Test chamber and method

Abstract

The invention relates to a test chamber and a method for conditioning air, the test chamber comprising: a test space for receiving test material, which can be isolated from the surrounding environment and is heat-insulated, and a temperature control device for controlling the temperature of the test space, the temperature control device allowing a temperature in the temperature range of -20°C to +180°C to be established in the test space, the temperature control device having a cooling device (10), the cooling device comprising a cooling circuit (11) with a refrigerant, a heat exchanger (12), a compressor (13), a condenser (14) and an expansion element (15), wherein the cooling circuit has an internal storage device (24), which is connected to the high-pressure side (18) of the cooling circuit upstream of the expansion element and downstream of the condenser in the flow direction, and is connected to the low-pressure side (19) of the cooling circuit upstream of the compressor and downstream of the heat exchanger in the flow direction via a bypass (25) of the cooling circuit, the heat energy being stored by the internal storage device and exchanged with the refrigerant.

Description

Technical Field

[0001] The invention relates to a test chamber and a method for conditioning air, the test chamber comprising a test space for receiving test materials and which can be isolated from the surrounding environment and is insulated, and a temperature control device for controlling the temperature of the test space, the temperature control device allowing a temperature in the temperature range of -20°C to +180°C to be established in the test space, the temperature control device having a cooling device, the cooling device comprising a cooling circuit with a refrigerant, a heat exchanger, a compressor, a condenser and an expansion element. Background Art

[0002] In particular, such test chambers are often used to test the physical and / or chemical properties of objects and devices. For example, temperature test cabinets or climate test cabinets are known in which temperatures in the range of -20°C to +180°C can be set. In the climate test cabinet, the desired climatic conditions can be set in addition, and then the device or test material is exposed to a defined period of time. Such test chambers are usually or partially configured as mobile devices, which are connected to the building only by the required power supply lines and include all modules required for temperature control and air conditioning. The temperature control of the test space in which the test material to be tested is maintained is usually carried out in a circulating air duct within the test space. The circulating air duct forms an air handling space within the test space, in which a heat exchanger for heating or cooling the air flowing through the circulating air duct and flowing through the test space is provided. The fan or ventilator draws in the air located in the test space and guides it to the corresponding heat exchanger in the circulating air duct, and vice versa. In this way, the test material can be temperature controlled or can be exposed to a defined temperature change. For example, during the test interval, the temperature can be repeatedly changed between the highest temperature and the lowest temperature of the test chamber. Such a test chamber is known, for example, from EP 0 344 397 A2.

[0003] In view of the high demands placed on temperature control within the temperature range of the test space, the load requirements change regularly during the operation of the test room. Therefore, it must be possible to continuously control the cooling capacity generated by the compressor and the expansion element. Likewise, it is desirable that the compressor is not frequently switched on and off in order to extend the service life of the compressor. This requirement is usually solved by a bypass, which includes a controllable expansion element and through which the cooling capacity can be circulated through a heat exchanger, which is established between the high-pressure side and the low-pressure side of the cooling circuit. By this on-demand distribution of the mass flow generated by the compressor in the cooling circuit, even small temperature differences between the current temperature and the target temperature can be equalized at the heat exchanger without an unfavorable load occurring at the compressor. However, there is a disadvantage that if there are small temperature differences at the heat exchanger, the compressor always has to be operated, no matter how large the temperature difference equalized by the cooling device is. For example, in the case of a required cooling of <1% of the total capacity, the full cooling capacity of the compressor must be provided in order to be able to maintain the required target temperature at the heat exchanger. Most of the cooling capacity will be recirculated to the compressor via the bypass. Since the compressor cannot be switched on and off repeatedly and the ventilator must be operated on the condenser, the known operating mode described here leads to a higher energy consumption of the cooling device even in the case of very small temperature differences to be equalized. Summary of the invention

[0004] It is therefore an object of the present invention to provide a test chamber and a method for conditioning the air in a test space of a test chamber, by means of which the test chamber can be operated in an energy-saving manner.

[0005] This object is achieved by a test chamber having the features of the solution according to the invention and by a method having the features of the solution according to the invention.

[0006] The test chamber for conditioning air according to the present invention comprises a test space for receiving test material, which can be isolated from the surrounding environment and is thermally insulated, and a temperature control device for controlling the temperature of the test space, the temperature control device allowing a temperature in the temperature range of -20°C to +180°C to be established in the test space, the temperature control device having a cooling device, the cooling device comprising a cooling circuit with a refrigerant, a heat exchanger, a compressor, a condenser and an expansion element, wherein the cooling circuit has an internal storage device, the internal storage device is connected to the high-pressure side of the cooling circuit upstream of the expansion element and downstream of the condenser in the flow direction through a bypass of the cooling circuit, and is connected to the low-pressure side of the cooling circuit upstream of the compressor and downstream of the heat exchanger in the flow direction, wherein thermal energy is stored and exchanged with the refrigerant through the internal storage device.

[0007] In this context, the term thermal energy refers to thermal energy or heat expressed in joules, heat supply increases thermal energy and heat dissipation reduces thermal energy. In this way, the internal storage device of the present invention can also store thermal energy in such a way that cooling capacity can be stored by heat dissipation.

[0008] In the case of the test chamber according to the invention, heat exchange with the surroundings of the test space is largely avoided by the temperature insulation of the side walls, the bottom wall and the top wall. The heat exchanger is connected to or integrated in the cooling circuit, in which the refrigerant circulates, thereby flowing through the heat exchanger. The heat exchanger of the cooling circuit can be arranged in the test space, or more precisely, in the air handling space of the test space, or, if the cooling device has two cascaded cooling circuits, it is alternatively connected to another cooling circuit of the cooling device. In this case, the heat exchanger serves as a condenser for another cooling circuit. The cooling device also includes a compressor and a condenser for the compressed refrigerant, the condenser being arranged downstream of the compressor in the flow direction of the refrigerant. The compressed refrigerant, which is high pressure and essentially gaseous after being compressed, is condensed in the condenser, and then it is essentially in a liquid state. The liquid refrigerant flows through the expansion element, during which it becomes gaseous again by expansion due to the pressure drop. In doing so, it flows through the heat exchanger, thereby cooling it. Thereafter, the gaseous refrigerant is sucked in and compressed again by the compressor. The term expansion element refers at least to an expansion valve, a throttle, a throttle or other suitable narrowing of a fluid conduit.

[0009] According to the present invention, the internal storage device is connected via a bypass or integrated in the cooling circuit upstream of the expansion element in the flow direction between the high-pressure side and the low-pressure side, downstream of the condenser, upstream of the compressor, and downstream of the heat exchanger. In the case where the heat exchanger only requires a small cooling capacity, the refrigerant or the corresponding mass flow of the compressed refrigerant can be transferred from the high-pressure side to the internal storage device and recirculated to the compressor. The heat energy inherent to the compressed refrigerant on the high-pressure side can be transferred to the internal storage device, or the heat energy can be taken out from the internal storage device so that the cold capacity is stored in the internal storage device. Therefore, the internal storage device can be cooled or provided with cold capacity instead of the heat exchanger. The cold capacity can be circulated to the low-pressure side again by the refrigerant, which allows the compressor to be closed in advance. When the compressor is closed, the gaseous refrigerant upstream of the compressor in the flow direction on the low-pressure side can flow through the bypass and the internal storage device, wherein the refrigerant can condense in the internal storage device due to the cold capacity or the low heat energy stored there. As the density of the refrigerant increases due to condensation, the pressure on the low-pressure side of the cooling circuit drops. Since the condensing pressure of the expansion element changes only slightly after the compressor has been shut down, the pressure difference at the expansion element persists and can be used to cool the heat exchanger. A substantial aspect is that an early shut-down of the compressor and, if present, of the ventilator becomes possible in this way, while the target temperature at the heat exchanger can still be maintained for a while or the temperature difference can be compensated. The cold capacity generated by the compressor and not required can be intermittently stored in an internal storage device and delivered again by condensation of the refrigerant. Since the operating time of the compressor is thus reduced, the test chamber can be operated in a particularly energy-saving manner.

[0010] The internal storage device can consist of an internal heat exchanger and a controllable second expansion element, wherein the second expansion element can be arranged between the high-pressure side and the internal heat exchanger in the bypass. This also allows the liquid refrigerant from the high-pressure side to evaporate via the second expansion element in such a way that the refrigerant can be discharged as required and reintroduced again in the gaseous state into the internal heat exchanger due to the pressure drop, the internal heat exchanger being cooled as a result. The gaseous refrigerant leaving the internal heat exchanger will have a higher temperature, because the cold capacity transferred in the internal heat exchanger can be recycled to the compressor.

[0011] The internal heat exchanger may be formed by a plate heat exchanger, the secondary side of which may be filled with a storage fluid. For example, the storage fluid may be a phase change material (PCM), a salt solution or a gas that is liquefiable within a temperature range, such as carbon dioxide. The secondary side may be provided with suitable means that can compensate for pressure increases or decreases by changing the density of the storage fluid.

[0012] A second bypass with at least a controllable third expansion element can be formed in the cooling circuit, wherein the second bypass can be connected to the high-pressure side upstream of the expansion element and downstream of the condenser in the flow direction and to the low-pressure side upstream of the compressor and downstream of the heat exchanger in the flow direction, wherein the refrigerant can be supplied from the third expansion element to the low-pressure side, wherein the second bypass and the third expansion element can form a controllable internal additional cooling system. By means of the second bypass or the third expansion element, the refrigerant can be metered in such a way that the suction temperature and / or the suction pressure of the refrigerant can be controlled upstream of the compressor on the low-pressure side of the cooling circuit. In this way, for example, it is possible to prevent the compressor from overheating and thus damaging. Thus, the gaseous refrigerant located upstream of the compressor can be cooled via the second bypass by actuating the third expansion element and adding metered refrigerant that is still liquid. The third expansion element can be actuated by a controller that is connected to a pressure sensor and / or a temperature sensor in the cooling circuit upstream of the compressor. It is particularly advantageous that a suction temperature of ≤30°C, preferably ≤40°C, can be set by the second bypass. For example, the refrigerant can be directed through the internal storage device via the third bypass in order to delay the automatic shut-off of the compressor or to extend the operating time of the compressor. In addition, the internal storage device can be supplied with refrigerant dynamically, or, depending on the current load conditions, excess liquid refrigerant that is not required to cool the suction temperature can be introduced into the internal storage device during the operation of the compressor.

[0013] Another bypass including at least another controllable expansion element can be formed in the cooling circuit, wherein the other bypass can be connected to the high pressure side downstream of the compressor and upstream of the condenser in the flow direction, and connected to the low pressure side upstream of the compressor and downstream of the heat exchanger in the flow direction, wherein the refrigerant can be supplied to the low pressure side from the other expansion element, wherein the other bypass and the other expansion element can form a re-injection device for the refrigerant. In this way, the hot gaseous refrigerant can be recycled from the high pressure side downstream of the compressor to the low pressure side upstream of the compressor. Another bypass can be provided, which is directly connected to the bypass adjacent to the internal storage device. This allows an increase in the cold capacity or thermal energy stored in the internal heat exchanger. Then, by means of another bypass or re-injection device, the refrigerant can continue to be superheated downstream of the internal heat exchanger, which can form a so-called hot gas bypass, thereby achieving overflow operation of the internal heat exchanger during normal operation of the compressor, and this increase in efficiency allows the internal heat exchanger or the internal storage device to cool faster. As a result, the operating time of the compressor can be further shortened.

[0014] According to an alternative embodiment, a further bypass comprising at least one further controllable expansion element can be formed in the cooling circuit, wherein the further bypass can be connected to the high-pressure side downstream of the compressor and upstream of the condenser in the flow direction, and to an internal storage device between the second expansion element and the internal heat exchanger, wherein the refrigerant can be supplied to the internal heat exchanger from the further expansion element, wherein the further bypass and the further expansion element can form a re-injection device for the refrigerant. After the refrigerant is recondensed in the internal heat exchanger on the low-pressure side, if recondensation is no longer possible due to the temperature increase in the internal heat exchanger, the compressor must be put into operation again. Due to the resulting drop in vapor pressure, the refrigerant in the internal heat exchanger evaporates and the flow direction of the refrigerant in the internal heat exchanger changes. It would be disadvantageous if the refrigerant recondensed in the internal heat exchanger was sucked into the compressor. This can prevent the introduction of hot gaseous refrigerant into the internal heat exchanger by the further bypass or the re-injection device formed thereby, thereby allowing the liquid refrigerant accumulated in the internal heat exchanger to be pre-evaporated.

[0015] It is particularly advantageous if the suction gas temperature and / or the suction gas pressure of the refrigerant on the low-pressure side of the cooling circuit can be controlled upstream of the compressor and / or the pressure difference between the high-pressure side and the low-pressure side of the cooling circuit can be equalized. In this way, a possible overheating of the compressor and thus damage can be prevented. It is particularly advantageous if a suction gas temperature of ≤30° C., preferably ≤40° C., can be set. Moreover, the refrigerant can be metered so that the operating time of the compressor can be controlled. This is generally disadvantageous if the compressor is repeatedly switched on and off. If the compressor is operated for a longer period of time, the service life of the compressor can be extended. In this case, the compressor can also be switched off for a longer period of time.

[0016] The temperature control device may comprise a control device having a pressure sensor and / or a temperature sensor at least in the cooling circuit, wherein the magnetic valve of the expansion element may be actuated by a control unit as a function of the measured temperature or pressure. The control unit may comprise means for data processing, which processes the data sets from the sensors and controls the magnetic valve. In this case, the function of the cooling device may also be adjusted to the refrigerant used, for example by a corresponding computer program. In addition, the control unit may emit a fault signal and, if necessary, initiate the closing of the test chamber in order to protect the test chamber or the test material from damage due to critical or undesirable operating states of the test chamber.

[0017] If the expansion element is implemented as a throttle valve including a magnetic valve, the refrigerant can be metered via the throttle valve and the magnetic valve. In this case, the throttle valve can be an adjustable valve or a capillary tube via which the refrigerant can be routed through the magnetic valve. The magnetic valve itself can be actuated using a control unit.

[0018] By means of the temperature control device, a temperature in the temperature range of -40°C to +180°C, preferably -70°C to +180°C, can be established in the test space. An essential aspect is that the temperature in the temperature range of >+60°C to +180°C in the test space can be reduced by the temperature control device. The refrigerant in the heat exchanger is strongly heated by the higher temperature in the test space, which is why the cooling circuit can be technically adapted in terms of construction, at least on the low-pressure side of the cooling circuit, to a refrigerant heated in this temperature range. Otherwise, the refrigerant heated in this way can no longer be used optimally on the low-pressure side of the cooling circuit.

[0019] In one embodiment of the test chamber, the heat exchanger can be arranged in the test space. Moreover, the heat exchanger can be arranged in the air handling space of the test space, which allows the air circulated by the ventilator to come into contact with the heat exchanger. As a result, the circulating air volume of the test space can be cooled directly in the test space by the cooling device via the heat exchanger.

[0020] In this way, the cooling device may have only one cooling circuit. The single cooling circuit of the test chamber may be directly connected to the test space. Moreover, in this case, the lowest temperature achievable in the test space may not be lower than -20°C.

[0021] In another embodiment of the test chamber, the heat exchanger can form a cascade heat exchanger for another cooling circuit of the cooling device. Thus, the test chamber can have at least two cooling circuits, in which case the cooling circuit forms the first stage of the cooling device, while another cooling circuit directly connected to the test space forms the second stage of the cooling device. The cascade heat exchanger or heat exchanger also serves as a condenser for another cooling circuit. Thus, in this embodiment of the test chamber, a particularly low temperature can be established in the test space. Another cooling circuit can have another refrigerant, another compressor, another heat exchanger, another condenser and another expansion element, wherein another heat exchanger can be arranged in the test space, wherein another cooling circuit can be connected to the cascade heat exchanger of the cooling circuit by another cooling circuit. In this case, the cooling device has two circuits connected in series, which form a so-called cooling cascade. Each of the two cooling circuits can also have an internal storage device as described above.

[0022] The temperature control device may have a heating device, which includes a heater in the test space and a heating heat exchanger. For example, the heating device may be a resistance heater that heats the heat exchanger in such a way that the temperature in the test space can be increased by heating the heat exchanger. If the air circulating in the test space can be cooled or heated by the heat exchanger and the heating heat exchanger specifically controlled by the control unit, a temperature in the temperature range indicated above can be established in the test space by the temperature control device. Regardless of the test material or the operating state of the test material, a temperature constancy of ±1K, preferably ±0.3K to ±0.5K can be established in the test space during the test interval. The term test interval refers to the time period of a complete test cycle, in which the test material is exposed to essentially constant temperature or climatic conditions. The heating heat exchanger can be combined with the heat exchanger of the cooling circuit so that a common heat exchanger body is formed, through which the refrigerant can flow and has the heating element of the resistance heater. The condenser can be cooled by air or water or another cooling fluid. In principle, the condenser can be cooled with any suitable fluid. The important point is that the heat load occurring at the condenser is dispersed by the cooling air or cooling water so that the refrigerant can condense until it is completely liquefied.

[0023] In the method according to the invention for conditioning the air in a test space of a test chamber, the test chamber being used to receive test materials and being closed and thermally insulated from the surrounding environment, a cooling device (comprising a cooling circuit, a refrigerant, a heat exchanger, a compressor, a condenser and an expansion element) of a temperature control device of the test chamber is used to establish a temperature in the temperature range of -20°C to +180°C in the test space, thermal energy being stored and exchanged with the refrigerant by an internal storage device of the cooling circuit, the internal storage device of the cooling circuit being connected to the high-pressure side of the cooling circuit in the flow direction upstream of the expansion element and downstream of the condenser and being connected to the low-pressure side of the cooling circuit in the flow direction upstream of the compressor and downstream of the heat exchanger via a bypass of the cooling circuit.

[0024] With regard to the advantages of the method according to the invention, reference is made to the description of the advantages of the device according to the invention. Overall, the thermal efficiency of the cooling device can be increased, so that a considerable amount of energy can be saved. The heat exchanger can be cooled for a relatively long time by the expansion element without operating the compressor. In addition to shutting down the compressor, other components of the cooling device can also be shut down, such as the ventilator of the condenser or, if the condenser is water-cooled, the water cooling system. In addition, when the compressor is shut down, the cooling device can be controlled more accurately, since the compressor does not interfere with the pressure and temperature conditions in the cooling circuit.

[0025] The refrigerant can be directed from the high pressure side to the low pressure side through the internal storage device. When the compressor is running, the refrigerant can be directed from the high pressure side to the low pressure side, and when the compressor is off, the refrigerant can flow from the low pressure side into the internal storage device. Therefore, the refrigerant can change the flow direction in the bypass depending on whether the internal storage device is storing or transferring heat energy.

[0026] In a first step, liquid refrigerant from the high-pressure side may be expanded into gaseous refrigerant by means of an internal storage device and directed to the low-pressure side.

[0027] The compressor can then be operated in such a way that the refrigerant is evaporated by the controllable second expansion element and is led through the internal heat exchanger of the internal storage device, wherein thermal energy can be transferred from the storage fluid of the internal heat exchanger to the refrigerant.

[0028] Subsequently, in a second step, the gaseous refrigerant from the low-pressure side can be condensed into liquid refrigerant by the internal storage device. This depends on whether the internal storage device is sufficiently cooled or stores sufficiently little thermal energy to enable the condensation of the gaseous refrigerant. In this context, the internal storage device can be provided to be cooled until a significant temperature difference can be achieved by said cooling.

[0029] By condensing the refrigerant in the internal storage device, a pressure difference can be established between the low-pressure side and the high-pressure side. The internal storage device can then be used as a cooling heat sink.

[0030] Thus, the compressor can be turned off and the refrigerant can be introduced into the internal heat exchanger of the internal storage device and condensed, wherein heat energy can be transferred from the refrigerant to the storage fluid of the internal heat exchanger. This exchange of heat energy from the refrigerant to the storage fluid reheats the storage fluid and cools the refrigerant, which causes the refrigerant to condense. This process can be performed until the temperature difference between the storage fluid and the refrigerant is such that condensation of the refrigerant in the internal heat exchanger is no longer possible or until the internal heat exchanger is filled with liquid refrigerant. The compressor can then be operated again.

[0031] Further embodiments of the method are apparent from the description of the features of the inventive solution of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Hereinafter, preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings.

[0033] Figure 1 is a schematic diagram of an embodiment of a cooling device;

[0034] Figure 2 is a schematic diagram of a second embodiment of a cooling device;

[0035] Figure 3 is a schematic diagram of a third embodiment of a cooling device. DETAILED DESCRIPTION

[0036] Figure 1 A schematic diagram of a cooling device 10 comprising a cooling circuit 11 is shown, in which a refrigerant can circulate. In addition, the cooling device 10 comprises a heat exchanger 12, a compressor 13, a condenser 14 and an expansion element 15 arranged in a test space 38 (implied in the drawing) or in another cooling circuit (not shown). The expansion element 15 consists of a throttle valve 16 and a magnetic valve 17. The cooling circuit 11 has a high-pressure side 18 and a low-pressure side 19, which extends from the compressor 13 to the expansion element 15 in the flow direction of the refrigerant, and the low-pressure side 19 extends from the expansion element 15 to the compressor 13. In the pipe section 20 from the compressor 13 to the condenser 14, the refrigerant is gaseous and has a relatively high temperature. The refrigerant compressed by the compressor 13 flows in the cooling circuit 11 toward the condenser 14, and the gaseous refrigerant is liquefied in the condenser 14. In the flow direction of the refrigerant in the cooling circuit 11, the condenser 14 is followed by the expansion element 15, and the refrigerant is therefore in a liquid state in a pipe section 21 of the cooling circuit 11 between the condenser 14 and the expansion element 15. The heat exchanger 12 is cooled by the expansion of the refrigerant downstream of the expansion element 15, and the refrigerant is converted into a gaseous state in a pipe section 22 between the expansion element 15 and the heat exchanger 12 and is guided from the heat exchanger 12 to the compressor 13 via a pipe section 23.

[0037] In the cooling circuit 11, the internal storage device 24 is also connected to the high-pressure side 18 upstream of the expansion element 15 and downstream of the condenser 14 in the flow direction, and to the low-pressure side 19 upstream of the compressor 13 and downstream of the heat exchanger 12 in the flow direction via a bypass 25 of the cooling circuit 11. Thermal energy can be stored and exchanged with the refrigerant via the internal storage device 24. The internal storage device 24 consists of an internal heat exchanger 26 and a controllable second expansion element 27. The second expansion element 27 is arranged in the bypass 25 between the high-pressure side 18 and the internal heat exchanger 26. When the compressor 13 is running and a small cold capacity is required at the heat exchanger 12, the control unit (not shown) of the test chamber is used to expand the refrigerant via the second expansion element 27 and guide it through the internal heat exchanger 26 of the internal storage device 24. The internal heat exchanger 26 has a storage fluid (not shown) which transfers thermal energy to the refrigerant in such a way that the storage fluid is cooled. When a significant temperature difference can no longer be achieved by cooling the storage fluid, the compressor 13 is turned off and refrigerant is introduced from the low-pressure side 19 into the internal heat exchanger 26. The refrigerant condenses in the internal heat exchanger 26, and heat energy is transferred from the refrigerant to the storage fluid. This process can continue until the storage fluid is heated enough that the refrigerant is no longer condensing or until the internal heat exchanger 26 is full. By condensing and accumulating the refrigerant, the density of the refrigerant increases and the pressure on the low-pressure side 19 decreases. This reduction again creates a pressure difference at the expansion element 15, which can be used to expand the refrigerant through the heat exchanger 12. Subsequently, the compressor 13 can be operated again, and the subsequent decompression causes the refrigerant in the internal heat exchanger 26 to evaporate.

[0038] Furthermore, a further bypass 28 comprising a further controllable expansion element 29 is provided in the cooling circuit 11, which is connected to the high-pressure side 18 downstream of the compressor 13 and upstream of the condenser 14 in the flow direction and to the internal storage device 24 between the second expansion element 27 and the internal heat exchanger 26. Thus, hot gaseous refrigerant from the high-pressure side 18 can be introduced into the internal heat exchanger 26 via the further expansion element 29. Furthermore, the suction of liquid refrigerant in the hot internal heat exchanger 26 located inside can be prevented during the start-up of the compressor 13 if the refrigerant mixes with the hot gaseous refrigerant.

[0039] Figure 2 The cooling device 30 includes a cooling circuit 31. Figure 1The cooling device of the cooling circuit 31 shown differs in that it has a further bypass 32 comprising a further controllable expansion element 33, which is connected to the high-pressure side 18 in the flow direction downstream of the compressor 13 and upstream of the condenser 14, and to the low-pressure side 19 in the flow direction upstream of the compressor 13 and downstream of the heat exchanger 12. This allows hot and gaseous refrigerant to be recirculated from the high-pressure side 18 to the low-pressure side 19 upstream of the compressor 13, whereby the suction gas temperature and / or the suction gas pressure of the refrigerant on the low-pressure side 19 become controllable. In addition, the pressure difference between the high-pressure side 18 and the low-pressure side 19 can be equalized. Control of the suction gas temperature is advantageous in particular if the refrigerant is expanded via the internal heat exchanger 26.

[0040] Figure 3 Another cooling device 34 is shown, which comprises a cooling circuit 35. Figure 2 The cooling device of FIG. 1 is different in that it has a second bypass 36. The second bypass 36 is provided with a controllable third expansion element 37. The second bypass 36 is connected to the high-pressure side 18 upstream of the expansion element 15 and downstream of the condenser 14 in the flow direction, and is connected to the low-pressure side 19 upstream of the compressor 13 and downstream of the heat exchanger 12 in the flow direction. Refrigerant can be supplied to the low-pressure side 19 via the third expansion element 37, thereby again allowing the refrigerant upstream of the compressor 13 to expand and the suction gas temperature to be reduced or controlled.

[0041] Reference numerals

[0042] 10Cooling device

[0043] 11Cooling circuit

[0044] 12Heat exchanger

[0045] 13. Compressor

[0046] 14 Condenser

[0047] 15 expansion element

[0048] 16 throttle valve

[0049] 17 Magnetic valve

[0050] 18 High-voltage side

[0051] 19 Low pressure side

[0052] 20 pipe sections

[0053] 21 pipe section

[0054] 22 pipe sections

[0055] 23 pipe section

[0056] 24 internal storage devices

[0057] 25 Bypass

[0058] 26 Internal heat exchanger

[0059] 27 Second expansion element

[0060] 28 Another Bypass

[0061] 29 Another expansion element

[0062] 30 Cooling device

[0063] 31 Cooling circuit

[0064] 32 Another bypass

[0065] 33 Another expansion element

[0066] 34 Cooling device

[0067] 35 Cooling circuit

[0068] 36 Second bypass

[0069] 37 The third expansion element

[0070] 38Test Space

Claims

1. A test chamber for conditioning air, comprising: a test space (38) for receiving the test material, which can be isolated from the surrounding environment and is thermally insulated, and A temperature control device for controlling the temperature of the test space, the temperature control device allowing a temperature in the temperature range of -20°C to +180°C to be established in the test space, the temperature control device having a cooling device (10, 30, 34), the cooling device comprising a cooling circuit (11, 31, 35) with a refrigerant, a heat exchanger (12), a compressor (13), a condenser (14) and an expansion element (15), It is characterized in that The cooling circuit has an internal storage device (24), which is connected to the high-pressure side (18) of the cooling circuit upstream of the expansion element and downstream of the condenser in the flow direction, and is connected to the low-pressure side (19) of the cooling circuit via a bypass (25) of the cooling circuit upstream of the compressor and downstream of the heat exchanger in the flow direction, thermal energy being stored by the internal storage device and exchanged with the refrigerant, The internal storage device (24) consists of an internal heat exchanger (26) and a controllable second expansion element (27), which is arranged between the high-pressure side (18) and the internal heat exchanger in the bypass (25), and A second bypass (36) having at least one controllable third expansion element (37) is formed in the cooling circuit (35), the second bypass being connected to the high-pressure side (18) upstream of the expansion element (15) and downstream of the condenser (14) in the flow direction, and being connected to the low-pressure side (19) upstream of the compressor (13) and downstream of the heat exchanger (12) in the flow direction, refrigerant being supplied to the low-pressure side from the third expansion element, the second bypass and the third expansion element forming a controllable internal additional cooling system.

2. The test chamber according to claim 1, It is characterized in that The internal heat exchanger (26) is formed by a plate heat exchanger, the secondary side of which is filled with a storage fluid.

3. The test chamber according to claim 1 or 2, It is characterized in that A further bypass (28) having at least one further controllable expansion element (27) is formed in the cooling circuit (11), the further bypass being connected to the high-pressure side (18) downstream of the compressor (13) and upstream of the condenser (14) in the flow direction, and being connected to the low-pressure side (19) upstream of the compressor and downstream of the heat exchanger (12) in the flow direction, the refrigerant being supplied to the low-pressure side from the further expansion element, the further bypass and the further expansion element forming a refrigerant reinjection device.

4. The test chamber according to claim 1 or 2, It is characterized in that A further bypass (32) having at least one further controllable expansion element (33) is formed in the cooling circuit (31), the further bypass being connected to the high-pressure side (18) downstream of the compressor (13) and upstream of the condenser (14) in the flow direction and being connected to the internal storage device (24) between the second expansion element (27) and the internal heat exchanger (26), the refrigerant being supplied from the further expansion element to the internal heat exchanger, the further bypass and the further expansion element forming a re-injection device for the refrigerant.

5. The test chamber according to claim 1, It is characterized in that The suction gas temperature and / or the suction gas pressure of the refrigerant is controlled upstream of the compressor (13) on the low-pressure side (19) of the cooling circuit (11, 31, 35) and / or in that the pressure difference between the high-pressure side (18) and the low-pressure side of the cooling circuit is equalized.

6. The test chamber according to claim 1, It is characterized in that The temperature control device comprises a control unit having at least a pressure sensor and / or a temperature sensor in the cooling circuit (11, 31, 35), and the magnetic valve (17) is actuated by the control unit according to the measured pressure and / or temperature.

7. The test chamber according to claim 1, It is characterized in that A temperature within the temperature range of -40°C to +180°C is established in the test space (38) by the temperature control device.

8. The test chamber according to claim 1, It is characterized in that The heat exchanger is arranged in the test space (38).

9. The test chamber according to claim 1, It is characterized in that The cooling device (10, 30, 34) has only one cooling circuit.

10. The test chamber according to claim 1, It is characterized in that The heat exchanger (12) forms a cascade heat exchanger for a further cooling circuit of the cooling device (10, 30, 34).

11. The test chamber according to claim 1, It is characterized in that The temperature control device has a heating device, which includes a heater and a heating heat exchanger in the test space (38).

12. A method for conditioning the air in a test space (38) of a test chamber, the test space being intended for receiving test material, being separable from the surroundings and being thermally insulated, wherein a temperature in the temperature range of -20°C to +180°C is established in the test space by means of a cooling device (10, 30, 34) of a temperature control device of the test chamber, the cooling device comprising a cooling circuit (11, 31, 35) with a refrigerant, a heat exchanger (12), a compressor (13), a condenser (14) and an expansion element (15), It is characterized in that Thermal energy is stored and exchanged with the refrigerant via an internal storage device (24) of the cooling circuit, which is connected to the high-pressure side (18) of the cooling circuit in the flow direction upstream of the expansion element and downstream of the condenser, and is connected to the low-pressure side (19) of the cooling circuit via a bypass (25) of the cooling circuit in the flow direction upstream of the compressor and downstream of the heat exchanger, The internal storage device (24) consists of an internal heat exchanger (26) and a controllable second expansion element (27), which is arranged between the high-pressure side (18) and the internal heat exchanger in the bypass (25), and A second bypass (36) having at least one controllable third expansion element (37) is formed in the cooling circuit (35), the second bypass being connected to the high-pressure side (18) upstream of the expansion element (15) and downstream of the condenser (14) in the flow direction, and being connected to the low-pressure side (19) upstream of the compressor (13) and downstream of the heat exchanger (12) in the flow direction, refrigerant being supplied to the low-pressure side from the third expansion element, the second bypass and the third expansion element forming a controllable internal additional cooling system.

13. The method according to claim 12, It is characterized in that The refrigerant is guided from the high-pressure side to the low-pressure side through the internal storage device (24).

14. The method according to claim 12, It is characterized in that In a first step, liquid refrigerant from the high-pressure side (18) is expanded into gaseous refrigerant through the internal storage device (24) and directed to the low-pressure side (19).

15. The method according to claim 14, It is characterized in that The compressor (13) is operated, the refrigerant is evaporated by a controllable second expansion element (27) and is led through an internal heat exchanger (26) of the internal storage device (24), heat energy being transferred from the storage fluid of the internal heat exchanger to the refrigerant.

16. The method according to claim 14, It is characterized in that In the second step, the gaseous refrigerant from the low pressure side (19) is condensed into liquid refrigerant through the internal storage device (24).

17. The method according to claim 16, It is characterized in that By condensing the refrigerant in the internal storage device (24), a pressure difference is established between the low-pressure side (19) and the high-pressure side (18).

18. The method according to claim 16 or 17, It is characterized in that The compressor (13) is turned off and the refrigerant is directed into an internal heat exchanger (26) of the internal storage device (24) and condenses, with heat energy being transferred from the refrigerant to a storage fluid of the internal heat exchanger.

Images