Heat Pump Suction Flow Path Length Optimization
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Solution Overview
Problem
Conventional heat pump cycle devices face challenges in mixing refrigerants with different enthalpies without compromising compressor protection and productivity, often resulting in increased device size and decreased mountability.
Innovation Solution
A heat pump cycle device configuration that includes a compressor, branch portion, heating unit, decompression unit, bypass passage, and regulating unit, where the suction-side flow path length is optimized to equal or exceed the relaxation distance, ensuring homogeneous refrigerant mixing and preventing liquid compression issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If refrigerants with different enthalpies are mixed in a short flow path, then device size is reduced, but refrigerant mixing homogeneity deteriorates and compressor protection is compromised
Solution Approach 1:
The patent applies parameter changes by optimizing the suction-side flow path length to be equal to or longer than the relaxation distance Lv. This parameter optimization ensures that refrigerants with different enthalpies mix homogeneously before entering the compressor, preventing liquid compression while maintaining a compact device design. The relaxation distance Lv is calculated based on droplet density, diameter, gas viscosity, and flow velocity, providing a quantitative basis for the flow path length design.
Solution Approach 2:
The suction-side flow path acts as an intermediary mixing zone between the heating-unit side refrigerant and bypass-side refrigerant. This intermediate flow path allows the refrigerants to mix and reach homogeneous state before entering the compressor, serving as a buffer zone that ensures reliable compressor operation while maintaining compact overall device dimensions.
2Reliability
If suction-side flow path length is increased to ensure homogeneous mixing, then compressor protection is improved, but device size increases
Solution Approach 1:
The patent resolves this contradiction by establishing a minimum flow path length criterion (equal to or longer than relaxation distance Lv) rather than arbitrarily increasing the length. This parameter-based approach ensures sufficient mixing for compressor protection while avoiding excessive length that would unnecessarily increase device size. The relaxation distance Lv provides a precise quantitative threshold for optimal design.
3Reliability
If refrigerant mixing is accelerated to prevent liquid compression, then compressor protection is improved, but mixing homogeneity may be compromised
Solution Approach 1:
The patent uses parameter changes by optimizing the flow path length to match the relaxation distance Lv, which is calculated from fundamental fluid dynamics parameters (droplet density, diameter, gas viscosity, and flow velocity). This ensures that the refrigerant mixture achieves homogeneous composition stability before compressor entry, preventing liquid compression while maintaining proper mixing quality.
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 effectively protects the compressor and maintains productivity by ensuring homogeneous refrigerant mixing, preventing liquid compression and reducing the risk of compressor damage while minimizing device size.
Implementation Method 1
the suction refrigerant sucked into the compressor can be easily made homogeneous
Implementation Method 2
droplets that are particles of a liquid-phase refrigerant contained in the refrigerant
Data Source
AI summary
A heat pump cycle device includes: a compressor; a branch portion; a heating unit configured to heat a heating object using one refrigerant branched at the branch portion as a heat source; a decompression unit configured to decompress the refrigerant flowing out of the heating unit; a bypass passage through which an another refrigerant branched at the branch portion flows; a regulating unit; and a joining portion. When a length of a suction-side flow path from an outlet port of the joining portion to a suction port of the compressor is defined as a suction-side flow path length L1, the suction-side flow path length L1 is equal to or longer than a relaxation distance Lv. The relaxation distance Lv is a flow length that is necessary for the refrigerant mixed in the joining portion to be made in a homogeneous state.