Compressor Bypass Injection Cooling for High-Temperature Air Conditioning
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Solution Overview
Problem
Air-conditioning apparatuses using R32 refrigerant face challenges with high discharge temperatures from compressors, leading to degradation of refrigerating machine oil and potential damage, especially when using inexpensive compressors without special structures for refrigerant injection, resulting in unreliable operation and insufficient cooling or heating capacity.
Innovation Solution
The air-conditioning apparatus employs an auxiliary heat exchanger and a flow regulating unit to control the refrigerant flow into the compressor's suction part, ensuring the refrigerant is in a subcooled liquid state, thereby reducing the discharge temperature and preventing oil degradation, while allowing for increased compressor rotation speed and improved system reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the rotation speed of the compressor is lowered to reduce the compression ratio, then the discharge temperature is reduced, but the cooling capacity and heating capacity become insufficient
Solution Approach 1:
The invention changes the thermodynamic parameters of the refrigerant by injecting gas-liquid two-phase refrigerant into the compression chamber. This alters the compression process parameters, enabling the compressor to maintain high rotation speed while achieving lower discharge temperatures through the evaporative cooling effect of the injected refrigerant
Solution Approach 2:
The invention performs preliminary cooling of the refrigerant by injecting gas-liquid two-phase refrigerant into the compression chamber before the compression process completes. This preliminary cooling action reduces the discharge temperature while allowing the compressor to operate at high speed, thereby maintaining both temperature control and high capacity
2Temperature
If refrigerant in a gas-liquid two-phase state is injected into the medium-pressure chamber, then the discharge temperature is lowered and compressor rotation speed can be increased, but the system requires a special compressor structure with injection ports
Solution Approach 1:
The invention makes the compressor structure universal by using the existing suction port and compression chamber, which are standard components in all compressors. The gas-liquid two-phase refrigerant is injected through the suction port, eliminating the need for special injection ports while achieving the same temperature reduction effect
Solution Approach 2:
The invention utilizes the self-service capability of the compressor's existing structure by employing the suction port and compression chamber for their intended purposes while simultaneously enabling the temperature reduction function. The standard compressor components serve multiple functions: the suction port serves both for refrigerant intake and for injecting the gas-liquid two-phase refrigerant, and the compression chamber serves both for compression and for the evaporative cooling process
3Temperature
If a compressor with special structure for refrigerant injection is used, then discharge temperature can be controlled, but the system cost increases
Solution Approach 1:
The invention replaces expensive special-purpose components with inexpensive standard components. By using the existing suction port and compression chamber instead of expensive specialized injection ports and modified compressor structures, the system achieves the same temperature control function at a fraction of the cost, making the solution economically viable
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 limits excessive discharge temperature rises, preventing compressor damage and ensuring reliable operation with inexpensive compressors, while maintaining sufficient heating and cooling capacities, thus enhancing user comfort and system stability.
Implementation Method 1
an auxiliary heat exchanger and a flow regulating unit to control the refrigerant flow into the compressor's suction part, ensuring the refrigerant is in a subcooled liquid state
Implementation Method 2
ensuring the refrigerant is in a subcooled liquid state, thereby reducing the discharge temperature
Implementation Method 3
Refrigerant circulates in the refrigerant circuit, and air is heated or cooled by utilizing the rejection or absorption of heat by the refrigerant
Implementation Method 4
when the saturation temperature of high-pressure refrigerant becomes equal to or higher than the temperature of the indoor or outdoor air after activation of the air-conditioning apparatus, the high-pressure refrigerant in a gaseous state liquefies as the refrigerant rejects heat
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An air-conditioning apparatus (100) includes a bypass pipe (41) that has one end connected to the discharge side of a compressor(10) and through which refrigerant exiting the compressor (10) flows, an auxiliary heat exchanger (40) that is connected to the other end of the bypass pipe (41) and the suction part of the compressor (10), and cools refrigerant flowing through the bypass pipe (41) and supplies the cooled refrigerant to the suction part of the compressor (10), and a flow regulating unit (42) that is provided on the refrigerant outlet side of the auxiliary heat exchanger (40), and regulates the flow rate of refrigerant routed into the suction part of the compressor (10) from the auxiliary heat exchanger (40).