Test chamber and method for controlling

Abstract

The invention relates to a test chamber and a method for conditioning air in a temperature-insulated test chamber, in particular a climate chamber, which can be sealed off from the environment, for holding test specimens, wherein a temperature control device of the test chamber, comprising a cooling circuit (11) with carbon dioxide as a refrigerant, a heat exchanger (12) in the test chamber, a low-pressure compressor (13) and a high-pressure compressor (14) following the low-pressure compressor in the direction of refrigerant flow, a gas cooler (15) and an expansion valve (16), is used to establish a temperature within a range of -20°C to +180°C within the test chamber, wherein the temperature and / or relative humidity in the test chamber is controlled and / or regulated by means of a control device of the test chamber, wherein a dehumidifier bypass (20) of the cooling circuit is used.air in the test chamber is dehumidified by a second expansion valve (21) and a second heat exchanger (22).

Claims

1. A method for conditioning air in a test chamber, in particular a climate chamber, which is sealable from the environment and temperature-insulated, for accommodating test specimens, wherein a temperature in a temperature range of -20 °C to +180 °C is formed within the test chamber by means of a cooling device (10, 30, 34, 41, 46) of a temperature control device of the test chamber, with a cooling circuit (11, 31, 35, 42, 47) with carbon dioxide (CO2) as a refrigerant, a heat exchanger (12) in the test chamber, a low-pressure compressor (13) and a high-pressure compressor (14) following the low-pressure compressor in a flow direction of the refrigerant, a gas cooler (15, 33, 43) and an expansion valve (16), wherein the temperature and / or a relative humidity in the test chamber is controlled and / or regulated by means of a control device of the test chamber, characterized by thatby means of a dehumidifier bypass (20, 36) of the cooling circuit, with a second expansion valve (21, 37) and with a second heat exchanger (22, 38) in the test chamber, air in the test chamber is dehumidified.

2. Method according to claim 1, characterized by that the dehumidifier bypass (20 36) is connected in the flow direction after the gas cooler (15, 33, 43) and before the expansion valve (16) to a high-pressure side (19, 49) of the cooling circuit (11, 31, 35, 42, 47) and after the heat exchanger (12) and before the low-pressure compressor (13) to a low-pressure side (17, 40) of the cooling circuit, wherein refrigerant is metered from the high-pressure side to the low-pressure side via the second expansion valve (21, 37) in such a way that the second heat exchanger (22, 38) is cooled.

3. Method according to claim 1 or 2, characterized by thata second bypass (26) with at least one third expansion valve (27) is formed in the cooling circuit (11, 31, 35, 42, 47), wherein the second bypass is connected in the flow direction downstream of the gas cooler (15, 33, 43) and upstream of the expansion valve (16) to a high-pressure side (19, 49) of the cooling circuit and downstream of the heat exchanger (12) and upstream of the low-pressure compressor (13) to a low-pressure side (17, 40) of the cooling circuit, wherein a suction gas temperature and / or a suction gas pressure of the refrigerant on the low-pressure side of the cooling circuit upstream of the low-pressure compressor is regulated in such a way that refrigerant is metered into the low-pressure side via the third expansion valve.

4. Method according to one of the preceding claims, characterized by thatin the cooling circuit (11, 31, 35, 42, 47) a further bypass (28) with at least one further valve (29) is formed, wherein the further bypass is connected in the flow direction downstream of the high-pressure compressor (14) and upstream of the gas cooler (15) to a high-pressure side (19, 49) of the cooling circuit and downstream of the heat exchanger (12) and upstream of the low-pressure compressor (13) to a low-pressure side (17, 40) of the cooling circuit, wherein a suction gas temperature and / or a suction gas pressure of the refrigerant on the low-pressure side of the cooling circuit upstream of the low-pressure compressor is regulated in such a way and / or a pressure difference between the high-pressure side and the low-pressure side of the cooling circuit is compensated in such a way that refrigerant is metered into the low-pressure side via the further valve.

5. Method according to one of the preceding claims, characterized by that a speed of the high-pressure compressor (14) and / or the low-pressure compressor (13) is regulated.

6. Method according to one of the preceding claims, characterized by that while increasing or maintaining constant the temperature in the test chamber, a suction gas pressure in a low-pressure side (17, 40) of the cooling circuit (11, 31, 35, 42, 47) is reduced, whereby a temperature difference between the second heat exchanger (22, 38) and the test chamber is increased.

7. Method according to one of the preceding claims, characterized by that a temperature difference between the heat exchanger (12) and the test chamber is increased such that air in the test chamber is dehumidified.

8. Method according to one of claims 1 to 5, characterized by that during a reduction in the temperature in the test chamber, a suction gas pressure in a low-pressure side (17, 40) of the cooling circuit (11, 31, 35, 42, 47) is increased, whereby a temperature difference between the second heat exchanger (22, 38) and the test chamber is reduced.

9. Method according to one of the preceding claims, characterized by that the cooling circuit (47) has a medium-pressure bypass (48) which, in the flow direction, is connected downstream of the gas cooler (43) and upstream of the expansion valve (16) to a high-pressure side (49) of the cooling circuit and upstream of the high-pressure compressor (14) and downstream of the low-pressure compressor (13) to a medium-pressure side (50) of the cooling circuit, wherein refrigerant is metered from the high-pressure side to the medium-pressure side by means of a further expansion valve (51).

10. Method according to one of claims 1 to 8, characterized by thatthe cooling circuit (11) has an internal heat exchanger (23) which is connected to a high-pressure side (19) of the cooling circuit downstream of the gas cooler (15) and upstream of the expansion valve (16) in the direction of flow, wherein the internal heat exchanger is coupled to a medium-pressure bypass (24) of the cooling circuit, wherein the medium-pressure bypass is connected to a medium-pressure side (18) of the cooling circuit downstream of the internal heat exchanger or the gas cooler and upstream of the expansion valve on the high-pressure side, as well as upstream of the high-pressure compressor (14) and downstream of the low-pressure compressor (13), wherein refrigerant is metered from the high-pressure side into the medium-pressure side via the internal heat exchanger by means of a further expansion valve (25).

11. Method according to one of claims 1 to 8, characterized by thata medium-pressure side (32) of the cooling circuit (31, 35) is connected to the gas cooler (33) upstream of the high-pressure compressor (14) and downstream of the low-pressure compressor (13), wherein refrigerant is conducted from the low-pressure compressor to the high-pressure compressor via the gas cooler.

12. Method according to one of claims 1 to 8, characterized by that a medium-pressure side (44) of the cooling circuit (42) is connected to a medium-pressure cooler (45) upstream of the high-pressure compressor (14) and downstream of the low-pressure compressor (13), wherein refrigerant is conducted from the low-pressure compressor to the high-pressure compressor via the medium-pressure cooler.

13. Method according to one of the preceding claims, characterized by that the cooling circuit (11, 31, 35, 42, 47) is operated in a thermodynamically subcritical or transcritical operating state.

14. Method according to one of the preceding claims, characterized by thatpure carbon dioxide (CO2) is used as the refrigerant.

15. Method according to one of the preceding claims, characterized by that by means of the temperature control device, a temperature in a temperature range of -40 °C to +180 °C, preferably from -50 °C to +180 °C, is formed within the test chamber.

16. Method according to one of the preceding claims, characterized by that by means of the temperature control device, a relative humidity in a range of 10% to 95%, preferably from 5% to 99%, at a temperature in a temperature range of +10 °C to +90 °C, preferably from +5 °C to +98 °C, is formed within the test room.

17. Test chamber, in particular a climatic chamber, for conditioning air, comprising a test chamber which is closable from the environment and temperature-insulated for accommodating test material, and a temperature control device for temperature control of the test chamber, wherein by means of the temperature control device a temperature in a temperature range of -20 °C to +180 °C can be formed within the test chamber, wherein the temperature control device has a cooling device (10, 30, 34, 41, 46) with a cooling circuit (11, 31, 35, 42, 47) with carbon dioxide as a refrigerant, a heat exchanger (12) in the test chamber, a low-pressure compressor (13) and a high-pressure compressor (14) following the low-pressure compressor in a flow direction of the refrigerant, a gas cooler (15, 33, 43) and an expansion valve (16), wherein the test chamber has a control device for controlling and / or regulating the temperature and / or relative humidity in the test room, characterized by that the cooling circuit has a dehumidifier bypass (20, 36) with a second expansion valve (21, 37) and with a second heat exchanger (22, 38) in the test chamber for dehumidifying air in the test chamber.

18. Test chamber according to claim 17, characterized by that in the dehumidifier bypass (36) a check valve (39) is arranged downstream of the second heat exchanger (38) in the flow direction.

19. Test chamber according to claim 17 or 18, characterized by that the high-pressure compressor (14) and the low-pressure compressor (13) are formed with a common compressor housing.

20. Test chamber according to one of claims 17 to 19, characterized by that the heat exchanger (12) and the second heat exchanger (22, 38) are formed with separate exchanger bodies or a common exchanger body.

21. Test chamber according to one of claims 17 to 20, characterized by thatthe temperature control device has a heating device with a heater and a heating heat exchanger in the test chamber.

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