Refrigeration system with refrigerant charge control
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Solution Overview
Problem
Conventional refrigeration systems face challenges in maintaining refrigerant charge during power shutdowns, leading to undesired loss of refrigerant to the ambient environment.
Innovation Solution
A refrigeration system with a third compressor and a flash tank, coupled with a control system and pressure transducers, operates to pump down refrigerant to the flash tank during power loss, using an uninterruptible power supply to maintain refrigerant charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional refrigeration systems operate without additional components during normal operation, then device complexity is low, but refrigerant charge is lost during power shutdowns
Solution Approach 1:
The third compressor is activated before complete power shutdown occurs (during transitional power loss) to pump down refrigerant to the flash tank in advance, preventing refrigerant loss that would otherwise occur during full power outage. This preliminary action ensures refrigerant charge maintenance without requiring continuous operation of additional components during normal operation.
Solution Approach 2:
The flash tank serves as an intermediary storage vessel that temporarily holds liquid refrigerant during power shutdown conditions. By introducing this intermediate component, the system can isolate and protect the refrigerant charge from being lost to the ambient environment during power outages, resolving the contradiction between maintaining refrigerant charge and avoiding additional system complexity.
2Reliability
If an auxiliary condensing unit is added to maintain refrigerant charge, then refrigerant loss is prevented, but device complexity increases
Solution Approach 1:
The third compressor is designed with multi-functionality: during normal operation it remains inactive or performs minimal functions, but during power shutdown it activates to pump down refrigerant to the flash tank. This universal component serves both normal operation and emergency refrigerant charge maintenance functions, preventing refrigerant loss without significantly increasing device complexity under normal conditions.
Solution Approach 2:
The system changes operational parameters of the third compressor based on power status: during normal operation the compressor operates at low or zero capacity, but during power shutdown it transitions to high-capacity pump-down mode. This parameter change allows the same component to effectively prevent refrigerant loss during outages without requiring continuous operation that would increase overall system complexity and energy consumption.
3Reliability
If the third compressor operates continuously to maintain refrigerant charge, then refrigerant loss is prevented, but energy consumption increases
Solution Approach 1:
The third compressor operates periodically rather than continuously: it activates during transitional power loss events to pump down refrigerant to the flash tank, then remains inactive during normal operation. This periodic operation pattern prevents refrigerant charge loss during power outages while minimizing energy consumption by avoiding continuous compressor operation.
Solution Approach 2:
The control system automatically detects power status changes and autonomously activates the third compressor only when needed (during power shutdown transitions). The system serves itself by monitoring its own operational state and triggering the compressor without continuous external control, thereby preventing refrigerant loss only when necessary and reducing unnecessary energy consumption during normal 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
Effectively prevents refrigerant loss during power outages by converting vapor refrigerant to liquid and storing it in the flash tank, ensuring system integrity and efficiency.
Implementation Method 1
at least one third compressor configured to pump down at least a portion of the refrigerant fluid to the flash tank
Implementation Method 2
at least one gas cooler/condenser fluidly coupled to the first and second refrigeration subsystems and configured to cool a vapor phase of the refrigerant fluid from the one or more first compressors and the one or more second compressors to a liquid phase or mixed phase of the refrigerant fluid
Data Source
AI summary
A refrigeration system includes a refrigeration subsystem that includes a set of primary compressors operating at a primary suction pressure to compress a refrigerant fluid, evaporators fluidly coupled to the primary compressors, and expansion valves fluidly coupled to the evaporators. The refrigeration system includes a gas cooler/condenser fluidly coupled to the refrigeration subsystem and configured to cool a vapor phase of the refrigerant fluid from the primary compressors to a liquid phase or mixed phase of the refrigerant fluid; a flash tank fluidly coupled to the gas cooler/condenser; and a secondary compressor configured to pump down at least a portion of the refrigerant fluid to the flash tank. The secondary compressor includes a suction side fluidly coupled to an outlet of the flash tank and a discharge side fluidly coupled to an inlet of the gas cooler/condenser.