Test chamber and method for control

Abstract

To provide a test chamber and a method for conditioning air in a temperature-insulated test space (17), in particular, an artificial climate chamber.SOLUTION: A cooling element (11) of a temperature-control device (10) of the test chamber, and a first cooling circuit (12) having a first refrigerant, a heat exchanger (13) in the test space, a compressor (14), a gas cooler (15), a cascade heat exchanger (20), and an expansion valve (16) are used to yield a temperature ranging from -20°C to +150°C within the test space. The cascade heat exchanger is connected to a high-pressure portion (18) of the first cooling circuit. The cascade heat exchanger is coupled with a second cooling circuit (21) of the cooling element. The temperature in the test space is controlled and / or regulated by the control device of the test chamber. The first refrigerant is an unfluorinated refrigerant, preferably pure carbon dioxide. The second cooling circuit comprises a pump and a liquid as a heat carrier. The temperature is yielded within the test space.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a test chamber and a method for air-conditioning an insulated test space of the test chamber, in particular a climate chamber. The test space is sealable from the ambient environment and configured to receive test materials, and a temperature in the test space ranging from -20°C to +150°C is generated by a first cooling circuit having a cooling element of a temperature control device of the test chamber, a first refrigerant, a heat exchanger in the test space, a compressor, a gas cooler, a cascade heat exchanger, and an expansion valve. The cascade heat exchanger is connected to a high-pressure section of the first cooling circuit, and the cascade heat exchanger is connected to a second cooling circuit of the cooling element, and the temperature of the test space is controlled and / or regulated by the control device of the test chamber. [Background technology]

[0002] Such test chambers are typically used to test the physical and / or chemical properties of objects, particularly equipment. For this purpose, temperature and climate test chambers capable of setting temperatures ranging from -50°C to +150°C are known. Climate test chambers can also set additional desired climatic conditions to which equipment and / or test materials are exposed for a specified period of time. The temperature of the test space containing the test materials is typically controlled in an air circulation duct within the test space. The air circulation duct forms an air handling space within the test space, in which a heat exchanger is located to heat or cool the air flowing through the air circulation duct and / or the test space. Air from the test space is drawn in by a fan and / or ventilation device and directed toward the corresponding heat exchanger within the air circulation duct. This allows the temperature of the test materials to be controlled or to be exposed to specified temperature changes. Between tests, for example, the temperature of the test chamber is varied between a maximum and minimum temperature. A test chamber of this type is known, for example, from US Pat. No. 5,629,499.

[0003] To meet high temperature control requirements within the temperature range of the test space using such cooling elements and avoid fluctuations in load requirements, the cooling elements can also be configured in the form of a cascade refrigeration system. In this cascade refrigeration system, a first cooling circuit and a second cooling circuit are linked and / or connected via a common cascade heat exchanger, and the heat exchanger of the first cooling circuit is used to control the temperature of the test space in the test chamber. The second cooling circuit is used to cool and / or condense the refrigerant of the first cooling circuit when high cooling loads are required.

[0004] The refrigerants used in the refrigeration circuits must have a relatively low carbon dioxide equivalent value, i.e., as low a global warming potential (GWP) as possible, to avoid indirect damage to the environment if the refrigerant is released. Legal regulations require that refrigerants do not contribute significantly to the depletion of the atmospheric ozone layer or global warming.

[0005] It is also known to use hydrocarbons as refrigerants, but these have the disadvantage of being highly flammable. Flammability here refers to the refrigerant's ability to react with ambient oxygen and release heat. Refrigerants are particularly flammable if they fall into fire class C according to classes A2, A2L, and A3 of the latest European Standards DN2 and / or DIN 378 in force at the priority date.

[0006] In principle, fluorinated gases and substances should not be used as refrigerants. For this reason, natural refrigerants such as carbon dioxide (CO2) are being considered. Compared to refrigerants with relatively high GWPs, the disadvantage of such refrigerants with low GWPs is that they can significantly reduce the cooling capacity in the temperature range relevant to the refrigeration circuit. Low GWPs can be achieved with refrigerant mixtures containing a relatively high mass fraction of carbon dioxide. However, these mixtures are non-azeotropic due to the mixing of different substances, which is undesirable for many refrigeration circuits. Furthermore, the proportion of carbon dioxide must be very high to prevent the refrigerant from becoming flammable. For example, Patent Document 2 describes a test chamber with a refrigerant essentially consisting of carbon dioxide, pentafluoroethane, and difluoromethane. A disadvantage here is that the refrigerant must be subcooled by an internal heat exchanger in the refrigeration circuit to achieve particularly low temperatures. Furthermore, this refrigerant is non-azeotropic and contains a fluorinated gas as a component. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent Application Publication No. 0344397 [Patent Document 2] International Publication No. 2019 / 048250 Summary of the Invention [Problem to be solved by the invention]

[0008] The cooling capacity of carbon dioxide is so high that it limits the scope of climate tests. The test space must be kept at a defined relative humidity and temperature. This is especially true if, for example, the air in the test space is cooled during a test cycle. This requires dehumidification of the air in the test space. When cooling the air, the high cooling capacity can make it difficult to control condensation in the heat exchanger, which can lead to undesired dehumidification of the air in the test space. Furthermore, dehumidification can be insufficient if, for example, a test cycle is planned that involves only very slow temperature changes. Therefore, this type of cooling element does not always allow for a climate test cycle to be performed with satisfactory accuracy.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for air conditioning within a test space of a test chamber and a test chamber, both of which are environmentally friendly and capable of carrying out climatic tests efficiently. [Means for solving the problem]

[0010] This object is achieved by a method having the features of claim 1, a test chamber having the features of claim 16 and a system having the features of claim 21.

[0011] In a method according to the present invention for air conditioning an insulated test space in a test chamber, in particular a climate chamber, the test space is sealable from the surrounding environment and configured to receive a test material, and a temperature of -20°C to +150°C is generated in the test space by a first cooling circuit having a first refrigerant, a heat exchanger in the test space, a compressor, a gas cooler, a cascade heat exchanger, and an expansion valve, which form the cooling element of a temperature control device for the test chamber. The cascade heat exchanger is connected to a high-pressure section of the first cooling circuit, and the cascade heat exchanger is connected to a second cooling circuit of the cooling element, and the temperature of the test space is controlled and / or regulated by the control device of the test chamber. The first refrigerant is a non-fluorinated refrigerant, preferably pure carbon dioxide, and the second cooling circuit has a pump and a liquid as a heat transfer medium, and temperature generation in the test space is achieved.

[0012] According to the present invention, the cooling element is configured in the manner of at least a cascade refrigeration system. However, in the second cooling circuit, a heat transfer medium is used instead of a second refrigerant, and a pump is used instead of a compressor. Essentially, the heat transfer medium is circulated through the second cooling circuit by a pump. The heat transfer medium also passes through a cascade heat exchanger through which a first refrigerant flows. The first refrigerant is cooled and / or desuperheated in the cascade heat exchanger. The thermal energy generated in the cascade heat exchanger is dissipated by the second cooling circuit, and the cooled first refrigerant is sent to the heat exchanger in the test space. The heat exchanger is thus cooled, and the thermal energy generated in the heat exchanger in the test space is removed through the first cooling circuit, which operates with a first refrigerant that is a non-fluorinated refrigerant, preferably pure carbon dioxide. Pure carbon dioxide has a GWP of 1, is non-flammable, non-toxic, and inexpensively available. Furthermore, because carbon dioxide is a pure substance and / or an azeotrope, various variations of this method are inherently possible. The heat transfer medium in the second cooling circuit also ensures that the first refrigerant is liquefied at a relatively stable temperature within the cascade heat exchanger. Furthermore, the second cooling circuit requires only one pump to circulate the heat transfer medium, allowing for a particularly simple and cost-effective design. This type of pump is less susceptible to high switching cycles than a compressor, allowing the second cooling circuit to operate with relatively low energy consumption when required. Furthermore, the pump operates quieter than a compressor, thereby reducing the generation of unwanted noise. This method of operating the test chamber therefore allows for an overall more environmentally friendly and safer test chamber operation, while also allowing the cooling elements to be easily adapted to a wide range of operating requirements with low energy consumption.

[0013] In this way, the heat transfer medium can circulate through the second cooling circuit without undergoing a phase change. The pressure of the heat transfer medium in the second cooling circuit, for example, a pressure of about 1 MPa, can be generated with a relatively low pressure difference, for example, 10 kPa to 50 kPa, between the inlet and return passages of the second cooling circuit. This pressure difference can vary depending on flow resistance and / or thermal expansion in the second cooling circuit. The heat transfer medium can be, for example, brine, oil, or other suitable liquid.

[0014] The second cooling circuit may have a valve element, preferably a three-way valve, between the inlet and return flow paths of the second cooling circuit, bypassing the cascade heat exchangers and allowing an adjusting element of the control device to adjust the mass flow rate of the heat transfer medium through the cascade heat exchangers. Alternatively, the valve element may consist of a plurality of solenoid valves controlled by the control device to adjust the heat transfer medium flow rate. If the valve element is configured as a three-way valve, it may be arranged in the second cooling circuit downstream of the cascade heat exchangers in the flow direction and upstream of the pump. The inlet flow path from the pump to the cascade heat exchangers in the flow direction of the heat transfer medium may be connected to the three-way valve. The three-way valve allows the cascade heat exchangers to be optimally pressurized with the heat transfer medium, eliminating the need to completely close the three-way valve, thereby achieving very high control accuracy. For example, the three-way valve can be easily controlled by a motor, stepper motor, or other actuator to optimally adjust the volumetric and / or mass flow ratio between the inlet and return flow paths through the three-way valve, and the volumetric and / or mass flow ratio between the inlet and return flow paths through the cascade heat exchanger, depending on the operating requirements.

[0015] The second cooling circuit can have a liquid bypass between its inlet and return flow paths, which can extend through a heat exchanger, allowing the first and / or second cooling circuits to generate temperature in the test space. As a result, because the liquid bypass extends through the test space and / or a heat exchanger disposed therein, the liquid bypass of the second cooling circuit can also be used to affect the temperature of the test space. Depending on the temperature to be generated in the test space, the second cooling circuit can be operated with the liquid bypass if a relatively high temperature, such as -10°C, needs to be kept as constant as possible. Alternatively, the first cooling circuit can be operated alone if a rapid temperature change is required. If a particularly low temperature is to be achieved in the test space, the first and second cooling circuits can be operated simultaneously, with or without the liquid bypass. In this case, the liquid bypass can also be used, at least within the appropriate temperature range. Changing the operation of the first and second cooling circuits requires particularly precise adjustment to prevent undesired changes in the temperature of the test space.

[0016] The liquid bypass can be provided with a bypass valve element, preferably a bypass three-way valve, between the inlet and return flow paths of the liquid bypass. The bypass valve element bypasses the heat exchanger, and the regulating element of the control device can regulate the mass flow rate of the heat medium through the heat exchanger via the bypass valve element. The bypass valve element can be formed by a plurality of solenoid valves or, for example, a three-way valve. The liquid bypass can be connected to the inlet flow path downstream of the pump and upstream of the cascade heat exchangers in the flow direction of the heat medium, and to the return flow path downstream of the cascade heat exchangers and upstream of the pump. If the bypass valve element is formed by a bypass three-way valve, the bypass three-way valve can be arranged in the inlet or return flow path of the liquid bypass. In this case, a tube connection can be provided from the inlet flow path to the bypass three-way valve or from the bypass three-way valve to the return flow path in the opposite direction, thereby bypassing the heat exchanger. The bypass valve element can be used to regulate the supply of heat medium to the heat exchanger and / or the mass flow rate of the heat medium through the heat exchanger. This allows for particularly precise regulation of the temperature in the test space.

[0017] A separate pump capable of transporting the heat transfer medium can also be placed in the liquid bypass. This additional pump can be located in the inlet or return flow path of the liquid bypass. This allows the additional pump to be used for a continuous mass flow of the heat transfer medium, which can be easily throttled using the bypass valve element, thereby achieving further improved temperature control. This avoids any fluid inhomogeneities in the second cooling circuit.

[0018] The expansion valves and / or three-way valves, each with a PID controller, of the regulating elements of the control device can be adjusted depending on the temperature of the test space as a reference variable. In principle, other suitable regulators can also be used. In particular, each of the aforementioned valves and / or throttles can be adjusted using a dedicated regulator of the regulating elements. The regulating elements can be configured to combine the corresponding regulator with a cascade regulator of the regulating elements. These valves can be controlled by suitable actuators, such as stepper motors. The cascade regulator can be adjusted depending on the temperature in the test space, which is specified by the control device as a reference variable.

[0019] The control device can activate the pump when the temperature of the test space, as the reference variable, is above 0°C and the compressor when it is below 0°C. The heat transfer medium can reach temperatures of, for example, -20°C to 0°C in the inlet channel of the second cooling circuit. Therefore, the second cooling circuit is particularly suitable when a constant temperature below 0°C or a temperature change with a small temperature gradient is required in the test space. On the other hand, the first cooling circuit is suitable for temperatures as low as -50°C, for example, when using carbon dioxide as the first cooling medium. This relatively low temperature can be effectively achieved using carbon dioxide. Therefore, the first cooling circuit can be effectively used when temperatures below 0°C, temperature changes with a large temperature gradient, or large thermal compensation are required. The second cooling circuit can also be used to liquefy the first cooling medium in the first cooling circuit. In this case, the compressor and pump are operated simultaneously. For example, the temperature of the heat transfer medium at the inlet channel can be 5 to 10 Kelvin lower than the temperature required to liquefy the first cooling medium. As shown, operating the second cooling circuit can result in a particularly uniform and stable spatial distribution of climatic and temperature conditions.

[0020] The rotation speed of the compressor and / or pump can be adjusted. The compressor and / or pump can be configured with a frequency converter, which allows adjusting the rotation speed of the compressor and / or pump, respectively. The adjustment can be performed by a PID controller, which is an adjusting element of the control device. By reducing the rotation speed, the mass flow rate of the first refrigerant and / or the second refrigerant can be reduced in a part-load operating state of the corresponding cooling circuit, thereby further increasing the efficiency of the corresponding cooling capacity in this operating state. Furthermore, adjusting the compressor rotation speed allows the control device to increase or decrease the compressor rotation speed in order to change and adapt the suction gas pressure in the low-pressure part of the first cooling circuit in a desired manner.

[0021] The first cooling circuit can be operated in a subcritical or supercritical thermodynamic operating state. The control device can be used to change the operating state appropriately depending on the cooling load demand in the test space. During subcritical operation of the first cooling circuit, the first refrigerant is liquefied below its critical point in the gas cooler and / or desuperheater and / or cascade heat exchanger, and then expanded through the expansion valve to a gas phase or wet vapor. The compressor and pump can operate at least in a subcritical operating state or at low ambient temperatures. The subcritical operating state of the first cooling circuit corresponds to partial load operation. In a supercritical operating state, the first refrigerant circulates essentially in a gaseous state within the first cooling circuit. This means that the temperature difference is small enough that the first refrigerant does not liquefy in the gas cooler or cascade heat exchanger. In a supercritical operating state, pressures exceeding the critical point of the first refrigerant in the gas cooler and / or cascade heat exchanger can also be reached. For example, when the cooling load is high, the cooling circuit can be operated in a supercritical state. If the cooling load in the test space is small, e.g. the temperature needs to be kept constant, or the ambient temperature is low, the cooling circuit can be operated subcritically.

[0022] The first cooling cycle (first cooling circuit) may be provided with a bypass having at least one bypass expansion valve, which may extend through the heat exchanger and be connected to the high-pressure part of the first cooling cycle downstream of the gas cooler or cascade heat exchanger and upstream of the expansion valve in the flow direction, and to the low-pressure part of the first cooling cycle downstream of the heat exchanger and upstream of the compressor in the flow direction, and the temperature in the test space may be adjusted so that the first refrigerant can be metered into the heat exchanger via the bypass expansion valve. The bypass of the first cooling circuit can be used particularly effectively when the cooling load requirement is high.

[0023] The air in the test space can be dehumidified by a dehumidifying bypass, and the first cooling cycle has a dehumidifying expansion valve, or the second cooling cycle (second cooling circuit) has a dehumidifying valve element, preferably a dehumidifying three-way valve, and a dehumidifying heat exchanger in the test space. Dehumidification can be performed at certain times during the test cycle, particularly whenever the temperature in the test space is between 0°C and 100°C. If the temperature generated in the test space is below or above this range, the dehumidifying bypass will not function in these regions because moisture will not condense into liquid form in the dehumidifying heat exchanger. Therefore, the first cooling circuit of the cooling element can be configured to generate temperatures from -20°C to +180°C in the test space as part of the test cycle, with the dehumidifying bypass dehumidifying the air only within a portion of this temperature range. Dehumidification is performed by supplying the first refrigerant from the high-pressure section of the first refrigerant circuit to the low-pressure section of the first refrigerant circuit using a dehumidifying expansion valve. This cools the dehumidifying heat exchanger located downstream of the dehumidifying expansion valve in the direction of the first refrigerant flow through the dehumidifying bypass. The control device can supply the first refrigerant through the dehumidifying expansion valve so as to achieve a desired temperature difference between the temperature of the air in the test space and the temperature of the dehumidifying heat exchanger. This temperature difference can be selected so that moisture in the air in the test space condenses on the dehumidifying heat exchanger. This essentially makes it possible to achieve the desired dehumidification of the air in the test space, regardless of the temperature generated in the test space. In other words, the expansion valve and the dehumidifying expansion valve can be controlled independently of each other using the control device. This allows, for example, to reduce the temperature of the test space with stronger or weaker dehumidification, and the relative humidity can be set and / or adjusted more precisely. Overall, this allows for more accurate climatic test cycles to be performed in a compact test chamber with fewer components.

[0024] The dehumidifying bypass can be connected to a high-pressure section of the refrigeration circuit downstream of the gas cooler or cascade heat exchanger and upstream of the expansion valve in the flow direction, and can be connected to a low-pressure section of the refrigeration circuit downstream of the heat exchanger and upstream of the compressor in the flow direction, and can supply refrigerant from the high-pressure section to the low-pressure section via the dehumidifying expansion valve to cool the dehumidifying heat exchanger. Optionally, the dehumidifying bypass can be connected to and / or formed by a second refrigeration circuit. The dehumidifying bypass can be connected to an inlet flow path of the second refrigeration circuit upstream of the cascade heat exchanger, and to a return flow path of the second refrigeration circuit downstream of the cascade heat exchanger and upstream of the pump.

[0025] Within the test space, a temperature control device can control the relative humidity in the range of 10% to 95%, preferably 5% to 99%, and the temperature in the range of +10°C to +90°C, preferably +5°C to +98°C.

[0026] The first cooling circuit may be provided with a regulating bypass having at least one regulating expansion valve. The regulating bypass may be connected to a high-pressure section of the first cooling cycle (first cooling circuit) downstream of the gas cooler and upstream of the expansion valve in the flow direction, and to a low-pressure section of the first cooling cycle downstream of the heat exchanger and upstream of the compressor in the flow direction. The suction gas temperature and / or pressure of the first refrigerant may be regulated in the low-pressure section of the first cooling cycle upstream of the compressor, so that the first refrigerant is supplied to the low-pressure section via the regulating expansion valve. Optionally, the regulating bypass may be connected to the high-pressure section downstream of the cascade heat exchanger of the first cooling circuit. The regulating expansion valve may affect the suction gas temperature and / or pressure upstream of the compressor so that the compressor's final temperature falls within the compressor's intended operating range. Therefore, if the temperature of the test space is to be reduced from +180°C to a lower temperature, the compressor's suction gas temperature may rise particularly rapidly. Since the heat exchanger is located within the test space, if the temperature of the test space is particularly high, for example +180°C, the first refrigerant can flow from the heat exchanger to the compressor at this temperature. The first refrigerant with a high degree of superheat can be cooled by the first refrigerant supplied via the regulating expansion valve before being supplied to the compressor.

[0027] The first refrigeration circuit may include a separate regulating bypass having at least a separate expansion valve. The separate regulating bypass is connected to the high-pressure section of the first refrigeration circuit downstream of the compressor and upstream of the gas cooler in the flow direction, and to the low-pressure section of the first refrigeration circuit downstream of the heat exchanger and upstream of the compressor in the flow direction. The suction gas temperature and / or pressure of the first refrigerant can be adjusted in the low-pressure section of the first refrigeration circuit so that the first refrigerant is supplied to the low-pressure section via the separate regulating expansion valve. The separate regulating bypass may be configured so that the first refrigerant flows from the high-pressure section to the low-pressure section via the separate regulating expansion valve. The first refrigerant may be in a superheated and / or gaseous state. When the first refrigeration circuit is operating under no-load conditions, introducing the superheated first refrigerant from the high-pressure section to the low-pressure section via the separate regulating bypass is particularly effective. If the expansion valve opens only slightly or infrequently, the suction pressure upstream of the compressor may become too low. When using carbon dioxide as the first refrigerant, dry ice can form completely (in solid form) at pressures below 5.16 bar, which could prevent safe operation of the first refrigeration circuit and damage the compressor. A separate regulating bypass can be used immediately downstream of the compressor to supply a highly superheated first refrigerant upstream of the compressor, effectively preventing dry ice from forming. Furthermore, the separate regulating bypass can also balance the pressure difference between the high-pressure and low-pressure parts of the first refrigeration circuit, for example, when the cooling element is not operating and the first refrigerant heats up as a result of temperature equilibration with the ambient environment, which could lead to an undesirably high pressure in the first refrigeration circuit.

[0028] The temperature control device allows for the generation of temperatures within the test space ranging from -40°C to +150°C, preferably from -50°C to +180°C.

[0029] The test chamber, particularly a climate chamber for air conditioning, comprises an insulated test space that is sealable from the surrounding environment and configured to accommodate test materials, and a temperature control device for controlling the temperature of the test space. The temperature control device generates temperatures in the test space ranging from -20°C to +150°C. The temperature control device includes a cooling element with a first refrigerant and a first refrigeration cycle including a heat exchanger in the test space, a compressor, a gas cooler, a cascade heat exchanger, and an expansion valve. The cascade heat exchanger is connected to the high-pressure section of the first refrigeration cycle, and the cascade heat exchanger is connected to a second refrigeration cycle of the cooling element. The test chamber includes a control device for controlling and / or regulating the temperature in the test space. The first refrigerant is a non-fluorinated refrigerant, preferably pure carbon dioxide, and the second refrigeration cycle includes a pump and a liquid as a heat transfer medium. Regarding the advantages of the test chamber according to the present invention, please refer to the description of the advantages of the method according to the present invention.

[0030] The cascade heat exchanger can be connected to the high-pressure part of the first refrigeration cycle downstream of the gas cooler and upstream of the expansion valve in the flow direction of the first refrigerant, so that, for example, the first refrigerant can be effectively liquefied in the cascade heat exchanger.

[0031] The second cooling circuit can be connected to a second cascade heat exchanger of a third cooling circuit of the cooling element. The third cooling circuit can include a second refrigerant, a second cascade heat exchanger, a second compressor, a second gas cooler, and a second expansion valve. The second refrigerant can be the same as or different from the first refrigerant. However, in principle, other means for generating cooling power and / or dissipating heat energy can be used instead of the third cooling circuit. Alternatively, the third cooling circuit can be configured with a second pump and a second liquid as a second heat transfer medium. Importantly, the third cooling circuit can be used to dissipate heat energy from the second cooling circuit.

[0032] The liquid bypass of the second cooling cycle can extend through a heat exchanger in the test space. The heat exchanger can be configured to include a first exchanger body for the first cooling cycle and a second exchanger body for the second cooling cycle, or a shared exchanger body for the first and second cooling circuits. If the liquid bypass of the second cooling circuit extends through the test space, the temperature of the test space can also be controlled by the second cooling circuit. The heat exchanger can include individual exchanger bodies for each corresponding cooling circuit, or a shared exchanger body. The exchanger body can be, for example, composed of one or more parts and can be a body through which the refrigerant flows. This can also include a tube structure with fins for improved heat transfer. In this case, the layered body (fins) and the tube structure form the exchanger body. The exchanger body has a surface effective for heat transfer.

[0033] The temperature control device can include a heating element having a heater and a heating heat exchanger within the test space. The heating element can be, for example, an electrical resistance heater that heats the heating heat exchanger to enable the heating heat exchanger to increase the temperature of the test space. The temperature control device can generate temperatures within the above-specified temperature ranges within the test space, provided that the controller can specifically control and / or adjust the heat exchanger and the heating heat exchanger to cool or heat the air circulating through the test space.

[0034] Further embodiments of the test chamber are derived from the characterizing statements of the dependent claims which refer back to method claim 1.

[0035] The system includes a test chamber according to the present invention and at least one additional test chamber, the additional test chamber including a separate test space that is sealable from the ambient environment and configured to contain a test material and is insulated, and a separate temperature controller for controlling the temperature of the separate test space. The separate temperature controller generates a temperature in the separate test space ranging from -20°C to +150°C, and the separate temperature controller includes a separate cooling element including a separate first refrigerant, a separate heat exchanger in the separate test space, a separate compressor, a separate gas cooler, a separate cascade heat exchanger, and a separate expansion valve. The separate cascade heat exchanger is connected to a high-pressure section of the separate first refrigeration cycle, and the separate cascade heat exchanger is connected to a second refrigeration cycle of the test chamber, and the separate cascade heat exchanger is provided with a separate controller for controlling and / or regulating the temperature in the separate test space.

[0036] Thus, the system according to the present invention comprises at least a test chamber according to the present invention, equipped with a second cooling circuit, and another test chamber. The other test chamber is connected and / or coupled to the second cooling circuit of the test chamber via a separate cascade heat exchanger integrated into the separate first cooling circuit. The separate cascade heat exchanger is switched in parallel with the second cooling circuit of the test chamber. This can be achieved by connecting the separate cascade heat exchanger to the inlet and return channels of the second cooling circuit via a separate bypass of the second cooling circuit. A separate bypass valve element, preferably a separate bypass three-way valve, may allow a controlled supply of heat transfer medium to the separate cascade heat exchanger. Advantageously, the existing second cooling circuit can be used for the other test chamber as well as the test chamber. This eliminates the need for a second cooling circuit exclusively for the additional test chamber. The system may include three or more test chambers, in which case all other test chambers can be connected to the second cooling circuit of the test chamber. Overall, this allows the other test chambers to utilize the effects of the second cooling circuit, thereby enabling particularly efficient operation of these test chambers.

[0037] Further embodiments of the system result from the characterizing statements of the dependent claims which refer to claim 16 relating to the method.

[0038] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. [Brief explanation of the drawings]

[0039] [Figure 1] FIG. 1 shows a circuit diagram of a first embodiment of a temperature control device. [Figure 2] FIG. 2 shows a circuit diagram of a second embodiment of the temperature control device. [Figure 3] FIG. 3 shows a circuit diagram of a third embodiment of the temperature control device. [Figure 4] FIG. 4 shows a circuit diagram of a fourth embodiment of the temperature control device. DETAILED DESCRIPTION OF THE INVENTION

[0040] FIG. 1 shows a possible embodiment of a temperature control device 10 for a test chamber (not shown). The temperature control device 10 includes a cooling element 11, which forms a first cooling circuit 12 including carbon dioxide as a first refrigerant, a heat exchanger 13, a compressor 14, a gas cooler 15, and an expansion valve 16. The gas cooler 15 is configured as a heat exchanger and / or condenser and is cooled by a heat medium such as air or water. The heat exchanger 13 is arranged in an air treatment passage of a test space 17 of the test chamber so that the air in the test space 17 circulating through the air treatment passage (not shown) can be cooled by the heat exchanger 13. Furthermore, the first cooling circuit 12 includes a high-pressure section 18 and a low-pressure section 19. In the low-pressure section 19, the pressure of the first refrigerant is relatively lower than that in the high-pressure section 18. The first cooling circuit 12 further comprises a cascade heat exchanger 20 which is connected to the first cooling circuit 12 downstream of the gas cooler 15 and upstream of the expansion valve 16 in the flow direction of the first refrigerant.

[0041] The cooling element 11 also has a second cooling circuit 21 connected to the cascade heat exchanger 20. The second cooling circuit 21 has a pump (not shown) and a liquid as a heat transfer medium that can circulate within the second cooling circuit 21. The second cooling circuit 21 is connected to the cascade heat exchanger 20 by an inlet flow path 22 and a return flow path 23. The second cooling circuit 21 is further provided with a valve element 24 formed by a three-way valve 25. The valve element 24 is connected (bypass connection, bridge connection) to the cascade heat exchanger 20 by a tube 26. This allows the heat transfer medium to bypass the cascade heat exchanger 20 from the three-way valve 25 through the tube 26, thereby enabling the mass flow rate of the heat transfer medium passing through the cascade heat exchanger 20 to be suitably adjusted.

[0042] The first cooling circuit 12 further includes a bypass 27 having a bypass expansion valve 28. The bypass 27 extends through the heat exchanger 13 and is connected to the high-pressure section 18 downstream of the cascade heat exchanger 20 and upstream of the expansion valve 16 in the flow direction of the first refrigerant, and to the low-pressure section 19 downstream of the heat exchanger 13 and upstream of the compressor 14 in the flow direction of the first refrigerant. The first cooling circuit 12 also includes a dehumidifying bypass 29 having a dehumidifying expansion valve 30 and a dehumidifying heat exchanger 31 in the test space 17. The dehumidifying heat exchanger 31 can be used to dehumidify the air in the test space 17.

[0043] Furthermore, the first cooling circuit 12 is configured with a regulating bypass 32 having a regulating expansion valve 33 and a further regulating bypass 34 having a further regulating expansion valve 35 .

[0044] FIG. 2 shows an embodiment of a temperature control device 36 having a first cooling circuit 37 and a second cooling circuit 38. The first cooling circuit 37 includes a heat exchanger 39, a compressor 40, a gas cooler 41, and an expansion valve 42. Furthermore, the first cooling circuit 37 is connected to the second cooling circuit 38 by a cascade heat exchanger 43. Unlike the second cooling circuit 38 of FIG. 1, the second cooling circuit 38 is configured with a liquid bypass 44 connected to the inlet flow path 45 and the return flow path 46 of the second cooling circuit 48. The liquid bypass 44 extends through the heat exchanger 39 located in a test space 47. Thus, the test space 47 can be arbitrarily controlled by the first cooling circuit 37 and / or the second cooling circuit 38. A bypass valve element 50 formed by a bypass three-way valve is provided between the inlet flow path 48 and the return flow path 49 of the liquid bypass 44. A bypass three-way valve 51 is arranged in the return flow path 49 and connected to the inlet flow path 48 by a tube 52, so that the heat transfer medium can be guided through the tube 52 to bypass the heat exchanger 39, and thus the mass flow rate of the heat transfer medium to the heat exchanger 39 can be adjusted.

[0045] 3 shows a temperature control device 53 which, unlike the temperature control device of FIG. 2, has a second cooling circuit 54 with a liquid bypass 55 having a separate pump 56. This separate pump 56 is arranged in an inlet flow path 57 of the liquid bypass 55. The second cooling circuit 54 has a valve element 58 formed by a plurality of switchable valves 59 in an inlet flow path 60 and a return flow path 61 of the second cooling circuit 54. A control device (not shown) of the temperature control device 53 can switch and / or throttle the valves 59 so as to set a desired mass flow rate of the heat transfer medium in the cascade heat exchanger 62.

[0046] FIG. 4 shows a system 63 including a temperature control device 64 for a test chamber (not shown in detail) and a separate temperature control device 65 for a separate test chamber (not shown in detail). The test chamber includes a test space 66 (shown diagrammatically) and a cooling element 67, while the separate test chamber includes a separate test space 68 and a separate cooling element 69. The cooling element 67 includes a first cooling circuit 70 with an expansion valve 71, a heat exchanger 72 in the test space 66, a compressor 73, a gas cooler 74, and a cascade heat exchanger 75. The refrigerant in the first cooling circuit is carbon dioxide. The cooling element 67 includes a second cooling circuit 76 connected to the cascade heat exchanger 75, which includes a pump 77 and a three-way valve 78 for regulating the mass flow rate of the heat transfer medium in the second cooling circuit 76. A second cascade heat exchanger 79 is also connected to the second cooling circuit 76. The second cascade heat exchanger 79 is connected to a third cooling circuit 80 of the cooling element 67. The third cooling circuit 80 comprises a second compressor 81, a second gas cooler 82, and a second expansion valve 83. Here too, a non-fluorinated refrigerant, for example carbon dioxide, is used as the refrigerant, although in principle other means for cooling could also be used instead of the third cooling circuit 80.

[0047] The separate cooling element 69 includes a separate compressor 85, a separate gas cooler 86, a separate expansion valve 87, a separate heat exchanger 88 in the separate test space 68, and a separate first cooling circuit 84 equipped with a separate cascade heat exchanger 89. In this example, the refrigerant is a non-fluorinated refrigerant such as pure carbon dioxide. The separate cascade heat exchanger 89 is connected to the second cooling circuit 76 via a separate bypass 90. This separate bypass 90 is equipped with a separate three-way valve 91, which can adjust the mass flow rate of the heat transfer medium passing through the separate cascade heat exchanger 89. In principle, separate test chambers (not shown) can be connected in parallel to the second cooling circuit 76 via the separate bypass 90, each equipped with its own dedicated bypass, similar to the separate test chambers described above. Thus, the second cooling circuit 76 can be used for multiple test chambers.

Claims

1. 1. A method for air conditioning an insulated test space (17, 47, 66) of a test chamber, in particular a climate chamber, comprising: the test space is sealable from the ambient environment and configured to accommodate a test material, a temperature in the range of -20°C to +150°C is generated in the test space by a first cooling circuit (12, 37, 70) having a cooling element (11, 67) of a temperature control device (10, 36, 53, 64) of the test chamber, a first refrigerant, a heat exchanger (13, 39, 72) in the test space, a compressor (14, 40, 73), a gas cooler (15, 41, 74), a cascade heat exchanger (20, 43, 62, 75) and an expansion valve (16, 42, 71), the cascade heat exchanger being connected to a high-pressure section (18) of the first cooling circuit, and the cascade heat exchanger being connected to a second cooling circuit (21, 38, 54, 76) of the cooling element, and the temperature of the test space is controlled and / or regulated by the control device of the test chamber; The method comprises: The first refrigerant is a non-fluorinated refrigerant, preferably pure carbon dioxide (CO ２ ) wherein the second cooling circuit includes a pump (77) and a liquid as a heat transfer medium, and temperature generation in the test space is performed.

2. 10. The method of claim 1, The heat transfer medium circulates in the second cooling circuit (21, 38, 54, 76) without changing its phase. A method characterized by:

3. 3. The method according to claim 1 or 2, The second cooling circuit (21, 38, 54, 76) has a valve element (24, 58), preferably a three-way valve (25, 78), between an inlet flow path (22, 45, 60) and a return flow path (23, 46, 61) of the second cooling circuit, the valve element (24, 58) bypassing the cascade heat exchangers (20, 43, 62, 75), and a control element of the control device regulating the mass flow rate of the heat medium through the cascade heat exchangers by means of the valve element. A method characterized by:

4. The method according to any one of claims 1 to 3, The second cooling circuit (38, 54, 76) is formed with a liquid bypass (44, 55) between an inlet flow path (45, 60) and a return flow path (46, 61) of the second cooling circuit, the liquid bypass extending through the heat exchanger (39, 72), and the temperature of the test space (47, 66) is generated by the first cooling circuit (37, 70) and / or the second cooling circuit. A method characterized by:

5. 5. The method of claim 4, The liquid bypass (44, 55) has a bypass valve element (50), preferably a bypass three-way valve (51, 78), between the inlet flow path (45, 60) and the return flow path (46, 61) of the liquid bypass, the bypass valve element bypassing the heat exchanger (39, 72), and a control element of the control device regulating the mass flow rate of the heat medium through the heat exchanger by means of the bypass valve element. A method characterized by:

6. 6. The method according to claim 4 or 5, A separate pump (56) for transporting the heat medium is disposed in the liquid bypass (55). A method characterized by:

7. 7. The method according to claim 1, wherein The expansion valves (16, 42, 71, 83) and / or three-way valves (25, 51, 78, 91), each having a PID controller, of the adjusting elements of the control device are adjusted in response to the temperature in the test space (17, 47, 66) as a reference variable. A method characterized by:

8. 8. The method according to any one of claims 1 to 7, The control device operates the pump (77) when the temperature in the test space (17, 47, 66) as a reference variable is higher than 0°C, and operates the compressor when the temperature is lower than 0°C. A method characterized by:

9. 9. The method according to any one of claims 1 to 8, The rotational speed of the compressor (14, 40, 73) and / or the pump (77, 81) is adjusted. A method characterized by:

10. 10. The method according to any one of claims 1 to 9, The first refrigeration cycle (12, 37, 70) is operated in a thermodynamic subcritical or supercritical operating state. A method characterized by:

11. 11. The method according to any one of claims 1 to 10, The first refrigeration cycle (12, 37, 70) is provided with a bypass (27) having at least one bypass expansion valve (28), the bypass extending through the heat exchanger (13, 39, 72) and connected to the high-pressure part (18) of the first refrigeration cycle downstream of the gas cooler (15, 41, 74) or the cascade heat exchanger (20, 43, 62, 75) in the flow direction and upstream of the expansion valve (16, 42, 71), and connected to the low-pressure part (19) of the first refrigeration cycle downstream of the heat exchanger and upstream of the compressor (14, 40, 73) in the flow direction, and the temperature in the test space (17, 47, 66) is regulated by supplying a first refrigerant to the heat exchanger via the bypass expansion valve. A method characterized by:

12. 12. The method according to any one of claims 1 to 11, The air in the test space (17) is dehumidified by a dehumidifying bypass (29), and the first refrigeration cycle (12) has a dehumidifying expansion valve (30), or the second refrigeration cycle has a dehumidifying valve element, preferably a dehumidifying three-way valve, and a dehumidifying heat exchanger (31) in the test space. A method characterized by:

13. 13. The method according to any one of claims 1 to 12, A regulating bypass (32) having at least one regulating expansion valve (33) is formed in the first cooling circuit (12, 37, 70), the regulating bypass (32) being connected to the high-pressure part (18) of the first cooling cycle downstream of the gas cooler (15, 41, 74) and upstream of the expansion valve (16, 42, 71) in the flow direction, and to the low-pressure part (19) of the first cooling cycle downstream of the heat exchanger (13, 39, 72) and upstream of the compressor (14, 40, 73) in the flow direction, and an intake gas temperature and / or an intake gas pressure of the first refrigerant is regulated in the low-pressure part upstream of the compressor in the first cooling cycle so that the first refrigerant is supplied to the low-pressure part via the regulating expansion valve. A method characterized by:

14. 14. The method according to any one of claims 1 to 13, The first refrigeration cycle (12, 37, 70) is provided with a separate regulating bypass (34) having at least a separate regulating expansion valve (35), the separate regulating bypass being connected to a high-pressure section (18) of the first refrigeration cycle downstream of the compressor (14, 40, 73) and upstream of the gas cooler (15, 41, 74) in the flow direction, and connected to a low-pressure section of the first refrigeration cycle downstream of the heat exchanger (13, 39, 71) and upstream of the compressor (14, 40, 73) in the flow direction, and an intake gas temperature and / or an intake gas pressure of the first refrigerant is regulated in the low-pressure section upstream of the compressor in the first refrigeration cycle so that the first refrigerant is supplied to the low-pressure section via the separate regulating expansion valve. A method characterized by:

15. 15. The method of any one of claims 1 to 14, The temperature control device (10, 36, 53, 64) generates a temperature in the test space (17, 47, 66) ranging from -40°C to +150°C, preferably from -50°C to +180°C. A method characterized by:

16. A test chamber, in particular a climate chamber for air conditioning, comprising: The apparatus comprises an insulated test space (17, 47, 66) that is sealable from the ambient environment and configured to contain a test material, and a temperature control device (10, 36, 53, 64) for controlling the temperature of the test space, the temperature control device producing a temperature in the test space in the range of -20°C to +150°C, the temperature control device comprising a first refrigerant, a heat exchanger (13, 39, 72) in the test space, a compressor (14, 40, 73), a gas cooler (15, 41, a cooling element (11, 67) with a first cooling cycle (12, 37, 70) having a cascade heat exchanger (20, 43, 62, 75) and an expansion valve (16, 42, 71), the cascade heat exchanger being connected to a high pressure section (18) of the first cooling cycle, the cascade heat exchanger being connected to a second cooling cycle (21, 38, 54, 76) of the cooling element, the test chamber having a control device for controlling and / or regulating the temperature within the test space; The test chamber comprises: The first refrigerant is a non-fluorinated refrigerant, preferably pure carbon dioxide (CO ２ ) and the second cooling cycle includes a pump (77) and a liquid as a heat transfer medium. A test chamber characterized by:

17. 17. The test chamber of claim 16, The cascade heat exchanger (20, 43, 62, 75) is connected to the high-pressure section (18) of the first refrigeration cycle (12, 37, 70) downstream of the gas cooler (15, 41, 74) and upstream of the expansion valve (16, 42, 71) in the flow direction of the first refrigerant. A test chamber characterized by:

18. 18. The test chamber according to claim 16 or 17, The second cooling cycle (21, 38, 54, 76) is connected to a second cascade heat exchanger (79) of a third cooling cycle (80) of the cooling element (11, 67). A test chamber characterized by:

19. 19. The test chamber according to any one of claims 16 to 18, A liquid bypass (44, 55) of the second refrigeration cycle (38, 54, 76) extends through a heat exchanger (39, 72) in the test space (47, 66), the heat exchanger being configured to have a first exchanger body for the first refrigeration cycle (37, 70) and a second exchanger body for the second refrigeration cycle, or a shared exchanger body. A test chamber characterized by:

20. 20. The test chamber of any one of claims 16 to 19, The temperature control device (10, 36, 53, 64) includes a heating element having a heater and a heating heat exchanger within the test space (17, 47, 66). A test chamber characterized by:

21. A system comprising a test chamber according to any one of claims 16 to 20 and at least one further test chamber, a separate test space (68) that is sealable from the ambient environment, configured to contain a test material, and insulated; and a separate temperature control device (65) for controlling the temperature of the separate test space, the separate temperature control device producing a temperature in the separate test space in a range of -20°C to +150°C; the separate temperature control device comprising a separate cooling element (69) including a separate first refrigerant, a separate first refrigeration cycle (84) having a separate heat exchanger (88) in the separate test space, a separate compressor (85), a separate gas cooler (86), a separate cascade heat exchanger (89), and a separate expansion valve (87), the separate cascade heat exchanger being connected to a high-pressure section of the separate first refrigeration cycle, the separate cascade heat exchanger being connected to the second refrigeration cycle (21, 38, 54, 76) of the test chamber; and the separate test chamber comprising a separate control device for controlling and / or regulating the temperature in the separate test space.

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