in the process of FIG. 63 .

FIG. 65 is a flowchart of a procedure for incorporating the evaporator completed in the procedure of FIG. 63 onto the cyclic heat exchange system of FIG. 47 .

66A and 66B are perspective views showing steps in the process of FIG. 65 .

The same reference numbers refer to the same elements in different figures.

Detailed ways

As mentioned above, in a Loop Heat Pipe (LHP) the accumulator is placed together with the evaporator so that the accumulator is thermally and hydraulically connected to the accumulator by heat pipe-like tubes. In this way, liquid from the reservoir can be pumped to the evaporator, ensuring that the main wick of the evaporator is fully wetted or "primed" during start-up. In addition, the design of the LHP also reduces the loss of liquid from the main wick of the evaporator during steady state or transient operation of the evaporator within the heat transfer system. Furthermore, vapor and/or bubbles of non-condensable gas (NCG bubbles) are discharged from the core of the evaporator into the reservoir through a heat pipe-like conduit.

Conventional LHPs require liquid to be present in the reservoir prior to start-up (ie, power is applied to the LHP's evaporator). However, if the working fluid in the LHP is supercritical prior to LHP start-up, the fluid will not be present in the reservoir prior to start-up. The supercritical state is a state in which the temperature of the LHP is higher than the critical temperature of the working fluid. The critical temperature of a fluid is the highest temperature at which the fluid can exhibit liquid-vapor equilibrium. For example, the LHP may be in a supercritical state if the working fluid is a cryogenic fluid i.e. a fluid having a boiling point below -150°C, or if the working fluid is a subambient fluid i.e. has a boiling point below the ambient temperature in which the LHP operates of fluid.

Conventional LHPs also require the liquid returning to the evaporator to be subcooled, that is, cooled to a temperature lower than the boiling point of the working fluid. This constraint makes it impractical to operate the LHP at temperatures below room temperature. For example, if the working fluid is a cryogenic fluid, the LHP may operate in an environment having a temperature greater than the boiling point of the fluid.

Referring to Figure 1, a heat transfer system 100 is designed to overcome the limitations of conventional LHPs. Heat transfer system 100 includes heat transfer system 105 and perfusion system 110 . The perfusion system 110 is configured to convert fluid within the heat transfer system 105 into a liquid, thereby perfusing the heat transfer system 105 . The term "fluid" as used in this specification is a general term that refers to a substance that is both a liquid and a vapor in a saturated equilibrium state.

The heat transfer system 105 includes a main evaporator 115 and a condenser 120 coupled to the main evaporator 115 by a liquid line 125 and a vapor line 130 . Condenser 120 is in thermal communication with radiator 165, and main evaporator 115 is in thermal communication with heat source Qin 116. If desired, the system 105 may also include a thermal reservoir 147 coupled to the steam line 130 as an additional pressure vessel. In particular, thermal storage 147 increases the volume of system 100 . If the working fluid is at a temperature above its critical temperature (ie the highest temperature at which the working fluid can exhibit liquid-vapor equilibrium), its pressure is proportional to the mass (load) in the system 100 and inversely proportional to the volume of the system. Increasing the volume of the heat reservoir 147 reduces the fill pressure.

The main evaporator 115 includes a vessel 117 containing a main wick 140 within which a wick 135 is defined. The main evaporator 115 includes an insertion tube 142 and a second wick 145 within the wick 135 . The insertion tube 142 , the main core 140 and the second core 145 define a liquid passage 143 , a first vapor passage 144 and a second vapor passage 146 . The second core 145 provides phase control, i.e., liquid/vapor separation in the core 135, as taught in U.S. Application No. 09/896,561, filed June 29, 2001, which is incorporated herein in its entirety as refer to. As shown, primary evaporator 115 has three ports, liquid inlet 137 into liquid passage 143, vapor outlet 132 out of secondary vapor passage 146 into vapor line 130, and fluid outlet 139 from liquid passage 143 (described below, And possibly the first steam channel 144) comes out. Further details of the construction of the three-port evaporator are set forth below with respect to Figures 5A and 5B.

The perfusion system 110 includes a second or perfusion vaporizer 150 coupled to the vapor line 130 and a reservoir 155 co-located with the second vaporizer 150 . The reservoir 155 is joined to the core 135 of the main evaporator 115 via a second fluid line 160 and a second condenser 122 . The second fluid line 160 is coupled to the fluid outlet 139 of the main evaporator 115 . The perfusion system 110 also includes a controlled heat source Qsp 151 in thermal communication with the second vaporizer 150.

The second evaporator 150 includes a vessel 152 containing a main wick 190 within which a wick 185 is defined. Second evaporator 150 includes an insert tube 153 and a second wick 180 extending from wick 185 through conduit 175 and into reservoir 155 . The second wick 180 provides a capillary connection between the reservoir 155 and the second evaporator 150 . Insertion tube 153 , primary core 190 and second core 180 define a liquid channel 182 in conjunction with fluid line 160 , a first vapor channel 181 in conjunction with reservoir 155 , and a second vapor channel 183 in conjunction with vapor line 130 . The reservoir 155 is thermally and hydraulically coupled to the wick 185 of the second evaporator 150 through the liquid passage 182 , the second wick 180 and the first vapor passage 181 . Vapor and/or NCG bubbles from the wick 185 of the second evaporator 150 are swept through the first vapor channel 181 to the reservoir 155 and the condensable liquid is returned from the reservoir 155 to the second evaporator 150 through the second wick 180 . The main wick 190 hydraulically connects the liquid in the core 185 to the heat source Qsp 151, allowing the liquid at the outer surface of the main wick 190 to evaporate in the second vapor channel 183 and form a vapor when heat is applied to the second evaporator 150.

The reservoir 155 is cold biased, and thus, it is cooled by a cooling source that would allow the reservoir 155 to operate at a temperature lower than the operating temperature of the heat transfer system 105 if not heated. In one embodiment, the reservoir 155 and the second condenser 122 are in thermal communication with a heat sink 165 thermally coupled to the condenser 120 . For example, reservoir 155 can be mounted to heat sink 165 using shunt 170, which can be made of aluminum or any thermally conductive material. In this way, the temperature of the reservoir 155 tracks the temperature of the condenser 120 .

FIG. 2 shows an example of an embodiment of a heat transport system 100 . In this embodiment, the condensers 120 and 122 are mounted to a cryocooler 200 serving as a refrigerator, and heat is transferred from the condensers 120 , 122 to the radiator 165 . Additionally, in the embodiment of FIG. 2 , the tubing 125 , 130 , 160 is coiled in order to reduce the space required for the heat transfer system 100 .

Although not shown in Figures 1 and 2, elements such as, for example, the reservoir 155 and the main vaporizer 115 may be equipped with temperature sensors that can be used for diagnostic or testing purposes.

Referring also to FIG. 3 , the system 100 performs a process 300 for transferring heat from the heat source Qin 116 and for ensuring that the primary evaporator 115 is wetted by liquid prior to start-up. This procedure 300 is particularly useful when the heat transfer system 105 is in a supercritical state. Before the process 300 begins, the system 100 is filled with a working fluid at a certain pressure called the "fill pressure".

Initially, the reservoir 155 is cold biased, such as by mounting the reservoir 155 to the heat sink 165 (step 305). The reservoir 155 may be cold biased to a temperature below the critical temperature of the working fluid, which as stated is the highest temperature at which the working fluid can exhibit liquid-vapor equilibrium. For example, if the fluid is ethane with a critical temperature of 33°C, reservoir 155 is cooled below 33°C. As the temperature of the reservoir 155 drops below the critical temperature of the working fluid, the reservoir 155 is partially filled with liquid condensate formed by the working fluid. The formation of liquid within the reservoir 155 wets the second wick 180 and the main wick 190 of the second evaporator 150 (step 310).

Simultaneously, power is applied to the perfusion system 110 by applying heat from the heat source Qsp 151 to the second evaporator 150 (step 315 ) to increase or initiate fluid circulation within the heat transfer system 105 . Due to the capillary pressure at the interface between the main wick 190 and the second vapor channel 183, the vapor output by the second evaporator 150 is pumped through the vapor line 130 and through the condenser 120 (step 320). When the vapor reaches condenser 120, it is converted to liquid (step 325). The liquid formed in the condenser 120 is pumped to the main evaporator 115 of the heat transfer system 105 (step 330). When the primary evaporator 115 is at a temperature higher than the critical temperature of the fluid, liquid entering the primary evaporator 115 evaporates and cools the primary evaporator 115 . The process (steps 315-330) continues, causing the main evaporator 115 to reach a set point temperature (step 335), at which point the main evaporator is able to retain liquid and is wetted and operates like a capillary pump. In one embodiment, the set point temperature is the temperature at which the reservoir 155 has been cooled. In another embodiment, the set point temperature is a temperature below the critical temperature of the working fluid. In a further embodiment, the set point temperature is a temperature above which the reservoir 155 has been cooled.

If the set point temperature has been reached (step 335), the system 100 operates in the main mode (step 340), wherein heat from the heat source Qin 116 applied to the main evaporator 115 is transferred by the heat transfer system 105. Specifically, in the main mode, the main evaporator 115 generates capillary pumping to facilitate circulation of the working fluid through the heat transfer system 105 . Simultaneously, in master mode, the set point temperature of the reservoir 155 is decreased. The rate at which the heat transfer system 105 cools down during the main mode depends on the cold bias of the reservoir 155 because the temperature of the main evaporator 115 closely follows the temperature of the reservoir 155 . Additionally, although not required, a heater can be used to further control or adjust the temperature of the reservoir 155 during the main mode. Also, in the main mode, the power applied by the heat source Qsp 151 to the second evaporator 150 is reduced, thereby causing the heat transfer system 105 to drop to the normal operating temperature of the fluid. For example, in the main mode, the heat load from the heat source Qsp 151 to the second evaporator 150 is maintained at a value equal to or exceeding the heat conditions defined below. In one embodiment, the heat load from heat source Qsp is maintained at approximately 5 to 10% of the heat load applied to primary evaporator 115 from heat source Qin 116.

In this particular embodiment, the main mode is triggered by determining that the set point temperature has been reached (step 335). In alternative embodiments, master mode may be initiated at other times or due to other triggers. For example, main mode may start after the perfusion system has been wetted (step 310) or after the reservoir has been cold biased (step 305).

At any time during operation, heat transfer system 105 can experience thermal conditions such as those caused by heat conduction across main core 140 and parasitic heat applied to liquid lines 125 . Both conditions cause the formation of vapor on the liquid side of the evaporator. Specifically, heat conduction across the main wick 140 can cause the liquid in the wick 135 to form vapor bubbles that, if left within the wick 135, will grow and block the liquid supply to the main wick 140, causing the main The evaporator 115 is damaged. Parasitic heat input into liquid line 125 (referred to as “parasitic heat gain”) can cause liquid within liquid line 125 to form vapor.

To reduce the adverse impact of the thermal conditions described above, the perfusion system 110 is operated at a power level Qsp 151 greater than or equal to the sum of the thermal conditions and the parasitic heat gain, as described above, for example, the perfusion system can be Operate at 5-10% of power. In particular, fluid comprising a combination of vapor bubbles and liquid is swept out of the core 135 for discharge into the second fluid line 160 leading to the second condenser 122 . In particular, vapor formed within core 135 travels around insert tube 143 directly into fluid outlet port 139 . The steam formed in the first steam channel 144 either travels through the second wick 145 (if the pore size of the second wick 145 is large enough to accommodate the steam bubbles) or through an opening at the end of the second wick 145 near the outlet port 139. While entering the fluid outlet port 139 , the opening provides an unobstructed passage from the first vapor passage 144 to the outlet port 139 . Second condenser 122 condenses air bubbles in the fluid and pushes the fluid to reservoir 155 for reintroduction into heat transfer system 105 .

Similarly, in order to reduce the parasitic heat input to the liquid line 125, the second fluid line 160 and the liquid line 125 can form a coaxial configuration, and the second fluid line 160 surrounds the liquid line 125 and connects the liquid line 125 is insulated from surrounding heat. This embodiment is described further below with reference to Figures 8A and 8B. As a result of this configuration, ambient heat can cause vapor bubbles to form in the second fluid line 160 instead of the liquid line 125 . As stated, fluid flows from the primary evaporator 115 to the secondary condenser 122 by capillary action acting at the secondary wick 145 . This fluid flow and the relatively low temperature of the second condenser 122 causes the sweeping of vapor bubbles within the second fluid line 160 through the condenser 122 where the vapor bubbles condense to liquid and are pumped into the reservoir 155 .

As shown in Figure 4, data from the test run is shown. In this example, the temperature 400 of the main evaporator 115 is substantially higher than the temperature 405 of the reservoir 155, which has been cold biased to the set point temperature (step 305), before the temperature 410 activates the main evaporator 115. . Since the perfusion system 110 is wetted (step 310), at time 452 power Qsp450 is applied to the second evaporator 150 (step 315), causing liquid to be pumped to the main evaporator 115 (step 330), the temperature of the main evaporator 115 400 descends until it reaches temperature 405 of reservoir 155 at time 410 . When system 100 is operating in LHP mode (step 340), power Qin 460 is applied to primary evaporator 115 at time 462. As shown, the power input Qin 460 to the main evaporator 115 remains relatively low while the main evaporator 115 cools down. Also shown are the temperatures 470 and 475 of the second fluid line 160 and the liquid line 125 , respectively. After time 410 , temperatures 470 and 475 track temperature 400 of main evaporator 115 . Also, because of the thermal communication between the second evaporator 150 and the reservoir 155 , the temperature 415 of the second evaporator 150 closely follows the temperature 405 of the reservoir 155 .

As noted, in one embodiment, ethane may be used as the fluid in the heat transfer system 105 . Although the critical temperature of ethane is 33°C, the system 100 is capable of starting from a supercritical state where the system 100 is at a temperature of 70°C for reasons generally described above. Due to the application of power Qsp to the second evaporator 150, the temperature of the condenser 120 and the reservoir 155 drops rapidly (between times 452 and 410). A trim heater can be used to control the temperature of the reservoir 155 and thus the condenser 120 to -10°C. To start the primary evaporator 115 from a supercritical temperature of 70° C., a heat load or power input Qsp of 10 W is applied to the secondary evaporator 150 . Once the primary evaporator 115 is primed, both the power input from the heat source Qsp 151 to the secondary evaporator 150 and the power applied to and through the trim heater are reduced such that the temperature of the system 100 drops to approximately -50°C for nominal operation temperature. For example, during the main mode, if a power input Qin of 40W is applied to the main evaporator 115, the power input Qsp to the second evaporator 150 can be reduced to about 3W while operating at -45°C in order to pass the thermal conditions (as above described) to moderate the 3W loss. As another example, the primary evaporator 115 can operate with power input Qin from about 10W to about 40W, 5W applied to the secondary evaporator 150, and a temperature 405 of the reservoir 155 at about -45°C.

Referring to Figures 5A and 5B, in one embodiment, the main evaporator 115 is designed as a three-port evaporator 500 (which is the design shown in Figure 1). Generally, in three-port evaporator 500, liquid flows into liquid inlet 505 into core 510 defined by main core 540, and fluid from core 510 flows from fluid outlet 512 to a cold bias reservoir (e.g., reservoir 155) . The fluid and core 510 are housed in a container 515, for example made of aluminium. In particular, fluid flowing from the liquid inlet 505 into the core 510 flows through the insertion tube 520 into the liquid channel 521 that flows through and around the insertion tube 520 . Fluid can flow through a second wick 525 (eg, second wick 145 of evaporator 115 ) made of wick material 530 and annular trunk 535 . The core material 530 is detachable from the first vapor channel 560 to the annular main line 535, and as the power from the heat source Qin116 is applied to the evaporator 500, the liquid from the core 510 enters the main core 540 and evaporates, forming along the The second steam channel 565 of 545 is free to flow and enters the steam from the steam outlet 550 into the steam line 130 . Vapor bubbles formed within the first steam channel 560 of the wick 510 are swept out of the wick 510 through the first steam channel 560 and into the fluid outlet 512 . As mentioned above, if the pore size of the second wick 525 is large enough to accommodate the steam bubbles, the steam bubbles in the first steam channel 560 can pass through the second wick 525 . Alternatively, or in addition, vapor bubbles within the first vapor passage 560 may pass through openings of the second wick 525 formed at any suitable location along the second wick 525 to enter the liquid passage 521 or the fluid outlet 512 .

Referring to FIG. 6 , in another embodiment, the main evaporator 115 is designed as a four-port evaporator 600 , which is the design described in US Application No. 09/896,561 filed June 29,2001. Briefly, and with emphasis on the different configurations of the three-port evaporator, liquid flows into the evaporator 600 through the fluid inlet 605 , through the insert tube 610 and into the wick 615 . Liquid in the wick 615 enters the main wick 620 and evaporates to form a vapor that flows freely along the vapor slots 625 and out the vapor outlet 630 into the vapor line 130 . The second core 633 within the core 615 separates the liquid within the core from the vapor or gas bubbles within the core (generated when the liquid within the core 615 is heated). Liquid carrying air bubbles formed in the first fluid channel 635 inside the second core 633 flows out of the fluid outlet 640, and vapor or air bubbles formed in the vapor channel 642 between the second core 633 and the main core 620 flows out of the steam Exit 645.

Referring also to FIG. 7 , a heat transfer system 700 is shown in which the main evaporator is the four port evaporator 600 . The system 700 includes one or more heat transfer systems 705 and a perfusion system 710 configured to convert fluid within the heat transfer systems 705 to a liquid in order to perfuse the heat transfer systems 705 . Four port evaporator 600 is coupled to one or more condensers 715 via vapor line 720 and fluid line 725 . The perfusion system 710 includes a cold bias reservoir 730 hydraulically and thermally connected to a perfusion evaporator 735 .

Design considerations for the heat transfer system 100 include startup of the main evaporator 115 from a supercritical state, management of parasitic heat leakage, heat transfer across the main core 140, cold biasing of the cold reservoir 155, and The pressure-volume of the outside temperature within the critical temperature of the working fluid. To accommodate these design considerations, the body or vessel of the evaporator 115 or 150 (eg, vessel 515) can be made of extruded 6063 aluminum and the main core 140 and/or 190 can be made of a fine-porous core. In one embodiment, the outer diameter of the evaporator 115 or 150 is about 0.625 inches and the length of the vessel is about 6 inches. The reservoir 155 can be cold biased to the end plate of the radiator 165 using an aluminum shunt 170 . Also, a heater such as a Cape Town heater may be installed at the side of the reservoir 155 .

In one embodiment, the vapor line 130 is made of smooth wall stainless steel tubing having an outside diameter (OD) of 3/16", and the liquid line 125 and second fluid line 160 are made of 1/8" OD smooth wall stainless steel tubing. The tubing 125, 130, 160 may be bent in a serpentine route and gold plated to reduce parasitic heat gain. Additionally, the lines 125, 130, 160 can be enclosed in a stainless steel box with heaters in order to simulate the specific environment during the test. The stainless steel box can be insulated by multilayer insulators (MLI) in order to reduce heat leakage through the panels of the heat sink 165 .

In one embodiment, the condenser 122 and the second fluid line 160 are made of tubing having an OD of 0.25 inches. The tubing is bonded to the panel of the heat sink 165 using, for example, epoxy. Each panel of the radiator 165 is an 8 x 19 inch direct condensing aluminum radiator using 1/16 inch thick face sheets. A Cape Town heater can be attached to the panel of the radiator 165, near the condenser 120 to prevent inadvertent freezing of the working fluid. During operation, temperature sensors such as thermocouples can be used to monitor the temperature of the overall system 100 .

Heat transfer system 100 may be implemented in any environment where the critical temperature of the working fluid of heat transfer system 105 is lower than the ambient temperature in which system 100 operates. The heat transfer system 100 can be used to cool components requiring cryogenic cooling.

Referring to FIGS. 8A-8D , the heat transfer system 100 can be implemented in a miniaturized cryogenic chemistry system 800 . In the miniaturized system 800 the tubing 125 , 130 , 160 is made of flexible material to allow for a space saving coil configuration 805 . The miniaturized system 800 is capable of operating at -238°C using neon fluid. The power input Qin 116 is about 0.3 to 2.5W. The miniaturized system 800 thermally couples a cryogenic component (or heat source requiring cryogenic cooling) 816 to a cryogenic cooling source, such as a cryogenic cooler 810 , which is incorporated to cool the condensers 120 , 122 .

The miniaturized system 800 reduces mass, increases flexibility, and provides hot-swappable capability when compared to conventional hot-swappable, vibration-isolated systems. A traditional thermally switchable, vibration-isolated system requires two flexible conductive links (FCLs), a cryogenic thermal switch (CTSW), and a conductive bar (CB), which form a loop to transfer heat from the cryogenic component to the cryogenic cooling source. In the miniaturized system 800, thermal performance is improved because the number of mechanical interfaces is reduced. Thermal conditions at the mechanical interface account for a large proportion of the heat gain in conventional thermally switchable, vibration-isolated systems. The CB and two FCLs are replaced with low-mass, flexible, thin-wall tubing for the coil configuration 805 of the miniaturized system 800 .

Also, the miniaturized system 800 can feature a wide range of heat transfer distances, which allows configurations in which cooling sources (eg, cryocooler 810 ) are placed remotely from cryogenic components 816 . The coil construction 805 has low mass and low surface area, thereby reducing parasitic heat gain through the lines 125 and 160 . The configuration of the cooling source 810 within the miniaturized system 800 facilitates integration and packaging of the system 800, and reduces vibrations on the cooling source 810, which becomes particularly important in infrared sensor applications. In one embodiment, the miniaturized system 800 was tested using neon, operating at 25-40K.

Referring to Figures 9A-9C, the heat transfer system 100 can be implemented in an adjustably mounted or gimbaled system 1005 in which a main evaporator 115 and a portion of piping 125, 160, and 130 are installed for ± 45° around an elevation axis 1020, and a portion of tubing 125, 160 and 130 is mounted to rotate around an azimuth axis 1025 within ±220°. Conduits 125, 160 and 130 are formed from thin-walled tubing and coiled around each axis of rotation. The system 1005 incorporates a cryogenic component (or a heat source requiring cryogenic cooling) 1016, such as a sensor of a cryogenic telescope, to a cryogenic cooling source, such as a cryocooler 1010, which is combined to cool a condenser 120 , 122. The cooling source 1010 is located on the stationary spacecraft 1060 to reduce mass at the cryogenic telescope. The motor torque used to control the rotation of the tubes 125 , 160 , 130 , the power demand of the system 1005 controls the demand of the spacecraft 1060 and improves the pointing accuracy of the sensor 1016 . The cryocooler 1010 and radiator or heat sink 165 can be moved away from the sensor 1016 , reducing vibrations within the sensor 1016 . In one embodiment, the system 1005 was tested to operate in the range of 70-115K when the working fluid was nitrogen.

Heat transfer system 105 may be used in medical applications, or applications where the device must be cooled below ambient temperature. As another example, heat transfer system 105 may be used with infrared (IR) sensors that operate at cryogenic temperatures to reduce ambient noise. The heat transfer system 105 may be used to cool vending machines, which often contain items that are preferably frozen below ambient temperature. The heat transfer system 105 may be used to cool components such as the display or hard drive of a computer, such as a laptop, handheld or desktop computer. The heat transfer system 105 can be used to cool one or more components in a transportation device such as an automobile or aircraft.

Other embodiments are within the scope of the following claims. For example, the condenser 120 and the radiator 165 can be designed as an integral system, such as a radiator. Similarly, the second condenser 122 and the radiator 165 can consist of radiators. The radiator 165 can be a passive radiator such as a radiator or a subcooler that actively cools the condensers 120 , 122 .

In another embodiment, a heater is used to control the temperature of the reservoir 155 . In a further embodiment, the reservoir 155 is heated using parasitic heat.

In another embodiment, a concentric ring of insulator is formed and placed between the liquid line 125 and the second fluid line 160, which surrounds the ring of insulator.

evaporator design

The evaporator is an integral component in a two-phase heat transfer system. For example, as shown above in FIGS. 5A and 5B , the evaporator 500 includes an evaporator body or vessel 515 in contact with a main wick 540 that surrounds the wick 510 . The core 510 defines a flow channel for the working fluid. The main core 540 is surrounded at its periphery by a plurality of peripheral flow channels or vapor grooves 545 . Channel 545 collects vapor at the interface between wick 540 and evaporator body 515 . The channel 545 is in contact with a steam outlet 550 that feeds into a steam line that feeds into the condenser for venting the steam formed in the evaporator 115 .

Evaporator 500 and the other evaporators described above often have a cylindrical geometry, that is, the core of the evaporator forms a cylindrical channel through which the working fluid passes. The cylindrical geometry of the evaporator is useful for cooling applications where the heat harvesting surface is cylindrical hollow. Many cooling applications require heat transfer away from a heat source with planar surfaces. In these types of applications, the evaporator can be modified to include a planar conductive pallet in order to match the footprint of a heat source with a planar surface. Such a design is shown, for example, in US Patent No. 6,382,309.

The cylindrical geometry of the evaporator is conveniently compatible with the thermodynamic constraints of LHP operation (ie, minimization of heat leakage into the reservoir). This constraint on LHP operation stems from the amount of subcooled LHP demand in order to produce normal balanced operation. Additionally, the cylindrical shape of the evaporator is relatively easy to fabricate, handle, machine, and process.

However, as described hereinafter, the evaporator can be designed to have a planar form to more naturally mount to a planar heat source.

graphic design

10, an evaporator 1000 for a heat transfer system includes a vapor barrier wall 1005, a liquid barrier wall 1010, a main core 1015 between the vapor barrier wall and the inner side of the liquid barrier wall 1010, a vapor removal channel 1020, and a liquid flow channel 1025.

The vapor barrier wall 1005 is in intimate contact with the main core 1015 . The liquid blocking wall 1010 contains the working fluid on the inner side of the liquid blocking wall 1010 so that the working fluid flows only along the inner side of the liquid blocking wall 1010 . Liquid barrier walls 1010 close the evaporator housing and help organize and distribute the working fluid through liquid flow channels 1025 . The vapor removal channel 1020 is located at the interface between the vaporization surface 1017 of the main wick 1015 and the vapor barrier wall 1005 . The liquid flow channel 1025 is located between the liquid blocking wall 1010 and the main core 1015 .

The vapor blocking wall 1005 serves as a heat obtaining surface of the heat source. The vapor barrier wall 1005 is made of a thermally conductive material such as sheet metal. The material selected for vapor barrier wall 1005 is typically capable of withstanding the internal pressure of the working fluid.

The vapor removal channel 1020 is designed to balance the hydraulic resistance of the channel 1020 via heat conduction through the vapor barrier wall 1005 into the main core 1015 . Channel 1020 can be electroetched, machined, or formed into a surface by any convenient method.

The vapor removal channels 1020 are shown as grooves inside the vapor barrier wall 1005 . Depending on the chosen design approach, however, the vapor removal channels can be designed and arranged in several different ways. For example, according to other embodiments, the vapor removal channels 1020 are grooved in the outer surface of the main core 1015 or embedded in the main core 1015 such that they are below the surface of the main core. The design of the vapor removal channel 1020 is chosen to increase ease and convenience of manufacture, and to closely approximate one or more of the following criteria.

First, the hydraulic diameter of the vapor removal passages 1020 should be sufficient to handle the vapor flow generated on the evaporative surface 1017 of the main core 1015 without significant pressure drop. Second, the contact surface between the vapor barrier wall 1005 and the main wick 1015 should be maximized in order to provide efficient heat transfer from the heat source to the evaporation surface of the main wick 1015 . Third, the thickness 1030 of the vapor barrier wall 1005 in contact with the main core 1015 should be minimized. Due to the increased thickness 1030, evaporation at the surface of the main core 1015 is reduced and vapor transmission through the vapor removal channels 1020 is reduced.

The evaporator 1000 can be assembled from separate components. Alternatively, the evaporator 1000 can be made as a single piece by sintering the main core 1015 in situ between two walls with a specific mandrel to form channels on both sides of the core.

The main wick 1015 provides an evaporative surface 1017 and pumps or supplies working fluid from the liquid flow channel 1025 to the evaporative surface of the main wick 1015 .

The size and design of the main core 1015 includes several considerations. The thermal conductivity of the main core 1015 should be low enough to reduce heat leakage from the evaporation surface 1017 through the main core 1015 and to the liquid flow channels 1025 . Heat leakage can also be affected by the linear dimensions of the main core 1015 . For this reason, the linear dimensions of the main core 1015 should be properly optimized in order to reduce heat leakage. For example, an increase in the thickness 1019 of the main core 1015 can reduce heat leakage. The increased thickness 1019 can however increase the hydraulic resistance of the main core 1015 to the flow of working fluid. In a working LHP design, the hydraulic resistance of the working fluid due to the main core 1015 can be significant, and a proper balance of these factors is important.

The force driving or pumping the working fluid of the heat transfer system is the temperature or pressure differential between the vapor and liquid sides of the main core. This pressure differential is supported by the main core and it is maintained by proper management of the thermal balance into the working fluid.

Liquid returning from the condenser to the evaporator passes through the liquid return line and is slightly subcooled. The degree of subcooling biases the heat leakage through the main core and from the surroundings into the reservoir in the liquid return line. The subcooling of the liquid maintains the thermal balance of the reservoir. There are however other useful methods to maintain the thermal balance of the reservoir.

One way is to organize the heat exchange between the reservoir and the environment. For evaporators with a planar design, such as those often used in land applications, the heat transfer system includes heat exchange fins on the reservoir and/or on the liquid barrier wall 1010 of the evaporator 1000 . The forces of natural convection over these fins provide subcooling and reduce stress on the condenser and reservoir of the heat transfer system.

The temperature of the reservoir or the temperature difference between the reservoir and the evaporative surface 1017 of the main wick 1015 supports circulation of the working fluid through the heat transfer system. Some heat transfer systems will require an additional amount of subcooling. Even if this condenser were completely blocked, the amount required would be greater than what the condenser could produce.

In designing evaporator 1000, three variables need to be managed. First, the organization and design of the fluid flow channel 1025 needs to be determined. Second, vapor venting from the liquid flow channels 1025 needs to be considered. Third, the evaporator 1000 should be designed to ensure that the liquid fills the liquid flow channel 1025 . These three variables are interrelated and thus should be considered and optimized together in order to form an efficient heat transfer system.

As mentioned, it is important to obtain the proper balance between heat leakage into the liquid side of the evaporator and the pumping capacity of the main wick. This balancing process cannot be done independently of the optimization of the condenser providing subcooling, because the greater the heat leakage allowed in the design of the evaporator, the more subcooling needs to be produced in the condenser. The longer the condenser, the greater the hydraulic loss in the fluid lines, which would require a different core material with better pumpability.

In operation, as power from a heat source is applied to the evaporator 1000 , liquid from the liquid flow channels 1025 enters the main wick 1015 and evaporates, forming a free-flowing vapor along the vapor removal channels 1020 . Liquid flow into the evaporator 1000 is provided through liquid flow channels 1025 . The liquid flow channels 1025 supply the main wick 1015 with sufficient liquid to replace evaporated liquid on the vapor side of the main wick 1015 and to replace evaporated liquid on the liquid side of the main wick 1015 .

The evaporator 1000 may include a secondary wick 1040 that provides phase management on the liquid side of the evaporator 1000 and supports the supply of the primary wick 1015 in the critical mode of operation (as described above). The second core 1040 is formed between the liquid flow channel 1025 and the main core 1015 . The second core can be a mesh screen (as shown in Figure 10), or an advanced and complex main line, or a plate core structure. In addition, the evaporator 1000 may include a vapor discharge channel 1045 at the interface between the main wick 1015 and the second wick 1040 .

Heat conduction through the main wick 1015 can initiate evaporation of the working fluid in the wrong place—near the liquid flow channel 1025 or inside on the liquid side of the evaporator 1000 . Vapor exhaust channel 1045 conveys unwanted vapor away from the wick into the two-phase reservoir.

The fine pore structure of the main core 1015 can create significant flow resistance for liquids. Therefore, it is important to optimize the number, geometry and design of the liquid flow channels 1025 . The goal of this optimization is to support a uniform or near uniform supply flow. The feed stream goes to the evaporation surface 1017. Also, due to the reduced thickness 1019 of the main core 1015, the liquid flow channels 1025 can be spaced farther apart.

The evaporator 1000 may require significant vapor pressure in order to operate with a particular working fluid within the evaporator 1000 . The use of working fluids with high vapor pressures can cause several problems in terms of the pressure volume of the vapor enclosure. Traditional solutions to the pressure-volume problem, such as thickening the walls of the evaporator, do not always work. For example in planar evaporators with significant planar areas, the walls become so thick that the temperature difference increases and the evaporator thermal conductivity decreases. In addition, the microscopic deflection of the wall due to the pressure volume results in a loss of contact between the wall and the main core. This contact loss affects heat transfer through the evaporator. And the microscopic offset of the walls creates difficulties at the interface between the evaporator and the heat source and any external cooling equipment.

ring design

Referring to Figures 10-13, the annular evaporator 1100 is formed by effectively rolling the planar evaporator 1000 such that the main core 1015 loops back into itself and forms a ring shape. The evaporator 1100 can be used in applications where the heat source has a cylindrical outer profile, or where the heat source can be shaped as a cylinder. The annular shape combines the strength of a cylinder for a pressure volume with a curved interface for the best possible contact with a cylindrical heat source.

Evaporator 1100 includes vapor barrier wall 1105 , liquid barrier wall 1110 , main core 1115 disposed between vapor barrier wall 1105 and the inside of liquid barrier wall 1110 , vapor removal channel 1120 and liquid flow channel 1125 . The liquid barrier wall 1110 is coaxial with the main core 1115 and the vapor barrier wall 1105 .

The vapor barrier wall 1105 is in close contact with the main core 1115 . The liquid blocking wall 1110 contains the working fluid on the inner side of the liquid blocking wall 1110 such that the working fluid flows only along the inner side of the liquid blocking wall 1110 . The liquid barrier wall 1110 closes the shell of the evaporator and helps organize and distribute the working fluid through the liquid flow channels 1125 .

The vapor removal channel 1120 is located at the interface between the vaporization surface 1117 of the main wick 1115 and the vapor barrier wall 1105 . The liquid flow channel 1125 is located between the liquid blocking wall 1110 and the main core 1115 . The vapor blocking wall 1105 serves as a heat obtaining surface and the vapor generated on this surface is removed through the vapor removing channel 1120 .

The main wick 1115 fills the volume between the vapor barrier wall 1105 and the liquid barrier wall 1110 of the evaporator 1100 to provide reliable opposite meniscus evaporation.

The evaporator 1100 can also be equipped with heat exchange fins 1150 that contact the liquid barrier wall 1110 to cold bias the liquid barrier wall 1110 . Liquid flow channel 1125 receives liquid from liquid inlet 1155 and vapor removal channel 1120 extends to vapor outlet 1160 and provides vapor to vapor outlet 1160 .

The evaporator 1100 can be used in a heat transfer system including an annular reservoir 1165 proximate to the main core 1115 . The reservoir 1165 may be cold biased by heat exchange fins 1150 extending across the reservoir 1165 . The cold offset of the reservoir 1165 allows the use of the entire condenser area without the need for subcooling at the condenser. The supercooling provided by cold bias reservoir 1165 and evaporator 1100 compensates for parasitic heat leakage through main core 1115 into the liquid side of evaporator 1100 .

In another embodiment, the evaporator design can be switched and the evaporation feature can be placed on the outer perimeter and the liquid return feature can be placed on the inner perimeter.

The annular shape of the evaporator 1100 may provide one or more of the following and additional advantages. First, in the annular evaporator 1100, pressure volume issues can be reduced or eliminated. Second, the main core 1115 may not have to be sintered inside, allowing more space for more complex designs of the vapor and liquid sides of the main core 1115 .

Referring also to Figures 14A-H, an annular evaporator 1400 is shown having a liquid inlet 1455 and a vapor outlet 1460, the annular evaporator 1400 comprising a vapor barrier wall 1700 (Figures 14G, 14H and 17A-D, a liquid barrier wall 1500 (Figures 14G, 17A-D). 14H and 17A-17D), the main core 1600 placed between the inside of the vapor barrier wall 1700 and the liquid barrier wall 1500 (Figs. Flow channel 1505 (Fig. 14H). The annular evaporator 1400 also includes a ring 1800 (Fig. Ring 1900 (FIGS. 14G, 14H and 19A-D) at the base of evaporator 1400 of the support of main wick 1600. Vapor barrier wall 1700, liquid barrier wall 1500, ring 1800, ring 1900 and wick 1600 are preferably formed of stainless steel .

The upper portion of the evaporator 1400 (ie, above the wick 1600) includes an expansion volume 1470 (FIG. 14H). The liquid flow channel 1505 formed in the liquid blocking wall 1500 is fed by the liquid inlet 1455 . Core 1600 separates liquid flow channels 1505 from vapor removal channels 1465 leading to vapor outlet 1460 through vapor annulus 1475 ( FIG. 14H ) formed in ring 1900 . Vapor channels 1465 may be photoetched into the surface of vapor barrier wall 1700, as described in more detail below.

The evaporators disclosed herein can operate in any combination of materials, sizes and arrangements so long as they contain the features as described above. There are no limitations other than the guidelines mentioned here; the evaporator can be made in any shape size and material. The only design constraints are that the applicable materials are compatible with each other and the working fluid is chosen taking into account structural constraints, corrosion, non-condensable gas generation and lifetime issues.

Many land applications can combine LHP with annular evaporator 1100 . The orientation of the annular evaporator in the gravitational field is predetermined by the application properties and the shape of the thermal surface.

Cyclic heat exchange system

The cyclic heat exchange system can be configured with one or more heat transfer systems in order to control the temperature at the area of the heat exchange system. The cyclic heat exchange system may be any system that operates using a thermodynamic cycle, such as a cyclic heat exchange system, a Stirling heat exchange system (also known as a Stirling engine), or an air conditioning system.

Referring to Figure 20, a Stirling heat exchange system 2000 utilizes an environmentally friendly and efficient refrigeration cycle of a known type. The Stirling heat exchange system 2000 functions by directing a working fluid (such as helium) through four corresponding operations; namely, constant temperature heat addition operation, constant volume heat rejection operation, constant temperature heat rejection operation, and constant Volumetric hot addition operation.

The Stirling Heat Exchange System 2000 is designed as a Free Piston Stirling Cooler (FPSC), such as Global Cooling Model M100B (available from Global Cooling Manufacturing Company, 94 N. Columbus Rd., Athens, Ohio). The FPSC 2000 includes a linear motor section 2005 housing a linear motor (not shown) that receives an AC power input 2010 . The FPSC 2000 includes a thermal receiver 2015 , a cooler 2020 and a heat extractor 2025 . The FPSC 2000 includes a balance mass 2030 coupled to the body of the linear motor within the linear motor section 2005 to absorb vibrations during operation of the FPSC. The FPSC 2000 also includes a charging port 2035 . The FPSC 2000 includes internal components such as those shown in FPSC 2100 of FIG. 21 .

The FPSC 2100 includes a linear motor 2105 housed inside a linear motor portion 2110 . The linear motor portion 2110 houses a piston 2115 coupled at one end to a leaf spring 2120 and at the other end to a displacer 2125 . The displacer 2125 is joined to an expansion space 2130 and a compression space 2135 forming the cold and hot sides, respectively. The heat receiver 2015 is mounted to the cold side 2130 and the heat extractor is mounted to the hot side 2135 . The FPSC 2100 also includes a balance mass 2140 coupled to the linear motor portion 2110 to absorb vibrations during FPSC 2100 operation.

Referring also to FIG. 22, in one embodiment, a FPSC 2200 includes a heat extractor 2205 made of a copper sleeve and a heat receiver 2210 made of a copper sleeve. The heat extractor 2205 has an outer diameter (OD) of approximately 100 mm and a width of approximately 53 mm to provide a 166 cm ² heat rejecting surface capable of delivering a flux of 6 W/cm ² when operating in the temperature range of 20-70°C. The thermal receiver 2210 has an OD of about 100 mm and a width of about 37 mm to provide a 115 cm ² heat receiving surface capable of delivering a flux of 5.2 W/cm ² when in the temperature range of -30-5°C.

Briefly, in operation an FPSC is filled with a cryogen (eg, helium) that is reciprocated back and forth by combined piston and displacer motion. In an ideal system, thermal energy is rejected to the environment through the heat extractor, while the refrigerant is compressed by the piston, and thermal energy is extracted from the environment through the heat receiver while the refrigerant expands.

Referring to FIG. 23 , thermodynamic system 2300 includes a cyclic heat exchange system, such as cyclic heat exchange system 2305 (eg, systems 2000 , 2100 , 2200 ), and heat transfer system 2310 thermally coupled to a portion 2315 of cyclic heat exchange system 2305 . The cyclic heat exchange system 2305 is cylindrical and the heat transfer system 2310 is shaped around a portion 2315 of the cyclic heat exchange system 2305 to remove heat from the portion 2315 . In this embodiment, this portion 2315 is the hot side (ie heat rejector) of the cyclic heat exchange system 2305 . The thermodynamic system 2300 also includes a fan 2320 located on the hot side of the cyclic heat exchange system 2305 to force air over the condenser of the heat transfer system 2310 and thereby provide additional convective cooling.

The cold side 2335 (ie, heat receiver) of the cyclic heat exchange system 2305 is thermally coupled to the CO ₂ return 2340 of the thermosiphon 2345 . The thermosiphon 2345 includes a cold side heat exchanger 2350 configured to cool air within the thermodynamic system 2300 that is forced across the heat exchanger 2350 by a fan 2355 . A thermosiphon is a closed system of tubes connected to a cooling engine (in this case, heat exchanger 2350 ) that allows natural circulation and cooling of liquid within the reflux.

Referring to FIG. 24, in another embodiment, a thermodynamic system 2400 includes a cyclic heat exchange system such as a cyclic heat exchange system 2405 (e.g., systems 2000, 2100, 2200) and a thermally coupled Heat transfer system 2410. The thermodynamic system 2400 includes a heat transfer system 2420 thermally coupled to a cold side 2425 of the cyclic heat exchange system 2405 . The thermodynamic system 2400 also includes fans 2430,2435. A fan 2430 is located on the hot side 2415 to force air through the condenser of the heat transfer system 2410. A fan 2435 is located on the cold side 2425 to force air through the condenser of the heat transfer system 2420.

Referring to FIG. 25 , in one embodiment, a thermodynamic system 2500 includes a heat transfer system 2505 coupled to a cyclic heat exchange system, such as cyclic heat exchange system 2510 . The heat transfer system 2505 is used to cool the hot side 2515 of the cyclic heat exchange system 2510 . The heat transfer system 2505 includes an annular evaporator 2520 comprising an expansion volume (or reservoir) 2525 , a liquid return line 2530 providing fluid communication between a liquid outlet 2535 of the condenser 2540 and a liquid inlet of the evaporator 2520 . The heat transfer system 2505 also includes a steam line 2545 providing fluid communication between the steam outlet of the evaporator 2520 and the steam inlet 2550 of the condenser 2540 .

The condenser 2540 is constructed from smooth walled tubing and fitted with heat exchange fins 2555 or fin blocks to enhance heat exchange on the outside of the tubing.

The evaporator 2520 includes a main wick 2560 sandwiched between a vapor barrier wall 2565 and a liquid barrier wall 2570 and separating liquid and vapor. Liquid blocking wall 2570 is cold biased by heat exchange fins 2575 formed along the outer surface of wall 2565 . The heat exchange fins 2575 provide subcooling for the entire liquid side of the reservoir 2525 and evaporator 2520. The heat exchange fins 2575 of the evaporator 2520 can be designed separately from the heat exchange fins 2555 of the condenser 2540 .

The liquid return line 2530 extends into the reservoir 2525 located above the main core 2560, at the interface of the main core 2560 and the vapor barrier wall 2565, if any, vapor bubbles from the liquid return line 2530 and the vapor removal channels exit into the storage device 2525. Typical working fluids for heat transfer system 2505 include, but are not limited to, methanol, butane, _CO2 , propylene, and ammonia.

An evaporator 2520 is mounted to the hot side 2515 of the cyclic heat exchange system 2510 . In one embodiment, the installation is integral in that the evaporator 2520 is an integral part of the cyclic heat exchange system 2510 . In another embodiment, the mounting can be non-integral in that the evaporator 2520 can be clamped to the outer surface of the hot side 2510 . The heat transfer system 2505 is cooled by a forced convection radiator which can be provided by a simple fan 2580. Alternatively, the heat transfer system 2505 is cooled by natural or forced convection.

Initially, the liquid phase of the working fluid collects in the evaporator 2520 , liquid return line 2530 and the lower part of the condenser 2540 . The primary wick 2560 is wet due to capillary forces. Whenever heat is applied (e.g., cyclic heat exchange system 2510 is on), main core 2560 begins to generate steam, which travels through the steam removal channels of evaporator 2520 (similar to steam removal channels 1120 of evaporator 1100), and the steam passing through evaporator 2520 exits and enters steam line 2545.

The steam then enters the condenser 2540 at its upper portion. The condenser 2540 condenses the vapor into a liquid and the liquid is collected at the lower part of the condenser 2540 . The liquid is pushed into the reservoir 2525 because of the pressure differential between the reservoir 2525 and the lower portion of the condenser 2540 . Liquid from reservoir 2525 enters the liquid flow channel of evaporator 2520 . The liquid flow channels of the evaporator 2520 are configured similarly to the channels 1125 of the evaporator 1100 and are appropriately sized and positioned to provide adequate liquid replacement for evaporated liquid. The capillary pressure generated by the main wick 2560 is sufficient to withstand the entire LHP pressure drop and prevent vapor bubbles from traveling through the main wick 2560 towards the liquid flow channels.

If the cold offset described above is sufficient to compensate for the increased heat leakage across the main core 2560 caused by the increase in the surface area of the heat exchange surfaces of the annulus relative to the surface area of the liquid flow channels, the liquid flow of the evaporator 2520 The channel can be replaced by a simple ring.

Referring to FIGS. 26-28 , heat transfer system 2600 includes evaporator 2605 coupled to cyclic heat exchange system 2610 and expansion volume 2615 coupled to evaporator 2605 . The vapor channel of the evaporator 2605 feeds a vapor line 2620 which feeds a series of channels 2625 of the condenser 2630 . Condensed liquid from condenser 2630 is collected in liquid return channel 2635 . Heat transfer system 2600 also includes fin block 2640 thermally bonded to condenser 2630 .

Evaporator 2605 includes vapor barrier wall 2700 , liquid barrier wall 2705 , main core 2710 between vapor barrier wall 2700 and the inside of liquid barrier wall 2705 , vapor removal channel 2715 and liquid flow channel 2720 . The liquid barrier wall 2705 is coaxial with the main core 2710 and the vapor barrier wall 2700 . Liquid flow channel 2720 is fed by liquid return channel 2725 and vapor removal channel 2715 feeds into vapor outlet 2730 .

The vapor barrier wall 2700 is in close contact with the main core 2710 . The liquid blocking wall 2705 contains the working fluid on the inside of the liquid blocking wall 2705 so that the working fluid flows only along the inside of the liquid blocking wall 2705 . Liquid barrier walls 2705 close the evaporator housing and help organize and distribute working fluid through liquid flow channels 2720 .

In one embodiment, the evaporator 2605 is about 2" tall and the expansion volume 2615 is about 1" tall. Evaporator 2605 and expansion volume 2615 are wrapped around a portion of cyclic heat exchange system 2610 having a 4" outer diameter. Vapor line 2620 has a 1/8" radius. The cyclic heat exchange system 2610 includes approximately 58 condenser channels 2625, each condenser channel 2625 having a length of 2" and a radius of 0.012", the channels 2625 spread out such that the width of the condenser 2630 is approximately 40". The liquid return channel 2725 has 1/16" radius. Heat exchanger 2800 (which includes condenser 2630 and fin blocks 2640) is approximately 40" long and is wound as inner and outer rings (see Figures 30, 33 and 34) to create a circulating heat exchanger with an outer diameter of approximately 8" . The evaporator 2605 has a cross-sectional width 2750 of approximately 1/8", which is defined by the evaporator barrier wall 2700 and the liquid barrier wall 2705. The vapor removal channels 2715 have a width of approximately 0.020" and a depth of approximately 0.020", and are separated from each other by approximately 0.020" to yield 25 channels per inch.

As noted above, a heat transfer system (eg, system 2310) is thermally coupled to a portion (eg, portion 2315) of a cyclic heat exchange system. Thermal bonding between the heat transfer system and the part can be by any suitable method. In one embodiment, if the evaporator of the heat transfer system is thermally coupled to the hot side of the cyclic heat exchange system, the evaporator can surround and contact the hot side and pass heat applied between the hot side and the evaporator Grease complexes may enable thermal bonding. In another embodiment, if the evaporator of the heat transfer system is thermally coupled to the hot side of the cyclic heat exchange system, the evaporator can directly enter the hot side of the cyclic heat exchange system by forming a steam channel to be integrated with the cyclic heat exchange system. Overall construction of the hot side.

Referring to FIGS. 30-32 , a heat transfer system 3000 is packaged around a cyclic heat exchange system 3005 . The heat transfer system 3000 includes a condenser 3010 surrounding an evaporator 3015 . The vaporized working fluid exits the evaporator 3015 through a vapor outlet 3020 connected to the condenser 3010 . The condenser 3010 is looped at junction 3025 and folded in half into itself.

The cyclic heat exchange system 3005 is surrounded by an evaporator 3015 around its heat rejecting surface 3100 . The evaporator 3015 is in intimate contact with the heat-repelling surface 3100 . A refrigeration assembly (which is a combination of a cyclic heat exchange system 3005 and a heat transfer system 3000) is installed in the tube 3205, and a fan 3210 is installed at the end of the tube 3205 to force air through the fins 3030 of the condenser 3010 to the exhaust Channel 3035.

The evaporator 3015 has a wick 3215 where the working fluid absorbs heat from the heat rejecting surface 3100 and changes phase from liquid to vapor. The heat transfer system 3000 includes a reservoir 3220 at the top of the evaporator 3015 providing an expansion volume. For simplicity of illustration, the evaporator 3015 has been illustrated in this manner as a simple hatched block showing no internal details. These internal details are described elsewhere in this specification.

The vaporized working fluid exits the evaporator 3015 through the vapor outlet 3020 and enters the vapor line 3040 of the condenser 3010 . Working fluid flows down from vapor line 3040 , through passage 3045 of condenser 3010 to liquid return line 3050 . As the working fluid flows through the channels 3045 of the condenser 3010, it loses heat through the fins 3030 to the air passing between the fins, changing phase from vapor to liquid. Air passing through the fins 3030 of the condenser 3010 flows away through exhaust channels 3035 . Liquefied working fluid (and possibly some uncondensed vapor) flows from liquid return line 3050 back into evaporator 3015 through liquid return port 3055 .

Referring to FIGS. 33 and 34 , the heat transfer system 3300 surrounds a portion of a cyclic heat exchange system 3302 which in turn is surrounded by an exhaust passage 3305 . Heat transfer system 3300 includes an evaporator 3310 having an upper portion surrounding a cyclic heat exchange system 3302 . A steam port 3315 connects the evaporator 3310 to the steam line 3312 of the condenser 3320 . The vapor line 3312 includes an outer region that wraps around the evaporator 3310 and is then folded in half on itself at a joint 3325 to form an inner region that wraps back around the evaporator 3310 in the opposite direction. The heat transfer system 3300 also includes cooling fins 3330 on the condenser 3320 .

The heat transfer system 3300 also includes a liquid return port 3400 that provides a path for condensed working fluid from the liquid line 3405 of the condenser 3320 to return to the evaporator 3310 .

As noted above, the interface between the evaporator 3310 and the heat-repelling surfaces of the cyclic heat exchange system 3302 may be implemented according to one of several alternative embodiments.

Referring to FIG. 35 , in one embodiment, an evaporator 3500 slides over a heat-repelling surface 3502 of a cyclic heat exchange system 3505 . Evaporator 3500 includes vapor barrier wall 3510 , liquid barrier wall 3515 , and wick 3520 sandwiched between walls 3510 and 3515 . The core 3520 is equipped with a vapor channel 3525 and a liquid flow channel 3530 is formed at the liquid blocking wall 3515 in exemplary form for simplicity.

The evaporator 3500 slides over the cyclic heat exchange system 3050 and can be held in place by using a clamp 3600 (shown in FIG. 36 ). To aid in heat transfer, thermally conductive grease 3535 is placed between the circulating heat exchange system 3050 and the vapor barrier wall 3510 of the evaporator 3500 . In an alternative embodiment, vapor passages 3525 are formed in vapor barrier wall 3510 rather than core 3520 .

Referring to Figure 37, in another embodiment, an evaporator 3700 fits over a heat-repelling surface 3702 of a cyclic heat exchange system 3705 by an interference fit. The evaporator 3700 includes a vapor barrier wall 3710 , a liquid barrier wall 3715 and a wick 3720 sandwiched between walls 3710 and 3715 . The evaporator 3700 is dimensioned to have an interference fit with the heat rejecting surface 3702 of the cyclic heat exchange system 3705 .

The evaporator 3700 is heated such that its inner diameter expands to allow it to slide over the unheated heat-repelling surface 3702 . As the evaporator 3700 cools, it contracts to secure in an interference fit relationship to the recirculating heat exchange system 3705 . Because of the tight fit, no heat transfer grease is required to improve heat transfer. Core 3720 is equipped with steam channels 3725 . In an alternative embodiment, the vapor passage is formed in the vapor barrier wall 3710 instead of the wick 3720 . A liquid flow channel 3730 is formed at the liquid blocking wall 3715 in exemplary form for simplicity.

Referring to FIG. 38 , in another embodiment, an evaporator 3800 is mounted on a heat-repelling surface 3802 of a recirculating heat exchange system 3805 , and features previously designed in the evaporator 3800 are now integrally formed within the heat-repelling surface 3802 . In particular, the evaporator 3800 is constructed together with the heat rejecting surface 3802 as a unitary assembly. The heat rejecting surface 3802 is modified to have vapor channels 3825; in this way, the heat rejecting surface 3802 acts as a vapor barrier wall for the evaporator 3800.

The evaporator 3800 includes a wick 3820 and a liquid barrier wall 3815 formed around a modified heat-repelling surface 3802 integrally bonded to the heat-repelling surface 3802 to form a sealed evaporator 3800 . Liquid flow channels 3830 are depicted in exemplary form for simplicity. In this way, a hybrid cycle heat exchange system with an integral evaporator is formed. This unitary configuration provides enhanced thermal performance compared to clamp and interference fit configurations because of the reduced thermal resistance between the cyclic heat exchange system and the core of the evaporator.

Referring to FIG. 29, graphs 2900 and 2905 show the maximum temperature at the surface of the portion of the hydronic heat exchange system cooled by the heat transfer system and the temperature between the heat transfer system and the portion of the hydronic heat exchange system being cooled. The relationship between the surface area of the interface. The maximum temperature indicates the maximum amount of heat rejection. In diagram 2900, the interface between the part and the heat transfer system is completed by a thermal grease compound. In diagram 2905, the heat transfer system is integrated with the part.

As shown, with an air flow of 300 CFM, if the interface is a thermal grease interface, the maximum amount of heat rejection will fall at the maximum heat rejection surface temperature ²⁹⁰⁷ (eg, 70 ℃). When the evaporator is integrally constructed with the part by forming vapor passages directly in the heat rejecting surface, the heat rejecting surface will operate below the maximum heat rejecting surface temperature of the thermal grease interface with significantly less heat exchange surface area.

Referring to FIG. 39 , the condenser 3900 is formed by fins 3905 that provide thermal communication between the air or ambient and the vapor line 3910 of the condenser 3900 . The steam line 3910 is joined to a steam outlet 3915 which is connected to an evaporator 3920 located within the condenser 3900 .

Referring to FIGS. 40-43 , in one embodiment, the condensers 3900 are stacked and formed by flow channels extending through the plates 4000 of the condenser 3900 between the vapor header 3925 and the liquid header 3930 . Copper is a suitable material for making laminated condensers. The laminated configuration condenser 3900 includes a bottom 4200 with fluid flow channels 4205 (shown shaded) formed therein, and a top layer 4210 bonded to the bottom 4200 to cover and seal the fluid flow channels 4205 . The fluid flow channels 4205 are designed as trenches formed in the bottom 4200 and sealed below the top layer 4210 . Grooves for fluid flow channels 4205 may be formed by chemical etching, electrochemical etching, mechanical machining, or electrical discharge machining processes.

Referring to FIGS. 44 and 45 , in another embodiment, the condenser 3900 is extruded and a small flow channel 4400 extends through a flat plate 4405 of the condenser 3900 . Aluminum is a suitable material for such extruded condensers. An extruded microchannel plate 4405 extends between a vapor head 4410 and a liquid head 4415. Also, corrugated fin blocks 4420 are bonded (eg, soldered or epoxy bonded) to both sides of the flat plate 4405 .

Referring to FIG. 46 , a cross-section of one side of a heat transfer system 4600 coupled to a cyclic heat exchange system 4605 . This view shows the relative dimensions that provide a particularly compact package of the heat transfer system. In this view, the fins 4610 are depicted 90 degrees out of phase for ease of illustration. To cool the heat rejecting surface 4615 of the cyclic heat exchange system 4605 having a diameter of 4 inches, the evaporator 4620 has a thickness of 0.25 inches and the radial thickness of the condenser is 1.75 inches. This provides for the overall size of the package (combination of the heat transfer system 4600 and the 8 inch cyclic heat exchange system 4605).

As mentioned, the evaporator used in the heat transfer system is equipped with a wick. Because the wick is employed inside the evaporator of the heat transfer system, the condenser can be placed at any position relative to the evaporator and relative to gravity. For example, the condenser can be placed above the evaporator (pull relative to gravity), below the evaporator (pull relative to gravity), or close to the evaporator so as to experience the same gravitational pull as the evaporator.

Other implementations are within the scope of the following claims.

In particular, the terms Stirling engine, Stirling heat exchange system and free piston Stirling cooler have been referenced in several of the above embodiments. However, the features and principles described with respect to those embodiments may also be applied to other engines capable of converting between mechanical and thermal energy.

Furthermore, the features and principles described above can be applied to any heat engine, which is a thermodynamic system capable of undergoing cycles, ie a sequence of transformations eventually returning to its initial state. If each transformation is reversible in a cycle, the cycle is reversible and heat transfer occurs in the opposite direction and the workload switching flag is completed. The simplest reversible cycle is the Carnot cycle, which exchanges heat through two heat reservoirs.

manufacture

Referring to FIG. 47 , a thermodynamic system 4700 includes a heat source such as a cyclic heat exchange system 4705 and a heat transfer system 4710 thermally coupled to a portion 4715 of the cyclic heat exchange system 4705 . The heat transfer system 4710 is designed with an annular evaporator 4713 such as the annular evaporator 1100 of FIG. 11 . The evaporator 4713 is shaped around a portion 4715 of the cyclic heat exchange system 4705 to reject heat from the portion 4715 . Thermodynamic system 4700 also includes fan 4720 positioned to force air along path 5100 ( FIG. 51 ) over condenser 4712 of heat transfer system 4710 and thereby provide additional convective cooling.

Referring also to FIGS. 48-51 , the heat transfer system 4710 includes a liquid line 4800 that pumps liquid from the condenser 4712 into the evaporator 4713 and a vapor line 4805 that supplies steam into the condenser 4712 . A description of the operation of the heat transfer system is provided above and will not be repeated here. Heat transfer system 4710 may also include reservoir 4810 coupled to steam line 4805 via port 4812 for additional pressure volume, if desired. In particular, reservoir 4810 increases the volume of heat transfer system 4710, also as described above.

As shown, the cyclic heat exchange system 4705 is cylindrical. The cyclic heat exchange system 4705 includes a cold side 4735 (ie, heat receiver) and a hot side (ie, heat rejector or portion 4715 surrounded by evaporator 4713 ).

Referring also to FIG. 52 , the cold side 4735 of the cyclic heat exchange system 4705 may be thermally bonded to the reflux 4740 of the thermosiphon 4745 . The thermosiphon 4745 includes a cold-side heat exchanger 4750 configured to cool air within the thermodynamic system 4700 that is drawn by a thermosiphon fan (not shown in FIGS. 50 and 52 , but mounted adjacent to the heat exchanger 4750). Forced across heat exchanger 4750. The thermosiphon fan blows air into the thermosiphon along path 5000 and out of the thermosiphon along path 5005 (FIG. 50). The thermosiphon includes a vapor line 5200 from reflux 4740 to heat exchanger 4750 and a liquid line 5205 from heat exchanger 4750 to reflux 4740 . Steam heated at cold side 4735 flows from line 5200 through a heat exchanger where it condenses and is cooled by a thermosiphon fan, and the condensed liquid returns to reflux 4740 through line 5205 .

Referring to Figure 48 and also to Figures 53A-E, the evaporator 4713 includes a wick subassembly 5300 surrounded by an outer subassembly. The outer subassembly includes an outer ring or liquid barrier wall 5305 and a subcooler 5310. The subcooler 5310 is an array of fins that help dissipate heat from the liquid blocking wall 5305 . The wick subassembly 5300 includes an inner ring or vapor barrier wall 5315, such as the vapor barrier wall 1700 of Figures 14A-H, 15A, 15B, and 17A-D. Core subassembly 5300 also includes core 5320, such as core 1600 of Figures 14G, 14H and 16A-D. Vapor barrier wall 5315 includes vapor removal channels 5325, such as channel 1465 of Figures 14A-H, 15A, 15B, and 17A-D. Vapor barrier wall 5315 is surrounded by core 5320 .

As described above with respect to evaporator 1400, in one embodiment, wick 5320 and vapor barrier wall 5315 are made of stainless steel. Prior to fabrication, core 5320 had a pore size of about 9.8 microns, an outer diameter of about 4.141 inches, an inner diameter of about 3.985 inches, and a length of about 1.75 inches. The vapor barrier wall 5315 has, for example, 186 vapor removal channels 5325, each channel 5325 formed as a semicircle with a radius of approximately 0.025 inches (FIG. 53B). Vapor barrier wall 5315 has a thickness of approximately 0.035 inches.

The liquid blocking wall 5305 includes one or more liquid flow channels 5330, such as the liquid flow channels 1505 of the wall 1500 of Figures 14A-H. Liquid flow channels 5330 are formed along the inner surface of the wall 5305 . The liquid blocking wall 5305 can also include cooling grooves 5335 formed along the outer surface of the wall 5305 to provide additional convective cooling for the liquid. The liquid blocking wall 5305 also includes a liquid port 5340 for receiving liquid from the liquid line 4800 .

The liquid blocking wall 5305 can be made of stainless steel and can have seven liquid flow channels 5330, each channel 5330 having a radius of approximately 0.030 inches. The liquid barrier wall 5305 can have an outer diameter of about 4.24 inches, an inner diameter of about 4.13 inches, and a length of about 1.69 inches prior to fabrication.

Subcooler 5310 includes an array of fins 5345 surrounding inner body 5350 . Fin 5345 and inner body 5350 include opening 5355 for steam line 4805 and opening 5360 for reservoir port 4812 . Subcooler 5310 can be made of copper or any other suitable heat transfer metal. The subcooler 5310 can be designed with, for example, 119 fins. The inner body 5350 can have, for example, an outer diameter of 4.25 inches and a length of 1.57 inches.

The evaporator 4713 also includes a reservoir plate 5365 (FIG. 53E) sealed to the edge of the liquid barrier wall 5305, shown in more detail below. The reservoir plate 5365 is in fluid communication with the reservoir 4810 and the vapor line 4805.

Referring to FIG. 54 , a process 5400 is performed for fabricating the thermodynamic system 4700 of FIG. 47 . Initially, the wick subassembly 5300 (ie, the vapor barrier wall 5315 and the wick 5320) is prepared (step 5405). Next, the liquid blocking wall 5305 is prepared (step 5410). The outer subassembly (ie, liquid barrier wall 5305 and subcooler 5310) is then prepared (step 5415), and the prepared outer subassembly is joined to the core subassembly to form the evaporator body (step 5420). Next, the evaporator body is completed to form the evaporator 4713 (step 5425), and the evaporator 4713 is coupled to a heat source (eg, a cyclic heat exchange system) (step 5430).

Referring to FIG. 55 , a procedure 5405 is performed for preparing the core subassembly 5300 . Initially, core subassembly 5300 is assembled (step 5500). Assembly of the wick subassembly 5300 includes forming the vapor removal channel 5325 material that will form the vapor barrier wall 5315 (Figures 15A and 15B show the materials used to form the vapor barrier wall 5315). For example, vapor removal channels 5325 can be photoetched into the material. The photoetched material is rolled into cylindrical form and welded at its edges to form the vapor barrier wall 5315. Core 5320 is formed from a core material that is cut to length, rolled, and formed around vapor barrier wall 5315 . The wick 5320 is mechanically pressed against the vapor barrier wall 5315 to improve the fit between the wick 5320 and the vapor barrier wall 5315 and to reduce the space between the wick 5320 and the wall 5315, thereby improving the relationship between the wick 5320 and the vapor barrier wall 5315. heat transfer between. Next, the core is welded at its seams to form a complete cylindrical form.

In another embodiment, the core 5320 may also be sintered on the vapor barrier wall 5315 by heating the core 5320 and wall 5315 at a temperature below the melting point of the material used for the core 5320 and wall 5315 . During this heating, pressure may be applied to core 5320 and wall 5315 to help form a sinter bond. Sintering can be used to further enhance heat transfer between the wick 5320 and the vapor barrier wall 5315.

After the core subassembly 5300 is assembled (step 5500), the core subassembly is heat shrunk to ensure that it is as round as desired for proper integration with the outer subassembly at step 5420. Initially during the heat shrink process, the core subassembly 5300 is heated (step 5505). In one embodiment, the subassembly 5300 is placed in a furnace 5600 (shown in Figures 56A and B) that heats the subassembly to 460°C ± 15°C. Next, as also shown in FIG. 56A, the temperature control block 5605 is cooled to a temperature at which its outer diameter is smaller than the inner diameter of the heated subassembly 5300 (step 5510). The temperature control block 5605 can be cooled using liquid nitrogen. Referring also to Figures 56C and D, the cooled temperature control block 5605 is inserted into the heated core subassembly 5300 (step 5515). Next, as shown in Figure 56E, when the control block 5605 is inserted (step 5515), heat is removed from the wick subassembly 5300 and cooling is removed from the temperature control block 5605, allowing the temperature of the wick subassembly 5300 to stabilize (step 5520). After the temperature of the core subassembly 5300 stabilizes (step 5520), the core subassembly 5300 is inspected to ensure that the outer diameter of the core subassembly 5300 is as round as desired (step 5525).

Referring to FIG. 57 , a procedure 5410 is performed for preparing the liquid barrier wall 5305 . Initially, the liquid barrier wall 5305 is formed by rolling the material and then welding the material at the seams to form an approximately cylindrical shape (FIG. 53C) (step 5700). The soldered material is then photoetched on its inner surface to form liquid flow channels 5330 and on its outer surface to form cooling grooves 5335 (FIG. 53C).

The formed liquid barrier wall 5305 is heat shrunk to ensure it is as round as desired to properly prepare the outer subassembly at step 5415. Initially during the heat shrink process, the liquid barrier wall 5305 is heated (step 5705). In one embodiment, the liquid barrier wall 5305 is placed in an oven 5800 (shown in Figures 58A and B) that heats the wall 5305 to 460°C ± 15°C. Next, as also shown in FIG. 58A, the temperature control block 5805 is cooled to a temperature at which its outer diameter is smaller than the inner diameter of the vapor barrier wall 5305 (step 5710). The temperature control block 5805 can be cooled using liquid nitrogen. Referring also to Figures 58C and D, the cooled temperature control block 5605 is inserted into the heated liquid barrier wall 5305 (step 5715). Next, as shown in Figure 58E, when the control block 5805 is inserted, heat is removed from the liquid blocking wall 5305 and cooling is removed from the temperature control block 5805, allowing the temperature of the liquid blocking wall 5305 to stabilize (step 5720). After the temperature of the liquid blocking wall 5305 stabilizes, the liquid blocking wall 5305 is inspected to ensure that the outer diameter of the wall 5305 is as round as desired (step 5725).

Referring to FIG. 59 , a procedure 5415 is performed for preparing the outer subassembly, ie, the liquid barrier wall 5305 and the subcooler 5310 . Initially, subcooler 5310 is heated (step 5900). In one embodiment, the subcooler 5310 is placed in a furnace 6000 (shown in Figures 60A and B) that heats the subcooler 5310 to 235°C ± 15°C. Next, as also shown in FIGS. 60A and B, the temperature control block 5805 and the liquid barrier wall 5305 thermally bonded to the block 5805 are cooled to a temperature at which the outer diameter of the wall 5305 is smaller than the inner diameter of the subcooler 5310 (step 5905). For example, the liquid barrier wall 5305 can be cooled to below about -120°C. The temperature control block 5805 can be cooled using liquid nitrogen. Referring also to Figure 60C, the cooled temperature control block 5805 and liquid barrier wall 5305 are inserted into the heated subcooler 5310 to form the outer subassembly 6001 (step 5910). Next, as shown in Figure 60D, when the control block 5805 is inserted (step 5910), heat is removed from the subcooler 5310 and cooling is removed from the temperature control block 5805, allowing the temperature of the outer subassembly 6001 to stabilize (step 5915). After the temperature of the outer subassembly 6001 stabilizes (step 5915), the temperature control block 5805 is removed from the liquid blocking wall 5305 (step 5920), as shown in Figure 60E.

Next, referring also to Figures 60F and G, the various components are assembled to the outer subassembly 6001 (step 5925). First, the reservoir plate 6005 is mounted to the liquid barrier wall 5305 and adjacent to the subcooler 5310 as shown in FIG. 60F . Plate 6005 can be installed by welding plate 6005 to wall 5305 to form weld 6010 . Second, as shown in Figure 60G, the liquid line 4800 is sealed to the liquid barrier wall 5305, such as by welding. After assembly is complete, the outer subassembly and all welded joints are inspected to ensure that the welds are sealed and that the inner diameter of the wall 5305 is as round as necessary to interface with the core subassembly in later processing (step 5930).

Referring to FIG. 61 , a procedure 5420 is performed for combining the outer subassembly 6001 with the wick subassembly to form the evaporator body. Typically, during this process, the outer subassembly 6001 is heat shrunk over the core subassembly 5300 to ensure proper bonding of the pieces. Initially, the outer subassembly 6001 is heated (step 6100). In one embodiment, the outer subassembly 6001 is placed in a furnace 6200 (shown in Figure 62A) that heats the outer subassembly 6001 to 350°C ± 10°C. Next, as also shown in FIG. 62B, the temperature control block 5605 is cooled to a temperature at which the outer diameter of the core subassembly 5300 is smaller than the inner diameter of the heated outer subassembly 6001 (step 6105). The temperature control block 5605 can be cooled using liquid nitrogen. Referring also to Figures 62C and D, the cooled temperature control block 5605 and wick subassembly 5300 are inserted into the heated outer subassembly 6001 to form the evaporator body 6101 (step 6110). Next, as shown in Figure 62D, when the control block 5605 and wick subassembly 5300 are inserted, heat is removed from the outer subassembly 6001 and cooling is removed from the temperature control block 5605, allowing the temperature of the evaporator body 6101 to stabilize (step 6115). Referring to Figure 62E, after the temperature of the vaporizer body 6101 has stabilized, the vaporizer body 6101 can be inspected to ensure that the heat shrink process was successful.

Referring to FIG. 63 , process 5425 is performed to complete the evaporator body 6101 , thereby forming the evaporator 4713 . Referring to Figures 49 and 64, the various components are now assembled to the evaporator body 6101 (step 6300). For example, the volume plate 6400 is nailed to the liquid barrier wall 5305 and the core 5320 and tubes are welded to the reservoir plate 6005 and the volume plate 6400. Reservoir 4810 is welded to reservoir plate 6005 and vapor barrier plate 6405 is welded to reservoir plate 6005 and core subassembly 5300 . Caps 6410 and 6415 are placed over volume plate 6400 and vapor barrier plate 6405, respectively. Next, the vaporizer body 6101 is inspected and tested (step 6305) and then additional components are installed on the vaporizer body 6101 (step 6310). For example, steam line 4805 is welded to cap 6410, and cap 6410 is machined as desired due to possible bending during the welding process. Cap 6410 is welded to volume plate 6400 and vapor barrier wall 5315 , and cap 6415 is welded to reservoir plate 6005 and vapor barrier wall 5315 . Next, the evaporator body 6101 is checked for leaks (step 635).

Referring to FIG. 65 , procedure 5430 is performed for coupling evaporator 4713 to heat source or cyclic heat exchange system 4705 . Initially, the outer diameter of the heat source is machined as desired (step 6500) to ensure that the evaporator 4713 will fit on the heat source. Next, referring also to Figures 66A and B, the evaporator 4713 is prepared by welding the vapor and liquid lines to the evaporator body and then aligning the evaporator 4713 with the system 4705 using a suitable alignment system (step 6505).

The vaporizer 4713 is then heat shrunk over the system 4705 to ensure proper bonding of the pieces. Initially, the evaporator 4713 is heated (step 6510). In one embodiment, the evaporator 4713 is placed in a furnace 6600 (shown in Figures 66A and B) that heats the evaporator 4713 to about 375°C. Next, the system 4705, and in particular the hot end 4715, is cooled to a temperature at which the outer diameter of the hot end 4715 is smaller than the inner diameter of the heated evaporator 4713 (step 6515). The system 4705 can be cooled using liquid nitrogen. The cooled system 4705 is inserted into the heated evaporator 4713 (step 6520). When the cooled system 4705 is inserted, heat is removed from the evaporator 4713 and cooling is removed from the system 4705, allowing the temperature of the evaporator 4713 and system 4705 to stabilize (step 6525).

Referring also to Figure 47, after the temperature has stabilized (step 6525), the evaporator 4713 and system 4705 are removed from alignment and oven setup, and the heat transfer system 4710 is assembled (step 6530). For example, liquid line 4800 and vapor line 4805 are connected to condenser 4712 . The heat transfer system 4710 and the cyclic heat exchange system 4705 are then installed in the housing 5090, as shown in Figures 50 and 52 (step 6535).

Other implementations are within the scope of the following claims. For example, core subassembly 5300 may be assembled at step 5500 by heat shrinking core 5320 over vapor barrier wall 5315 . In this embodiment, the core 5320 is formed from a core material that is cut to length, rolled into cylindrical form and then welded at its mating edges to form the cylinder. The cylindrical core 5320 is then heated and placed on the vapor barrier wall 5315. After the cylindrical core 5320 cools, a thermal interface is formed between the core 5320 and the vapor barrier wall 5315. At this point, sintering can then be used to further enhance heat transfer between the wick 5320 and the vapor barrier wall 5315 .

The parts of the core subassembly and the outer subassembly can be made of other materials as long as thermal contact can be obtained through these other materials. For example, subcooler 5310 can be made of stainless steel or liquid barrier wall 5305 and vapor barrier wall 5315 can be made of copper.

Heat may be removed from the core subassembly 5300 and cooling may be removed from the control block 5605 prior to insertion into the control block 5605 . Likewise, heat may be removed from the liquid blocking wall 5305 and cooling may be removed from the control block 5805 before the control block 5805 is inserted into the liquid blocking wall 5305 . Similarly, heat may be removed from outer subassembly 6001 and cooling may be removed from temperature control block 5605 before control block 5605 is inserted and core subassembly 5300 is inserted into outer subassembly 6001 . Finally, heat can be removed from the evaporator 4713 and cooling can be removed from the system 4705 before the system 4705 is inserted into the heated evaporator 4713 .

Claims (31)

1. method of making evaporimeter, this method comprises:

Directed vapor barrier wall makes the heat absorbing surface of vapor barrier wall limit at least a portion outer surface of evaporimeter, and this outer surface is configured to receive heat;

Directed liquid barrier is near the vapor barrier wall, and wherein the liquid obscures wall has the surface that is configured to confined liquid;

Between vapor barrier wall and liquid obscures wall, locate core;

Wherein, at least one is included in the vapour removal of the qualification at the interface passage between core and the vapor barrier wall in directed vapor barrier wall, directed liquid barrier and the location core; And

Wherein, at least one is included between liquid obscures wall and the main core and limits liquid flow path in directed vapor barrier wall, directed liquid barrier and the location core.

2. the method for claim 1 further comprises forming the vapor barrier wall and forming the liquid obscures wall.

3. method as claimed in claim 2 wherein forms the vapor barrier wall and comprises the vapor barrier wall is formed flat shape, and forms the liquid obscures wall and comprise the liquid obscures wall is formed flat shape.

4. method as claimed in claim 2 wherein forms the vapor barrier wall and comprises the vapor barrier wall is formed annular shape, and forms the liquid obscures wall and comprise the liquid obscures wall is formed annular shape.

5. method as claimed in claim 4 is wherein located core and is included in thermal contraction core on the vapor barrier wall.

6. method as claimed in claim 4 is wherein located core and is included in thermal contraction liquid obscures wall on the core.

7. the method for claim 1 is wherein located between the liquid limiting surface that is included in vapor barrier wall and liquid obscures wall and is located core.

8. the method for claim 1 comprises that further the directed cooler that divides is near the liquid obscures wall.

9. method as claimed in claim 8, wherein directed branch cooler comprises minute cooler thermal contraction to the liquid obscures wall.

10. the method for claim 1 further comprises:

Form the vapor barrier wall, and

Electroetching vapour removal passage enters in the vapor barrier wall.

11. the method for claim 1 further comprises:

Form the vapor barrier wall, and

Machined vapour removal passage enters in the vapor barrier wall.

12. the method for claim 1 further comprises the vapour removal passage is embedded in-core.

13. the method for claim 1 further comprises:

Form the vapor barrier wall, and

Photoetch vapour removal passage enters in the vapor barrier wall.

14. the method for claim 1 further comprises by rolling vapor barrier material being that matched edges cylindrical and the sealed steam barrier material form the vapor barrier wall.

15. the method for claim 1 further comprises by rolling liquid-barrier being that matched edges cylindrical and the seal fluid barrier material form the liquid obscures wall.

16. the method for claim 1, wherein directed liquid barrier comprises thermal contraction liquid obscures wall.

17. the method for claim 1 further comprises:

Form the liquid obscures wall, and

The photoetch liquid flow path enters in the liquid obscures wall.

18. a method of making evaporimeter, this method comprises:

Orientation has the liquid obscures wall of annular shape;

Directed coaxial, as to have annular shape vapor barrier wall with the liquid obscures wall; And

Locate core between liquid obscures wall and vapor barrier wall, this core is coaxial with the liquid obscures wall.

19. method as claimed in claim 18 further comprises forming the vapor barrier wall and forming the liquid obscures wall.

20. method as claimed in claim 18 is wherein located core and is included in thermal contraction core on the vapor barrier wall.

21. method as claimed in claim 18 is wherein located core and is included in thermal contraction liquid obscures wall on the core.

22. method as claimed in claim 18 is wherein located between the liquid limiting surface that is included in vapor barrier wall and liquid obscures wall and is located core.

23. method as claimed in claim 18 comprises that further the directed cooler that divides is near the liquid obscures wall.

24. method as claimed in claim 23, wherein directed branch cooler comprises minute cooler thermal contraction to the liquid obscures wall.

25. method as claimed in claim 18 further comprises:

Form the vapor barrier wall, and

Electroetching vapour removal passage enters in the vapor barrier wall.

26. method as claimed in claim 18 further comprises:

Form the vapor barrier wall, and

Machined vapour removal passage enters in the vapor barrier wall.

27. method as claimed in claim 18 further comprises the vapour removal passage is embedded in-core.

28. method as claimed in claim 18 further comprises:

Form the vapor barrier wall, and

Photoetch vapour removal passage enters in the vapor barrier wall.

29. method as claimed in claim 18 further comprises by rolling vapor barrier material being that matched edges cylindrical and the sealed steam barrier material form the vapor barrier wall.

30. method as claimed in claim 18 further comprises by rolling liquid-barrier being that matched edges cylindrical and the seal fluid barrier material form the liquid obscures wall.

31. method as claimed in claim 18, wherein directed liquid barrier comprises thermal contraction liquid obscures wall.

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