Subcooling Circuit Control for Energy-Efficient Refrigeration Systems
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Solution Overview
Problem
Refrigeration circuits require significant energy to operate efficiently, with existing systems consuming excessive power due to high gas phase fractions in the refrigerant, which reduces cooling performance and increases energy consumption.
Innovation Solution
A cooling system with a subcooling circuit and a control unit that adjusts the operation of compressors in both the refrigeration and subcooling circuits to maintain specific temperature ranges at heat exchangers, optimizing heat transfer and energy efficiency by controlling the subcooling process and compressor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a subcooling circuit is added to increase cooling efficiency, then the cooling performance is improved, but the device complexity increases
Solution Approach 1:
The patent combines the subcooling circuit with the main refrigeration circuit by integrating the economizer heat exchanger into the existing system architecture. The subcooling circuit shares components such as the expansion device and heat exchangers with the main circuit, creating a unified system that achieves subcooling functionality without requiring completely separate independent systems.
Solution Approach 2:
The economizer heat exchanger serves multiple functions: it acts as both a subcooling device for the liquid refrigerant and an economizer for flash gas removal. The expansion device controls refrigerant flow to both the evaporator and the subcooling circuit, demonstrating multi-functionality that reduces overall system complexity while maintaining enhanced cooling efficiency.
2Productivity
If compressors operate at higher capacity to meet cooling demands, then the cooling capacity is improved, but the energy consumption increases
Solution Approach 1:
The patent changes the thermodynamic parameters of the refrigerant by implementing subcooling, which lowers the temperature of the liquid refrigerant below its saturation temperature. This parameter change increases the refrigeration effect per unit mass of refrigerant, allowing the system to meet cooling demands with reduced compressor workload and lower energy consumption.
Solution Approach 2:
The control unit continuously monitors system conditions and adjusts the expansion device and compressor operation to optimize performance. By using feedback control, the system can meet varying cooling demands while minimizing compressor energy consumption, preventing over-compression and unnecessary energy use.
3Ease of operation
If the temperature at heat exchange means is not precisely controlled, then the system operation is simpler, but the heat transfer efficiency decreases
Solution Approach 1:
Temperature sensors are installed at critical heat exchange locations to provide real-time feedback to the control unit. The control unit uses this feedback to automatically adjust the expansion device and compressor operation, maintaining optimal temperature differences for heat transfer without requiring complex manual control or excessive system complexity.
Solution Approach 2:
The system is designed to automatically maintain optimal heat transfer conditions through the interaction of the expansion device, subcooling circuit, and control unit. The system self-regulates to preserve the temperature range necessary for efficient heat transfer, reducing the need for external intervention while maintaining high heat transfer efficiency.
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 approach significantly enhances the overall energy efficiency of the cooling system, reducing power consumption while maintaining the required cooling capacity, and allows for a transition from R404A-based systems to CO2-based systems without efficiency loss.
Implementation Method 1
at least one heat exchange means being arranged downstream of the at least one condenser and being configured for heat exchange between the refrigeration circuit and the subcooling circuit
Implementation Method 2
a subcooling circuit for subcooling the refrigerant circulating in the refrigeration circuit
Implementation Method 3
at least one compressor; at least one subcooler compressor
Data Source
AI summary
A cooling system comprises a refrigeration circuit (1) circulating a refrigerant and comprising in the flow direction of the refrigerant at least one compressor (2a, 2b, 2c, 2d); at least one condenser (4); at least one expansion device (8, 10); and at least one evaporator (11) for providing a cooling capacity. The cooling system further comprises a subcooling circuit (20) for subcooling the refrigerant circulating in the refrigeration circuit (1), the subcooling circuit (20) being configured to circulate a subcooling refrigerant and comprising at least one subcooler compressor (22, 23); at least one heat exchange means (6, 7) being arranged downstream of the at least one condenser (4) and being configured for heat exchange between the refrigeration circuit (1) and the subcooling circuit (20), the at least one heat exchange means (6, 7) comprising at least one temperature sensor; and a control unit (15) which is configured for controlling at least one compressor (2a, 2b, 2c, 2d) of the refrigeration circuit (1) and at least one subcooler compressor (22, 23) of the subcooling circuit (20) such that the cooling capacity to be provided by the at least one evaporator (11) is met and such that the temperature at the at least one heat exchange means (6, 7) measured by at least one temperature sensor is in a predetermined range.