Refrigeration Cycle Two-Phase Pipe Flow to Reduce Refrigerant Volume
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Solution Overview
Problem
Refrigeration cycle apparatuses face inefficiencies and increased costs due to the need for smaller pipe diameters, which lead to higher refrigerant requirements and pressure losses, especially when pipe lengths increase, limiting their operating range and requiring more refrigerant.
Innovation Solution
A refrigeration cycle apparatus design that includes an outdoor unit with a compressor, heat exchanger, and expansion valves, and an indoor unit with another expansion valve, connected by pipes where the refrigerant is maintained in a two-phase state, reducing the amount of refrigerant needed by controlling the expansion valves to manage pressure and flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If pipe diameter is made smaller, then volume and cost are reduced, but pressure loss increases and operating range is limited
Solution Approach 1:
The patent changes the refrigerant state parameter from liquid to two-phase state in the connection pipe. This parameter change allows the system to use smaller pipe diameters while maintaining acceptable pressure loss characteristics, as two-phase refrigerant flow has different pressure drop characteristics compared to liquid refrigerant flow.
Solution Approach 2:
The patent utilizes phase transition by converting refrigerant from liquid phase to two-phase state before it enters the connection pipe through the first expansion valve. This phase transition enables the refrigerant to absorb heat during evaporation, which helps maintain temperature and pressure characteristics that reduce pressure loss in small-diameter pipes.
2Adaptability or versatility
If pipe length is increased, then installation flexibility is improved, but required refrigerant amount increases
Solution Approach 1:
The patent changes the refrigerant state to two-phase in the connection pipe, which fundamentally alters the relationship between pipe length and refrigerant quantity. Two-phase refrigerant has higher heat absorption capacity per unit length, meaning less total refrigerant is needed to achieve the same cooling effect over longer pipe distances.
Solution Approach 2:
By maintaining two-phase state in the connection pipe, the system utilizes the latent heat of evaporation to efficiently transfer heat over longer distances. This phase transition mechanism allows the refrigerant to effectively cool the indoor unit even when pipe length is increased, without proportionally increasing the total refrigerant charge.
3Ease of manufacture
If pipe diameter is made smaller, then cost is reduced, but operating range is limited
Solution Approach 1:
The patent changes the refrigerant state parameter to two-phase in the connection pipe, which extends the operating range of small-diameter pipes. This parameter change allows the system to maintain effective heat transfer and pressure characteristics that enable small pipes to handle a broader range of operating conditions and loads.
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 design reduces the amount of refrigerant required, stabilizes the operating state, and decreases the Global Warming Potential (GWP) by optimizing the refrigerant flow and pressure management, regardless of pipe length, thus enhancing efficiency and reducing costs.
Implementation Method 1
the first expansion valve converts refrigerant from a liquid-phase state to a two-phase state and sends two-phase refrigerant to the first pipe
Data Source
AI summary
A refrigeration cycle apparatus includes an outdoor unit including a compressor, a first heat exchanger, and a first expansion valve, an indoor unit including a second expansion valve and a second heat exchanger, and a first pipe and a second pipe connected between the outdoor unit and the indoor unit. In a cooling operation, refrigerant delivered from the compressor sequentially passes through the first heat exchanger, the first expansion valve, the first pipe, the second expansion valve, the second heat exchanger, and the second pipe and returns to the compressor, and in the cooling operation, the first expansion valve converts refrigerant from a liquid-phase state to a two-phase state and sends two-phase refrigerant to the first pipe.