Compressor Refrigerant Injection for R32 Discharge Temperature Control
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Solution Overview
Problem
Conventional air-conditioning systems face issues with high compressor discharge temperatures when using R32 refrigerant, leading to refrigerant and oil degradation, especially during heating operations at low outside air temperatures, and lack effective methods for simultaneous cooling and heating operations.
Innovation Solution
An air-conditioning apparatus with a refrigeration cycle that includes a compressor with a low-pressure shell structure, a first heat exchanger, a first expansion device, and one or more second heat exchangers, utilizing a refrigerant mixture of R32 and HFO1234yf or R32 and HFO1234ze, with a controller managing the injection of refrigerant into the compressor to control discharge temperature through an aperture unit and second expansion device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If R32 refrigerant is used in air-conditioning systems, then cooling efficiency is improved, but compressor discharge temperature becomes too high causing refrigerant and oil degradation
Solution Approach 1:
A liquid injection device is introduced as an intermediary component between the liquid line and compressor suction. This device injects liquid refrigerant directly into the compressor suction port, where the injected liquid refrigerant evaporates and absorbs heat, thereby cooling the discharge refrigerant and preventing degradation of the R32 refrigerant and refrigerant oil while maintaining the high cooling efficiency of R32 systems
Solution Approach 2:
The invention changes the temperature parameter of the discharge refrigerant by injecting liquid refrigerant into the compressor suction port. The injected liquid refrigerant undergoes evaporative cooling, changing its temperature state from liquid to vapor, and this cold vapor mixes with the discharge refrigerant to lower its temperature, thus preventing degradation while maintaining R32's high efficiency characteristics
2Reliability
If liquid refrigerant is injected into the compressor to lower discharge temperature, then refrigerant degradation is prevented, but the system cannot support simultaneous cooling and heating operations
Solution Approach 1:
The liquid injection device is designed with dynamic control capabilities, allowing the injection amount to be adjusted based on operating conditions. The device can be selectively activated or deactivated, and the injection rate can be modulated, enabling the system to adapt to different operating modes including simultaneous cooling and heating operations while maintaining discharge temperature control when needed
Solution Approach 2:
The liquid injection device is designed to serve multiple functions: it can prevent refrigerant degradation during high-temperature operations, it can be adjusted for different operating modes, and it can support simultaneous cooling and heating operations. This multi-functional design allows a single device to handle various operational requirements without compromising system versatility
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
The solution effectively controls discharge temperature, preventing refrigerant and oil degradation and enabling safe operation with R32, while supporting both cooling and heating modes by injecting refrigerant into the compressor, thus addressing the limitations of existing systems.
Implementation Method 1
a second expansion device that depressurizes the refrigerant flowing thereinto
Implementation Method 2
injecting refrigerant into the compression chamber... controls discharge temperature
Data Source
AI summary
An air-conditioning apparatus controls that a discharge temperature does not become too high with a refrigerant whose compressor discharge temperature readily rises, and thus suppress degradation of the refrigerant and a refrigerating machine oil. An injection pipe that injects a heat source side refrigerant into a compressor is installed, connected a pipe between a backflow prevention device and an opening and closing device installed on a branching pipe, and an aperture unit in the compressor.