EP1724536A2 - Heat exchanger with accumulator - Google Patents

Abstract

The apparatus has a longitudinal vessel connected to a collecting tube of a heat exchanger, and defining a heat exchanger chamber and an accumulator chamber. The chambers extend parallel over a portion of the length of the vessel. A flat multi-chamber tube is extruded to extend straight over the length of the vessel, where refrigerant on one side flows through the tube and refrigerant on another side flows through the vessel. A heat-conducting rib extends around a periphery of the tube, and fills up the remaining cross-section of the heat exchanger chamber.

Description

The invention relates to a device for the treatment of the refrigerant, which in a

Air circulating circulates, comprising: compressor, gas cooler, evaporator (heat exchanger) and expansion element and thereby passes through a high pressure side and a low pressure side, in which the refrigerant has different temperature, the device having a tube through which flows the one side and in a container is arranged, through which the other side flows to serve as an intermediate heat exchanger, wherein in the container, an accumulator chamber and a heat exchanger chamber is formed.

This device, which is often referred to as an internal heat exchanger in trans-critical air conditioning circuits, is from the DE 196 35 454A1 is known and can be considered advanced, because the achievable heat exchange rate meets the requirements and because it also includes a Akkumulatorkammer. However, the fabrication of this device - lying in the installation space of the motor vehicle - seems to be rather expensive, since the tubes are deformed as spirals and the insertion of the heat-conducting fins between the turns of the coils could also be complicated.

In the DE 103 22 028 B4 an intermediate heat exchanger was integrated as a coaxial tube in the manifold of the evaporator, creating a very compact design was created, which is apparently also cheaper to produce, but which has no accumulator.

In the German patent DE 199 18 617 C2 were an accumulator and - separately - and an internal heat exchanger combined with the gas cooler, creating a very compact design was created. The accumulator is connected to a manifold of the gas cooler. The inner heat exchanger is located at the upper or lower edge of the gas cooler, ie parallel to the tubes, and thus directly in the influence of the cooling air, which has a temperature of about 30 - 40 ° C in summer, whereby the intended effect of the inner heat exchanger is counteracted , The degree of intended cooling of the refrigerant on the high pressure side is somewhat reduced by the relatively high temperature of the cooling air. The inner heat exchanger is also quite expensive to produce. Its connection with the gas cooler also seems to be structurally difficult to carry out.

The object of the invention is to propose with other design features comparable in terms of compactness and functionality device that can be produced cheaper.

The solution according to the invention results in the device according to the preamble of claim 1 by the features in its characterizing part.

Because, according to the invention, the container containing the tube is connected to the manifold of the heat exchanger, preferably the gas cooler, to a structural unit, wherein the accumulator chamber and the heat exchanger chamber present in the container extend parallel to the manifold and over a substantial portion of the length of the container achieved a good result in terms of compactness. At the same time, the favorable possibility of arranging a dryer and optionally also a filter in the accumulator chamber and / or the heat exchanger chamber of the container, since the space available for this measure is sufficient. The filter and dryer ensure the desired drying and cleaning (treatment) of the transcritical refrigerant, which can be CO2, for example.

The accumulator serves the functionality of the system, since it contributes to the fact that only vaporous refrigerant reaches the compressor and thereby ensures its proper operation.

This is not precluded that the vaporous refrigerant shortly before leaving the heat exchanger chamber in the direction of the compressor via an opening in the longitudinal wall small amounts of oil and liquid refrigerant are supplied. At this point, the refrigerant vapor is in such a state that the supply of oil and liquid refrigerant results in further cooling by evaporative cooling. The vaporous state of the refrigerant at the compressor is thereby assisted and the refrigerant inlet temperature at the compressor is lowered again. In the above-mentioned prior art, the refrigerant must overcome a more or less large slope after the return of the oil, resulting in losses. According to the present invention, the recirculation is made bypassing the inner heat exchanger directly into the suction line, whereby a more favorable heat transfer is present.

The mentioned tube is preferably an extruded multi-chamber tube that extends substantially straight over at least one extends substantial length of the container, whereby, inter alia, the relatively inexpensive production of the device is effected. Preferably, the multi-chamber tube is covered around its entire circumference with the heat exchange rib.

A longitudinal wall is formed in the container, which divides the container into two parts, namely an accumulator chamber and a heat exchanger chamber. The longitudinal wall has at least one opening at one end to allow the refrigerant to flow from the accumulator chamber into the heat exchanger chamber. At the other end of the longitudinal wall, another opening is provided, via which accumulated in the accumulator oil can get into the refrigerant.

In the accumulator chamber, a drying agent and also a filter can be arranged. An inlet tube is disposed in the accumulator chamber to assist in the settling of any liquid refrigerant present in the low pressure phase. In or on the introduction tube, the dryer can be located and immediately below the filter can be arranged.

A plastic wall can be inserted into the container which suppresses the undesired heat transfer between the accumulator chamber and the heat exchanger chamber. The heat exchange should take place essentially in the heat exchanger chamber, since this was specially equipped for it. Overall, this results in slightly higher temperature differences between the low pressure side and the high pressure side in the heat exchange chamber itself, resulting in improved efficiency of heat exchange.

The independent claim 19 relates to a not with a heat exchanger, preferably the gas cooler, united device, which is rather at a suitable location in the air conditioning circuit and which is particularly inexpensive to produce and has high efficiency.

This device is characterized in that the container is designed as a slender, preferably produced by extrusion hollow body with a longitudinal wall or with holders for holding a longitudinal wall inserted, wherein the longitudinal wall has at least one opening to flow the refrigerant from the accumulator into the heat exchanger chamber and that the tube is formed as a preferably produced by the same extrusion process multi-chamber tube which extends through the heat exchanger chamber and is covered on all sides with heat exchange ribs. The device is particularly easy to manufacture and is also characterized by its slim Design that helps to accommodate a conventional air conditioning system and transcritical refrigerant air conditioning system, such as CO2, with substantially the same space requirements, which is a not inconsiderable advantage for automobile manufacturers, who are thus not constrained by their space concepts within a range of Change automobiles depending on the type of air conditioning. With global environmental regulations in mind, automobiles will want to equip one market with conventional air conditioning systems and another with CO2 air conditioning systems.

Hereinafter, some embodiments will be described with reference to the accompanying drawings. This description includes other features and associated benefits that may prove particularly important.

Brief description of the pictures

Fig. 1 shows a longitudinal section through a device according to the invention.

FIG. 2 shows a cross section through the device according to FIGS. 1 or 3.

Fig. 3 shows a longitudinal section in a preferred embodiment of the invention.

Fig. 4 shows an alternative design in a cross section through the container.

Fig. 5 shows a flat multi-chamber tube in a cross section according to another alternative.

Figs. 6, 7 and 8 show different embodiments of the container in cross section.

FIGS. 9-12 show, purely schematically, the connection of the device to a heat exchanger, preferably to the gas cooler.

The devices described in the exemplary embodiments are preferably intended for use in air conditioning systems of motor vehicles in an approximately vertical arrangement.

The device for the treatment of the refrigerant according to FIGS. 1 and 3 differs by the arrangement of a filter 23 in the accumulator chamber 21 and in the heat exchanger chamber 22. They otherwise agree that they have a container 20 with a longitudinal wall 26, the was produced by extrusion. The longitudinal wall 26 divides the container 20 into the two mentioned chambers 21, 22 which extend in parallel and substantially over the entire length of the container 20. In the accumulator chamber 21 is a dryer 24, which in this embodiment, outside a Introducer tube 25 has been arranged. Through the heat exchanger chamber 22 extends a flat multi-chamber tube 10, which is equipped with a heat conducting rib 11 which largely fills the remaining cross section of the heat exchanger chamber 22 in order to achieve good results in terms of heat exchange efficiency can. Furthermore, an insulation 50 was provided in both embodiments, which covers the surface of the container 20 . This measure is particularly suitable where you would like to avoid temperature effects from the environment on the heat exchange in the container 20 . Usually these are too high outside temperatures. The lower-pressure side, cooler refrigerant flows through an opening 40 in the upper lid 80 into the accumulator chamber 21 a. In order to support the accumulator function or the settling of liquid and oil, an introduction tube 25 projects into the accumulator chamber 21 . In the case of FIG. 1, this refrigerant flows through a filter basket 25 at the end of the introduction tube 25. Oil present in the refrigerant and residual liquid refrigerant settle in the accumulator chamber 21 at the bottom. The gaseous refrigerant flows above an inlet opening 31 in the longitudinal wall 26 in the heat exchanger chamber 22 to pass through the heat conducting rib 11 down in the direction of exit 41 , which is arranged in the wall of the container 20 . The high-pressure side and warmer refrigerant flows through a channel 70 in the upper lid 80 in the multi-chamber tube 10 , flows in the multi-chamber tube 10 down to the exit channel 71 in the lower lid 80, after heat release to the low-pressure side refrigerant and further cooled and therefore the performance-improving state of leaving the container 20 toward an expansion device (not shown) and the evaporator. The described direction of flow only serves to understand the figures. It is, moreover, determined in an appropriate manner. Down in the longitudinal wall 26 is a channel 30 and a bore 32 to supply the low-pressure side refrigerant after passing through the heat exchanger chamber 22 in the accumulator 21 settled oil. (FIG. 2) In the exemplary embodiment according to FIG. 3, two flat filter elements 24 have been provided. One of these was placed in front of the channel 30 and the second is located in front of the already mentioned exit 41 in the heat exchanger chamber 22. With this configuration it should be pointed out that the present invention offers greater design freedom for the designer with regard to the placement of such elements the state of the art.

Fig. 4 shows the cross section through the container 20 of another particularly noteworthy embodiment. In some cases, a larger or specially designed accumulator chamber 21 is required, which was achieved according to FIG. 4 in that the flat multi-chamber tube 10 was formed with a shape adapted to the contour of the container 20 and thus extends along part of the container wall. Again, a longitudinal wall 26 was used, which is also adapted to the mentioned contour. On the inside of the container wall there are receiving grooves 27 into which the longitudinal edges of the longitudinal wall 26 can be inserted. The grooves 27 do not limit the manufacturability of the container 20 by means of extrusion molding, ie they can be realized by means of this method. The multi-chamber tube 10 is preferably, but not necessarily, also an extruded tube, for example with two rows of apertures 12. More preferably, this configuration is then made when, as shown in Fig. 5, on the corrugated heat exchange ribs 11 is to be omitted as a single part by the multi-chamber tube 10 is equipped on the outside with rib-like channels. Here, according to a further development not shown, it is also possible to form the longitudinal wall 26 in one piece with the multi-chamber tube 10 , whereby the insertion of a longitudinal wall 26 and the requisite receiving grooves 27 or the like can be dispensed with. In this case all parts are made of metal, for example aluminum. However, it brings certain advantages already mentioned above for the heat exchange with it, when the longitudinal wall 26 is made of a material having a lower thermal conductivity, for example made of plastic, and used.

6, 7 and 8 show further embodiments in cross-section through an extruded container 20 with two longitudinal walls 26, which then form three chambers or compartments in the container 20 . These chambers may be formed according to the desired application as a battery chamber 22 or as a heat exchanger chamber 21 . In the example according to FIG. 6, the middle chamber was designed as a heat exchange chamber 22 and the other two chambers as accumulator chambers 21 . In the heat exchanger chamber 22 is a multi-chamber tube 10 which has already been described above with reference to FIG. 5. FIG. 7 shows another example in which all three chambers are designed as heat exchanger chambers 22 . With the reference numeral 90 was a design option, which is to partially increase the wall thickness of the container 20 in order to form the cross section of the chambers - while maintaining the circular cross-sectional shape of the container 20 - so that the insertion of the tube 10 is facilitated with the heat exchange fin 11 . It can be used in this case conventional corrugated fins 11 , which are spirally wound around the tube 10 . In other cases, such a "uniform" cross-section is also suitable for the collector chamber 21 . In Fig. 8, the "uniformed" cross-section was achieved with another measure, namely a slight deviation from the round container shape, which is still acceptable despite the high pressures in the system. As can be seen from the illustration, four graduations 60 distributed on the circumference of the container 20 have been provided, which result in that the cross section of the upper and the lower heat exchanger chamber 22 can be approximately rectangular. The middle chamber was designed here as an accumulator chamber 21 .

The device described so far was, as shown in the following Fig. 9-12, combined with the gas cooler 3 in order to achieve a particularly compact design of the entire system. The container 20 may in principle be such as shown for example in FIG. 3 and already described above.

As is customary in prior art air conditioning systems with two-phase refrigerant, the container 20 is arranged parallel to and connected to a header 30 of the condenser, here the gas cooler 3 . The difference further consists in that in the prior art it is only a collector, but in the present case an accumulator 21, combined with an internal heat exchanger 22, is connected to the gas cooler 3 . Specifically, in the illustrated embodiment, the container 20 is secured by means of two holders 5 on the manifold 4 . In FIG. 9, the necessary components of the air conditioning circuit at the inflow and outflow points for the low-pressure side ND and the high-pressure side HD refrigerant have been indicated by appropriate labeling. The gas cooler 3 receives high-pressure compressed gaseous HD refrigerant coming from the compressor, which is cooled in the gas cooler 3 by heat exchange with cooling air. The serpentine flow through the gas cooler 3 by groups of parallel flat tubes was indicated by arrows. In the headers 4 of the gas cooler 3 are partitions, the described flow cause. The HD - refrigerant into the heat exchanger chamber 22 occurs in the embodiment immediately, and indeed, as described in the extending through the chamber 22 multi-chamber tube 10 after leaving the gas cooler. 3

In Fig. 9 has been provided to make the passage from the gas cooler 3 to the container 20 by means of a short line 6 from the manifold 4 in the multi-chamber tube 10 . Alternatively, Fig. 12 shows a somewhat more compact design, which consists in that the conduit 6 passes through one of the holders 5 and is connected to the multi-chamber tube 10 . The ND refrigerant coming from the evaporator is in the state of subcooling. It passes through the reaching in the accumulator 21 insertion tube 25 into the accumulator 21 a and passes the dryer 24 and a filter 23 25 at the end of the insertion tube Unlike the previously described embodiments, the opening of the oil is in the longitudinal wall 26 directly in the area of the soil. At the upper end of the longitudinal wall 26, the inflow opening 31 is located for the gaseous ND refrigerant flowing into the heat exchange chamber 22 through the heat exchange fin 11, to flow out downward from the chamber 22 toward the compressor. It is enriched with oil and settled liquid refrigerant, which passes immediately because of the heat absorbed in the heat exchanger in the gaseous state and assumes a lower temperature, whereby the compressor is relieved. FIG. 10 shows, likewise schematically, a section from a plan view of the device according to FIG. 9.

FIG. 11 shows a further development idea, which is that the container 20 produced by extrusion has no integrated longitudinal wall 26 , but was equipped only with receiving grooves 40 . These receiving grooves 40 serve to be able to use a longitudinal wall made of plastic, which is otherwise formed as described. Such a design brings advantages in terms of the efficiency of the heat exchange, and it is executable despite the prevailing high pressure, because there are no significant differences in pressure between the heat exchanger chamber 22 and the accumulator 21 .

In Figs. 9 and 10, an additional plastic longitudinal wall has been added directly to the longitudinal metal wall 26 , as will be apparent from the two parallel lines.

The container 20 of the proposed device is also characterized by its slim design. The ratio of its length L to its diameter D is at least 3: 1, preferably the ratio is about 6: 1.

Claims (26)

1. A device for the treatment of the refrigerant circulating in a transcritical air conditioning circuit comprising: compressor (1), gas cooler (3), evaporator, (heat exchanger) and expansion element while passing through a high pressure side and low pressure side in which the refrigerant has different temperature, the apparatus comprising a flat multi-chamber tube (10) through which one side flows and which is disposed in a container (20) through which the other side flows to serve as an intermediate heat exchanger, wherein in the container (20) an accumulator chamber (21) and a heat exchanger chamber (22) is formed,
characterized in that
the container (20) containing the multichamber tube (10) is connected to a manifold (4) of a heat exchanger (3), the accumulator chamber (21) and the heat exchanger chamber (22) being parallel and at least over a substantial portion of the length of the slender container (20) extend. 2. Apparatus according to claim 1, characterized in that an introduction tube (25) for the low pressure side in the accumulator chamber (21) is arranged. ' 3. Device according to claim 1 and 2, characterized gekenrizeichnet that a dryer (24) is arranged in or on the insertion tube (25). 4. Device according to one of the preceding claims, characterized in that in the container (20) at least one longitudinal wall (26) is arranged, at one end of which at least one inflow opening (31) is present to the low pressure side of the accumulator chamber (21). into the heat exchanger chamber (22) of the container (20) to bring. 5. Device according to one of the preceding claims, characterized in that at the other end of the longitudinal wall (26) has at least one opening (32) for oil contained in the refrigerant. 6. Apparatus according to claim 4 or 5, characterized in that the longitudinal wall (26) preferably outside the center plane of the container (20). is arranged, so that the accumulator chamber (21) is greater than the heat exchanger chamber (22). 7. Device according to one of the preceding claims, characterized in that the inside of the container (20) located in the heat exchanger chamber (22) extends to a partial radius of the same. 8. Device according to one of the preceding claims, characterized in that the container (20) and the flat multi-chamber tube (10) are produced by extrusion. 9. The device according to claim 8, characterized in that the multi-chamber tube extends substantially undeformed by the heat exchanger chamber (22) of the container (20) and at least the largest part of the tube length is provided with heat-conducting ribs (11), preferably the entire remaining cross-section fill the heat exchange chamber (22). 10. Device according to one of the preceding claims, characterized in that the container (20) with or without longitudinal wall (26) is a tube produced by means of extrusion, the ends of which are closed with a lid (80). 10. Device according to one of the preceding claims, characterized in that an insulating plate or the like, adjacent to the longitudinal wall (26), is arranged. 11. Device according to one of the preceding claims 1-9, characterized in that instead of the longitudinal wall, an insulating plate can be inserted into the tube. 12. The device according to claim 11, characterized in that on opposite sides of the tube wall grooves or similar receptacles (27) are formed, in which the insulating plate can be used. 13. Device according to one of the preceding claims, characterized in that the container (20) relative to the through the heat exchanger, preferably through the gas cooler, flowing cooling air flow is shielded. 14. Device according to one of the preceding claims, characterized in that the collecting tube (4) of the heat exchanger, preferably of the gas cooler, and the container (20) are arranged at a small distance from each other and form a structural unit. 16. Device according to one of the preceding claims, characterized in that the container (20) is arranged in the air flow direction behind an air guide plate. 17. Device according to one of claims 1-15, characterized in that the container (20) is provided on its outside at least partially with an insulation (50). 18. Device according to one of the preceding claims, characterized in that in the container (20) one or more filters (23) are provided for the treatment of the refrigerant. 19. An apparatus for treating the refrigerant circulating in a transcritical air conditioning circuit comprising: compressor, gas cooler, evaporator, and expander while passing through a high pressure side and low pressure side in which the refrigerant has different temperature, the device being a flat multi-chambered tube (10) through which the one side flows and which is disposed in a container (20) through which the other side flows to serve as an intermediate heat exchanger, wherein in the container (20) an accumulator chamber (21) and a heat exchanger chamber (22) is formed
characterized in that
the container (20) is designed as a slender hollow body with at least one longitudinal wall (26) or with holders (27) for holding at least one inserted longitudinal wall, wherein the at least one longitudinal wall (26) has at least one opening (31) for allowing the refrigerant to flow through the chambers (21, 22), and wherein the accumulator chamber (21) and the heat exchange chamber (22) extend in parallel and over at least a substantial portion of the length of the slender container (20). 20. The apparatus according to claim 19, characterized in that the flat multi-chamber tube (10) extends longitudinally through the heat exchanger chamber (22) and is filled with heat-conducting ribs (11). 21. The apparatus of claim 19 or 20, characterized in that the inserted longitudinal wall has a lower heat transfer value, for example, consists of plastic. 22. Device according to claims 1 - 21, characterized in that the heat-conducting rib (11) at least largely fills the remaining cross section of the heat exchanger chamber (22). 23. Device according to one of claims 18 - 22, characterized in that the longitudinal wall (26) is arranged outside the median plane of the container. 24. Device according to one of the preceding claims, characterized in that the multi-chamber tube (10) including the heat-conducting fins (11) can be produced as an extruded product. 25. Device according to one of claims 19-24, characterized in that a dryer (24) in the accumulator chamber (21) and preferably also a filter (23) in the container (20) are arranged. 26. Device according to one of the preceding claims, characterized geknnzeichnet that the ratio of the length (L) to the diameter (D) of the container (20) ≥ 3: 1.

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