Test Chamber Internal Heat Exchanger for Low-GWP Cooling
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Solution Overview
Problem
Existing test chambers face challenges in achieving low temperatures below -30°C using environmentally friendly refrigerants with low global warming potential (GWP), as these refrigerants often have reduced cooling capacity, and require additional safety measures due to flammability concerns, increasing costs and operational complexities.
Innovation Solution
The test chamber incorporates an internal heat exchanger connected on the high-pressure side of the cooling circuit, coupled with a controllable supplementary cooling system, and a bypass with a second expansion element to enhance cooling capacity and adapt to temperature fluctuations, using non-flammable refrigerants with low GWP, allowing for temperature control from -30°C to +180°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If environmentally friendly refrigerants with low GWP are used, then environmental impact is reduced, but cooling capacity is reduced
Solution Approach 1:
The refrigerant is pre-cooled in the internal heat exchanger before entering the evaporator. This preliminary cooling action allows the low-GWP refrigerant to reach optimal temperature and pressure conditions earlier in the cycle, maximizing its cooling capacity in the evaporator while maintaining environmentally friendly properties.
Solution Approach 2:
The internal heat exchanger acts as an intermediary component that transfers heat from the high-pressure liquid refrigerant to the low-pressure suction gas. This intermediary heat exchange process optimizes the refrigerant's thermal state before it enters the evaporator, compensating for the reduced cooling capacity of low-GWP refrigerants.
2Power
If flammable refrigerants are used to improve cooling capacity, then cooling performance is enhanced, but safety requirements and operational complexity increase
Solution Approach 1:
The patent uses commercially available non-flammable refrigerants (R-134a, R-125, R-143a) that don't require special safety infrastructure. While individual refrigerant molecules have shorter operational lifetimes due to leakage concerns, the system avoids complex safety measures by selecting inherently safe refrigerants, reducing overall system complexity.
3Temperature
If temperatures below -30°C are achieved using conventional refrigerants, then low temperature capability is improved, but environmental regulations are violated
Solution Approach 1:
The system changes the thermodynamic parameters (pressure, temperature, flow rate) of the low-GWP refrigerant to optimize its performance for low-temperature applications. By adjusting these parameters and using the internal heat exchanger to pre-condition the refrigerant, the system achieves temperatures below -30°C while using environmentally friendly refrigerants that comply with regulations.
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
This configuration compensates for the reduced cooling capacity of low-GWP refrigerants, maintains temperature stability, and simplifies safety measures by using non-flammable refrigerants, enabling efficient and cost-effective operation while minimizing environmental impact.
Implementation Method 1
the cooling circuit having an internal heat exchanger, the internal heat exchanger being on a high-pressure side of the cooling circuit in a flow direction upstream of the expansion element and subsequently the condenser, wherein the refrigerant can be cooled by means of the internal heat exchanger
Implementation Method 2
an expansion element, wherein the refrigerant can be cooled by means of the internal heat exchanger
Implementation Method 3
having a condenser and an expansion element
Data Source
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AI summary
The invention relates to a test chamber for conditioning air, comprising a test space that can be closed off from the environment and is temperature-insulated for receiving test material, and a temperature control device for temperature control of the test space, with the temperature control device being used to set a temperature in a temperature range from -20 °C to +180 °C C can be formed within the test chamber, the temperature control device having a cooling device (10) with a cooling circuit (11) with a refrigerant, a heat exchanger (12), a compressor (13), a condenser (14) and an expansion element (15), the cooling circuit having an internal heat exchanger (24), the internal heat exchanger being connected to a high-pressure side (18) of the cooling circuit in a direction of flow upstream of the expansion element and downstream of the condenser, the refrigerant being able to be cooled by means of the internal heat exchanger, the internal heat exchanger with an adjustable E supplementary cooling (25) of the cooling device is coupled.