WO2008056594A1 - Refrigeration system - Google Patents

Abstract

A refrigeration system formed as a closed circuit to cool a high-temperature portion of a compression refrigeration machine, the closed circuit having liquid sealed in it and being provided with an evaporation section and condensation section for the liquid. The refrigeration circuit is provided with a thermal siphon for repeating a cycle of movement and phase change of the liquid in the closed circuit such that, after the liquid in the evaporation section receives heat and is evaporated, it is liquefied by heat radiation in the condensation section and returned to the evaporation section. The high-temperature section of the compression refrigeration machine can be efficiently cooled to a desired level, and the cooling shifts a use region to a region of a lower temperature to significantly increase efficiency and durability of the refrigeration cycle.

Description

 Specification

 Refrigeration system

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a refrigeration system, and more particularly to a refrigeration system that can efficiently cool a high-temperature portion of a compression refrigerator.

 Background art

 [0002] In compression chillers using carbon dioxide refrigerant, which has been actively developed in recent years, it is common to provide an internal heat exchanger in the refrigeration cycle in order to ensure a good coefficient of performance COP. (For example, Patent Document 1). However, in such a refrigeration cycle, the compressor has a high intake gas temperature and a large specific heat ratio of the carbon dioxide refrigerant. It was necessary to select materials and ensure strength to cope with high temperature and high pressure, which caused cost and productivity deterioration.

 [0003] In a conventional refrigeration system using carbon dioxide refrigerant, for example, as shown in FIG. 7 as an example of a refrigeration system in a vehicle air conditioner, carbon dioxide refrigerant compressed and discharged by a compressor 101 is gas cooler 102. After the heat exchange with the low-pressure side refrigerant by the high-pressure side refrigerant internal heat exchanger 103 from the gas cooler 102, the refrigerant is sent to the evaporator 105 via the expansion valve 104, and the refrigerant from the evaporator 105 is After passing through the accumulator 106, the internal heat exchanger 103 exchanges heat with the high-pressure side refrigerant and sucks it into the compressor 101.

 [0004] A refrigeration cycle in such a refrigeration system can be represented by a Mollier diagram as shown in FIG. 8, for example. In the compression refrigeration cycle using carbon dioxide refrigerant shown in Fig. 8, between points 1 and 2 is the compression work of the compressor 101, between points 2 and 3 is heat radiation by the gas cooler 102, between points 3 and 4 and point 7— 1 indicates heat exchange by the internal heat exchanger 103, points 4 and 5 indicate expansion by the expansion valve 104, and points 5 and 6 indicate evaporation by the evaporator 105. Points 6 and 7 are the same in the accumulator 106. It shows gas-liquid separation under pressure.

[0005] In such a refrigeration system, the compressor section as described above becomes high temperature and high pressure, It is desirable to cool appropriately in order to reduce power consumption. For compressors driven by an electric motor, a method of cooling the motor with suction gas is known, but in such a method, the degree of superheat of the suction gas is substantially increased (at the same time there is a decrease in gas density). As a result, the power consumption in the compressor may increase and the discharge gas temperature may increase. In addition, there is a method of driving the motor with an inverter in order to drive the motor efficiently. This inverter also needs to be cooled, and the same problem as the motor described above may occur.

 [0006] In a cooling system for a compressor, particularly in a system using a carbon dioxide refrigerant, the discharge gas may be, for example, more than 150 ° C and more than 12MPa, and there is concern about a decrease in durability and strength due to high temperature and pressure. Yes. In addition, equipment such as a power pump, which is also known for systems that use sensible heat of brine to cool electrical equipment, etc. (generally, water cooling) is added, and there is a concern about cost, failure risk, and increased energy consumption. . Furthermore, in an electric motor type compressor, the degree of superheat of the suction gas increases (at the same time the gas density decreases) due to the effects of motor waste heat and inverter waste heat, and compression efficiency may decrease. Also, especially in situations where the heat load is small, there is a risk that the amount of circulating refrigerant is small and the motor and inverter will be insufficiently cooled.

 [0007] On the other hand, a thermal siphon is known as a device in which heat is transferred by a phase change of an encapsulating medium without external power, and thereby the equipment can be cooled. However, there are no examples of applying a thermal siphon to a refrigeration system with a compression chiller configuration. Patent Document 1: JP-A-11 193967

 Disclosure of the invention

 Problems to be solved by the invention

[0008] Therefore, the object of the present invention is to focus on the problem due to insufficient cooling in the high temperature part of the compression refrigerator as described above, and the characteristics of a thermal siphon capable of cooling a specific part with a simple configuration, and compressing To provide a refrigeration system that can efficiently cool the high-temperature part of a refrigerator to the desired state and shift the operating area to a lower-temperature area by this cooling, thereby significantly improving the efficiency and durability of the refrigeration cycle It is in.

Means for solving the problem [0009] In order to solve the above problems, a refrigeration system according to the present invention is a closed circuit having a liquid enclosed therein and a liquid evaporation unit and a condensing unit in order to cool a high-temperature part of the compression refrigerator. A thermal siphon that repeats the liquid movement and phase change cycle in a closed circuit is configured so that the liquid inside the evaporation section is heat-received and vaporized, and then liquefied by heat dissipation in the condensation section and returned to the evaporation section. It consists of what is characterized by.

 [0010] Here, what moves heat by phase change of an encapsulated liquid as an encapsulating medium without external power is called a thermal siphon. As a typical encapsulated liquid, the case of water will be explained. Water boils at 87 ° C under 66661Pa pressure. By utilizing this in the closed circuit of the thermal siphon, it becomes possible to cool equipment that generates heat above 87 ° C to 87 ° C without power (however, the efficiency of heat exchange with the thermal siphon system is high). Assuming 100%). In other words, the thermal siphon can be used on the secondary side of the binary refrigeration system, and further can be used for cooling the compressor on the primary side, for example.

[0011] For example, the closed circuit is filled with pure water and the pressure is 66661Pa. The boiling temperature of water in this state is 87 ° C. Set the ambient temperature of the condensing part to around 25 ° C, for example. In the inside of the evaporation part of the thermal siphon that comes into contact with the equipment that needs to be cooled when the temperature exceeds 87 ° C, for example, water is distributed to multiple heat exchange pipes by the header part at the bottom of the evaporation part, and the liquid is vaporized. (Latent heat change). Vaporized water with low density rises and flows into the condensing part. When liquid remains in the evaporation section, a liquid surface is formed in the header tank in the upper part of the evaporation section and stays below, so that it does not flow out to the condensation section. Water is liquefied after heat dissipation in the condensation section and returns to the evaporation section by gravity. The thermal siphon that repeats the cycle of water movement and phase change makes it possible to efficiently cool the high-temperature part of the compression refrigerator, particularly the compressor. Note that the thermal siphon can be configured to have a condensing unit and a full liquid evaporation unit composed of header sections arranged above and below and a plurality of pipe sections that perform heat exchange connecting them. Since the thermal siphon increases the evaporation amount of the sealed liquid according to the heat load, the heat exchange corresponding to this can be performed in the condensing unit, and the heat exchange amount can be adjusted by the fan air volume, for example. In this case, arrange the condensers side by side above the high-pressure heat exchanger of the compression refrigerator and cool with a common fan. [0012] In the refrigeration system according to the present invention, the thermal siphon may be configured such that the evaporation temperature of the liquid can be adjusted by adjusting the internal pressure. For example, a pressure adjustment chamber for adjusting the internal volume is provided in the thermal siphon, and the internal temperature of the thermal siphon is increased or decreased to adjust the cooling temperature. Specifically, for example, a thermoresiphon adjusts the setting of the partition wall made of at least a flexible member, the partition wall support member that elastically changes the stroke in accordance with the pressure in the partition wall, and the stroke setting of the partition wall support member. It is the form which has a pressure regulation chamber provided with the adjusting screw. More specifically, for example, a pressure regulating chamber provided with a partition wall formed of a flexible member such as rubber, a metal bellows, or a metal diaphragm and a partition wall support member (for example, a spring) formed of an elastic member is provided. When boiling water below 100 ° C, balance the pressure difference between the pressure inside the partition wall and atmospheric pressure with a spring and adjusting screw. If water is boiled at 100 ° C or higher, the spring mounting method is reversed.

[0013] As a high-temperature portion of the compression refrigerator that is cooled by the thermal siphon, the compressor can be a cooling target. In addition, an electric motor integrated with the compressor may be included in the high temperature portion of the compression refrigerator that is to be cooled. Furthermore, an inverter that controls the electric motor that drives the compressor may be included in the high temperature portion of the compression chiller that is to be cooled.

 [0014] When the compressor section of such a compression refrigerator is cooled, for example, the compressor may be cooled by the evaporation section of the thermal siphon through the wall surface. With such an arrangement, the compressor as a cooling target is efficiently cooled.

 [0015] In addition, the liquid sealed in the thermal siphon in the refrigeration system according to the present invention is not particularly limited as long as the target cooling in the present invention is achieved. It is desirable that the liquid is clearly graspable, and it is desirable that the liquid is water as described above or water. For example, it is preferable that the liquid force contains 50% or more of water.

[0016] Further, as thermal siphons, there are those in which a copper or aluminum tube is connected substantially in an endless manner and filled with a refrigerant gas such as carbon dioxide or butane. Evaporative temperature (or condensation temperature) is 8 ° C, normal temperature Since a thermal siphon is established, the contradiction that the heat load of the compression refrigeration machine becomes higher may occur. Therefore, from this aspect, it is preferable to select a sealed liquid capable of changing the phase of gas and liquid (latent heat change) at an appropriate temperature, for example, a liquid containing 50% or more of water as described above.

[0017] The refrigerant used in the compression refrigerator in the present invention is not particularly limited. However, in the present invention, the high-temperature portion of the compression refrigerator can be efficiently cooled. The present invention is particularly effective when the refrigeration cycle has a high-temperature and high-pressure part. In other words, the present invention is particularly effective when the refrigerant circulating in the compression refrigerator is a refrigerant having a global warming potential (GWP) of 150 or less. However, a compression refrigerator using a refrigerant such as HFC134a can also be a target of the present invention.

 [0018] Further, in the refrigeration system according to the present invention, it is particularly preferable that heat exchange corresponding to the compressor power of the compression chiller is performed by the thermal siphon! /. This makes it possible to realize a very efficient refrigeration cycle, as described in the Mollier diagram described later, and in some cases, the possibility of omitting the gas cooler in the conventional cycle arises.

 [0019] In addition, the refrigeration system according to the present invention does not require any special external power! /, And uses a thermal siphon. Therefore, it is not preferable to install a new power source or the like. It is suitable for a refrigeration system used for an air conditioner. However, the refrigeration system according to the present invention is not limited to a vehicle air conditioner but can be applied to cooling other devices such as electronic devices.

[0020] The operation of the present invention will be described for the case where the sealed liquid is water. For example, in the case of a vehicle air conditioner, the lower limit of the housing surface temperature of the compressor is around 90 ° C in the normal operation mode. As the rotation speed increases, the force S increases to 160 ° C depending on the conditions. When the thermal siphon according to the present invention is activated, the temperature does not rise above the boiling temperature of water in the thermal siphon under any conditions. In other words, proper cooling is performed to prevent an undesirably high temperature. [0021] In the case of a compression refrigerator using carbon dioxide as a refrigerant, the critical point is as low as about 30 ° C, about 7MPa at a temperature! Due to the characteristics of the refrigerant, do not use a normal internal heat exchanger! / In the cycle configuration, the dryness at the evaporator inlet is large and the efficiency of the refrigeration system is not good. The internal heat exchanger provided to compensate for this raises the intake gas temperature of the compressor and consequently the discharge gas temperature in order to bring the gas cooler downstream and the piping downstream of the evaporator into contact with each other. In the present invention, for example, a space (jacket) in which water circulates is provided so as to cover the wall surface of the compressor of a compression refrigerator as described later, and connected to the condenser part of the thermal siphon above the jacket by a pipe. Configured to do. Water entering the jacket as a liquid from below is vaporized by the heat of the compressor. At this time, if the pressure force in the jacket is 6661 Pa, the temperature will be kept at 87 ° C, and the high temperature as described above will be surely prevented.

 [0022] Further, by providing the pressure adjusting chamber, even if the amount of gas after boiling when the thermal load on the thermal siphon increases, the boiling point does not fluctuate and stable cooling performance can be obtained. become. If this is used for cooling the high-pressure side equipment of a compression refrigeration machine using carbon dioxide refrigerant whose supercritical pressure is on the high-pressure side, the high-pressure side pressure is stable and stable operation is possible without advanced control. It becomes.

 The invention's effect

 As described above, according to the refrigeration system of the present invention, since the thermal siphon is provided and the latent heat at the time of phase change of the liquid sealed in the thermal siphon is used, the boiling determined by the pressure in the closed circuit is used. The temperature of the cooled part can be maintained at a desired constant temperature by the temperature (condensation temperature), and the target cooling can be performed efficiently and reliably.

 [0024] For the compressor housing of the compression refrigerator, a light alloy material is generally used because of its good formability, good machinability, and high thermal conductivity. However, light alloys have the property that their strength decreases significantly as the temperature rises. As a result of the cooling according to the present invention, the compressor temperature and the Uzing temperature can be lowered, so that it can be used in a substantially high strength region.

[0025] Further, by utilizing the cooling characteristic that keeps the temperature of the thermal siphon constant, deterioration of the seal material at high temperature can be prevented. [0026] Further, if the cooling characteristics that keep the temperature of the thermal siphon constant are utilized, the lubricating oil film thickness is secured by preventing the refrigeration machine oil viscosity from being lowered, so that the durability of the seal sliding part and the bearing part can be improved. it can.

[0027] Since this thermal siphon has no moving parts, it is extremely reliable and excellent in quietness. In addition, since no special external drive source is required, the present invention can be implemented at low cost and without requiring a large space.

[0028] Further, since the thermal siphon operates at a pressure lower than the atmospheric pressure, the reliability is extremely high even in this aspect where leakage to the outside is eliminated.

[0029] Further, by appropriate cooling by the thermal siphon, the high-pressure side heat exchanger of the compression refrigeration machine can be made smaller, and the amount of the enclosed refrigerant can be reduced correspondingly.

[0030] Furthermore, even when using a compression refrigeration machine equipped with a compressor with an electric motor body in a low heat load! / Situation, there is no decrease in the performance and durability of the compressor! /.

 Brief Description of Drawings

 FIG. 1 is an equipment system diagram when a refrigeration system according to an embodiment of the present invention is applied to a vehicle air conditioner.

 FIG. 2 is a Mollier fountain diagram of the refrigeration system of FIG.

 FIG. 3 is a schematic configuration diagram showing a basic configuration of the thermal siphon in FIG. 1.

 FIG. 4 is a schematic configuration diagram showing an example of a thermal siphon provided with a pressure regulating chamber.

 FIG. 5 is a schematic longitudinal sectional view of a conventional compressor shown for comparison.

 FIG. 6 is a schematic longitudinal sectional view of a compressor unit to which the present invention is applied.

 FIG. 7 is an equipment diagram showing an example of a vehicle air conditioner to which a conventional refrigeration system is applied.

FIG. 8 is a Mollier fountain diagram of the refrigeration system of FIG.

 Explanation of symbols

[0032] 11 Compressor

 12 Gas cooler

 13 Internal heat exchanger

14 Expansion valve 15 Evaporator

 16 Accumulator

 17 Thermore Siphon

 18 jacket

 19 Evaporator

 20 Condensing section

 21 Pressure control chamber

 22 Bellows as a bulkhead

 23 Spring as a bulkhead support member

 24 Adjustment screw

 41 Compression mechanism

 42 Electric motor

 43 Suction refrigerant

 44 Compressed refrigerant

 45 Inverter

BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an equipment layout when a refrigeration system according to an embodiment of the present invention is applied to a vehicle air conditioner. In FIG. 1, the carbon dioxide refrigerant compressed and discharged by the compressor 11 is sent to the gas cooler 12 and is exchanged with the low pressure refrigerant by the high pressure refrigerant refrigerant internal heat exchanger 13 from the gas cooler 12, and then the expansion valve 14 Then, the refrigerant from the evaporator 15 passes through the accumulator 16, and is then heat-exchanged with the high-pressure side refrigerant by the internal heat exchanger 13 and sucked into the compressor 11. The thermal siphon 17 according to the present invention is provided for the compressor 11 or a part of the compressor 11 of the refrigeration system configured as described above. The thermal siphon 17 includes an evaporation unit 19 for the sealed liquid formed in the form of a jacket 18 around the compressor 11 and a condensing unit 20 positioned above. The evaporating unit 19 is disposed around the compressor 11, but the condensing unit 20 is disposed above the compressor 11. [0034] The refrigeration cycle in the refrigeration system including the thermal siphon 17 as described above can be represented by, for example, a Mollier diagram as shown in FIG. In the compression refrigeration cycle using the carbon dioxide refrigerant shown in FIG. 2, boiling cooling of the liquid sealed in the thermal siphon 17 is used for cooling the compressor 11. In Figure 2, point 1 one! The interval between '~ 2 is equivalent to the compression work by the compressor 11 (virtual component), but due to the boiling cooling by the thermal siphon 17, the compressor 11 is cooled as between the points 1' 2 'and the compressor 1 The high temperature of 1 is prevented. Between points 2 'and 3, heat is dissipated by gas cooler 12, between points 3 and 4 and between points 7 and 1, heat is exchanged by internal heat exchanger 13, between points 4 and 5 is expansion by expansion valve 14, and points 5 and 6 The intervals indicate evaporation by the evaporator 15, and points 6 and 7 indicate gas-liquid separation in the accumulator 16 under the same pressure state. Thus, it is clear that the compressor 11 is efficiently cooled by the thermal siphon 17 even on the Mollier diagram. If the point 2 ′ is at the point 3, the gas cooler Omission of 12 is also possible.

 The thermal siphon 17 has a basic configuration as shown in FIG. 3, for example. In other words, the evaporation section 19 in which the sealed liquid flows in the liquid phase is located on the lower side, and the condensing section 20 in which the sealed liquid flows in the gas phase and is liquefied by heat dissipation is arranged above it! / These are configured in a closed circuit, and after the liquid inside the evaporation unit 19 has received heat and vaporized, the liquid moves in the closed circuit so that it is liquefied by heat dissipation in the condensation unit 20 and returned to the evaporation unit 19. The phase change cycle is repeated, and the high temperature part of the compression refrigerator is cooled by the endothermic heat generated by vaporization (latent heat change) in the evaporation part 19. As described above, the thermal siphon 17 circulates the sealed liquid without applying any special external power.

FIG. 4 illustrates the case where the pressure regulating chamber 21 is provided in the thermal siphon 17. In this example, the pressure regulating chamber 21 is made of a flexible member, and a rubber or metal bellows 22 as a partition wall through which the sealed liquid in the thermal siphon 17 circulates, and the pressure in the bellows 22. Accordingly, a spring 23 as a partition wall supporting member that changes the stroke in response to inertia and an adjusting screw 24 for adjusting the setting of the stroke of the spring 23 are provided. For example, when boiling water as an enclosed liquid at 100 ° C. or less, the difference between the pressure inside the bellows 22 and the atmospheric pressure may be balanced by the spring 23 and the adjusting screw 24. 100 ° C water When boiling above, the installation of the spring 23 is reversed.

 FIG. 5 shows an example of a conventional compressor 31 for comparison. The compressor 31 is formed by integrating a compression mechanism 32 and an electric motor 33 (for example, a DC brushless motor) that drives the compression mechanism 32, and the electric motor 33 is controlled by an inverter 34. In the compressor 31, the suction refrigerant 35 is sucked into the compression mechanism 32 through the electric motor 33, thereby cooling the electric motor 33 together with the compressor 31. The refrigerant compressed by the compression mechanism 32 is discharged as the compressed refrigerant 36.

 On the other hand, a compressor as a cooling target of a compression refrigerator to which the present invention is applied is configured as shown in FIG. 6, for example. FIG. 6 shows the configuration of the compressor 11 shown in FIG. 1 and its surroundings. Like the compressor 31 shown in FIG. 5, the compressor 11 is driven by an electric motor 42 with a built-in compression mechanism 41. The force suction refrigerant 43 is directly passed through the electric motor 42 without passing through it. Thus, the refrigerant introduced into the compression mechanism 41 and compressed by the compression mechanism 41 is discharged as the compressed refrigerant 44. The evaporator 11 of the thermal siphon 17 is arranged with respect to the compressor 11 in the structure of the jacket 18 described above, and the sealed liquid is circulated between the evaporator 19 and the condenser 20. In other words, the liquid movement and the phase change cycle in the closed circuit as described above are repeated. In this example, the jacket 18 for cooling is arranged so that the electric motor 42 part can be cooled by covering the electric motor 42 part, and the inverter 45 that controls the electric motor 42 can also be cooled. The compressor 11, the electric motor 42, and the inverter 45 are all cooled efficiently.

 [0039] As described above, by disposing the thermal siphon to the high temperature portion of the compression refrigerator, the high temperature portion that needs to be cooled is efficiently cooled, and the freezing of the refrigeration system is performed. The efficiency of the cycle will be greatly improved.

 [0040] It should be noted that the above embodiment is a force S exemplifying the case where the present invention is applied to cooling of a compressor portion in a vehicle-mounted air conditioner, and the present invention is applicable to other parts of the apparatus, Furthermore, it is applicable not only to a vehicle-mounted air conditioner but also to other refrigeration systems. Industrial applicability

[0041] The refrigeration system according to the present invention is used at room temperature, and can be cooled to a room temperature level. Suitable for required applications. For example, it is suitable for cooling electronic devices and compressors constituting a compression refrigerator.

Claims

The scope of the claims  [I] In order to cool the high-temperature part of the compression refrigerator, a liquid is enclosed and a closed circuit having an evaporation part and a condensation part of the liquid is formed, and after the liquid inside the evaporation part is received and vaporized, A refrigeration system provided with a thermal siphon that repeats the movement of liquid and the phase change cycle in a closed circuit so that it is liquefied by heat dissipation in the condenser and returned to the evaporator.  [2] The refrigeration system according to claim 1, wherein the thermal siphon is configured so that an evaporation temperature of the liquid can be adjusted by adjusting an internal pressure. [3] The thermal siphon includes a partition wall made of at least a flexible member, a partition wall support member that changes its stroke in accordance with the pressure in the partition wall, and an adjustment screw that adjusts the setting of the stroke of the partition wall support member. The refrigeration system according to claim 2, further comprising a pressure regulating chamber. [4] The refrigeration system according to claim 1, wherein the high-temperature portion of the compression refrigerator cooled by the thermal siphon includes the high-temperature portion of the compressor. [5] The refrigeration system according to claim 1, wherein the high-temperature portion of the compression-type refrigerator cooled by the thermal siphon includes an electric motor incorporated in the compressor. 6. The refrigeration system according to claim 1, further comprising an inverter that controls an electric motor that drives a high-temperature partial force compressor of the compression refrigerator cooled by the thermal siphon. 7. The refrigeration system according to claim 1, wherein the compressor of the compression refrigerator is cooled by the evaporator unit of the thermal siphon through the wall surface. [8] The refrigeration system according to [1], comprising a liquid containing 50% or more of liquid force water enclosed in the thermal siphon. [9] The refrigeration system according to claim 1, wherein the refrigerant used in the compression refrigerator is made of carbon dioxide.  10. The refrigeration system according to claim 1, wherein heat exchange corresponding to a compressor power of the compression refrigeration machine is performed by the thermal siphon.  [I I] The refrigeration system according to claim 1, wherein the refrigeration system is used for a vehicle air conditioner.