Accumulator Oil Return Layout for Non-Azeotropic Air Conditioning
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Solution Overview
Problem
Conventional air-conditioning apparatuses using HFC-R32 suffer from high global warming potential and pressure loss, while non-azeotropic refrigerant mixtures containing HFO-1234yf or HFO-1234ze result in degraded evaporation capacity and compressor suction pressure loss due to liquid refrigerant accumulation.
Innovation Solution
An air-conditioning apparatus employing a non-azeotropic refrigerant mixture with a higher boiling point refrigerant stored in the accumulator, and an oil return hole positioned higher than the accumulator's central portion to prevent liquid refrigerant suction by the compressor, maintaining refrigerant quality below 1 and optimizing refrigeration cycle efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If HFO-1234yf or HFO-1234ze is used as refrigerant, then global warming potential is reduced, but pressure loss increases and evaporation capacity is degraded
Solution Approach 1:
The patent uses a composite refrigerant mixture containing HFO-1234yf (5-20 mass%), HFO-1234ze (5-20 mass%), and R32 (60-80 mass%). This composite approach combines the low GWP benefits of HFO refrigerants with the high evaporation capacity of R32, achieving both environmental compliance and performance requirements.
Solution Approach 2:
The patent optimizes the composition ratios of the refrigerant mixture components to balance GWP reduction with pressure loss mitigation. By carefully controlling the proportions of HFO-1234yf, HFO-1234ze, and R32, the system achieves acceptable pressure characteristics while maintaining low environmental impact.
2Reliability
If refrigerant quality is maintained at 1 or higher to prevent liquid refrigerant storage, then compressor protection is improved, but accumulator function is degraded
Solution Approach 1:
The patent inverts the conventional approach by intentionally allowing liquid refrigerant to be stored in the accumulator (quality < 1) rather than preventing it. The oil return hole is positioned to prevent liquid suction, reversing the traditional priority from compressor protection to accumulator functionality.
Solution Approach 2:
The oil return hole acts as an intermediary mechanism that allows liquid refrigerant to be stored in the accumulator while preventing it from reaching the compressor. This mediator enables the coexistence of liquid storage and compressor protection functions.
3Ease of operation
If oil return hole is positioned at lower portion of accumulator, then oil return function is improved, but liquid refrigerant suction is caused
Solution Approach 1:
The patent changes the position parameter of the oil return hole from the conventional lower portion to a position above the central portion of the accumulator. This parameter change allows liquid refrigerant to be stored in the lower portion while the oil return hole remains in the upper portion where only gas and oil are present.
Solution Approach 2:
The patent applies different quality requirements to different locations within the accumulator. The lower portion is designed for liquid refrigerant storage, while the upper portion (where the oil return hole is located) maintains gas-phase conditions suitable for oil return without liquid suction.
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 the performance of the air-conditioning apparatus by maintaining higher HFC-R32 content in the circulating refrigerant, preventing compressor suction pressure loss, and maintaining high refrigeration cycle efficiency.
Implementation Method 1
the quality of the refrigerant flowing into the accumulator is controlled to be less than 1... the refrigerant having a higher boiling point can be stored in the accumulator with priority
Implementation Method 2
a pressure reducing device is controlled, in a normal operation, so as to maintain the quality of the refrigerant at 1 or higher
Implementation Method 3
a refrigeration cycle in which a compressor (1) that compresses refrigerant, a four-way valve (6) that switches a circulating direction of the refrigerant
Data Source
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AI summary
An air-conditioning apparatus 100 includes a refrigeration cycle charged with non-azeotropic refrigerant mixture and refrigerating machine oil. A suction pipe 21 which is a refrigerant pipe connecting between a suction port of a compressor 1 and an accumulator 2 has an end portion on the side of the accumulator 2 extending into the accumulator 2. In addition, the suction pipe 21 of the air-conditioning apparatus 100 includes an oil return hole 19 formed in a portion of the suction pipe 21 located inside the accumulator 2 at a position higher than a central portion of the accumulator 2. A controller 16 of the air-conditioning apparatus 100 controls an opening degree of a pressure reducing device 4 so as to make quality of refrigerant flowing into the accumulator 2 less than 1.