Air-conditioning apparatus
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Solution Overview
Problem
Existing air-conditioning apparatuses face challenges in controlling discharge temperature and subcooling independently, leading to unreliable operation and noise due to refrigerant flow issues, especially in multi-air-conditioning systems with long extension pipes, and require expensive compressors with special structures.
Innovation Solution
An air-conditioning apparatus with a refrigeration cycle including a compressor, heat-source-side and load-side heat exchangers, a bypass system with expansion devices, and an auxiliary heat exchanger to control refrigerant flow rate and temperature, allowing for reliable operation without a compressor with a special structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a bypass expansion device and refrigerant heat exchanger are used to control discharge temperature, then the discharge temperature can be controlled, but the degree of subcooling and discharge temperature cannot be individually controlled to reach different target temperatures
Solution Approach 1:
The patent divides the refrigerant flow control into two independent paths: one path through the bypass expansion device for discharge temperature control, and another path through the electronic expansion valve for subcooling control. This segmentation allows each parameter to be controlled independently without interference from the other.
Solution Approach 2:
The patent employs an electronic expansion valve that can universally control both the degree of subcooling and discharge temperature by adjusting its opening degree, providing flexible multi-functional control capability that adapts to different operating conditions.
2Temperature
If discharge temperature is controlled to a target temperature, then the discharge temperature is stabilized, but the degree of subcooling at the outlet of the outdoor unit cannot be controlled to a target value
Solution Approach 1:
The patent implements feedback control by using sensors to detect the actual discharge temperature and degree of subcooling, then adjusting the opening degrees of the bypass expansion device and electronic expansion valve accordingly to maintain both parameters at their target values, ensuring reliable operation.
3Productivity
If refrigerant in two-phase gas-liquid state flows into the inlet of the expansion device, then the refrigerant can be expanded, but noise is generated and control becomes unstable
Solution Approach 1:
The patent applies preliminary action by ensuring the refrigerant is fully condensed into liquid phase in the outdoor unit heat exchanger before flowing to the indoor expansion device, preventing two-phase flow conditions that cause noise and instability. This is achieved through proper subcooling control.
4Temperature
If a compressor with special structure is used to enable intermediate pressure refrigerant injection, then the discharge temperature can be reduced, but the compressor cost increases
Solution Approach 1:
The patent replaces the expensive compressor with special structure with a standard, inexpensive compressor by implementing the discharge temperature reduction function through external refrigerant injection via the bypass expansion device and electronic expansion valve, achieving the same effect without modifying the compressor itself.
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 provides a reliable air-conditioning system with independent control of discharge temperature and subcooling, reducing noise and operational instability, and can be implemented using standard compressors, enhancing system reliability and efficiency.
Implementation Method 1
a first expansion device disposed in the bypass and depressurizing the refrigerant flowing through the bypass
Implementation Method 2
an auxiliary heat exchanger disposed downstream of the first expansion device of the bypass and cooling the refrigerant depressurized at the first expansion device
Implementation Method 3
a second expansion device disposed downstream of the auxiliary heat exchanger of the bypass and controlling a flow rate of the refrigerant flowing from the auxiliary heat exchanger to the suction side of the compressor
Implementation Method 4
a refrigeration cycle circulating refrigerant and connecting a compressor
Implementation Method 5
an outdoor unit, which is a heat source unit disposed outside the building
Implementation Method 6
an indoor unit disposed inside the building that are connected with pipes. The air-conditioning apparatus circulates refrigerant through the refrigerant circuit to heat or cool air through radiation or reception of heat by the refrigerant
Data Source
AI summary
An air-conditioning apparatus includes a refrigeration cycle circulating refrigerant and connecting a compressor, a heat-source-side heat exchanger, one or more of load-side expansion devices, and one or more of load-side heat exchangers by refrigerant pipes, a bypass having one end connected to a discharge side of the compressor of the refrigeration cycle and the other end connected to a suction side of the compressor of the refrigeration cycle to bypass a portion of the refrigerant discharged from the compressor, a first expansion device depressurizing the refrigerant flowing through the bypass, an auxiliary heat exchanger cooling the refrigerant depressurized at the first expansion device, a second expansion device controlling a flow rate of the refrigerant flowing from the auxiliary heat exchanger to the suction side of the compressor, and a controller controlling an opening degree of the second expansion device.