Test Chamber And Method For Control
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Solution Overview
Problem
Existing test chambers face challenges in achieving precise temperature and humidity control within a wide range while using environmentally friendly refrigerants, particularly due to the high cooling capacity of carbon dioxide, which leads to condensation issues and limited climatic test capabilities.
Innovation Solution
A two-stage refrigerating plant system using pure carbon dioxide as an unfluorinated refrigerant in the first cooling circuit and a liquid heat carrier in the second cooling circuit, with a cascade heat exchanger and a pump, allowing for precise temperature control and dehumidification, and utilizing a control device for regulating the temperature and humidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If carbon dioxide is used as refrigerant in the first cooling circuit, then the GWP is reduced and environmental friendliness is improved, but condensation issues occur due to high cooling capacity
Solution Approach 1:
The cascade heat exchanger serves as an intermediary between the first cooling circuit (using CO2 refrigerant) and the second cooling circuit (using liquid heat carrier). It enables heat transfer between the two circuits, allowing the CO2 circuit to provide cooling while the liquid circuit removes excess heat to prevent condensation, thus resolving the contradiction between using environmentally friendly refrigerant and avoiding condensation issues
2Measurement precision
If a two-stage refrigerating plant is used, then temperature control precision is improved, but device complexity increases
Solution Approach 1:
The cooling system is segmented into two independent cooling circuits: the first cooling circuit using CO2 refrigerant for primary cooling, and the second cooling circuit using liquid heat carrier for heat removal and temperature regulation. This segmentation allows each circuit to be optimized for its specific function, improving overall temperature control precision while managing complexity through modular design
3Object-affected harmful factors
If hydrocarbons are used as refrigerant, then GWP is reduced, but flammability risk increases
Solution Approach 1:
The cascade heat exchanger acts as an intermediary that enables the system to use CO2 refrigerant (low GWP, non-flammable) in the first cooling circuit while the second cooling circuit with liquid heat carrier provides additional heat management, thus achieving low GWP without the flammability risks associated with hydrocarbon refrigerants
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient, environmentally friendly, and accurate climatic testing with stable temperature and humidity conditions, reducing energy consumption and noise emissions, and minimizing condensation issues.
Implementation Method 1
The refrigerant is cooled and/or desuperheated at the cascade heat exchanger so that any thermal energy generated at the cascade heat exchanger can be dissipated by the second cooling circuit
Implementation Method 2
heat exchangers are disposed to heat or cool the air flowing through the air-circulation duct and/or the test space
Data Source
AI summary
A test chamber and a method for conditioning air in a temperature-insulated test space of the test chamber, the test space being sealable and configured to receive test materials, a cooling element of a temperature-control device of the test chamber, 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 yielding a temperature ranging from −20° C. to +150° C. within the test space, the cascade heat exchanger being connected to a high-pressure side of the first cooling circuit, the cascade heat exchanger being coupled with a second cooling circuit of the cooling element, the temperature in the test space being controlled and/or regulated by a control device of the test chamber. The first refrigerant is an unfluorinated refrigerant and the second cooling circuit comprising a pump and a liquid as a heat carrier.