Refrigeration Cycle Startup Control for Disproportionation-Prone Mixtures
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Solution Overview
Problem
HFO-1123, a refrigerant with excellent performance, undergoes a disproportionation reaction under high-temperature high-pressure conditions, leading to potential malfunctions in refrigeration cycles, especially when used in zeotropic refrigerant mixtures with high composition ratios of low boiling refrigerants accumulating in accumulators.
Innovation Solution
A refrigeration cycle apparatus employing a zeotropic refrigerant mixture with a first refrigerant prone to disproportionation and a second refrigerant of higher boiling point, utilizing an initial operation to decrease the temperature and pressure of the refrigerant discharged from the compressor, thereby reducing the likelihood of disproportionation reactions by adjusting the composition ratio and partial pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HFO-1123 is used as a refrigerant with high composition ratio in a zeotropic refrigerant mixture, then excellent performance and low GWP are achieved, but disproportionation reaction occurs under high-temperature high-pressure conditions
Solution Approach 1:
The system performs preliminary action by detecting liquid refrigerant accumulation in the accumulator before disproportionation reaction can occur. The control unit identifies the condition (liquid refrigerant in accumulator) and preemptively adjusts compressor operation to prevent the high-temperature high-pressure conditions that would trigger the harmful reaction.
Solution Approach 2:
The system implements feedback control by continuously monitoring the accumulator state and adjusting compressor operation accordingly. When liquid refrigerant is detected in the accumulator, the control unit provides feedback to reduce compressor capacity or stop operation, thereby preventing the refrigerant conditions that cause disproportionation reaction while maintaining safe operation.
2Object-affected harmful factors
If compressor operation is reduced to prevent disproportionation reaction, then safety is improved, but refrigeration capacity decreases
Solution Approach 1:
The system applies partial action by selectively reducing compressor operation only when necessary (when liquid refrigerant accumulates in the accumulator). Instead of continuously operating at reduced capacity, the compressor runs at full capacity during normal conditions and only reduces operation temporarily when the harmful condition is detected, thereby minimizing impact on overall refrigeration productivity.
Solution Approach 2:
The control system implements periodic monitoring and intermittent adjustment of compressor operation. The control unit periodically checks for liquid refrigerant accumulation and applies capacity reduction only during specific periods when the condition exists, allowing the system to maintain high productivity during normal operation while preventing disproportionation reaction when needed.
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
The apparatus effectively prevents disproportionation reactions and maintains high performance by quickly adjusting the refrigerant composition ratio, ensuring safe operation even under conditions that might otherwise cause the reaction.
Implementation Method 1
a main passage sequentially connecting a compressor, a first heat exchanger, an expansion valve, a gas-liquid separator, and a second heat exchanger
Data Source
AI summary
A refrigeration cycle apparatus avoids refrigerant conditions causing a disproportionation reaction and exhibit high performance with safety even when a refrigerant causing the disproportionation reaction is used in a zeotropic refrigerant mixture. The refrigeration cycle apparatus uses, as a working refrigerant, the zeotropic refrigerant mixture of a first refrigerant and a second refrigerant having a higher boiling point than that of the first refrigerant under the same pressure, and includes at least a main passage sequentially connecting a compressor, a first heat exchanger, an expansion valve, a gas-liquid separator, and a second heat exchanger. The first refrigerant causes the disproportionation reaction. In an initial state after startup of the compressor, the refrigeration cycle apparatus performs an initial operation decreasing a temperature or a pressure of refrigerant discharged from the compressor to be lower than that in a normal operation based on an amount of liquid refrigerant in the gas-liquid separator.