EP2135025B1 - Heat exchanger for evaporating a liquid portion of a medium having a bypass for an evaporated portion of the medium - Google Patents

Description

The invention relates to a heat exchanger as an evaporator, as used in particular for a heating or air conditioning system for motor vehicles, according to the preamble of claim 1. Such a heat exchanger is off FR 1 510 961 known. Although the invention hereinafter refers to the evaporator of a heating or air conditioning system for motor vehicles, it should be noted that this purpose is not restrictive, but that the heat exchanger according to the invention can also be used in other air conditioning systems and the like.

Heat exchangers are known in which the two-phase refrigerant is distributed from an inlet chamber to a flow-through device, preferably tubes, in particular flat tubes. After flowing through the flat tubes, the vaporous refrigerant exits through an outlet chamber from the evaporator.

In this case, the uniform distribution of the liquid refrigerant in the entire length of the inlet chamber presents difficulties. The reason for this is among other things the formation of different flow forms depending on the operating condition. Furthermore, the segregation of the two-phase refrigerant mixture which is homogeneous at the time of evaporator entry also plays a special role over the length of the inlet chamber. Individual pipes are thus supplied exclusively with refrigerant vapor, whereby the evaporator performance deteriorates.

It is therefore desirable to uniformly distribute the liquid refrigerant to the tubes and effectively combat segregation of the biphasic refrigerant.

In the layout DE 24 36 733 the tubes of a falling-film evaporator extend beyond the tubesheet. Above the tube bottom a collecting space is provided. In the bottom of this collecting space distribution pipes are arranged, which are extended downwards so that they protrude into the liquid space between the tubes of the falling-film evaporator. Thus, the tubes of the falling-film evaporator should be supplied evenly with an overflow liquid.

The DE 195 15 527 A1 shows an evaporator having a distributor which divides the refrigerant via an output-side flow connection to the inlet openings of a plurality of parallel connected flat tubes. The flow connection, which consists of a plurality of channels, opens into a housing which forms a plurality of closed chambers by inserted partitions.

However, the construction of such evaporators is relatively complicated and therefore expensive.

The FR 1 510 961 B discloses a radiator in which a by-pass between the inlet-side header tank and the outlet-side header tank.

It is an object of the invention to provide an improved heat exchanger in which a uniform distribution of the liquid refrigerant to individual flat tubes is possible.

This object is achieved by a heat exchanger with the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

According to a basic concept of the invention, a heat exchanger with at least one inlet chamber, at least one communicating with the inlet chamber, of a first medium as a refrigerant, preferably R134a, R744 or other, can be flowed through and flowed around by a second medium flow device for evaporation of a liquid part of the first medium, wherein the inlet chamber is provided with at least one by-pass for a vaporous part of the first medium to bypass the at least one flow-through device.

By this configuration it is achieved that the vapor phase is at least partially sucked out of the inlet chamber. The hydraulic diameter of the by-pass opening is preferably determined so that, largely independent of the load case, the vapor phase is withdrawn from the inlet chamber.

In an advantageous embodiment of the invention, the bypass is connected to an outlet chamber, so that the vapor phase can be sucked directly from the evaporator. Such a configuration additionally reduces the refrigerant side pressure loss via the flow device and thus increases the performance of the evaporator.

In a further advantageous embodiment of the invention, at least one by-pass is provided with a valve, so that a load-case-dependent adjustment of the hydraulic diameter of the by-pass can be realized because with a solid by-pass cross-section sometimes there is a risk that some liquid drops be carried away.

In an alternative embodiment of the invention, at least one by-pass is connected to an intermediate chamber, so that drops of liquid entrained by the by-pass are nevertheless vaporized and thus contribute to increasing the cooling capacity.

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.

It is advantageous that at least one by-pass is tubular.

It is advantageous that the inlet chamber has at least one by-pass at one end.

It is advantageous that at least one by-pass is spaced from both ends.

It is advantageous that the medium flowing through the throughflow device is a refrigerant, preferably R744, R134a or others.

It is advantageous that the flow-through device consists of tubes, in particular flat tubes.

Heat exchanger according to one of the preceding claims, characterized in that the flow-through device consists of discs.

It is advantageous that ribs, preferably corrugated ribs, are arranged between the tubes and / or discs.

It is advantageous that the inlet chamber and / or the outlet chamber and / or the intermediate chamber is formed as a tube and / or as a box.

The features of the present invention will become apparent from the following detailed description taken in conjunction with the claims and the drawings.

Hereinafter, preferred embodiments of a heat exchanger according to the invention will be described and explained in more detail with reference to the accompanying drawings.

• Fig. 1 eine Explosivdarstellung eines Ausführungsbeispiels eines Wärmeübertragers gemäß vorliegender Erfindung,
• Fig. 2a, 2b, 2c, 2e und 2f eine nicht erfindungsgemäße Verschaltungsvarianten eines Wärmeübertragers,
• Fig. 2d eine erfindungsgemäße Verschaltungsvariante eines Wärmeübertragers,
• Fig. 3 eine Explosivdarstellung eines weiteren Ausführungsbeispiels eines Wärmeübertragers gemäß vorliegender Erfindung, und
• Fig. 4 eine schematische Perspektivdarstellung eines nicht erfindungsgemäßen Wärmeübertragers.

Show it:

• Fig. 1 an exploded view of an embodiment of a heat exchanger according to the present invention,
• Fig. 2a, 2b, 2c, 2e and 2f a non-inventive Verschaltungsvarianten a heat exchanger,
• Fig. 2d a Verschaltungsvariante invention of a heat exchanger,
• Fig. 3 an exploded view of another embodiment of a heat exchanger according to the present invention, and
• Fig. 4 a schematic perspective view of a heat exchanger not according to the invention.

For identical or similar components, the same reference numbers are used in the drawings.

Fig. 1 shows a heat exchanger 1, in particular an evaporator for an automotive air conditioning system, according to an embodiment of the present invention in an exploded view. Such a heat exchanger has at least one inlet chamber 2, via which the refrigerant is supplied to the evaporator from a refrigerant circuit, not shown, via an inlet opening 18 (indicated by arrow A). The inlet chamber 2 is elongate and bounded by two ends. According to Fig. 1 the inlet opening 18 is positioned at one end of the inlet chamber. According to a variant, not shown, the inlet opening can be positioned at a distance from both ends.

Furthermore, the heat exchanger 1 has a collector 12, which consists of an injection plate 5, a distributor plate 6 and a bottom plate 7. By this collector, the refrigerant to the tubes 8, preferably flat tubes, which are designed for example as a multi-chamber tubes supplied.

In one embodiment, not shown, the flow device 8 consists of discs.

In an embodiment not shown, the tubes 8 protrude into the inlet chamber in order to achieve an even liquid distribution to the tubes in an overflow.

Thermally conductive ribs, preferably corrugated ribs, are arranged between the tubes and can be flowed around by a medium, preferably air L (indicated by an arrow).

The tubes, as well as the holes of the bottom plate 7 are divided in the middle by a web (not shown), so that two flow regions 14 and 15 are formed, which passes through the refrigerant in the opposite direction.

Therefore, the refrigerant flows through first, following the arrow B, a flow region 14, is then through an intermediate chamber 13, which consists of a bottom plate 9, a baffle plate 10 and a cover plate 11, following the arrow C, deflected and flows through a flow region 15 in opposite direction, following the arrow D, in the collector 12, Preferably, the flow area 15 of the inflowing air L faces.

In the injection plate 5 of the collector 12 a plurality of injection holes 16 are provided, so that the refrigerant from the inlet chamber 2 can flow into the flow area 14. Furthermore, suction holes 17 are provided in the injection plate 2, so that the refrigerant can flow from the flow area 15 into the discharge chamber 3. About the outlet chamber 3, the refrigerant then passes into a refrigerant circuit, not shown (shown by arrow E). The injection and / or suction bores can be provided in the injection plate and / or inlet chamber.

The inlet chamber 2 and / or the outlet chamber 3 are designed as a tube. It is also possible to carry out the inlet chamber and / or the outlet chamber as a box. In this case, the inlet chamber and outlet chamber are formed from formed sheets, wherein the cross-section of a chamber is preferably D-shaped. It is also possible that inlet chamber and outlet chamber are formed from a formed sheet metal.

In one embodiment, not shown, the collector is a part of the inlet chamber and / or the outlet chamber.

In a further embodiment, not shown, the inlet chamber and the outlet chamber is arranged on the same side of the heat exchanger.

Furthermore, the heat exchanger 1 has a by-pass 4 between inlet chamber 2 and outlet chamber 3. According to Fig. 1 the By-pass is connected at the inlet 19 opposite the inlet end 18 of the inlet chamber to the outlet chamber.

The hydraulic diameter of the by-pass is set such that, largely independent of the load case of the heat exchanger, the vapor phase is withdrawn from the inlet chamber and the liquid phase is fed to the tubes 8. The load case (for example, full load or partial load) provides information about the operating point of a heat exchanger and thus about the injected amount of fluid in the heat exchanger.

In an embodiment, not shown, the by-pass is provided with a valve that can adjust the hydraulic diameter of the by-pass depending on the load.

In the Fig. 2a to 2c, 2e and 2f are not possible Verschaltungsvarianten invention of a heat exchanger and in Figure 2d an interconnection variant according to the invention is shown according to the present invention. By way of example, the heat exchanger in the embodiments 2a to 2f each have four suction holes 17 and injection holes 16, each supplying one or more tubes on. In one embodiment, not shown, a heat exchanger has up to 45 injection holes and suction holes.

According to Fig. 2b, Fig. 2d and Fig. 2f the entry of the fluid F into the heat exchanger (represented by an arrow) and the exit of the fluid from the heat exchanger (represented by an arrow) can take place on the same side. It is also possible, depending on the operating conditions of the heat exchanger, to arrange the inlet and outlet of the fluid F advantageously on opposite sides of the heat exchanger.

The by-pass 4 can according to Fig. 2a and Fig. 2b connect the end of the inlet chamber to the outlet 20 of the heat exchanger.

In an embodiment, not shown, it is possible that the by-pass connects the end of the inlet chamber with a portion of the refrigerant circuit, which is located between the output 20 of the heat exchanger and a pressure sink of the refrigerant circuit.

It is advantageous depending on the operating conditions of the heat exchanger, as in the embodiments according to Fig. 2c and Fig. 2d shown when the By-pass connects the end of the inlet chamber with the end opposite the outlet of the outlet chamber and thus the outlet 20 of the heat exchanger.

In the examples Fig. 2a to Fig. 2d the by-pass is tubular.

In two other examples according to the FIGS. 2e and 2f three By-pass 4 are formed by crossover to the exit chamber. At least one passage is spaced from both ends of the inlet chamber. The crossover are formed as overflow or in adjacent pipes as openings, which connect the inlet chamber and outlet chamber communicating.

Fig. 3 shows an example of a heat exchanger. This heat exchanger is constructed similar to the heat exchanger according to Fig. 1 , However, by-pass 4 is connected to an intermediate chamber 13 in this embodiment. By this arrangement it is achieved that liquid drops, which are entrained by the by-pass opening, the intermediate chamber 13 and subsequently the tubes 8 can be supplied. The liquid drops can therefore be evaporated in the flow region 15 and thus contribute to the cooling capacity.

Fig. 4 shows a further non-inventive embodiment of a heat exchanger. In this embodiment, a heat exchanger is shown in Mehrblockverschaltung. In such an arrangement, the fluid, preferably a refrigerant, is deflected at least twice, preferably several times.

According to Fig. 4 For example, a liquid phase entrained with the gas phase is withdrawn through the by-pass 4 from the 3rd block and returned to the 6th block to evaporate therein. Preferably, it is also possible to withdraw refrigerant from one of the other first blocks (for example, the first or second block) by means of a by-pass, to supply it to the heat exchanger in a later block again.

Claims (10)

1. A heat exchanger (1) with at least one inlet chamber (2), at least one throughflow device (8) which is communicatively connected to the inlet chamber and through which a first medium can flow and around which a second medium can flow, wherein at least one bypass communicatively connects the inlet chamber to an outlet chamber (3) of the heat exchanger, wherein the heat exchanger is designed for an evaporator, the throughflow devices are intended for an evaporation of a liquid part of the first medium, the inlet chamber (2) is provided with the at least one bypass (4) for a vaporous part of the first medium in order to bypass the at least one throughflow device and wherein the inlet chamber and the outlet chamber are arranged on the same side of the heat exchanger, wherein the inlet chamber is designed in a longitudinal fashion with two ends, characterised in that at least one bypass is arranged on the end which is further away from the inlet of the inlet chamber.
2. The heat exchanger according to claim 1, characterised in that at least one bypass is designed as a breakthrough in the inlet chamber.
3. The heat exchanger according to claim 1 or 2, characterised in that at least one bypass has a valve.
4. The heat exchanger according to claim 3, characterised in that an adjustment of the hydraulic diameter of the bypass depending on the load case can be realised through the valve.
5. The heat exchanger according to one of the preceding claims, characterised in that the tubes are inserted into the inlet chamber.
6. The heat exchanger according to claim 5, characterised in that the tubes protrude into the inlet chamber with or without an overhang.
7. The heat exchanger according to one of the preceding claims, characterised in that a collector connects the inlet and/or outlet chamber with the throughflow device.
8. The heat exchanger according to claim 7, characterised in that the inlet and/or outlet chamber is a component of the collector.
9. The heat exchanger according to claim 7, characterised in that the inlet and/or outlet chamber is communicatively connected to the collector via bores.
10. The heat exchanger according to claim 9, characterised in that the bores are arranged in the collector and/or in the inlet chamber and/or in the outlet chamber.

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