Refrigerant Injection Control for Multi-Mode Air Conditioning
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Solution Overview
Problem
Existing air-conditioning apparatuses struggle to perform injection operations across various modes, such as cooling, heating, and mixed operations, with inadequate control over intermediate pressure and injection flow rates, leading to excessive discharge temperatures.
Innovation Solution
An air-conditioning apparatus with a refrigerant circuit that includes a compressor, refrigerant flow switching device, heat exchangers, and expansion devices, allowing for switching between cooling and heating operations, and featuring a controller to adjust the opening degree of expansion devices to control the injection flow rate and intermediate pressure, ensuring stable operation and managing discharge temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If injection is performed in limited operation modes using conventional circuits, then the system structure remains simple, but the system cannot adapt to various operation modes such as cooling, heating, and mixed operations
Solution Approach 1:
The patent implements a universal injection circuit that can operate across multiple operation modes (cooling, heating, mixed operations) by using a common pressure reducing device and injection circuit structure. The system achieves multi-functionality by controlling the injection flow rate adaptively based on the current operation mode, eliminating the need for separate injection circuits for each mode while maintaining comprehensive operational capability.
Solution Approach 2:
The patent employs dynamic control of the injection flow rate by adjusting the opening degree of the expansion device based on detected operation modes and intermediate pressure conditions. This dynamic adaptation allows the same injection circuit to serve multiple operation modes effectively, transforming a static limited-system into a dynamic multi-functional system without increasing structural complexity.
2Temperature
If injection flow rate is increased to control discharge temperature, then discharge temperature decreases, but intermediate pressure becomes unstable
Solution Approach 1:
The patent implements a feedback control mechanism where the controller detects the operation mode and intermediate pressure conditions, then adjusts the injection flow rate accordingly. The system monitors intermediate pressure stability and dynamically modifies the expansion device opening degree to maintain both discharge temperature control and pressure stability, creating a closed-loop control system that balances these two parameters.
Solution Approach 2:
The patent changes the injection flow rate parameter dynamically based on operation mode and intermediate pressure conditions. By adjusting the opening degree of the expansion device, the system modifies the injection parameter adaptively rather than using a fixed flow rate, allowing optimal balance between discharge temperature reduction and intermediate pressure stability for each operating condition.
3Productivity
If intermediate pressure is reduced to improve injection efficiency, then injection efficiency increases, but the system cannot maintain stable operation across different operation modes
Solution Approach 1:
The patent maintains injection efficiency while ensuring operation stability by dynamically adjusting the injection flow rate based on the detected operation mode and intermediate pressure conditions. The system does not use a fixed low intermediate pressure but rather adapts the pressure and flow rate parameters in real-time, allowing efficient injection during cooling modes while maintaining stable operation during heating and mixed modes through coordinated control of the expansion device and injection circuit.
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 enables stable injection control across different operation modes, preventing excessively high discharge temperatures and enhancing the reliability of the air-conditioning system.
Implementation Method 1
a third expansion device disposed in the injection pipe
Implementation Method 2
a low-pressure refrigerant flows through at least one or all of the second heat exchangers so that the at least one or all of the second heat exchangers operate as an evaporator
Implementation Method 3
a first heat exchanger, a first expansion device, and second heat exchangers by using a pipe
Implementation Method 4
a compressor having a low-pressure shell structure
Data Source
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AI summary
An air-conditioning apparatus 100 controls an opening degree of at least one of a second expansion device (expansion device 14a) and a third expansion device (expansion device 14b) to adjust the amount of refrigerant to flow through the injection pipe 4c.