Non-Azeotropic Refrigerant Mixture to Prevent Low-Pressure Vacuum
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Solution Overview
Problem
Refrigeration cycle apparatuses using tetrafluoropropane as a refrigerant face issues with negative pressure in low-pressure circuits due to chemical instability and decomposition by air or moisture, leading to operational interference, safety concerns, and the need for costly and time-consuming maintenance.
Innovation Solution
A non-azeotropic refrigerant mixture with tetrafluoropropane and low-boiling refrigerants is used, with a predetermined mixing ratio to maintain a saturated vapor line pressure below −45°C, preventing negative pressure in low-pressure circuits, and a controller adjusts the composition to ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If tetrafluoropropane is used as a single refrigerant to achieve low GWP, then global warming potential is reduced, but negative pressure occurs in low-pressure circuits causing air and moisture suction
Solution Approach 1:
The patent uses a composite refrigerant mixture comprising tetrafluoropropane (HFO-1234ze) combined with other refrigerants (R32, R125, R134a) in specific proportions. This composite approach maintains the low GWP benefit of tetrafluoropropane while the other components adjust the vapor pressure characteristics to prevent negative pressure in the low-pressure circuit, thereby eliminating air and moisture suction issues.
Solution Approach 2:
The patent changes the physical and chemical parameters of the refrigerant system by using a non-azeotropic mixture with specific composition ratios. The mixture's vapor pressure-temperature characteristics are modified so that the saturated vapor line remains above -45°C across the operating range, preventing negative gauge pressure while maintaining low GWP.
2Object-affected harmful factors
If tetrafluoropropane is used as refrigerant, then chemical decomposition occurs when exposed to air or moisture, but this leads to sludge accumulation and operational interference
Solution Approach 1:
The patent applies preliminary anti-action by designing the refrigerant mixture composition and system operating parameters to prevent the harmful chemical decomposition of tetrafluoropropane before it can occur. By maintaining positive pressure in the low-pressure circuit through the mixed refrigerant formulation, air and moisture are excluded from contacting the refrigerant, thereby preventing decomposition and sludge formation in advance.
Solution Approach 2:
The patent creates an inert environment by maintaining positive pressure in the refrigeration system using the mixed refrigerant composition. This prevents air and moisture from entering the system and contacting the chemically unstable tetrafluoropropane, effectively isolating it from substances that would trigger decomposition and sludge accumulation.
3Temperature
If evaporation temperature is lowered to -45°C for low-temperature refrigeration, then refrigeration capacity is improved, but low-pressure circuit becomes negative pressure
Solution Approach 1:
The patent changes the pressure-temperature parameters of the refrigerant system by using a mixed refrigerant composition. The mixture is formulated so that its saturated vapor pressure remains above atmospheric pressure at evaporation temperatures down to -45°C, ensuring the low-pressure circuit maintains positive gauge pressure while achieving the desired low evaporation temperature for enhanced refrigeration capacity.
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 solution prevents negative pressure in low-pressure circuits, enhancing the reliability and safety of refrigeration cycle apparatuses by maintaining stable refrigerant composition and preventing chemical decomposition, thus reducing maintenance efforts and costs.
Implementation Method 1
the saturated vapor line where a gauge pressure that suppresses refrigerant decomposition due to incorporation of the fluid is 0.00 MPa is not higher than −45° C. in a low-pressure circuit
Implementation Method 2
A non-azeotropic refrigerant mixture which circulates through a refrigeration cycle configured at least by a compressor, a condenser, a decompressor and an evaporator
Data Source
AI summary
Disclosed is a non-azeotropic refrigerant mixture containing tetrafluoropropane as a high-boiling refrigerant and a refrigeration cycle apparatus in which a non-azeotropic refrigerant mixture containing tetrafluoropropane as a high-boiling refrigerant circulates through a refrigeration cycle so as to avoid occurrence of negative pressure in a low-pressure circuit.The non-azeotropic refrigerant mixture is characterized in that a mixing ratio of a high-boiling refrigerant and a low-boiling refrigerant is determined so that a saturated vapor line where pressure is 0.00 MPa is not higher than −45° C. in a low-pressure circuit formed between the decompressor to the compressor.