Refrigeration circuit device and method for operating such a refrigeration circuit device

Description

[0001] The invention relates to a refrigeration circuit device according to the preamble of claim 1 and a method for operating such a refrigeration circuit device according to claim 7.

[0002] A refrigeration cycle device of the type mentioned above is known from document EP 2 083 229 B1. It consists of a compressor for compressing a refrigerant, wherein – viewed in the direction of refrigerant flow – a condenser is connected downstream of the compressor, a first expansion device to the condenser, a heat exchanger to the first expansion device, a second expansion device to the heat exchanger, an evaporator to the second expansion device, and the compressor is connected downstream of the evaporator, the heat exchanger being connected to an electronic device to be cooled. In this solution, the first expansion device is designed as a fixed throttle and the second expansion device as a variable throttle.The stipulation "in the further course of events" means (and also in the following) that the evaporator is optionally connected to the compressor directly or via one or more intermediate components such as a liquid separator.

[0003] The invention is based on the objective of improving a refrigeration circuit device of the type mentioned above, as well as the method for its operation. In particular, a refrigeration circuit device is to be created in which the so-called suction gas temperature, i.e., the temperature of the refrigerant drawn in by the compressor, can also be influenced.

[0004] This problem is solved in the present case by a refrigeration circuit device of the type mentioned above, by the features listed in the characterizing portion of claim 1. The process engineering features for solving this problem are listed in claim 7.

[0005] According to the invention, the heat exchanger for the additional transfer of heat to the refrigerant is designed as an internal heat exchanger and has a primary side connected to the first and second expansion units on one side and a secondary side connected to the evaporator on one side and the compressor on the other. In process terms, the temperature of the electronic device, preferably a frequency converter, is selectively controlled by means of the first and / or second expansion unit. These provisions ensure that the dew point at the electronic device is not undershot and that the maximum permissible temperature of the electronic device is not exceeded.

[0006] In other words, the refrigeration circuit device according to the invention is characterized by the fact that the heat exchanger, designed as a so-called "internal heat exchanger," is now simultaneously configured to exchange heat with both the electronic device to be cooled and the refrigerant flowing from the evaporator to the compressor. More precisely, an "internal heat exchanger" is understood to be a heat exchanger in which energy is transferred from the condensed refrigerant (refrigerant condensate) to the refrigerant (suction gas) drawn in by the compressor for suction gas temperature control.

[0007] Other advantageous embodiments of the refrigeration circuit device according to the invention and of the method for its operation are set out in the dependent patent claims.

[0008] For the sake of completeness, reference is also made to document DE 11 2015 003 005 T5. Document D1=DE 11 2015 003005 T5 discloses a refrigeration circuit device with the features according to the preamble of claim 1.

[0009] However, this solution lacks the electronic device to be cooled on the inner heat exchanger; it should also be noted that, due to the foreseeable high complexity of the control system, this solution would not encourage a person skilled in the art to place an electronic device to be cooled on the inner heat exchanger.

[0010] Reference is also made to the documents US 2006 / 0080989 A1, DE 102 39 877 A1, JP H02-73562 U and US 2019 / 0257562 A1.

[0011] According to the present invention, the above-mentioned objective is achieved by the features of claim 1 and claim 7. Preferred embodiments are defined in the dependent claims.

[0012] The refrigeration circuit device according to the invention, including its advantageous further developments according to the dependent claims, is explained in more detail below with reference to the graphic representation of various exemplary embodiments.

[0013] It shows schematically Figure 1 shows a first embodiment of the refrigeration circuit device according to the invention with adjustable expansion devices; Figure 2 shows, in part, a second embodiment of the refrigeration circuit device according to the invention with an additional expansion device; and Figure 3 shows, in part, a third embodiment of the refrigeration circuit device according to the invention with a non-adjustable or fixed second expansion device.

[0014] The refrigeration cycle device shown in the figures consists in a known manner of a compressor 1 for compressing a refrigerant, wherein - viewed in the direction of flow of the refrigerant - a condenser 2 is connected to the compressor 1, a first expansion device 3 to the condenser 2, a heat exchanger 4 to the first expansion device 3, a second expansion device 5 to the heat exchanger 4, an evaporator 6 to the second expansion device 5 and the compressor 1 is connected further downstream of the evaporator 6, wherein the heat exchanger 4, preferably its primary side 4.1, is connected to an electronic device 7 to be cooled.

[0015] As from Figure 1As can be seen, it is particularly preferred that a switching valve 10, preferably a 4-2-way valve, is provided for switching between heating and cooling operation (i.e., two operating modes in which the refrigeration circuit device can be operated). This switching valve is connected to both a pressure side 1.1 and a suction side 1.2 of the compressor 1. In the Figure 1 In the switching position of the changeover valve 10 shown, which is hereinafter referred to as operating mode I, the condenser is assigned reference numeral 2 and the evaporator reference numeral 6, as indicated above. After switching the switching valve 10 (hereinafter referred to as operating mode II), the heat exchanger with reference numeral 6 then becomes the condenser and, correspondingly, the heat exchanger with reference numeral 2 becomes the evaporator.

[0016] Whether operating mode I is described as heating or cooling mode ultimately depends only on the direction in which the heat transfer occurs or is intended to occur. For the sake of simplicity – and also due to the symmetrical design of the refrigeration circuit device according to the invention – operating mode I will be equated with heating mode and operating mode II with cooling mode.

[0017] Essential to the refrigeration circuit device according to the invention, and this applies to all illustrated and conceivable embodiments, is that the heat exchanger 4 is designed as an internal heat exchanger for the additional transfer of heat to the refrigerant and has a primary side 4.1 connected on one side to the first and on the other side to the second expansion device 3, 5, and a secondary side 4.2 connected on one side to the evaporator 6 and on the other side to the compressor 1. It is particularly preferred that the heat exchanger 4 is designed as a plate heat exchanger (see also https: / / de.wikipedia.org / w / index.php?title=Plattenw%C3%A4rme%C3%BCbertrager&ol-did=199812395), wherein the (relatively warm) primary side 4.1 of the heat exchanger 4 is formed by external channels of the plate heat exchanger to prevent condensation; and the secondary side 4.2 is thus arranged internally.Or in other words: In heat exchanger 4, the "hot side" is on the outside.

[0018] In procedural terms, it is accordingly provided that the temperature of the electronic device 7 is optionally regulated by means of the first and / or second expansion device 3, 5.

[0019] As can be seen from the figures, there are various ways to practically implement these guidelines.

[0020] In the solution according to Figure 1 It is preferably provided that the first and second expansion devices 3, 5 are designed to be controllable.

[0021] In the solutions according to the Figures 2 and 3 It is preferably provided that an additional expansion device 8 (preferably also controllable) is arranged parallel to the heat exchanger 4 and between the condenser 2 and the evaporator 6. In the solution according to Figure 2All expansion devices 3, 5 and 8 are controllable, according to the solution. Figure 3 The expansion devices 3 and 8. The second expansion device 5 is designed to be fixed or unregulated. Alternatively, it can also be provided (which is not shown separately) that the expansion devices 5 and 8 are designed to be adjustable and the expansion device 3 to be fixed. Or, in other words: It is preferably provided that the additional expansion device 8 is adjustable and optionally the first or second expansion device 3, 5 is designed to be fixed or unregulated. Or, expressed in terms of the process: It is preferably provided that the temperature of the electronic device 7 is controlled optionally by means of the first or the second expansion device 3, 5 and by means of an additional expansion device 8 arranged parallel to the heat exchanger 4 and between the condenser 2 and the evaporator 6.

[0022] Further with reference to Figure 1 , however this also applies to the embodiments according to Figure 2 and 3 It is further preferably provided that, in the selected switching position (operating mode I) of the switching valve 10 and viewed in the direction of refrigerant flow, a liquid separator 9 is arranged between the evaporator 6 and the secondary side 4.2 of the internal heat exchanger 4. In other words, it is preferably provided that the refrigerant evaporated at the evaporator 6 is first fed to a liquid separator 9 and then to the secondary side 4.2 of the internal heat exchanger 4. Starting from the other operating mode, i.e., operating mode II, the liquid separator 9 is then naturally arranged between the heat exchanger 2, which is acting as an evaporator, and the secondary side 4.2 of the internal heat exchanger 4.

[0023] As from Figure 1As can be seen, such a liquid separator consists of a container which is connected at its lower end to the evaporator 6 (or, in operating mode II, to the condenser). Furthermore, a U-shaped tube is provided, which has an opening at one free end and at its lowest point. Its other free end is connected to the secondary side 4.2 of the internal heat exchanger 4. Refrigerant vapor is drawn in through the opening at the free end. The opening at the lowest point serves to extract the mixture of refrigerant and oil that has settled in the container and supply it to the compressor for lubrication.

[0024] According to another embodiment, which is not shown separately, it is preferably provided that the refrigerant is supplied to a liquid separator 9 arranged between the compressor 1 and the first expansion device 3, i.e., is arranged on the so-called high-pressure side of the refrigeration circuit.

[0025] Furthermore, it is preferably provided that, during heating operation, either the first expansion device 3 and / or the second expansion device 5 are optionally regulated to a suction gas superheat of 5 to 15 K. This ensures that the dew point at the electronic device and the minimum oil temperature are not undershot and that, at the same time, the oil sump temperature is not exceeded.

[0026] Looking at it in more detail, it is even particularly preferred that, especially in heating operation, the first expansion device 3 and / or the second expansion device 5 are optionally controlled depending on the speed of the compressor 1 for suction gas temperature control.

[0027] With regard to this speed dependency, it is particularly preferred that, at a low speed of the compressor 1 in heating mode, either the first expansion device 3 and / or the second expansion device 5 are selectively controlled to a suction gas superheat of 10 to 15 K. At a higher speed of the compressor 1 in heating mode, it is alternatively preferred that either the first expansion device 3 and / or the second expansion device 5 are selectively controlled to a suction gas superheat of 5 to 10 K.

[0028] Finally, it is preferably provided that, in order to prevent the dew point from being undershot or condensation from forming during cooling operation, in which the maximum oil sump temperature cannot be exceeded, the expansion device 5 (see Figure 1) or 8 (see Figure 8) upstream of the heat exchanger 4 in the direction of refrigerant flow is designed to prevent maximum suction gas superheating. Figure 3 ) is fully opened. The embodiment according to Figure 2 is rather unsuitable for cooling operation; in the embodiment according to Figure 3 The expansion device 3, arranged between the heat exchanger 4 and the heat exchanger which then acts as an evaporator, is almost completely closed.

[0029] For the sake of completeness, the functionality of the [system / device] will be explained in conclusion. Figure 1The refrigeration circuit device shown is explained in both operating modes (apart from the additional expansion device 8, this applies accordingly to the embodiments according to Figure 2 and 3 As already explained, this shows Figure 1Operating mode I, in which the heat exchanger designated with reference numeral 2 operates as a condenser. In this operating mode, the refrigerant is first compressed by the compressor 1 and conveyed to a first flow path of the changeover valve 10 and then to the condenser 2. Once there, the refrigerant condenses and releases heat. It then flows to the first expansion unit 3, where it is reduced to a lower pressure. At the heat exchanger 4, heat is transferred from the electronic unit 7 to the refrigerant flowing from the first expansion unit 3 through the primary side 4.1 of the heat exchanger 4. Simultaneously, heat is transferred from the primary side 4.1 of the heat exchanger 4 to its secondary side 4.2, which will be discussed in more detail below. After the primary side 4.1...The refrigerant then enters the second expansion unit 5, where it is further reduced to an even lower pressure. Afterwards, the refrigerant flows to the evaporator 6, where heat is supplied to it, causing it to partially evaporate. Following the evaporator 6, the refrigerant enters the second flow path of the changeover valve 10 and from there to the liquid separator 9, which has already been described in more detail above. From there, the essentially vaporous refrigerant flows to the secondary side 4.2 of the heat exchanger 4, where, as mentioned above, it absorbs heat from the primary side 4.1 of the heat exchanger 4. Depending on the position of the expansion valves 3 and 5, this results in advantageous suction gas superheating of the refrigerant subsequently flowing to the compressor 1.

[0030] If only the changeover valve 10 is switched to the other operating mode (here cooling mode), the refrigerant after the compressor 1 no longer flows to the heat exchanger (formerly condenser) 2 at the changeover valve 10, but directly to the heat exchanger 6, which now operates as a condenser. The second expansion unit 5, the primary side 4.1 of the heat exchanger 4, the first expansion unit 3 and the heat exchanger with reference numeral 2, which then operates as an evaporator, are then traversed in the opposite direction until the refrigerant reaches the changeover valve 10 again and from there is directed to the liquid separator 9, in order to then, after passing through the secondary side 4.2 of the heat exchanger 4, also return to the compressor. Reference symbol list

[0031] 1 Compressor 1.1 Pressure side 1.2 Suction side 2 Condenser 3 First expansion device 4 Internal heat exchanger 4.1 Primary side of the internal heat exchanger 4.2 Secondary side of the internal heat exchanger 5 Second expansion device 6 Evaporator 7 Electronic device 8 Auxiliary expansion device 9 Liquid separator 10 Diverter valve

Claims

1. A refrigeration circuit device, comprising an electronic device (7) and a compressor (1) for compressing a refrigerant, wherein - in each case as viewed in the flow direction of the refrigerant - a condenser (2) is connected downstream of the compressor (1), a first expansion device (3) is connected downstream of the condenser (2), a heat exchanger (4) is connected downstream of the first expansion device (3), a second expansion device (5) is connected downstream of the heat exchanger (4), an evaporator (6) is connected downstream of the second expansion device (5) and the compressor (1) is later connected downstream of the evaporator (6), wherein the heat exchanger (4) is configured as an internal heat exchanger for the additional transfer of heat to the refrigerant, and comprises a primary side (4.1) which is connected on the one hand to the first expansion device (3) and on the other hand to the second expansion device (5), and a secondary side (4.2) which is connected on the one hand to the evaporator (6) and on the other hand to the compressor (1), characterized in that the heat exchanger (4) is configured so as to be connected to the electronic device (7) that is to be cooled.

2. The refrigeration circuit device according to claim 1, characterized in that the first and second expansion devices (3, 5) are configured to be controllable.

3. The refrigeration circuit device according to claim 1 or 2, characterized in that an additional expansion device (8) is arranged parallel to the heat exchanger (4) and between the condenser (2) and the evaporator (6).

4. The refrigeration circuit device according to claim 3, characterized in that the additional expansion device (8) is configured to be controllable.

5. The refrigeration circuit device according to claim 1 and 3, characterized in that the additional expansion device (8) is configured to be controllable and selectively the first or second expansion device (3, 5) are configured to be uncontrollable.

6. The refrigeration circuit device according to one of claims 1 to 5, characterized in that the heat exchanger (4) is configured as a plate heat exchanger.

7. A method for operating a refrigeration circuit device according to claim 1, characterized in that the temperature of the electronic device (7) is selectively controlled with the aid of the first and / or second expansion device (3, 5).

8. The method according to claim 7, characterized in that the temperature of the electronic device (7) is selectively controlled with the aid of the first or the second expansion device (3, 5) and with the aid of an additional expansion device (8) arranged parallel to the heat exchanger (4) and between the condenser (2) and the evaporator (6).

9. The method according to claim 7 or 8, characterized in that the refrigeration circuit device is selectively operated in heating mode or cooling mode.

10. The method according to claim 9, characterized in that in cooling mode, the expansion device (5, 8) is fully opened for maximum suction gas superheat.

11. The method according to claim 9, characterized in that in heating mode, the first expansion device (3) and / or the second expansion device (5) are selectively controlled for a suction gas superheat of 5 to 15 K.