Indoor Heat Exchanger Control for Low-Load Dehumidification
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Solution Overview
Problem
Conventional air conditioners face challenges in maintaining effective dehumidification across varying loads, as lowering evaporation temperature can lead to freezing issues and decreased efficiency, while raising it may prevent dehumidification, especially under low loads.
Innovation Solution
The air conditioner dynamically adjusts the evaporation region in the indoor heat exchanger based on load conditions by controlling the compressor and expansion valve, ensuring the evaporation temperature remains within a suitable range for dehumidification, and includes an auxiliary heat exchanger with a larger size and adjustable fan speed to manage varying loads effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the evaporation temperature is lowered to handle high load, then the cooling capacity is increased, but the heat exchanger may freeze and the refrigeration cycle efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the evaporation region extent variable rather than fixed. The liquid refrigerant flow rate is dynamically adjusted based on load conditions, allowing the evaporation region to expand or contract within the heat exchanger. This dynamic adjustment prevents freezing under high load while maintaining adequate cooling capacity, as the system adapts the evaporation temperature and region size to match actual cooling demands.
Solution Approach 2:
The patent changes the parameter of evaporation temperature by controlling the liquid refrigerant flow rate to the heat exchanger. By adjusting this parameter based on load conditions, the system can lower the evaporation temperature when high cooling capacity is needed while preventing it from dropping too low and causing freezing. The control system monitors and adjusts the refrigerant flow to maintain optimal evaporation temperature across varying loads.
2Reliability
If the evaporation temperature is raised to prevent freezing under low load, then the heat exchanger safety is improved, but dehumidification cannot be performed
Solution Approach 1:
The system dynamically adjusts the liquid refrigerant flow rate based on load conditions. Under low load conditions, the reduced refrigerant flow allows the evaporation temperature to rise slightly, preventing freezing while still maintaining dehumidification capability through the controlled evaporation process. The dynamic flow adjustment ensures the evaporation temperature remains within the optimal range for both safety and dehumidification performance.
Solution Approach 2:
The control system uses feedback to monitor load conditions and adjust the liquid refrigerant flow rate accordingly. This feedback mechanism ensures that the evaporation temperature is maintained within an optimal range that prevents freezing while enabling effective dehumidification. The system continuously adapts to changing load conditions to balance safety and dehumidification effectiveness.
3Productivity
If the evaporation region is limited to the auxiliary heat exchanger, then dehumidification under low load is achieved, but the evaporation temperature must be lowered under high load leading to efficiency decrease
Solution Approach 1:
The patent applies universality by designing the heat exchanger system to serve multiple functions: the auxiliary heat exchanger handles dehumidification under low load, while the entire heat exchanger (auxiliary + main) participates in cooling under high load. The liquid refrigerant can evaporate in either or both regions depending on load conditions, making the system versatile across different operating scenarios without sacrificing efficiency in either mode.
Solution Approach 2:
The system dynamically shifts the evaporation region between the auxiliary heat exchanger and the main heat exchanger based on load conditions. Under low load, evaporation is confined to the auxiliary heat exchanger for effective dehumidification. Under high load, the evaporation region expands to include the main heat exchanger, allowing adequate cooling capacity while maintaining refrigeration cycle efficiency through appropriate evaporation temperature control.
4Adaptability or versatility
If the auxiliary heat exchanger size is increased to enlarge the evaporation region, then the dehumidification capability under varying loads is improved, but the device complexity and size increase
Solution Approach 1:
The patent applies segmentation by dividing the heat exchanger system into an auxiliary heat exchanger and a main heat exchanger. The auxiliary heat exchanger is specifically designed to handle dehumidification under low load conditions, while the main heat exchanger provides additional capacity for high load conditions. This segmentation allows the system to achieve versatility across different loads without requiring a single oversized heat exchanger, thereby controlling device complexity while improving adaptability.
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 allows for consistent dehumidification across a wide range of loads without excessive evaporation temperature changes, preventing freezing and ensuring efficient operation under both high and low loads, thereby maintaining performance and comfort.
Implementation Method 1
an auxiliary heat exchanger is disposed rearward of a main heat exchanger; and a refrigerant evaporates only in the auxiliary heat exchanger to locally perform dehumidification
Implementation Method 2
the extent of the evaporation region where the liquid refrigerant evaporates varies depending on the load in the indoor heat exchanger
Data Source
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AI summary
Dehumidification cannot be performed when a load decreases. In an air conditioner of the present invention, an indoor heat exchanger includes an auxiliary heat exchanger 20 and a main heat exchanger 21 disposed leeward from the auxiliary heat exchanger 20. In an operation in a predetermined dehumidification operation mode, a liquid refrigerant supplied to the auxiliary heat exchanger 20 all evaporates midway in the auxiliary heat exchanger 20. Therefore, only an upstream partial area in the auxiliary heat exchanger 20 is an evaporation region, while an area downstream of the evaporation region in the auxiliary heat exchanger 20 is a superheat region. In the predetermined dehumidification operation mode, a compressor and an expansion valve are controlled so that the extent of the evaporation region of the auxiliary heat exchanger 20 varies depending on the load.