Refrigeration Cycle Injection Pipe for Low-Load Capacity Control
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Solution Overview
Problem
Existing refrigeration cycle apparatuses face inefficiencies due to frequent compressor stop-start cycles when thermal loads are low, leading to reduced operation efficiency and compressor reliability issues.
Innovation Solution
A refrigeration cycle apparatus with a compressor, condenser, and evaporator connected by refrigerant pipes, featuring an injection pipe with a second expansion valve and a controller that adjusts compressor rotation speed and valve opening to reduce refrigerant flow through the evaporator during low load conditions, thereby reducing heat-exchange capability without changing compressor speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the rotation speed of the compressor is reduced to match low thermal load, then the capacity of the refrigeration cycle apparatus is adjusted, but the compressor cannot be stopped due to lower limit rotation speed requirements for reliable operation
Solution Approach 1:
The refrigerant flow path is segmented into multiple paths: a main path through the evaporator and a bypass path through the injection pipe. The bypass path allows a portion of the refrigerant to be injected into the suction side of the compressor, effectively dividing the refrigerant flow to achieve capacity control without stopping the compressor.
Solution Approach 2:
The injection pipe acts as an intermediary component that introduces refrigerant directly to the compressor suction side. This intermediary path enables capacity adjustment by controlling the amount of refrigerant injected, allowing the compressor to maintain rotation while effectively reducing its cooling capacity output.
2Adaptability or versatility
If the compressor is stopped and started frequently to match low thermal load, then the capacity is adjusted, but the operation efficiency is reduced due to pressure equalization and heat transfer between high-pressure and low-pressure refrigerant
Solution Approach 1:
The compressor operates continuously without stopping, maintaining continuous refrigerant circulation. The bypass mechanism allows capacity adjustment while keeping the compressor running, eliminating the losses associated with repeated start-stop cycles and pressure equalization.
Solution Approach 2:
The system dynamically adjusts capacity by varying the opening degree of the expansion valve in the bypass path, controlling the amount of refrigerant injected into the compressor suction side. This dynamic adjustment allows continuous operation at varying effective capacities without mechanical stop-start cycles.
3Adaptability or versatility
If the rotation speed of the compressor is excessively reduced, then the capacity matches low thermal load, but refrigerating machine oil cannot be sufficiently supplied to the slide portion, reducing compressor reliability
Solution Approach 1:
Instead of changing the rotation speed parameter to adjust capacity, the invention changes the refrigerant flow distribution parameter. By controlling the opening degree of the expansion valve in the bypass path, the system adjusts how much refrigerant goes through the evaporator versus being injected into the compressor, maintaining constant rotation speed and reliable lubrication.
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 allows for reduced compressor stop-start cycles and improved efficiency by adjusting capacity to match thermal loads, enhancing reliability and operation efficiency during low load conditions.
Implementation Method 1
a second expansion valve provided at the injection pipe
Implementation Method 2
an evaporator 103 and a suction portion 8a of the compressor 100 are connected by a refrigerant pipe 204
Implementation Method 3
reducing heat-exchange capability of the evaporator 103
Implementation Method 4
a compressor 100, a condenser 101
Data Source
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AI summary
A refrigeration cycle apparatus includes: a refrigeration cycle circuit in which a compressor, a condenser, a first expansion valve, and an evaporator are connected by refrigerant pipes; an injection pipe having a refrigerant inflow side end and a refrigerant outflow side end, the refrigerant inflow side being connected between the condenser and the first expansion valve, the refrigerant outflow side end being connected to a suction side of the compressor; a second expansion valve provided at the injection pipe; and a controller that controls a rotation speed of the compressor and an opening degree of the second expansion valve. In the case of reducing a heat-exchange capability of the evaporator when the rotation speed of the compressor is a specified rotation speed, the controller performs a low load operation during which refrigeration is caused to flow through the injection pipe.