WO2015014406A1 - Evaporator heat exchanger - Google Patents

Abstract

The present invention relates to an evaporator heat exchanger (1) for evaporating liquid working medium (2), comprising a housing (3), in which a first flow channel (4) for conducting the working medium (2) and a second flow channel (5) for conducting a gas (6) are arranged, wherein heat can be transferred from the gas (6) to the working medium (2). It is essential to the invention that the first flow channel (4) is formed by two cover plates (7, 8) and a profiled fluid plate (9) arranged therebetween, wherein the fluid plate (9), together with the two cover plates (7, 8), bounds at least one leakage channel (10) and/or leakage space (11) at the same time, the at least one leakage channel and/or leakage space being separated from the two flow channels (4, 5). Thus reliable operation can be achieved.

Description

 Evaporator heat exchanger

The present invention relates to an evaporator heat exchanger for

Evaporation of liquid working medium according to the preamble of

Claim 1.

To further reduce the fuel consumption of commercial vehicles and passenger cars is trying to regain some of the energy of the exhaust gas. This can be done thermally, i. the energy of the exhaust gas, for example, for heating a passenger compartment or to

Heating the internal combustion engine or the transmission used. In a variant that has been discussed for some time now, although thermal energy is also taken from the exhaust gas, it is returned to the internal combustion engine in mechanical form. This method is based on a

Steam power process in which a particular working fluid is vaporized and overheated in an evaporator and expanded in an adjoining expander, such as a turbine, thereby generating mechanical energy. The evaporation takes place by means of heating via the exhaust gas. The working medium to be evaporated is usually first heated in an evaporator to boiling temperature, then evaporated and then superheated. This can be done in principle in two different locations in a motor vehicle. For one thing, in an evaporator, instead of a

Exhaust gas cooler is used, heat is removed from the exhaust gas to evaporate the working fluid. In this case, the exhaust gas is cooled by the evaporation of the fluid to be evaporated and then returned to the engine together with the fresh air. On the other hand, the main exhaust gas flow is to be used as a heat source, here in a so-called

Main exhaust evaporator also vaporize working medium. Such a main exhaust gas evaporator is usually from the vehicle manufacturers behind the muffler or behind the entire exhaust aftertreatment arranged in the exhaust system. Alternatively, the charge air can be used as a heat source in turbocharged engines.

From WO 2012/010349 A1 is a generic

 Evaporator heat exchanger for vaporizing liquid working fluid and the use of waste heat of an internal combustion engine known. In the known system, an introduction of the working medium in the

Combustion engine supplied combustion air due to leakage or leakage at the evaporator heat exchanger substantially

be excluded. For this purpose, at least one first flow channel is formed by at least one first limiting component and at least one second flow channel of at least one second limiting component, wherein at least one of these limiting components is a fluid-conducting connection in the environment or in a receiving space, so that at a leakage at the boundary components Working medium in the environment or in the receiving space can be introduced.

In the prior art described concepts of a gas-powered

Evaporator heat transfer provide to reduce the risk of mixing gas and working fluid. For example, if a fluorinated refrigerant flows into the exhaust gas and is supplied to the internal combustion engine and burned in the latter, hydrofluoric acid is produced, which can escape from an exhaust pipe and cause damage there. If, for example, an alcohol is used instead of this refrigerant, then in the event of leakage the alcohol would be in the

Combustion engine are burned with, which would be noticeable by a sudden increase in power of the internal combustion engine. This may be difficult to handle, especially for inexperienced drivers. The present invention therefore deals with the problem of an improved for an evaporator heat exchanger of the generic type

Specify embodiment in which an undesired mixing of working fluid and gas, in particular exhaust gas or charge air, can be excluded.

This problem is inventively achieved by the subject matter of

independent claim solved. Advantageous embodiments are

Subject of the dependent claims.

The present invention is based on the general idea, a

Leakage channel or leakage space between a first, working medium leading flow channel and a second, gas, in particular exhaust gas or charge air, leading flow channel and provide both the first flow channel and the leakage channel or the leakage space through two cover plates and an interposed and profiled fluid disk in form a particularly simple design way. The inventive evaporator heat exchanger for vaporizing liquid working medium in this case has a housing in which said first flow channel for passing the working medium and the second flow channel to

Passage of the gas are arranged. By a heat transfer from the gas, for example, charge air or exhaust gas, to the working medium, an evaporation of the same, whereby this then in a

Expansion machine, for example, in a turbine, can be relaxed and thereby performs mechanical work. As mentioned, according to the invention, the first flow channel and at least one leakage channel and / or a

Leakage space formed by two comparatively strong cover plates and an interposed and profiled fluid disk, wherein one of two cover plates and an intermediate fluid disc formed

Disk package thus the first flow channel and the at least one fluidly separated from it leakage channel or leakage chamber accommodated. The connection between the two cover plates and the interposed fluid disc is cohesively, for example via a solder joint. In each case a second flow channel is arranged between two adjacent disk packages, in which the heat-transferring gas, for example exhaust gas or charge air, flows. If the fluid disk breaks and / or the solder seam between the fluid disk and the cover plate fails, the working medium is passed from the first one

Flow channel in the leakage channel or in the leakage chamber and can be removed from there, without leading to a direct mixing with the flowing gas in the second flow channel, such as exhaust gas leads. In the same way, the leakage channel or the leakage chamber also for

Discharging discharged from the second flow channel undesirably gas used, for example, if a loosening of a solder joint between the fluid disk and the cover plate or breaking a wall of the fluid disk would lead to a fluidic connection between the leakage channel and the second flow channel. As a result of this, the gas now flowing into the leakage channel or into the leakage chamber can be removed, thereby avoiding direct mixing with the working medium in the first flow channel. The leakage channel or the

Leakage space thus forms a natural, between the two

Flow channels lying safety barrier. The leakage channel or the leakage chamber is usually filled with air.

Suitably, the strength of a material of the fluid disk is less than the strength of a cover plate arranged on the fluid disk. This causes a kind of predetermined breaking point of the fluid disk, so that in case of overload of the

Evaporator heat exchanger in the region of the first flow passage is a passage of the guided in the first flow channel working fluid into the leakage channel. For example, breaks the fluid disk and expands Under circumstances, the cover plate delimiting the first flow channel and compresses the arranged, for example, in the second flow channel

Rib structure. When stretching the cover plate can be a the

Solder fluid disk with this cover plate connecting solder seam, whereby a fluidic connection between the first flow channel and the

Leakage channel is created. From this, the working medium can be removed without mixing with the gas flowing in the second flow channel. In the same way, such a predetermined breaking point can also be formed by a smaller wall thickness or material thickness of the fluid disk in comparison to the cover plates connected thereto. It is always important that, in the event of an overload, the fluid disk first breaks or tears and not the

Cover plates. In this way, regardless of the type of failure, it can always be guaranteed that the one between the first and the second

Flow channel lying leakage channel or leakage chamber for discharging the working medium or the gas can be used. The leakage channel or the leakage chamber are preferably embossed circumferentially on the fluid disk, larger areas being designated as a leakage space and a smaller one as a leakage channel.

In a further advantageous embodiment of the solution according to the invention, the evaporator heat exchanger has a plurality of stacked one above the other

Disk packages with each arranged therebetween second flow channel, wherein the leakage channel and / or the leakage chamber of a fluid disk having a first opening and a plurality of opposing cover plates of two adjacent disk packages each having a second opening, wherein between the second openings a leakage bushing to form a (leakage -) outlet channel is arranged. In this way, the leakage fluid or gas can be reliably discharged from the second flow channel or the working medium from the first flow channel. In an advantageous development of the solution according to the invention, the housing has a housing opening, which is connected via a housing cover bushing to the first or the second opening in the cover plate of a disk package arranged adjacent to the housing. The

Housing corner bushing and all other leakage bushing thereby form an outlet channel, also called leak discharge passage, for the passage of the leakage fluid, wherein at the housing cover bushing a line in the

Environment or periphery is attachable, in whose area a sensor

is arranged, which is designed for measuring the pressure and / or the flow and / or a chemical composition of the fluid in the conduit. In the outlet channel usually the ambient air pressure prevails. At the same time air is present with usual nature. If, due to an overload, the fluid disk breaks and / or tears and thus an outlet of working medium from the first flow channel or gas from the second flow channel into the leakage channel, the pressure, the temperature and / or the pressure change in this chemical composition, since the leakage fluid, whether exhaust or working fluid, other physical and / or chemical properties than air. If a corresponding change is detected by the sensor, which indicates a leak, it can for example control a pump or an exhaust gas recirculation valve conveying the working medium as a function of the signal detected by the sensor. Also conceivable is the output of a warning signal which visually and / or acoustically indicates a malfunction of the user of the motor vehicle

Evaporator heat exchanger indicates. As described above, the ambient air pressure of approximately 1 bar is usually applied to the sensor. If the evaporator heat exchanger is put into operation, the pressure rises in the

Leakage channel or in the leakage chamber due to the temperature-induced expansion to about 1 -1, 5 bar, which is normal. However, if the pressure does not rise, then either the sensor is defective or the leakage channel or

Leakage chamber has a leak, via which a pressure reduction takes place can. If the pressure increases significantly during operation of the evaporator heat exchanger, this usually indicates a leakage of the first

Flow channel or the second flow channel out. The operation of the leakage channel is thus checked at each restart of the motor vehicle, in particular at each cold start.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated

Description of the figures with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Show, in each case schematically,

Fig. 1 is a view of an inventive

 Evaporator heat exchanger,

Fig. 2 is a sectional view through the evaporator heat exchanger in

Range of first and second flow channels in intact condition, 3 is a representation as in FIG. 2, but with a broken fluid disk and the passage of working fluid into a leakage channel, FIG.

4 shows a representation as in FIG. 3, but with a transfer of gas from the second flow channel into the leakage channel, FIG.

5 shows a possible embodiment of the fluid disk according to the invention,

6 is an exploded view of the evaporator heat exchanger,

Fig. 7 is a sectional view through the evaporator heat exchanger in

 Area of the fluid inlet or outlet,

8 shows a representation as in FIG. 7, but in the region of an outlet channel for leakage fluid, FIG.

Fig. 9 is a pressure-time diagram with different curves on

 different operating conditions or leaks of

 indicate evaporator heat exchanger according to the invention.

According to Fig. 1, an inventive

 Evaporator heat exchanger 1 for evaporating liquid working medium 2 (see also Figs., 2 to 4), a housing 3, in which a first

Flow channel 4 for passing the working medium 2 and a second flow channel 5 are arranged for passing a gas 6. A heating of the working medium 2 takes place by a heat transfer of the gas 6, for example, exhaust gas or charge air. According to the first flow channel 4 is now formed by two cover plates 7 and 8 and an interposed and profiled fluid disk 9, wherein the fluid disk 9 together with the two cover plates 7 and 8 at least one of the two flow channels 4, 5 separate leakage channel 10 and

Leakage chamber 1 1 limited. The two cover plates 7, 8 together with a fluid disk 9 arranged therebetween form a disk pack 12, as illustrated for example in accordance with FIGS. 2 to 4. The respective leakage channel 10 and the leakage chamber 1 1 are laterally next to or

arranged on the edge side of the first flow channel 5, as can be seen in particular in FIG. 5.

The leakage channel 10 according to the invention creates a barrier between the two flow channels 4, 5, so that no direct mixing of the working medium 2 with the gas 6 and thus damage to an internal combustion engine can take place. In the known from the prior art evaporator heat exchanger flows to be evaporated

Working fluid in case of leakage into the exhaust and can, if

For example, a fluorinated refrigerant, such as e.g. R245fa is used in the

Combustion engine are burned, resulting in toxic hydrofluoric acid. This would leak at the exhaust and could cause damage there. If, instead of such a refrigerant, alcohol, e.g. Ethanol or methanol used, it would be burned in a leakage of this in the internal combustion engine, which would be reflected in a sudden increase in power of the engine. In particular, inexperienced drivers would be exposed to an increased risk of accidents. By the

inventive barrier in the nature of the leakage channel 10 and des

Leakage space 1 1, however, can be reliably prevented at a virtually any failure of the fluid disk 9, a mixing of the gas 6 with the working medium 2.

In addition to the provision of the leakage channel 10 and the leakage space 11 (see also Fig. 5), the strength of the material for the fluid disk 9 is less than the strength of the fluid disk 9 connected to the cover plates 7, 8, so that the Fluid disk 9 generally a kind of predetermined breaking point in the system of

Disk package 12 represents. Similarly, such

Predetermined breaking point can also be realized by a smaller wall thickness or material thickness of the fluid disk 9 with respect to the wall thickness or material thickness of the cover plates 7, 8.

In Fig. 2 is the evaporator heat exchanger 1 in normal

Operating state shown in which in the second flow channel 5, gas, in particular exhaust gas, flows and transfers heat to the working fluid 2 in the first flow channel 4. For better heat transfer, in the second flow channel 5, i. between two disc packages 12, a rib structure 13 may be arranged. A connection of the fluid disk 9 with the two cover plates 7, 8 and also a connection of the rib structure 13 with the respective cover plates 7, 8 takes place preferably cohesively, in particular via a solder joint 14.

In Fig. 3 now a failure of the fluid disk 9 is shown, in which the mean fluid disk 9 is broken and thereby has led to a deformation or an upward bending of the larger-sized cover plate 7. The deformation of the cover plate 7 in turn leads to a release of

Solder connection 14, whereby the existing in the first flow channel 4 working fluid 2 can flow into the leakage channel 10. A fluidic

Connection with the second flow channel 5 and thus with the gas 6 does not take place.

According to FIG. 4, a case is shown in which the fluid disk 9 has also been broken due to an overload, thereby creating a fluidic connection between the second flow channel 5 and the leakage channel 10. The gas 6 passing from the second flow channel 5 can be removed via the leakage channel 10, without interfering with the working medium 2 in the first flow channel 4 to mix. In both shown

Failures according to FIGS. 3 and 4 can thus be an undesirable

Mixing of the working medium 2 with the gas 6 and the resulting

resulting difficulties are reliably avoided.

If one looks at the fluid disk 9 according to FIG. 5, one can very nicely see the first flow channel 4 as well as the edge running on it

Leakage channel 10 and intervening leakage chambers 1 1 recognize.

Also visible is a fluid supply 15 and a fluid discharge 16, via which the fluid disk 9 working medium 2 can be supplied or discharged from this again. Likewise, the fluid disk 9 has a first opening 17, via which the leakage channel 10 or the leakage chamber 11 are connected to a (leakage) outlet channel 18 (see FIG. A plurality of opposing cover plates 7, 8 of two adjacent disk packs 12 additionally each have a second opening 19, wherein between two second

Openings 19 a leakage bushing 20 for forming the outlet channel 18, in particular the leakage outlet channel 18, is arranged. At a

assembled disc package 12 thus align the first openings 17 with the second openings 19 and the leakage bushings 20 and thereby form the outlet channel 18th

Looking further at the Fig. 6, it can be seen that the cover plates 7, 8 each have a third opening 21 for the passage of the working medium 2 through the first flow channel 4, wherein the third openings 21 between opposing cover plates 7, 8 of two adjacent each disc packs 12 are interconnected by a fluid sleeve 22 and the fluid sockets 22 have an at least partially circumferential, separated from the first flow channel 4 Fluidbuchsenringkanal 23 which is connected to the leakage channel 10 and / or the leakage chamber 1 1 of the fluid disk 9 of the disk package 12 , This can also be done a backup against from the fluid sockets 22 undesirable emerging working medium 2 are created. The third openings 21 together with the fluid bushes 22 arranged therebetween and the fluid supply 15 or fluid discharge 16 arranged in alignment therewith form a corresponding fluid supply channel 24 or fluid discharge channel 25 in the fluid disks 9.

7 shows a sectional view through the evaporator heat exchanger 1 according to the invention in the region of the fluid feed channel 24 and the fluid discharge channel 25, respectively. The uppermost fluid bushing 22 is welded to the housing 3 via a welded joint 26 in a fluid-tight manner. Between each two adjacent fluid bushings 22, a disk pack 12 with two cover plates 7, 8 and interposed or soldered fluid disk 9 can be seen.

In Fig. 8 is a sectional view through the invention

Evaporator heat exchanger 1 shown in the region of the outlet channel 18, wherein the uppermost leakage bushing 20 is in turn welded fluid-tightly to the housing 3 via a welded joint 26. The individual disk packs 12, in turn consisting of the two cover plates 7, 8 and the fluid disk 9 arranged therebetween, are soldered in a fluid-tight manner both to one another and to the individual leakage bushings 20 via a respective solder joint 14. The uppermost leakage bushing 20 is also called

Housing cover bushing 27 denotes. Connected to the housing cover bushing 27 is a line 28 (see FIG. 1) extending further from the evaporator heat exchanger 1 into the environment or the periphery. In line 28 and the outlet channel 18, a sensor 29 may be provided to the

Measurement of the pressure and / or flow and / or a chemical composition of the fluid in the conduit 28, that is, in particular also formed in the leakage channel 10 and in the outlet channel 18. Also may be provided a control and / or

Control device 30, which is used to evaluate a signal detected by the sensor 29, in particular the pressure, the flow and / or chemical composition of the fluid, in particular the leakage fluid, in the line 28 and for controlling / regulating a pump or the pumping medium which is not shown in the drawing a likewise not shown

Exhaust gas recirculation valve is formed in response to the detected signal.

At the sensor 29 is usually the ambient air pressure of about 1 bar, if the evaporator heat exchanger 1 is turned off and

Ambient temperature has. This is shown in FIG. 9 with the curve A. If the evaporator heat exchanger 1 is put into operation, the pressure inside the line 28 or within the leakage channels 10 rises to approximately 1 to 1.5 bar due to the temperature-related expansion of the air, which is represented by the curve B according to FIG is. Will the

Vaporiser 1 put into operation and the pressure does not rise, which is also shown with the curve A in Fig. 9, either the sensor 29 is defective or the line 28 and the leakage channel 10 have a leak. In the event of a leak in the fluid disk 9, the pressure increases significantly when the working medium 2 enters the leakage channel 10, which is shown in FIG. 9 with the curve C, and slightly less, if the fluid disk 9 in the direction of the second flow channel 5 breaks and thus a passage of gas 6 takes place in the leakage channel 10, which is shown in FIG. 9 with the curve D. In general, thus, the operation of the leakage channel 10 can be checked at each restart of the engine or the system, which also a high reliability can be guaranteed. Also, due to the curve can be closed directly on the failure mode. In general, the evaporator heat exchanger 1 according to the invention has the following advantages:

Vernneidung unwanted Vernnischung the Arbeitsmediunns 2 with the gas 6, for example, exhaust gas or charge air,

 no health risk when using refrigerants,

 no safety risk when using alcoholic working medium 2, ongoing testability of the function of the leakage concept.

Claims

claims 1 . Evaporator heat exchanger (1) for evaporating liquid  Working medium (2), with a housing (3) in which a first  Flow channel (4) for passing the working medium (2) and a second flow channel (5) for passing a gas (6) are arranged, wherein heat from the gas (6) on the working medium (2) is transferable,  characterized,  in that the first flow channel (4) is formed by two cover plates (7, 8) and a fluid disk (9) arranged therebetween, wherein the fluid disk (9) together with the two cover plates (7, 8) simultaneously at least one of the two Flow channels (4,5) separated leakage channel (10) and / or leakage space (1 1) limited. 2. evaporator heat exchanger according to claim 1,  characterized,  in that the at least one leakage channel (10) and / or a leakage chamber (11) is arranged laterally next to or at the edge of the first flow channel (4). 3. evaporator heat exchanger according to one of the preceding claims, characterized - That the strength of a material of the fluid disc (9) is less than the strength of a on the fluid disc (9) arranged cover plate (7,8), and / or - That the fluid disc (9) has a smaller wall thickness or  Material thickness than that on the fluid disc (9) respectively  arranged cover plates (7,8). 4. evaporator heat exchanger according to one of the preceding claims, characterized  that in each case two cover plates (7, 8) with a fluid disk (9) arranged therebetween form a disk pack (12) which has at least one, preferably two, leakage passages (10) circulating at least partially in the edge region. 5. evaporator heat exchanger according to claim 4,  characterized,  - that the evaporator heat exchanger (1) has a plurality of stacked disk packages (12) each with a second flow channel (5) arranged therebetween,  - That the leakage channel (10) and / or the leakage space (1 1) a  Fluid disk (9) has a first opening (17),  - That a plurality of opposing cover plates (7,8) of two adjacent disc packages (12) each having a second opening (19), wherein between the second openings (19) has a  Leakage bushing (20) for forming an outlet channel (18), in particular a leakage outlet channel (18) is arranged. 6. evaporator heat exchanger according to claim 5,  characterized,  that the first opening (17) with the leakage bush (20) is directly connected. 7. evaporator heat exchanger according to one of claims 4 to 6, characterized,  in that a plurality of cover plates (7, 8) each have a third opening (21) for the passage of the working medium (2) through the first flow channel (4), the third openings (21) between them  opposite cover plates (7,8) of two adjacently arranged disk packs (12) each by a fluid sleeve (22) are interconnected and the fluid sleeve (22) has an at least partially circumferential, from the first flow channel (4) separate fluid sleeve annular channel (23) with the leakage channel (10) and / or the leakage space (1 1) of the fluid disc (9) of the disc package (12) is connected. 8. evaporator heat exchanger according to claim 6 or 7,  characterized,  in that the housing (3) has a housing opening which has a housing cover bushing (20, 27) with the first and / or second opening (17, 19) in the cover plate (7, 8) of a disk pack arranged adjacent to the housing (3) (12) is connected. 9. evaporator heat exchanger according to claim 8,  characterized,  in that the housing cover bushing (27) and all other leakage bushes (20) form the outlet channel (18) for the passage of the fluid, wherein a line (28) can be attached to the housing cover bushing (27) in the surroundings or periphery, which has a sensor (29). which is designed to measure the pressure and / or the flow and / or a chemical composition of the fluid in the conduit (28). 10. evaporator heat exchanger according to one of claims 4 to 9, characterized, - That in the second flow channel (5) between each two  Disk packages (12) a rib structure (13) is arranged, and / or  - That the fluid disc (9) between two cover plates (7,8) soldered and / or welded. Steamer heat exchanger according to claim 9 or 10, characterized, in that a control and / or regulating device (30) is provided which is used to evaluate a signal detected by the sensor (29), in particular the pressure, the flow and / or the chemical composition of the fluid in the line (28) and Control / regulation of a working medium (2) pump and / or an exhaust gas recirculation valve is formed in response to the detected signal. *****