Air conditioning device using vapor injection cycle and method for controlling the device
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Solution Overview
Problem
Vapor injection compression systems face efficiency degradation due to high super-heating temperatures leading to compressor overload and reduced performance, especially when the super-heating temperature is low, causing liquid refrigerant to enter the compressor.
Innovation Solution
An air conditioning device with an inner heat-exchanger and an injection channel, where the compressor rotation speed is controlled based on air-conditioning load and super-heating temperatures, and the opening rates of expansion valves are adjusted to maintain optimal injection super-heating temperatures, ensuring efficient refrigerant flow and reducing compressor load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vapor injection compression system is used to improve cooling or heating capability, then the compression capability and refrigerant circulation amount are improved, but when the super-heating temperature of injected refrigerant is high, compressor super-heating occurs and system efficiency degrades
Solution Approach 1:
The patent dynamically adjusts the opening degree of the injection expansion valve to control the super-heating temperature of the injected refrigerant. By changing the valve opening parameter, the system optimizes the balance between compression capability and efficiency, preventing both compressor super-heating and liquid refrigerant entry while maximizing cooling or heating performance
Solution Approach 2:
The control device monitors the super-heating temperature at the compressor suction port and adjusts the injection expansion valve opening degree accordingly. This feedback mechanism ensures the super-heating temperature remains within the optimal range (5-15°C), resolving the contradiction between maintaining high compression capability and preventing efficiency degradation from excessive super-heating
2Reliability
If the super-heating temperature of injected refrigerant is increased to prevent liquid refrigerant entry, then compressor overload is avoided, but compressor super-heating occurs and system efficiency degrades
Solution Approach 1:
The system dynamically adjusts the injection expansion valve opening degree as a controllable parameter to achieve the optimal super-heating temperature range (5-15°C). This prevents both liquid refrigerant entry (which causes overload) and excessive super-heating (which causes efficiency degradation), ensuring reliable compressor operation while maintaining high system efficiency
Solution Approach 2:
The control device continuously monitors the super-heating temperature at the compressor suction port and adjusts the injection expansion valve opening degree in real-time. This feedback control maintains the super-heating temperature within the optimal range, simultaneously ensuring compressor reliability and preventing energy loss
3Temperature
If the compressor rotation speed is reduced to secure injection sub-cooling temperature with small air-conditioning load variation, then the injection super-heating temperature is maintained high, but the cooling or heating capacity may be reduced
Solution Approach 1:
The system adjusts the compressor rotation speed as a control parameter when air-conditioning load variation is small and injection sub-cooling temperature is insufficient. By reducing the rotation speed, the system maintains high injection super-heating temperature while compensating for potential capacity loss through optimized refrigerant flow management
Solution Approach 2:
The control system dynamically adjusts compressor rotation speed based on real-time conditions (air-conditioning load variation and injection sub-cooling temperature). This dynamic adjustment allows the system to maintain optimal injection super-heating temperature while minimizing impact on cooling or heating capacity through coordinated control of refrigerant flow parameters
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 solution improves cooling and heating performance by maintaining high injection super-heating temperatures, reducing power consumption, and ensuring sufficient refrigerant flow, thereby enhancing the overall efficiency of the air conditioning device.
Implementation Method 1
an inner heat-exchanger for allowing exchanging of heat between first refrigerant passing through a condenser and second refrigerant branched from the first refrigerant
Implementation Method 2
a compressor for compressing the refrigerant
Implementation Method 3
The branched tube is provided with an injection expansion valve to expand the refrigerant
Data Source
AI summary
An air conditioning device includes a vapor injection cycle in which an operating speed of a compressor is adjusted to improve efficiency, and a method for controlling the device. The air conditioning device includes an inner heat-exchanger for exchanging heat between a first portion of refrigerant passing through a condenser and a second portion of the refrigerant branched from the first refrigerant, and an injection channel through which the second portion of the refrigerant is injected into the compressor. The inner heat exchanger includes an outer tube and an inner tube disposed inside the outer tube. The first portion of the refrigerant flows into the inner tube, while the second portion of the refrigerant flows into the outer tube. Thus, when a variation of air-conditioning load is small and an injection super-heating temperature is low, the device enables reduction of the compressor rotation speed to ensure high injection super-heating temperature.