EP1576321A2

EP1576321A2 - Refrigerant circuit and a refrigerating system

Info

Publication number: EP1576321A2
Application number: EP03789276A
Authority: EP
Inventors: Roland Burk; Peter Geskes; Conrad Pfender
Original assignee: Behr GmbH and Co KG
Current assignee: Mahle Behr GmbH and Co KG
Priority date: 2002-12-16
Filing date: 2003-12-15
Publication date: 2005-09-21
Also published as: US20050229629A1; WO2004055450A2; AU2003293880A1; AU2003293880A8; DE10358944A1; WO2004055450A3; JP2006509991A

Abstract

The invention relates to a refrigerant circuit comprising at least one heat absorption element and at least one heat dissipation element. According to the invention, heat transfer elements carrying out the same function can be operational in the refrigerant circuit at different pressure levels of the refrigerant. A refrigerating system provided with the inventive refrigerant circuit is also disclosed.

Description

BEHR GmbH & Co. KG Mauserstrasse 3, 70469 Stuttgart

Refrigerant circuit and refrigeration system

The invention relates to a refrigerant circuit with heat sensors and heat emitters and a refrigeration system with a refrigerant circuit.

Such refrigerant circuits are used in refrigeration systems, such as air conditioning systems, to transport heat from at least a first spatial area to at least a second spatial area, in particular with a temperature level that is the same or higher than that of the first spatial area. The refrigerant absorbs heat in a heat exchanger operated as a heat exchanger in the first spatial area, is conducted to a heat exchanger operated as a heat transmitter in the second spatial area in order to give off heat there.

In order to enable heat to be transported from a relatively colder to a relatively warmer spatial area, the refrigerant is usually passed through the heat absorber in a relaxed state, i.e. at a reduced temperature, and in a compressed state, i.e. at an elevated temperature, through the heat emitter. For this purpose, the refrigerant circuit comprises a compression element, such as one

BESTATIGUNGSKOPIE Compressor, and a relaxation element, such as an expansion valve, so that the refrigerant flows through the circuit in the sequence compression element - heat emitter - relaxation element - heat absorber.

Condensers are often used as heat emitters, in which the refrigerant condenses by releasing heat energy, the temperature of the refrigerant changing only insignificantly during the phase transition condensation. In an analogous manner, so-called refrigerant evaporators are often used as heat absorbers, in which the refrigerant is evaporated, the temperature of the refrigerant likewise changing only insignificantly during the phase transition evaporation. However, since refrigerant circuits are sometimes operated without phase transitions of the refrigerant, the terms "condenser" and "evaporator" are sometimes misleading and, apart from specific examples, should not be used here.

For a given refrigerant, the temperature levels of a refrigerant circuit mainly depend on the pressure levels, with higher temperatures prevailing on the high-pressure side of the circuit, ie in the direction of flow of the refrigerant after the compression element, than on the low-pressure side after the expansion element. If several heat sensors are to be used in a refrigerant circuit, the pressure conditions on the low-pressure side of the circuit must be adapted to the heat sensor with the lowest desired operating temperature, since this heat sensor could not absorb enough thermal energy at higher temperatures. If a higher temperature is desired or sufficient for a further heat sensor, it is thermodynamically uneconomical to operate this additional heat sensor at a low temperature. The corresponding consideration also applies analogously to heat emitters. It is therefore an object of the invention to provide a refrigerant circuit and / or a refrigeration system in which a plurality of heat absorbers and / or a plurality of heat emitters can each be operated at different temperatures.

This object is achieved by a refrigerant circuit with the features of claim 1 and by a refrigeration system with the features of claim 16.

According to claim 1, a refrigerant circuit has at least one heat receiver, in which heat can be absorbed by a refrigerant, and at least one heat emitter, in which heat can be released by the refrigerant. The object of the invention is advantageously achieved in that a plurality of functionally identical heat exchangers, that is to say a plurality of heat absorbers or a plurality of heat emitters, can be operated at different refrigerant pressures. As a result, the basic idea of the invention, namely to adapt the operating temperatures of several functionally identical heat exchangers to different requirements, can be implemented in a simple manner.

Within the scope of the present invention, heat exchangers with the same function are to be regarded as those heat exchangers which simultaneously perform the same function during operation of the refrigerant circuit, ie either heat transfer from a medium to the refrigerant or from the refrigerant to a medium. As a medium, for example, a liquid, gaseous, supercritical or any other fluid can be considered, such as, for example, a solid or a device, in particular a heat-generating device or combinations thereof. The functional equality of two heat exchangers is not affected by possibly different functions that two or more heat exchangers fulfill carriers at different times, for example in different operating modes of the refrigerant circuit.

Two refrigerant pressure levels are different from one another in the context of the present invention if the difference between the pressure amounts of the individual levels is greater than a pressure drop which usually occurs, for example, along refrigerant lines or heat exchangers. In particular, two hydraulically connected heat exchangers cannot be operated at different refrigerant pressure levels, provided that no conveying or throttling means for the refrigerant are provided in or between the two heat exchangers. A pressure difference caused by a compression element or a relaxation element, on the other hand, is very well suited to generating two different refrigerant pressure levels within the scope of the invention.

Any device that is suitable for conveying refrigerant from one location of a circuit to another location of the circuit with higher pressure, that is to say compressing refrigerant, is referred to as a compression element. Compressors and pumps are examples of compression elements.

Any device that is suitable for generating a pressure drop between one location of a refrigerant circuit and another location of the circuit, that is to say refrigerant, is referred to as a relaxation element. Externally controllable and non-controllable expansion valves and throttles are examples of expansion elements, with each constriction in the refrigerant circuit, for example a tube of small diameter between two heat exchangers, possibly being suitable as a throttle. For a desired constriction, that is to say in this sense suitable as a throttle, a flow diameter reduced by half may be sufficient. In order to achieve a compact design, it is advantageous to structurally combine a compression element and / or a relaxation element with a heat exchanger. For example, a throttle can be easily integrated into a heat exchanger. If a heat exchanger has a plurality of flow paths which are hydraulically connected in series, a throttle integrated in the heat exchanger can also be realized by a reduced number of flow channels which form the first or last flow path of the heat exchanger and are hydraulically parallel to one another.

According to an advantageous embodiment, a first heat sensor, a second heat sensor and a heat emitter can be operated at three different pressure levels, the first heat sensor being able to be operated at higher pressure than the second heat sensor. This ensures two different cooling temperature levels with an independent heat emission temperature. In particular, the first and second heat sensors are connected hydraulically in parallel, each of the two heat sensors having its own expansion element connected upstream and / or downstream, so that the heat sensor can be acted on with refrigerant at different pressure levels. Under certain circumstances, it is sufficient if a relaxation element is connected upstream or downstream of only the first or only the second heat receiver. In another embodiment, a first and a second heat absorber are hydraulically connected in series, a pressure difference being able to be achieved by an intermediate relaxation element.

According to a preferred embodiment, a first heat sensor and a heat emitter can be operated at a common pressure level. As a result, additional compression and / or relaxation elements and an associated manufacturing, assembly and cost expenditure are saved wall. The operating temperature of the first heat sensor corresponds at least approximately to the operating temperature of the heat emitter.

A compensation element for the refrigerant, such as a collecting container, in which a filter element and / or a dryer can optionally be accommodated, is particularly preferably arranged downstream of the first heat receiver. The compensating element is essentially constructed in the same way as a compensating element usually connected downstream of a heat emitter and is used for collection and, if necessary, phase separation of the refrigerant, so that only liquid refrigerant is supplied to an expansion element.

According to a preferred development of the refrigerant circuit, the first heat receiver is arranged hydraulically between two sections of the heat emitter. This means that, after flowing through a first section of the heat transmitter, refrigerant is passed through the first heat receiver and then returned to the heat transmitter, where it subsequently flows through a second section.

In one embodiment, the entire refrigerant flow is conducted through the first heat sensor. In a further embodiment, only a part of the refrigerant flow is led through the first heat receiver, while another part of the refrigerant flow is conducted from the first to the second section of the heat transmitter through a bypass connection. The bypass connection particularly preferably comprises a third section of the heat transmitter, so that after the first section the refrigerant flows through either the first heat receiver or the third section of the heat transmitter and finally through the second section.

According to a preferred embodiment, the first heat absorber forms a closed partial circuit with a section of the heat emitter. The refrigerant is then removed from a main circuit downstream of the heat transmitter section, passed through the first heat receiver and fed back to the main circuit upstream of the heat transmitter section. In particular, the partial circuit contains a compression and a relaxation element, for example the compression element also serving as a compression element of the main circuit. However, the closed sub-circuit is preferably within a pressure level, ie no compression or expansion elements are contained in the sub-circuit.

According to an advantageous further development, the first heat absorber is arranged geodetically lower than the heat emitting section of the partial circuit. Refrigerant, which absorbs heat in the first heat receiver, that is to say is heated, rises upward, enters the heat emitting section in order to give off heat there, that is to say to be cooled, and to sink down again to the first heat receiver. No compression element is required for such a so-called natural circulation, which is why this heat transport also takes place when a compression element is either switched off or is not present at all. It can therefore be heated or cooled to save energy. In order to support natural circulation with regard to a flow resistance of the partial circuit, an additional refrigerant delivery device, such as a liquid pump, is particularly preferably provided, with which a pressure drop along the partial refrigerant circuit can be compensated.

Another advantageous development uses a suction element to maintain a refrigerant flow in the partial circuit, via which the first heat sensor communicates with the main circuit. The suction element, which is designed, for example, as a so-called Venturi nozzle or the like, sucks refrigerant out of the first heat absorber and feeds it to the main circuit. This also causes a pressure drop compensated or overcompensated along the partial refrigerant circuit. The suction element can advantageously be integrated into a heat emitter.

According to a preferred embodiment of the refrigerant circuit according to the invention, at least one heat sensor with at least one heat emitter forms a structural unit. In particular with the same or similar refrigerant pressure levels and thus the same or similar operating temperature levels, a simplified assembly in a given installation space can be realized with such a combined component.

According to a further embodiment, at least one heat absorber can also be cooled. This means that only part of the heat energy absorbed is transferred to the refrigerant and transported away, and part is given off directly to a cooling medium, such as air flowing past.

According to an advantageous embodiment, at least one heat sensor, which can be operated in particular at a higher refrigerant pressure than at least one other heat sensor, absorbs heat energy from a medium of a secondary circuit, the secondary circuit being particularly preferably a coolant circuit. This enables indirect cooling of one or more heat-generating components.

According to a preferred embodiment, a first heat sensor is designed as a cooler for electronic components. A second heat absorber is particularly preferably designed as a cold generator of an air conditioning system, in particular for motor vehicles. The idea of the invention is particularly noticeable here, since air conditioning refrigerators are usually operated at significantly lower temperatures than refrigerators. electronic components. It is therefore particularly advantageous in this case to operate two heat sensors at different pressure levels.

According to a preferred development, the refrigerant circuit according to the invention is used in a refrigeration system in order to cool or heat several components at different temperature levels.

The invention is explained in more detail below using exemplary embodiments with reference to the drawings. Show it:

1: A schematic view of a refrigerant circuit according to the present invention,

2-8: each a schematic view of a refrigerant circuit and

Fig. 9: a schematic view of a secondary circuit.

A refrigerant circuit 10 is shown in a schematic view in FIG. 1. A compression element 20 and a relaxation element 30 delimit a high-pressure side 40 and a low-pressure side 50 of the circuit 10. Starting from the compression element 20, refrigerant therefore flows counterclockwise through the circuit 10, by compression in the compression element 20, which is designed, for example, as a compressor the temperature of the refrigerant increases, whereupon heat of the refrigerant is dissipated in a heat emitter 60 to air flowing past, indicated by arrows 70.

The refrigerant then flows through a first heat receiver 80, in which it contains heat from a component, not shown, to be cooled, such as an electronic control device or the like. The refrigerant is then collected in a compensating or collecting tank 90 and fed to the expansion element 30, where it enters the low-pressure side 50.

As a result of the expansion in the expansion element, the temperature of the refrigerant drops significantly, so that a further component, not shown, such as an air flow or the like, can be cooled in a second heat receiver 100 while absorbing thermal energy. The cooling temperature of the component cooled by the low-pressure side heat sensor 100 is significantly lower than the cooling temperature of the component cooled by the high-pressure side heat sensor 80, since the heat sensor can be operated at the pressure level of the heat emitter. The refrigerant circuit 10 is closed by forwarding the refrigerant to the compression element 20.

If the refrigerant circuit 10 is operated with a two-phase refrigerant, such as R134a, the difference in the temperature levels on the high-pressure side 40 or on the low-pressure side 50 is particularly pronounced. When the circuit 10 is designed for conventional air conditioning systems, the temperature of the two-phase range of the refrigerant on the high pressure side is generally in the range from 40 ° C. to 70 ° C., on the other hand in the range of 0 ° C. The heat absorber 100 then operated as an evaporator on the low-pressure side is suitable for cooling air to air-condition a room, for example an interior in a motor vehicle, and the heat absorber 80 on the high-pressure side is at a preferred cooling temperature for electronic components such as control units and adapted similar. The refrigerant expanded in the expansion element 30 is thus evaporated in the evaporator 100, compressed in the compressor 20, condensed in the heat emitter 60, which then acts as a condenser, in the heat absorber. mer 80 at least partially evaporated and / or heated and finally collected in the compensating element 90, where the gaseous fraction is separated.

2 shows a refrigerant circuit 110 with a compression element 120, a heat emitter 130, a first heat absorber 140, a compensating element 150, a relaxation element 160 and a second heat absorber 170.Refrigerant flows here through a first section 180 of the heat emitter 130, then through the first Heat absorber 170 and then through a second section 190 of heat emitter 130. The first heat absorber 170 is flowed through by the entire refrigerant.

If the desired cooling temperature of the first heat absorber 140 is lower than the operating temperature of the heat emitter 130, the pressure level of the first heat absorber and thus also of the second section 190 of the heat emitter 130 may be reduced with the aid of a relaxation element 200. In the simplest case, the expansion element 200 is formed as a throttle through a small opening through which the refrigerant has to pass, the opening being able to be arranged, for example, in a partition of a header box of the heat emitter 130. In the case of a heat emitter with heat exchanger tubes connected in a serpentine manner, it is possible to reduce the throttling effect in one by a reduced number of tubes or channels of multi-chamber tubes, that is to say by a reduced flow cross section. Serpentine section, especially in the last serpentine section of the first heat emitting section 180 to be realized. It is also possible to use an externally controllable expansion valve as the expansion element 200, as a result of which the operating temperature of the first heat absorber 140 can be adapted to requirements which vary over time. In a similar exemplary embodiment, which is not shown, the compensating element, for example in the form of a collecting container and optionally equipped with a filter and / or dryer unit, forms with the heat emitter. a structural unit, wherein the refrigerant is passed through a so-called sub-cooling section of the heat emitter after flowing through the compensating element. This variation, which in principle is also possible in the other exemplary embodiments listed, without leaving the scope of the present invention, enables the first heat absorber and the compensating element to be connected in series, so that the second section 190 of the heat emitter 130 from the previous example ( Fig. 2) forms the subcooling section of the unit from heat emitter and compensating element.

In the refrigerant circuit 210 in FIG. 3, a first heat absorber 220 is only detected by a part 230 of the refrigerant flow, whereas another part 240 of the refrigerant flow flows through a third section 250 of the heat exchanger 260, the third section 250 between a first section 270 and a second section 280 of the heat emitter 260 is arranged. Refrigerant ¹ coming from the compression element 290 therefore flows through the first section 270 of the heat emitter 260, is then divided between the third section 250 and the first heat absorber 220 and is then combined again in the third section 280 of the heat emitter 260. The refrigerant is then again collected in a compensating element 300 so that a gaseous portion of the refrigerant can be separated if necessary.

The refrigerant circuit 310 in FIG. 4 differs in principle from the circuit 210 known from FIG. 3 in that the first heat absorber 320 is arranged geodetically lower than the heat emitter 360, in particular as its middle section 350, with which the first heat absorber is combined forms a closed sub-circuit. As with the The refrigerant circuit 410 shown in FIG. 5 enables heat to be transported from the first heat absorber 420 to the heat emitter 460 or its central section 450 even when the compression element 490 is switched off.

Such natural circulation cooling runs by itself, because the refrigerant through a. Heat absorption in the first heat absorber 420 is heated - and / or possibly partially evaporated, rises to the top and is cooled and / or condensed again in the central section 450 of the heat emitter 460, after which the refrigerant sinks again and arrives at the first heat absorber. The transported thermal energy is released to an air stream 470, for example. A cooling effect of the first heat absorber 420 is therefore retained even when the compression element 490 is switched off, for example in the winter operation of an air conditioning system. The associated saving in energy is evident. Compared to summer operation of the refrigerant circuit 310 (FIG. 4) with the compression element 390 switched on, however, the direction of flow of the refrigerant through the first heat absorber 420 has been reversed.

In a further embodiment, not shown, the natural circulation is supported by a small refrigerant delivery device, such as a liquid pump, the. Refrig ^{'ittelfördervorrichtung} may be located either before or after the first heat receiver.

FIG. 6 shows a further refrigerant circuit 510 with a heat transmitter 540 consisting of a first section 520 and a second section 530, in which a first heat receiver 550 forms a closed circuit with the second section 530 of the heat transmitter 540. In order to promote a return of the refrigerant from the first heat sensor 550, the first heat sensor communicates 550 via a suction element 560 with the heat emitter 540, the suction element 560 being designed, for example, as a so-called venturi nozzle, in which the pressure in the line 570 coming from the first heat absorber 550 is reduced within the heat emitter 540 by means of refrigerant flowing past.

7 shows a refrigerant circuit 610 with a suction element 660. In contrast to the circuit 510 in FIG. 6, in which the suction element 560 is integrated between the two sections 520 and 530 in the heat emitter 540, the suction element 660 is between the Compression element 680 and the heat emitter 640 arranged. As in FIG. 6, the direction of flow of the refrigerant is also indicated by arrows in FIG. 7.

8 shows a refrigerant circuit 710 as a further variant, in which a high-pressure side 720 and a low-pressure side 730 are separated from one another by a compression element 740 and two expansion elements 750, 760. A partial circuit 800 formed by a first heat absorber 770 and a section 780 of a heat emitter 790 extends on both sides 720, 730. In the partial circuit 800, the refrigerant from the first heat absorber 770 is released into the low-pressure side 730 by the expansion element 750, which is designed, for example, as a throttle dissipated to be finally compressed by the compression element 740 and supplied to the heat emitter 790. In the heat emitter 790, the refrigerant is divided into the sub-circuit 800 and a main circuit 810 of the refrigerant circuit 710. A second section 820 of the heat emitter 790, a compensating element 830, the relaxation element 760 and a second heat absorber 840 on the low pressure side 730 are located in the main circuit 810.

In a similar exemplary embodiment, the partial circuit 800 is located between the heat emitter 790 and the first heat absorber 770 a further relaxation element, so that the pressure and / or the temperature of the heat absorber 770 compared to the heat emitter 790 can, if necessary, be reduced to a reduced level.

In another embodiment, the second section 820 of the heat emitter 790 is omitted, so that the branch point of the partial circuit 800 from the main circuit 810 is hydraulically arranged between the heat emitter 790 and the relaxation element 760 and before or after the compensating element 830.

9 illustrates a section of a refrigerant circuit 910 according to the present invention. A heat receiver 920 is arranged on a high-pressure side of the refrigerant circuit 910 to receive thermal energy from a secondary cooling circuit 930. The secondary cooling circuit 930 is used to transport heat from several components 940, 950 and 960 connected in series or in parallel to one another to the heat exchanger 920, which from the perspective of the cooling circuit 930 is a heat emitter. A coolant circulation through the cooling circuit 930 is ensured by a compression element 970, which is designed, for example, as a coolant pump. The components 940, 950 and 960 to be cooled are, for example, electronic assemblies or controls or other heat-generating devices.

Claims

Patent claims

1. refrigerant circuit with at least one heat absorber and at least one heat emitter, characterized in that several functionally identical heat exchangers can be operated simultaneously with different refrigerant pressure.

2. Refrigerant circuit according to claim 1, characterized in that each refrigerant connection between two heat exchangers operable at different pressures contains at least one compression element and / or at least one expansion element.

3. A refrigerant circuit according to claim 2, characterized in that at least one compression element and / or at least one expansion element forms a structural unit with a heat exchanger.

4. Refrigerant circuit according to one of the preceding claims ^' , characterized in that a first heat absorber, a second

Heat absorbers and a heat emitter can be operated at three different pressure levels.

5. A refrigerant circuit according to one of the preceding claims, characterized in that a first heat absorber and a Heat emitters can be operated at a common or similar pressure level.

6. A refrigerant circuit according to claim 5, characterized in that a compensating element, in which in particular the refrigerant can be filtered and / or the refrigerant can extract water, is arranged downstream of the first heat absorber.

7. A refrigerant circuit according to claim 5 or 6, characterized in that the first heat absorber is arranged hydraulically between two sections of the heat emitter.

8. The refrigerant circuit according to claim 7, characterized in that the two sections communicate with one another via a bypass connection, the bypass connection in particular a third

Section of the heat emitter includes.

9. Refrigerant circuit according to one of claims 5 to 8, characterized in that the first heat absorber forms a closed sub-circuit with a section of the heat emitter, in particular within a pressure level.

10. The refrigerant circuit according to claim 9, characterized in that the first heat absorber is arranged geodetically lower than the heat transmitter section.

11. A refrigerant circuit according to claim 9 or 10, characterized in that the first heat absorber communicates with a main circuit via a suction element, wherein the suction element can in particular be integrated into a heat emitter.

12. The refrigerant circuit according to one of the preceding claims, characterized in that at least one heat absorber with at least one heat emitter forms a structural unit.

13. A refrigerant circuit according to one of the preceding claims, characterized in that at least one heat absorber can be additionally cooled, in particular with air flowing past.

14. A refrigerant circuit according to one of the preceding claims, characterized in that at least one heat absorber

Thermal energy of a secondary circuit, in particular a cooling circuit, can be absorbed.

15. Refrigerant circuit according to one of the preceding claims, characterized in that a first heat absorber is a cooler for electronic components and in particular a second heat absorber is a refrigeration device of an air conditioning system.

16. Refrigeration system, in particular air conditioning for a motor vehicle, with a refrigerant circuit, which is designed according to one of the preceding claims.