Refrigerant Circuit Switching for Faster Charge Redistribution
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Solution Overview
Problem
Conventional refrigeration systems experience efficiency losses due to refrigerant migration during compressor OFF cycles, leading to suboptimal performance during the initial phase of compressor ON cycles, as refrigerant redistributes and pools in the evaporator, reducing heat transfer efficiency.
Innovation Solution
The system employs a refrigerant circuit with primary and secondary evaporator conduits arranged in parallel, along with different pressure reduction levels and a valve system to control refrigerant flow, allowing for efficient redistribution of refrigerant during the initial compressor ON cycle by bypassing heat exchanging members, and then switching to optimal thermodynamic efficiency during steady-state operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If heat exchanging members (suction line heat exchangers and intercoolers) are used to improve steady-state efficiency, then system efficiency during steady-state operation is improved, but refrigerant migration during compressor OFF cycles is prolonged and exacerbated
Solution Approach 1:
The evaporator circuit is segmented into multiple independent circuits (first evaporator circuit, second evaporator circuit, etc.) with separate pressure reducing devices. This segmentation allows selective operation of different circuits during startup versus steady-state, enabling quick refrigerant redistribution during startup by activating alternative circuits while maintaining efficient heat exchange during steady-state operation.
Solution Approach 2:
The system changes operational parameters by switching between different evaporator circuits based on system state. During compressor startup, the system activates a different evaporator circuit than during steady-state operation, thereby changing the flow parameters and preventing refrigerant migration issues while maintaining heat exchange efficiency.
2Use of energy by moving object
If the compressor is turned OFF to save energy when cooling is not necessary, then energy consumption is reduced, but refrigerant migrates and pools in the evaporator causing efficiency losses
Solution Approach 1:
Before the compressor shuts off, the system performs preliminary actions by activating alternative evaporator circuits or adjusting pressure reducing devices to prevent refrigerant migration. This preliminary preparation ensures that when the compressor restarts, refrigerant is already in optimal distribution, eliminating the efficiency loss that would normally occur during startup.
Solution Approach 2:
The system maintains continuous useful action by having multiple evaporator circuits available. When one circuit is active during compressor operation, other circuits are prepared in advance. During compressor shutdown and restart, the system seamlessly switches between circuits, ensuring continuous refrigerant circulation and preventing migration without energy loss.
3Loss of energy
If a single evaporator circuit is used with heat exchanging members, then steady-state heat transfer efficiency is maximized, but refrigerant redistribution during compressor startup is slow and inefficient
Solution Approach 1:
The single evaporator circuit is divided into multiple parallel circuits (first evaporator circuit, second evaporator circuit, etc.), each with its own pressure reducing device. During startup, the system can activate different circuit combinations to accelerate refrigerant redistribution. During steady-state, the system switches to the optimal circuit configuration for heat transfer efficiency, thus achieving both fast redistribution and efficient heat transfer.
Solution Approach 2:
The system dynamically switches between different evaporator circuit configurations based on operational requirements. During compressor startup, the system activates circuits optimized for rapid refrigerant flow and redistribution. During steady-state operation, it switches to circuits optimized for heat exchange efficiency, making the system adaptive to different operational phases.
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 enables quicker redistribution of refrigerant, improving overall system efficiency by moving into a more efficient operational regime sooner, reducing efficiency losses associated with refrigerant migration and heat transfer inefficiencies.
Implementation Method 1
The liquid refrigerant then passes through the pressure reduction device, and experiences a significant drop in pressure. This results in evaporation of the refrigerant and a significant decrease in the temperature of the refrigerant.
Implementation Method 2
This results in evaporation of the refrigerant and a significant decrease in the temperature of the refrigerant.
Implementation Method 3
The use of heat exchanging members (e.g., suction line heat exchangers and intercoolers) in some refrigeration systems also can exacerbate the problem.
Data Source
AI summary
A refrigerator appliance including a refrigerant circuit between a condenser, an evaporator, and a compressor that includes two conduits and pressure reducing devices arranged in parallel between the evaporator and the condenser. The appliance also includes a valve system to direct refrigerant through one, both or none of the conduits and pressure reducing devices, and a heat exchanging member in thermal contact with either one pressure reducing device, or one conduit between the pressure reducing device and the valve system.