Accumulator Suction Pipe Layout for Mixed-Refrigerant Air Conditioning
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Solution Overview
Problem
Air-conditioning apparatus employing non-azeotropic refrigerant mixtures face performance degradation due to high global warming potential (GWP) of HFC-R32 and increased pressure loss with HFO-1234yf and HFO-1234ze, leading to inefficient evaporation capacity and suction pressure loss.
Innovation Solution
An air-conditioning apparatus with a non-azeotropic refrigerant mixture, where the suction pipe has an oil return hole positioned higher than the accumulator's central portion, and a controller adjusts the pressure reducing device to maintain refrigerant quality below 1, prioritizing storage of higher boiling point refrigerants and preventing liquid refrigerant suction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If HFC-R32 is used as refrigerant, then evaporation capacity is improved, but global warming potential increases
Solution Approach 1:
The patent uses a composite refrigerant mixture comprising HFO-1234yf, HFO-1234ze, and HFC-R32 in specific proportions (70-90 mass% HFO-1234yf, 5-30 mass% HFO-1234ze, and 1-20 mass% HFC-R32). This composite approach combines the low GWP benefits of HFO refrigerants with the high evaporation capacity of HFC-R32, achieving both environmental sustainability and operational performance.
2Object-affected harmful factors
If HFO-1234yf and HFO-1234ze are used as refrigerant, then global warming potential is reduced, but pressure loss increases
Solution Approach 1:
The patent creates a composite refrigerant mixture that combines HFO-1234yf and HFO-1234ze with HFC-R32 in optimized proportions. The HFC-R32 component compensates for the higher pressure loss characteristics of HFO refrigerants while maintaining low GWP, achieving a balance between environmental performance and system efficiency.
Solution Approach 2:
The patent optimizes the compositional parameters of the refrigerant mixture, specifically controlling the ratios of HFO-1234yf (70-90 mass%), HFO-1234ze (5-30 mass%), and HFC-R32 (1-20 mass%). By adjusting these parameters, the system achieves low GWP while minimizing pressure loss through the optimal contribution of HFC-R32.
3Reliability
If refrigerant quality is maintained at 1 or higher, then liquid refrigerant accumulation is prevented, but suction pressure loss increases
Solution Approach 1:
The patent inverts the conventional approach by intentionally allowing refrigerant quality to fall below 1 (creating a wet refrigerant state with liquid refrigerant in the accumulator) while preventing liquid refrigerant from entering the compressor through the elevated oil return hole. This inversion enables liquid refrigerant storage without the traditional penalty of suction pressure loss.
Solution Approach 2:
The patent changes the spatial dimension of the oil return hole by positioning it at a height higher than the central portion of the accumulator. This dimensional change creates a liquid barrier that prevents liquid refrigerant from entering the compressor while still allowing liquid refrigerant to be stored in the lower portion of the accumulator, thereby maintaining suction pressure.
4Reliability
If oil return hole is positioned at lower portion of accumulator, then refrigerating machine oil accumulation is prevented, but liquid refrigerant is suctioned into compressor
Solution Approach 1:
The patent changes the vertical position (dimension) of the oil return hole from the conventional lower portion to a position higher than the central portion of the accumulator. This dimensional change creates a liquid refrigerant barrier that prevents liquid refrigerant from reaching the oil return hole and entering the compressor, while still allowing the hole to function at its original horizontal position for oil return.
Solution Approach 2:
The patent applies different functional requirements to different regions of the accumulator: the lower portion stores liquid refrigerant, the central region allows oil return through the elevated hole, and the upper region maintains gas refrigerant. This local differentiation of quality and function enables simultaneous achievement of liquid storage and liquid prevention at compressor inlet.
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 enhances refrigeration cycle efficiency by increasing the HFC-R32 content in the circulating refrigerant, preventing performance degradation and suction pressure loss, resulting in a high-performance air-conditioning system.
Implementation Method 1
the controller is configured to control the opening degree of the pressure reducing device so as to make quality of refrigerant flowing into the accumulator less than 1
Implementation Method 2
the suction pipe includes an oil return hole formed in a portion of the suction pipe inside the accumulator, at a position higher than a central portion of the accumulator
Implementation Method 3
a refrigeration cycle in which a compressor, a condenser, a pressure reducing device, an evaporator and an accumulator are connected via a refrigerant pipe
Implementation Method 4
a compressor, a condenser, a pressure reducing device, an evaporator and an accumulator are connected via a refrigerant pipe
Data Source
AI summary
An air-conditioning apparatus includes a refrigeration cycle charged with non-azeotropic refrigerant mixture and refrigerating machine oil. A suction pipe which is a refrigerant pipe connecting between a suction port of a compressor and an accumulator has an end portion on the side of the accumulator extending into the accumulator. In addition, the suction pipe of the air-conditioning apparatus includes an oil return hole formed in a portion of the suction pipe located inside the accumulator at a position higher than a central portion of the accumulator. A controller of the air-conditioning apparatus controls an opening degree of a pressure reducing device so as to make quality of refrigerant flowing into the accumulator less than 1.