US-12618767-B2 - Test chamber and method for its operation

US12618767B2US 12618767 B2US12618767 B2US 12618767B2US-12618767-B2

Abstract

A test chamber and a method for conditioning air in which the test chamber comprises a temperature-insulated test space, which is closable to an environment and serves to receive test material, and a temperature control device for controlling the test space in temperature, a temperature ranging from −40° C. to +180° C. being generable within the test space by the temperature control device. The temperature control device comprises a cooling apparatus having a first and second cooling cycle, the first cooling cycle having a first refrigerant, a first heat exchanger, a first compressor, a first condenser and a first expansion element, the first refrigerant being a hydrocarbon or a refrigerant mixture made of hydrocarbons. The second cooling cycle has a heat transfer medium, a second heat exchanger in the test space and a pump, the second cooling cycle being coupled to the first cooling cycle by the first heat exchanger.

Inventors

Yannik Zahrt
Felix Diehl
Christian Haack

Assignees

WEISS TECHNIK GMBH

Dates

Publication Date: 20260505
Application Date: 20230731
Priority Date: 20220802

Claims (12)

1 . A test chamber for conditioning air, the test chamber comprising a temperature-insulated test space, which is closable to an environment and serves for receiving test material, and a temperature control device for controlling the test space in temperature, a temperature ranging from −40° C. to +180° C. being generable within the test space by the temperature control device, the temperature control device comprising a cooling apparatus having a first cooling cycle and a second cooling cycle, the first cooling cycle having a first refrigerant, a first heat exchanger, a first compressor, a first condenser and a first expansion element, the first refrigerant being a hydrocarbon or a refrigerant mixture made of hydrocarbons, wherein the second cooling cycle is made of a heat transfer medium, a second heat exchanger in the test space and a pump, the second cooling cycle being coupled to the first cooling cycle by the first heat exchanger; wherein the temperature control device comprises a regulator having at least one temperature sensor in the second cooling cycle, at least one valve apparatus being able to be actuated in the second cooling cycle by the regulator as a function of a measured temperature; and wherein the valve apparatus is formed having a three-way valve, which is disposed downstream of the second heat exchanger and upstream of the pump in the second cooling cycle, the second bypass being connected to the three-way valve.
2 . The test chamber according to claim 1 , wherein the first refrigerant is inflammable and the heat transfer medium is nonflammable.
3 . The test chamber according to claim 1 , wherein the first refrigerant is free of fluorinated hydrocarbons.
4 . The test chamber according to claim 1 , wherein a storage apparatus for the heat transfer medium is disposed in the second cooling cycle.
5 . The test chamber according to claim 1 , wherein the second cooling cycle has a second bypass having the valve apparatus, the second bypass being connected downstream of the first heat exchanger and upstream of the second heat exchanger as well as downstream of the second heat exchanger and upstream of the pump, the heat transfer medium being able to be dosed in such a manner via the valve apparatus that the second heat exchanger is able to be bridged by the second bypass.
6 . The test chamber according to claim 1 , wherein the test chamber comprises a detector having at least one gas sensor and a ventilation installation in an engine room of the test chamber separated from the test space in an airtight manner, the first cooling cycle being disposed entirely in the engine room.
7 . A method for conditioning air in a temperature-insulated test space of a test chamber, the test space being closable with respect to an environment and serving to receive test material, a temperature ranging from −40° C. to +180° C. being generated within the test space by a temperature control device of the test chamber, a temperature being generated within the test space by a cooling apparatus of the temperature control device having a first cooling cycle and a second cooling cycle, the first cooling cycle having a first refrigerant, a first heat exchanger, a first compressor, a first condenser and a first expansion element, the first refrigerant being a hydrocarbon or a refrigerant mixture made of hydrocarbons, wherein the second cooling cycle is made of a heat transfer medium, a second heat exchanger in the test space and a pump, the second cooling cycle being coupled to the first cooling cycle by the first heat exchanger, the heat transfer medium being circulated in the second cooling cycle by the pump; wherein the temperature control device comprises a regulator having at least one temperature sensor in the second cooling cycle, at least one valve apparatus being able to be actuated in the second cooling cycle by the regulator as a function of a measured temperature; and wherein the valve apparatus is formed having a three-way valve, which is disposed downstream of the second heat exchanger and upstream of the pump in the second cooling cycle, a second bypass being connected to the three-way valve.
8 . The method according to claim 7 , wherein the heat transfer medium is circulated in the second cooling cycle without phase changes.
9 . The method according to claim 7 , wherein the heat transfer medium being circulated in the second cooling cycle via the second heat exchanger and/or a second bypass by the valve device.
10 . The method according to claim 9 , wherein the heat transfer medium is circulated via the second bypass until a target temperature of the heat transfer medium has been reached, the heat transfer medium being circulated via the second heat exchanger when the target temperature has been reached.
11 . The method according to claim 9 , wherein a revolution speed of the pump is regulated by the regulator.
12 . The method according to claim 9 , wherein upon reaching a target temperature of the heat transfer medium, the first compressor is switched off by the regulator, the heat transfer medium being circulated in the second cooling cycle and the second heat exchanger via a storage apparatus for the heat transfer medium, and/or the second cooling cycle being coupled to a third heat exchanger of another cooling cycle, to another refrigerant, to another compressor, to another condenser and to a third expansion element, the heat transfer medium being cooled by the third heat exchanger.

Description

This patent application claims priority of the European Patent Application No. 22188399.4 filed on Aug. 2, 2022, the disclosure of which is incorporated herein by reference. The invention relates to a method and a test chamber for conditioning air, in particular a climate chamber or the like, the test chamber comprising a temperature-insulated test space, which is closable to an environment and serves for receiving test material, and a temperature control device for controlling the test space in temperature, a temperature ranging from −40° C. to +180° C. being generable within the test space by means of the temperature control device, the temperature control device comprising a cooling apparatus having a first cooling cycle and a second cooling cycle, the first cooling cycle having a first refrigerant, a first heat exchanger, a first compressor, a first condenser and a first expansion element, the first refrigerant being a hydrocarbon or a refrigerant mixture made of hydrocarbons. Test chambers of this kind are commonly used for observing physical and/or chemical properties of objects, in particular devices. Temperature test consoles or climate test consoles are thus known, within which temperatures ranging from −40° C. to +180° C. can be set. In climate test consoles, desired climate conditions can be additionally set, to which devices and/or the test material are exposed over a defined period of time. A temperature of the test space to receive the test material is regularly controlled in a circulating-air channel within the test space. The circulating-air channel forms an air-treatment space in the test space, heat exchangers for heating or cooling the air flowing through the circulating-air channel and/or the test space being disposed in the air-treatment space. In this context, a fan suctions the air present in the test space and conducts it in the circulating-air channel to the corresponding heat exchangers. The temperature of the test material can be controlled thus or even be subjected to a defined change in temperature. During a test interval, a temperature can change between a temperature maximum and a temperature minimum of the test chamber, for example. A test chamber of this kind is known from EP 0 344 397 A2, for example. The refrigerant used in a cooling cycle should have a relative low CO2 equivalent, i.e., a relative greenhouse potential or Global Warming Potential (GWP) should be as low as possible in order to avoid indirectly damaging the environment via the refrigerant upon its release. While it is also known to use hydrocarbons as a refrigerant, however, it is disadvantageous that hydrocarbons are easily inflammable. Inflammability is understood as the property of the refrigerant to react with ambient oxygen while releasing heat. A refrigerant is inflammable in particular when it falls under fire class C according to European standard DN 2 or DIN 378 classes A2, A2L and A3 in the version valid on the day of priority. If an inflammable refrigerant is used, a filling, a shipment and an operation of a cooling cycle and/or of a test chamber is made more complicated because of the security measures to be maintained. Production of the test chamber can also become more expensive because of the usage of an inflammable refrigerant as a consequence of the constructive measures consequently required. A significant problem is a possible leakage of the cooling cycle within the test space, in which electric resistance heaters and also electrically operated devices can be present as test material. In the event of a leakage, an explosion can be the result. As a result of statutory provisions, a refrigerant must not significantly contribute to the ozone depletion in the atmosphere or to global warming. Thus, essentially no fluorinated gases or fluorinated substances are to be used as refrigerants, for which reason natural refrigerants, such as carbon dioxide (CO2) are considered. A disadvantage of refrigerants having low GWP is that these refrigerants have a partially significantly lower cooling performance in comparison to refrigerants having comparatively higher GWPs in the temperature ranges relevant for a cooling cycle. A lower GWP can be attained with refrigerant mixtures, which have a comparatively high mass fraction of carbon dioxide, these refrigerant mixtures having zeotropic properties because of the different substances mixed with each other, which in turn is not desired in most cooling cycles. Moreover, a fraction of carbon dioxide must be large enough that the refrigerant is nonflammable. From WO 2019/048250 A1, a test chamber having a refrigerant is known, which consists essentially of carbon dioxide, pentafluoroethane and difluoromethane. A disadvantage in this case is that supercooling the refrigerant by means of an internal heat exchanger in a cooling cycle is required to attain particularly low temperatures. Further, the refrigerant has zeotropic properties and contains fluorinated gase