Ice making system with controlled dryness of refrigerant
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Solution Overview
Problem
The existing ice making systems with flooded evaporators require costly float switches and large accumulators to maintain refrigerant levels, leading to increased equipment costs.
Innovation Solution
An ice making system with a refrigerant circuit that includes a compressor, condenser, adjustable first expansion valve, flooded evaporator, and superheater, controlled by a device to maintain the dryness of refrigerant within a specific range, eliminating the need for float switches and large accumulators by ensuring the liquid refrigerant is not sucked into the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a float switch is used to maintain liquid refrigerant level in the flooded evaporator, then the cooling capacity is secured, but the equipment cost increases
Solution Approach 1:
The patent removes the float switch from the system by using a different control approach. The liquid refrigerant level in the flooded evaporator is maintained not by a float switch but by controlling the expansion valve opening degree based on superheat temperature feedback, thereby extracting the problematic component while preserving the desired function.
Solution Approach 2:
The mechanical float switch is replaced with an electronic control system that uses temperature sensors to measure superheat and automatically adjusts the expansion valve. This substitution eliminates mechanical wear and complexity while achieving more precise control of refrigerant distribution.
2Reliability
If a large accumulator is used to separate liquid and gas refrigerant, then liquid refrigerant is prevented from entering the compressor, but the equipment cost and system size increase
Solution Approach 1:
The patent removes the large accumulator from the system by preventing liquid refrigerant formation at the compressor inlet through proactive control. The expansion valve is regulated to maintain proper evaporation and ensure refrigerant leaves the evaporator as vapor or very low-quality two-phase mixture, eliminating the need for a large separation device.
Solution Approach 2:
The system performs preliminary action by controlling the expansion valve to prevent liquid refrigerant from reaching the compressor in the first place. By maintaining appropriate superheat at the evaporator outlet, the system ensures refrigerant is fully vaporized before compressor suction, preventing liquid slugging without requiring a large accumulator.
3Productivity
If the liquid refrigerant level in the flooded evaporator is maintained high, then the cooling capacity is improved, but the refrigerant discharged becomes wet vapor that requires an accumulator
Solution Approach 1:
The patent implements feedback control by measuring the superheat temperature at the evaporator outlet and using this information to automatically adjust the expansion valve opening degree. This closed-loop control maintains the liquid refrigerant level in the evaporator at the optimal point that maximizes cooling capacity while ensuring the discharged refrigerant has sufficient vapor quality.
Solution Approach 2:
The system dynamically changes the expansion valve opening degree based on measured superheat temperature. By adjusting this parameter in response to varying operating conditions, the system maintains both high cooling capacity and appropriate refrigerant vapor quality at the evaporator outlet, eliminating the need for an accumulator.
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 configuration reduces equipment costs by maintaining the refrigerant level and preventing liquid refrigerant from entering the compressor, thereby enhancing cooling capacity and efficiency.
Implementation Method 1
a superheater that imparts a degree of superheating to the refrigerant (i.e., superheats the refrigerant) discharged from the flooded evaporator
Implementation Method 2
a condenser that condenses refrigerant discharged from the compressor
Implementation Method 3
a flooded evaporator that evaporates the refrigerant decompressed by the first expansion valve
Data Source
AI summary
An ice making system includes: a refrigerant circuit that performs a vapor compression refrigeration cycle and that includes a compressor, a condenser that condenses refrigerant discharged from the compressor, a first expansion valve with an adjustable opening degree that decompresses the refrigerant from the condenser, a flooded evaporator that evaporates the refrigerant decompressed by the first expansion valve, and a superheater that imparts a degree of superheating to the refrigerant discharged from the flooded evaporator; a circulation circuit that circulates a medium that is cooled by the flooded evaporator; and a control device that controls the adjustable opening degree of the first expansion valve such that the superheater imparts to the refrigerant discharged from the flooded evaporator a degree of superheating at which dryness of the refrigerant is kept within a predetermined range of less than 1.