Parallel Refrigeration Loops for Low-GWP Container Safety
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Solution Overview
Problem
Refrigerated transport systems using low global warming potential (GWP) refrigerants face challenges with higher flammability and toxicity, posing risks of fire, explosion, and toxicity, which existing technologies have not adequately addressed.
Innovation Solution
The system employs a dual vapor compression loop configuration with mildly flammable refrigerants like R-1234ze(E), R-32, and R-1234yf, isolated flowpaths, and a supplemental locking mechanism triggered by refrigerant leakage detection, along with safety features such as non-dispersive infrared sensors, ventilation fans, and flame arrestors to mitigate risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low GWP refrigerants are used to replace conventional refrigerants, then environmental impact is reduced, but flammability and toxicity increase
Solution Approach 1:
The refrigeration system is divided into two independent vapor compression loops, each with its own refrigerant charge. This segmentation limits the potential harm from a single loop to half the total refrigerant charge, reducing the severity of flammability and toxicity risks while maintaining the use of low GWP refrigerants
Solution Approach 2:
A bulkhead with isolation valves is introduced as an intermediary barrier between the two vapor compression loops. This bulkhead with integrated valves allows the system to physically separate the refrigerant charges and control their isolation, providing an additional layer of safety against flammability and toxicity hazards
2Device complexity
If a single vapor compression loop is used, then system complexity is reduced, but refrigerant leakage risk increases
Solution Approach 1:
The system uses two separate vapor compression loops instead of one, dividing the refrigerant charge into two isolated systems. This segmentation ensures that a leakage or failure in one loop does not affect the other, improving reliability by containing potential hazards within half the total refrigerant charge
Solution Approach 2:
The bulkhead with isolation valves is installed beforehand to create a physical barrier and control mechanism between the two loops. This pre-configured safety feature allows for rapid isolation of one loop from the other in case of leakage, cushioning the impact of potential failures before they can spread throughout the entire system
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 reduces refrigerant leakage, minimizes the risk of flammable refrigerant spread and explosion, and provides safe operation by isolating refrigerant flows and triggering safety measures upon detection, enhancing safety and reducing mitigation requirements.
Implementation Method 1
non-dispersive infrared sensors
Implementation Method 2
heat absorption heat exchanger
Implementation Method 3
vapor compression system having a compressor, a heat rejection heat exchanger downstream of the compressor along a refrigerant flow path, an expansion device, and a heat absorption heat exchanger
Implementation Method 4
compressor for driving the refrigerant of the refrigerant charge
Implementation Method 5
compressor, a heat rejection heat exchanger downstream of the compressor along a refrigerant flow path
Data Source
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AI summary
A refrigerated transport system comprises a body enclosing a refrigerated compartment. A refrigeration system (29) comprises first and second vapor compression loops each having: a refrigerant charge; a compressor (36A,B) for driving the refrigerant of the refrigerant charge; a first heat exchanger (38A,B) positioned to reject heat to an external environment in a cooling mode; and a second heat exchanger (42A,B) positioned to absorb heat from the refrigerated compartment in the cooling mode.