Low charge packaged refrigeration systems
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Solution Overview
Problem
Existing industrial refrigeration systems, particularly ammonia-based ones, are highly compartmentalized and require large refrigerant charges, leading to regulatory challenges and safety concerns due to ammonia toxicity and potential leaks, necessitating complex and costly safety management plans and frequent inspections.
Innovation Solution
A packaged, pumped liquid, recirculating refrigeration system with a pre-packaged modular machine room housing the compressor and condenser, utilizing internal enhancements in evaporator and condenser coils, and replacing large receiver vessels with liquid-vapor separation structures, such as cyclonic separators, to reduce refrigerant charge to less than 10 lbs per ton of refrigeration capacity, and employing microchannel heat exchanger technology for efficient heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large receiver vessels are used to store backup refrigerant liquid, then refrigeration system reliability is improved, but refrigerant charge quantity increases leading to safety and regulatory issues
Solution Approach 1:
The invention extracts the large receiver vessel from the system and replaces it with a much smaller receiver tank combined with a heat exchanger. The heat exchanger serves as a thermal energy storage device that maintains system reliability without requiring large quantities of refrigerant, thus resolving the contradiction between reliability and refrigerant charge quantity.
Solution Approach 2:
The invention changes the operational parameters of the refrigeration system by using a heat exchanger to store thermal energy instead of storing large quantities of liquid refrigerant. This parameter change allows the system to maintain reliability through thermal management rather than refrigerant quantity, thereby reducing the refrigerant charge to safe and regulatory-compliant levels.
2Reliability
If highly compartmentalized system architecture is used with separate mechanical rooms, then system safety is improved through isolation, but device complexity and installation cost increase
Solution Approach 1:
The invention merges the compressor, receiver tank, heat exchanger, and other mechanical components into a single pre-packaged modular unit. This consolidation maintains safety through proper containment and isolation within the module while reducing overall system complexity and eliminating the need for separate mechanical rooms, thus resolving the contradiction between safety and complexity.
Solution Approach 2:
The pre-packaged modular unit serves multiple functions simultaneously - compression, refrigerant storage, heat exchange, and system control - all within a single integrated module. This multi-functionality reduces the number of separate components and locations needed, thereby reducing device complexity while maintaining safety through proper engineering of the universal module.
3Ease of manufacture
If standard evaporator and condenser coils are used, then manufacturing simplicity is maintained, but refrigerant charge quantity increases and heat exchange efficiency decreases
Solution Approach 1:
The invention applies internal enhancements to specific locations within the evaporator and condenser coils where heat transfer is most critical. These localized modifications improve heat exchange efficiency and reduce the refrigerant charge required without requiring complete redesign of the entire coil system, thus maintaining ease of manufacture while reducing refrigerant quantity.
4Power
If large quantities of ammonia are used in refrigeration systems, then refrigeration capacity is improved, but harmful factors increase due to toxicity and regulatory requirements
Solution Approach 1:
The invention changes the refrigerant charge parameter from traditional large quantities to a critically charged low-quantity system. The heat exchanger enables the system to maintain full refrigeration capacity with dramatically reduced ammonia charge by storing thermal energy instead of refrigerant mass, thus resolving the contradiction between power and harmful factors.
Solution Approach 2:
The invention converts the potential harm of large ammonia storage into a benefit by using a heat exchanger to store thermal energy instead. This approach maintains refrigeration capacity while eliminating the harmful effects of large ammonia quantities, effectively turning the design constraint into a safety advantage.
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 system achieves a significant reduction in ammonia usage, requiring less than 100 pounds for a 50-ton refrigeration system, minimizing safety risks and regulatory burdens, as the entire refrigerant charge can be discharged without causing significant harm to humans or the environment, while maintaining efficient operation.
Implementation Method 1
the liquid-vapor separation structure/device may be a single or dual phase cyclonic separator
Implementation Method 2
employing microchannel heat exchanger technology for efficient heat exchange
Data Source
AI summary
A packaged, pumped liquid, recirculating refrigeration system with charges of 10 lbs or less of refrigerant per ton of refrigeration capacity. The compressor and related components are situated in a pre-packaged modular machine room, and in which the condenser is mounted on the machine room and the evaporator is close coupled to the pre-packaged modular machine room. Prior art large receiver vessels may be replaced with a single or dual phase cyclonic separator also housed in the pre-packaged modular machine room.