Dual-Circuit Refrigeration Control for Stable Evaporation Capacity
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Solution Overview
Problem
The existing refrigeration cycle devices with suction injection pipes and subcooling heat exchangers face challenges in maintaining evaporation capacity at the use-side heat exchanger across varying operating conditions, particularly due to difficulties in reducing the enthalpy of the refrigerant effectively.
Innovation Solution
The introduction of a sub-refrigerant circuit and a control unit that switches between the cooling actions of the subcooling heat exchanger and the sub-refrigerant circuit based on outside air temperature and refrigerant conditions, allowing for enhanced enthalpy reduction and increased evaporation capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the suction injection pipe and subcooling heat exchanger are provided to cool the refrigerant, then the evaporation capacity of the use-side heat exchanger is increased, but the system cannot maintain sufficient evaporation capacity under all operating conditions (particularly when outside air temperature is high)
Solution Approach 1:
The invention divides the single refrigerant circuit into two separate circuits: a main refrigerant circuit and a sub-refrigerant circuit. The main circuit handles primary cooling through the use-side heat exchanger, while the sub-circuit provides additional cooling capacity through the sub-use-side heat exchanger. This segmentation allows the system to adapt to different operating conditions by selectively activating either circuit or both simultaneously, thereby maintaining evaporation capacity across varying outside air temperatures.
Solution Approach 2:
The sub-use-side heat exchanger is designed to serve dual functions: it acts as an evaporator for the sub-refrigerant circuit while simultaneously functioning as a subcooling heat exchanger for the main refrigerant circuit. This multi-functionality enables the system to optimize cooling performance under different operating conditions without requiring entirely separate components, thereby maintaining adaptability while improving evaporation capacity.
2Productivity
If the sub-refrigerant circuit is added to enhance cooling capacity, then the evaporation capacity is increased regardless of operating conditions, but the device complexity increases
Solution Approach 1:
The invention merges the subcooling function with the evaporator function by making the sub-use-side heat exchanger serve both purposes. The sub-refrigerant flows through the sub-use-side heat exchanger where it evaporates, and simultaneously this heat exchanger cools the main refrigerant. This merging eliminates the need for a separate subcooling heat exchanger, thereby reducing overall system complexity while maintaining the enhanced evaporation capacity provided by the dual-circuit configuration.
Solution Approach 2:
The sub-use-side heat exchanger performs multiple functions: it serves as the evaporator for the sub-refrigerant circuit and simultaneously acts as a subcooling heat exchanger for the main refrigerant circuit. This multi-functionality reduces the total number of components required in the system, thereby mitigating the increase in device complexity that would otherwise result from adding the sub-refrigerant circuit.
3Loss of energy
If the control unit switches between cooling actions based on operating conditions, then the coefficient of performance is optimized, but the control complexity increases
Solution Approach 1:
The control system is designed to dynamically switch between different cooling modes based on real-time operating conditions such as outside air temperature and refrigerant state. The control unit can operate the main compressor alone, the sub-compressor alone, or both compressors simultaneously, and can switch between using the subcooling heat exchanger or the sub-refrigerant circuit for cooling. This dynamic adaptability allows the system to optimize its coefficient of performance under varying conditions while keeping the control logic relatively simple through predefined switching criteria.
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 effectively increases the evaporation capacity of the use-side heat exchanger regardless of operating conditions, optimizing the coefficient of performance of the refrigeration cycle device by adjusting the cooling actions according to temperature and refrigerant state.
Implementation Method 1
the subcooling heat exchanger cooling a main refrigerant that flows between the main expansion mechanism and the main use-side heat exchanger by heat exchange with the main refrigerant that flows in the suction injection pipe
Implementation Method 2
The sub-use-side heat exchanger is a heat exchanger that functions as an evaporator of the sub-refrigerant and that cools the main refrigerant that flows between the main expansion mechanism and the main use-side heat exchanger
Implementation Method 3
The main compressor is a compressor that compresses a main refrigerant
Implementation Method 4
The sub-compressor is a compressor that compresses the sub-refrigerant
Implementation Method 5
The main heat-source-side heat exchanger is a heat exchanger that functions as a heat dissipater (a radiator) of the main refrigerant
Implementation Method 6
The sub-heat-source-side heat exchanger is a heat exchanger that functions as a heat dissipater of the sub-refrigerant
Implementation Method 7
The main use-side heat exchanger is a heat exchanger that functions as an evaporator of the main refrigerant
Implementation Method 8
The sub-use-side heat exchanger is a heat exchanger that functions as an evaporator of the sub-refrigerant
Data Source
AI summary
A suction injection pipe and a subcooling heat exchanger are provided at a main refrigerant circuit in which a main refrigerant circulates. Further, a sub-refrigerant circuit that differs from the main refrigerant circuit and in which a sub-refrigerant circulates is provided. A controller performs control for switching between a cooling action of the subcooling heat-exchanger that cools the main refrigerant that is sent to a main use-side heat exchanger by using the suction injection pipe and the subcooling heat exchanger, and a cooling action of the sub-refrigerant-circuit that cools the main refrigerant that is sent to the main use-side heat exchanger by using the sub-refrigerant circuit.