TEST CHAMBER AND METHOD

Abstract

A method for conditioning a fluid in a temperature-insulated test space and a test space of a test chamber for receiving test materials. A cascading cooling device creates a particular temperature range within the test space, and the cooling device has a first cooling circuit comprising a cascading heat exchanger, a first compressor, a condenser and a first expanding element, and a second cooling circuit comprising a heat exchanger, a second compressor, the cascading heat exchanger and a second expanding element. The cascading heat exchanger is cooled by the first cooling circuit, the heat exchanger is cooled by a bypass passing through the heat exchanger and bridging the cascading heat exchanger, the first compressor is turned off, and a first refrigerant is conducted and condensed in a gaseous state in the cascading heat exchanger on a low-pressure side of the bypass.

Claims

1. A test chamber for conditioning a fluid, particularly air, comprising a temperature-insulated test space (14), which is sealable against an environment, for receiving test materials and a temperature control device for controlling the temperature of the test space, a temperature ranging from −60° C. to +180° C. in temperature being able to be realized within the test space by means of the temperature control device, said temperature control device having a cascading cooling device (10) having a first cooling circuit (11) having a first refrigerant, a cascading heat exchanger (15), a first compressor (16), a condenser (17) and a first expanding element (18), and having a second cooling circuit (12) having a second refrigerant, a heat exchanger (13) arranged in the test space, a second compressor (27), the cascading heat exchanger and a second expanding element (28), said cascading heat exchanger being able to be cooled by means of the first cooling circuit, characterized in that the first cooling circuit is realized having a bypass (35) passing through the heat exchanger and bridging the cascading heat exchanger, said heat exchanger being able to be cooled by means of the first cooling circuit, and said temperature control device comprising an adjusting device by means of which the first compressor can be turned off and the first refrigerant being able to be conducted and condensed in a gaseous state in the cascading heat exchanger on a low-pressure side (22) of the bypass.

2. The test chamber according to claim 1, characterized in that the first cooling circuit (11) is thermally coupled to the second cooling circuit (12) by means of the cascading heat exchanger (15).

3. The test chamber according to claim 1, characterized in that the cascading heat exchanger (15) is formed by a plate heat exchanger whose primary side is connected to the first cooling circuit (11) and whose secondary side is connected to the second cooling circuit (12).

4. The test chamber according to claim 1, characterized in that the bypass (35) is connected to a high-pressure side (21) of the first cooling circuit (11) in a flow direction upstream of the first expanding element (18) and downstream of the condenser (17) and to the low-pressure side (22) of the first cooling circuit in a flow direction upstream of the first compressor (16) and downstream of the cascading heat exchanger (15).

5. The test chamber according to claim 1, characterized in that the temperature control device comprises a heating device having a heater and a heating heat exchanger in the test space (14).

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURE

[0031] In the following, a preferred embodiment of the invention is further described with reference to the attached drawing.

[0032] The Figure illustrates a schematic view of a cascading cooling device 10 having a first cooling circuit 11 and a second cooling circuit 12. Furthermore, the cascading cooling device 10 comprises a heat exchanger 13 which is arranged in an indicated test space 14 and is connected to the first cooling circuit 11 and the second cooling circuit 12.

DETAILED DESCRIPTION OF THE INVENTION

[0033] The first cooling circuit 11 is realized having a cascading heat exchanger 15, a first compressor 16, a condenser 17 and a first expanding element 18. In the first cooling circuit 11, a first refrigerant can be circulated by operating the first compressor 16. The first expanding element 18 is made of a throttle 19 and a magnetic valve 20. All other expanding elements of the cascading cooling device 10 can be realized accordingly. The first cooling circuit 11 comprises a high-pressure side 21, which passes from the first compressor 16 to the first expanding element 18 in the flow direction of the first refrigerant, as well as a low-pressure side 22, which passes from the first expanding element 18 to the first compressor 16. The first refrigerant is gaseous and has a comparatively high temperature in a tube section 23 extending from the first compressor 16 to the condenser 17. The first refrigerant, which is compressed by the first compressor 16, streams in the first cooling circuit 11 to the condenser 17, said gaseous first refrigerant being liquefied in the condenser 17. The expanding element 18 comes after the condenser 17 in the first cooling circuit 11 in the flow direction of the first refrigerant, said first refrigerant accordingly being available in a liquid state in a tube section 24 of the first cooling circuit 11 between the condenser 17 and the first expanding element 18. By expanding the first refrigerant downstream of the first expanding element 18, the cascading cooling device 15 is cooled, the first refrigerant transitioning to the gaseous state in a tube section 25 between the first expanding element 18 and the cascading heat exchanger 15 and being conducted to the first compressor 16 via a tube section 26 of the cascading heat exchanger 15.

[0034] The second cooling circuit 12 comprises the heat exchanger 13, a second compressor 27, the cascading heat exchanger 15 and a second expanding element 28 exchanger. The second cooling circuit 12 comprises a high-pressure side 29, which passes from the second compressor 27 to the second expanding element 28 in the flow direction of a second refrigerant, as well as a low-pressure side 30, which passes from the second expanding element 28 to the second compressor 27. Here as well, the second refrigerant is gaseous in a tube section 31 extending from the second compressor 27 to the cascading heat exchanger 15 and has a comparatively high temperature. The second refrigerant, which is compressed by the second compressor 27, flows in the second cooling circuit 12 to the cascading heat exchanger 15, said gaseous second refrigerant being liquefied in the cascading heat exchanger 15. In the second cooling circuit 12, the second expanding element 28 comes after the cascading heat exchanger 15 in the flow direction of the second refrigerant, said second refrigerant accordingly being available in the liquid state in a tube section 32 of the second cooling circuit 12 between the cascading heat exchanger 15 and the second expanding element 28. By expanding the second refrigerant downstream of the second expanding element 28, the heat exchanger 13 is cooled, said second refrigerant transitioning to the gaseous state in a tube section 33 between the second expanding element 28 and the heat exchanger 13, particularly in the heat exchanger 13, and being conducted to the second compressor 27 from the heat exchanger 13 via a tube section 34.

[0035] In the first cooling circuit 11, a bypass 35 is formed which passes through the heat exchanger 13 and bridges the cascading heat exchanger 15 of the cooling circuit 11. The bypass 35 is connected to the high-pressure side 21 in a flow direction upstream of the first expanding element 18 and downstream of the condenser 17 and is connected to the low-pressure side 22 in a flow direction upstream of the first compressor 16 and downstream of the cascading heat exchanger 15. Furthermore, an adjustable third expanding element 36 is arranged in the bypass 35 in the flow direction upstream of the heat exchanger 13. By means of the third expanding element 36, the first refrigerant can be expanded and be conducted to the low-pressure side 22 via the heat exchanger 13. As long as no particularly low temperatures have to be realized in the heat exchanger 13, the second cooling circuit 12 can be turned off using the second compressor 27 so that the heat exchanger 13 can be cooled via the bypass 35 of the first cooling circuit 11.

[0036] In this instance, the first expanding element 18 remains closed since the cascading heat exchanger 15 does not need to be cooled.

[0037] Nevertheless, the first refrigerant can be conducted from the high-pressure side 21 via the first expanding element 18 through the cascading heat exchanger 15 to the low-pressure side 22, if the second compressor 27 is stopped and the first compressor 16 is in operation, said cascading heat exchanger 15 or rather the second refrigerant therein from the second cooling circuit then being cooled. Since the second refrigerant is not circulated, the cascading heat exchanger 15 serves as a cold reservoir or rather thermal energy is emitted from the second refrigerant to the first refrigerant and thus a cold capacity is stored in the cascading heat exchanger 15. If, by means of the first cooling circuit 11, a comparatively low cold capacity is to be yielded in the heat exchanger 13 via the bypass or rather a difference in temperature to be compensated is comparatively slight, the first compressor 16 can be turned off also. The first refrigerant can then flow in the cascading heat exchanger 15 and condense in the cascading heat exchanger 15, a difference in pressure between the low-pressure side 22 and the high-pressure side 21 of the first cooling circuit 11 being maintained owing to a thus realized change in density of the refrigerant. This leads to first refrigerant continuing to flow via the third expanding element 36 and to the heat exchanger 13 being cooled until the first refrigerant can no longer be condensed in the cascading heat exchanger 15 even when the first condenser 16 is turned off. Subsequently, the first compressor 16 can be operated again, a pressure dropping enough in the cascading heat exchanger 15 so that the liquefied first refrigerant becomes gaseous again and thus is suctioned from the cascading heat exchanger 15. Overall, a significant amount of energy can thus be saved when operating the cascading cooling device 10.

[0038] Furthermore, an adjustable first internal supplementary refrigeration line is arranged in the first cooling circuit 11, said first internal supplementary refrigeration 37 being realized having a second bypass 38, which is connected to the high-pressure side 21 in the flow direction upstream of the first expanding element 18 and downstream of the condenser 17 and is connected to the low-pressure side 22 in the flow direction upstream of the first compressor 16 and downstream of the cascading heat exchanger 15 having an adjustable fourth expanding element 39. The first refrigerant can be supplied to the low-pressure side 22 via the fourth expanding element 39 so that the first refrigerant can lower a suction gas temperature upstream of the first compressor 16.

[0039] The second cooling circuit 12 also comprises an adjustable second internal supplementary refrigeration line 40 having a third bypass 41 between the high-pressure side 29 and the low-pressure side 30 having a fifth expanding element 42. In this instance as well, the second refrigerant can be cooled upstream of the second compressor 27 by means of the second internal supplementary refrigeration 40 if required.

[0040] The first cooling circuit 11 further comprises an adjustable first back-injection device 43 for the first refrigerant having a fourth bypass 44, which is connected to the high-pressure side 21 in the flow direction downstream of the first compressor 16 and upstream of the condenser 17 and is connected to the low-pressure side 22 in the flow direction upstream of the first compressor 16 and downstream of the cascading heat exchanger 15. A sixth expanding element 45 is arranged in the fourth bypass 44, hot and gaseous first refrigerant being able to be supplied from the high-pressure side 21 to the low-pressure side 22 by means of said sixth expanding element 45 whereby a suction gas temperature and/or a suction gas pressure of the first refrigerant becoming adjustable on the low-pressure side 22 upstream of the first compressor 16. Moreover, a difference in pressure can be compensated between the high-pressure side 21 and the low-pressure side 22.

[0041] The second cooling circuit 12 also comprises a second adjustable back-injection device 46 having a fifth bypass 47 and a seventh expanding element 48, via which hot and gaseous second refrigerant can be conducted from the high-pressure side 29 to the low-pressure side 30.