Switchable Heat Exchanger Flow Paths for Frost-Resistant Refrigeration
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Solution Overview
Problem
Non-azeotropic refrigerant mixtures in refrigeration cycles often result in varying temperature differences between the refrigerant inlet and outlet of the evaporator, leading to partial frost formation and dew condensation, which reduces efficiency and necessitates frequent defrosting operations.
Innovation Solution
A refrigeration cycle apparatus with a multi-way valve and a flow path switching device that adjusts the number of refrigerant flow paths in the evaporator between series and parallel configurations, controlled by a controller to minimize temperature differences and prevent frost and dew formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If non-azeotropic refrigerant mixture is used in the refrigeration cycle, then global warming potential is reduced and combustibility is eliminated, but temperature difference between refrigerant inlet and outlet of evaporator varies causing partial frost formation and dew condensation
Solution Approach 1:
The patent applies the dynamics principle by making the evaporator's flow path configuration adjustable rather than fixed. The flow path switching device dynamically changes the number of flow paths based on operating conditions, allowing the system to adapt to the varying temperature characteristics of non-azeotropic refrigerant mixtures and prevent both frost formation and dew condensation.
Solution Approach 2:
The patent implements parameter changes by modifying the flow path configuration parameters of the evaporator. By switching between different numbers of flow paths (series or parallel connections), the system changes the refrigerant flow distribution parameters to control temperature differences across the evaporator, thereby preventing harmful frost and dew condensation phenomena.
2Power
If the number of flow paths in the evaporator is increased to improve heat transfer performance, then heat transfer efficiency is enhanced, but pressure loss increases and temperature difference between inlet and outlet becomes larger
Solution Approach 1:
The patent makes the number of flow paths dynamically adjustable rather than fixed. The flow path switching device allows the system to optimize the balance between heat transfer efficiency and pressure loss by selecting appropriate flow path configurations based on operating conditions, preventing excessive temperature differences while maintaining effective heat transfer.
Solution Approach 2:
The system changes the flow path configuration parameters to optimize performance. By switching between series and parallel connections, the patent adjusts the refrigerant flow distribution to achieve an optimal balance between heat transfer efficiency and pressure loss, controlling temperature differences within acceptable ranges.
3Reliability
If defrosting operation is performed frequently to remove frost from the evaporator, then frost formation is eliminated, but system efficiency is reduced due to operational interruptions
Solution Approach 1:
The patent applies preliminary anti-action by preventing frost formation in the first place through optimized flow path configuration. By controlling the refrigerant flow distribution to minimize temperature differences across the evaporator, the system prevents the conditions that lead to frost formation, eliminating the need for frequent defrosting operations and maintaining continuous efficient operation.
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 enhances the operational efficiency of the refrigeration cycle by reducing temperature differences, preventing partial frost and dew condensation, and minimizing the frequency of defrosting operations, thereby improving overall system performance.
Implementation Method 1
a flow path switching device configured to switch connections of the plurality of refrigerant flow paths between (a) a series state in which the non-azeotropic refrigerant mixture flows through the plurality of refrigerant flow paths in series and (b) a parallel state in which the non-azeotropic refrigerant mixture flows through the plurality of refrigerant flow paths in parallel
Implementation Method 2
a first heat exchanger, a second heat exchanger
Implementation Method 3
for a condenser, the heat exchanger is used with a reduced number of branches at a fast flow rate, and for an evaporator, the heat exchanger is used with an increased number of branches at a slow flow rate
Implementation Method 4
an expansion valve
Implementation Method 5
a compressor
Implementation Method 6
the non-azeotropic refrigerant mixture flows in order of the first heat exchanger, the expansion valve, and the second heat exchanger
Data Source
AI summary
A refrigeration cycle apparatus includes a refrigeration circuit in which non-azeotropic refrigerant mixture circulates. The refrigeration circuit includes a compressor, an outdoor heat exchanger, an indoor heat exchanger, an expansion valve, and a four-way valve. The four-way valve is configured to assume a first state and a second state. The outdoor heat exchanger includes a plurality of refrigerant flow paths and a linear flow path switching valve configured to switch connections of the plurality of refrigerant flow paths between a series state in which the non-azeotropic refrigerant mixture flows through the plurality of refrigerant flow paths in series and a parallel state in which the non-azeotropic refrigerant mixture flows through the plurality of refrigerant flow paths in parallel. A controller switches the linear flow path switching valve between the series state and the parallel state when a multi-way valve is in the second state.