TEST CHAMBER AND METHOD

Abstract

A method and a test chamber for conditioning air, in which the test chamber comprises a temperature-insulated test space, which is closable to an environment and serves for receiving test material, and a temperature control device for controlling the test space in temperature, a temperature ranging from 40 C. to +180 C. being generable within the test space by the temperature control device. The temperature control device comprises a heating apparatus and a cooling apparatus having a cooling cycle, the cooling cycle having a refrigerant, a heat exchanger disposed in the test space, a compressor, a condenser and an expansion element, the refrigerant being a hydrocarbon or a refrigerant mixture made of hydrocarbons. A stop element is disposed in the cooling cycle downstream of the heat exchanger and upstream of the compressor, the stop element being able to stop reflux of refrigerant in the heat exchanger in the opposite direction of flow.

Claims

1. A test chamber for conditioning air, in particular a climate chamber or the like, the test chamber comprising a temperature-insulated test space, which is closable to an environment and serves for receiving test material, and a temperature control device for controlling the test space in temperature, a temperature ranging from 40 C. to +180 C. being generable within the test space by the temperature control device, the temperature control device comprising a heating apparatus and a cooling apparatus having a cooling cycle, the cooling cycle having a refrigerant, a heat exchanger disposed in the test space, a compressor, a condenser and an expansion element, the refrigerant being a hydrocarbon or a refrigerant mixture made of hydrocarbons, wherein a stop element is disposed in the cooling cycle downstream of the heat exchanger and upstream of the compressor, the stop element being able to stop a reflux of refrigerant in the heat exchanger in the opposite direction of flow.

2. The test chamber according to claim 1, wherein the refrigerant is inflammable and/or free of fluorinated hydrocarbons.

3. The test chamber according to claim 1, wherein the stop element is disposed directly downstream of the heat exchanger in the cooling cycle.

4. The test chamber according to claim 1, wherein the stop element is a non-return valve.

5. The test chamber according to claim 1, wherein the stop element is a magnet valve, a bypass having a pressure relief valve being disposed in the cooling cycle, the bypass being connected downstream of the heat exchanger and upstream of the magnet valve as well as downstream of the magnet valve and upstream of the compressor.

6. The test chamber according to claim 1, wherein the cooling cycle has a pressure compensation pipe, which extends between a high-pressure side and a low-pressure side of the cooling cycle, a magnet valve being disposed in the pressure compensation pipe.

7. The test chamber according to claim 1, wherein the temperature control device comprises a regulator having at least one pressure sensor in the cooling cycle, the pressure sensor being disposed downstream of the expansion element and upstream of the stop element, the expansion element being stoppable by the regulator and operation of the compressor being able to be continued as a function of a measured pressure.

8. The test chamber according to claim 1, wherein the test chamber comprises a detector having at least one gas sensor and one ventilation installation in an engine room of the test chamber separated with respect to the test space in an airtight manner.

9. A method for conditioning air in a temperature-insulated test space of a test chamber, in particular a climate chamber or the like, the test space being closable to an environment and serving for receiving test material, a temperature ranging from 40 C. to +180 C. being generated within the test space by a temperature control device of the test chamber, a temperature ranging from 50 C. to +180 C. being generated within the test space by the temperature control device, the temperature control device having a heating apparatus and the cooling cycle having a refrigerant, a heat exchanger disposed in the test space, a compressor, a condenser and an expansion element, the refrigerant being a hydrocarbon or a refrigerant mixture made of hydrocarbons, wherein a reflux of refrigerant in the heat exchanger in the opposite direction of flow is prevented by a stop element disposed in the cooling cycle downstream of the heat exchanger and upstream of the compressor.

10. The method according to claim 9, wherein the expansion element is stopped by a regulator of the temperature control device and a temperature of +50 C. to +180 C. is generated within the test space by the heating apparatus.

11. The method according to claim 9, wherein the expansion element is stopped by a regulator of the temperature control device and operation of the compressor is continued.

12. The method according to claim 10, wherein a pressure of the refrigerant is determined in the cooling cycle downstream of the expansion element and upstream of the stop element by at least one pressure sensor of the regulator, operation of the compressor being continued as a function of a measured pressure.

13. The method according to claim 12, wherein the compressor is switched off when the pressure ranges from 1.5 bar and >1 bar.

14. The method according to claim 9, wherein upon reaching a target pressure in a low-pressure side of the cooling cycle, the compressor is switched off by means of the regulator and the stop element is stopped.

Description

[0024] In the following, preferred embodiments of the invention are described in more detail with reference to the enclosed drawings.

[0025] FIG. 1 shows a schematic view of a cooling cycle according to a first embodiment;

[0026] FIG. 2 shows a schematic sectional view of a cooling cycle according to a second embodiment;

[0027] FIG. 3 shows a schematic sectional view of a cooling cycle according to a third embodiment.

[0028] FIG. 1 shows a cooling cycle 10 of a test chamber (not shown) for conditioning air together with a test space 11 of the test chamber. Cooling cycle 10 is filled with a refrigerant and has a heat exchanger 12 disposed in test space 11, a compressor 13, a condenser 14 and an expansion element 15. The used refrigerant is inflammable and a hydrocarbon or a refrigerant mixture made of hydrocarbons. The refrigerant is suctioned by compressor 13 on a low-pressure side 16 of cooling cycle 10 and conveyed to a high-pressure side 17 of cooling cycle 10. In this context, the refrigerant flows back to low-pressure side 16 through condenser 14, a storage container 18 and expansion element 15. The refrigerant is expanded when passing expansion element 15 and in this manner cools heat exchanger 12 in test space 11.

[0029] Furthermore, cooling cycle 10 comprises a first pressure compensation pipe 19 having a first magnet valve 20, which extends between high-pressure side 17 and low-pressure side 16. First pressure compensation pipe 19 is connected downstream of condenser 14 and upstream of expansion element 15 as well as downstream of heat exchanger 12 and upstream of compressor 13 in a flow direction of the refrigerant. Via the first pressure compensation pipe, compressed refrigerant and/or refrigerant liquefied in condenser 14 can be dosed from high-pressure side 17 upstream of compressor 13 using first magnet valve 20. For instance, operation of compressor 13 can be continued, without refrigerant flowing via expansion element 15. At least, it is possible to regulate a suction pressure on low-pressure side 16. This can take place using a regulator (not shown). Further, a second pressure compensation pipe 21 is provided, which has a second magnet valve 22. Second pressure compensation pipe 21 is connected to cooling cycle 10 downstream of compressor 13 and upstream of condenser 14 as well as downstream of heat exchanger 12 and upstream of condenser 13 directly in a flow direction of the refrigerant. Via second pressure compensation pipe 21, compressed or still gaseous, comparatively hot refrigerant can reflux upstream of compressor 13. Aside from pressure compensation, a suction pressure of compressor 13 as well as a temperature of the refrigerant can also be regulated upstream of compressor 13.

[0030] In cooling cycle 10, in particular a stop element 23 is provided, which is disposed downstream of heat exchanger 12 and upstream of compressor 13 in cooling cycle 10 in a flow direction of the refrigerant. Stop element 23 is also disposed upstream of first pressure compensation pipe 19 and second pressure compensation pipe 21. Stop element 23 enables stopping cooling cycle 10, meaning a reflux of the refrigerant can be avoided in heat exchanger 12 against the flow direction of the refrigerant. Thus, no refrigerant can move to heat exchanger 12 against the flow direction. This is particularly advantageous when a temperature is increased in test space 11 and expansion element 15 is closed. Then, heat exchanger 12 is not cooled and a heat expansion of the refrigerant does not take place in heat exchanger 12. The refrigerant can, moreover, be suctioned from heat exchanger 12 by means of compressor 13, meaning comparatively little refrigerant is present in heat exchanger 12. In the event of a leakage of compressor 13 or of cooling cycle 10 within test space 11, only very little inflammable refrigerant can enter test space 11.

[0031] FIG. 2 shows a cooling cycle 24, in which, in contrast to the cooling cycle of FIG. 1, a stop element 25 is provided, which is designed as a non-return valve 26. After closing expansion element 15, refrigerant can leak from heat exchanger 12 via non-return valve 26 in the flow direction, e.g., as a result of heat expansion when test space 11 is heated, a reflux of refrigerant to heat exchanger 12 being prevented by means of non-return valve 26. Optionally, it can be intended that heat exchanger 12 is evacuated by means of the compressor (not shown) and/or a pressure is lowered so far in heat exchanger 12 that it essentially corresponds to an ambient pressure and/or does not fall below it.

[0032] FIG. 3 shows a cooling cycle 27 having a stop element 28. In contrast to the cooling cycle of FIG. 1, stop element 28 is formed by a magnet valve 29. Furthermore, a bypass 30 is provided having a pressure relief valve 31. Bypass 30 is connected to cooling cycle 27 downstream of heat exchanger 12 and upstream of magnet valve 29 as well as downstream of magnet valve 29 and upstream of the compressor (not shown) in the flow direction of the refrigerant. After closing expansion element 15, as described above, the amount of refrigerant can be reduced in heat exchanger 12. Subsequently, magnet valve 29 can be closed. In the event of a malfunction of magnet vale 29, it could not be opened, meaning a large amount of refrigerant could flow into heat exchanger 12 after a renewed opening of expansion element 15. This refrigerant can then drain and/or overflow via pressure relief valve 31 when pressure has risen to an inadmissible level within heat exchanger 12.