Outdoor Unit Pipe Weak-Point Venting for HFO-1123 Explosion Risk
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Solution Overview
Problem
1,1,2-trifluoroethylene (HFO-1123) is prone to explosions in high-temperature and high-pressure states due to chain disproportionation reactions within refrigeration cycle apparatuses, posing safety risks.
Innovation Solution
Incorporating a breakage-guide structure with lower pressure resistance than the rest of the pipes at bend portions within the outdoor unit of a refrigeration cycle apparatus, which allows for controlled discharge of refrigerant mixture and prevention of chain reactions, along with a plate to contain the discharge and prevent jetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HFO-1123 refrigerant is used to achieve low GWP and high performance, then global warming potential is reduced and pressure loss is minimized, but explosion risk increases due to chain disproportionation reactions in high-temperature and high-pressure states
Solution Approach 1:
The breakage-guide structure is pre-installed at the bend portion of the pipe to create a predetermined weak point. This preliminary structural arrangement ensures that when abnormal high pressure occurs, the pipe will break at the designated location rather than randomly, enabling controlled discharge of refrigerant and preventing chain disproportionation reactions that lead to explosions
Solution Approach 2:
The breakage-guide structure acts as an intermediary safety device between the high-pressure refrigerant system and the outdoor environment. It mediates the pressure release process by providing a controlled failure point that discharges refrigerant in a controlled manner, preventing uncontrolled explosions while maintaining the performance benefits of HFO-1123
2Strength
If the pipe pressure resistance is increased to ensure safe operation under high pressure, then pressure containment is improved, but the ability to prevent chain reactions through controlled breakage is reduced
Solution Approach 1:
The pipe structure is designed with non-uniform properties: the majority of the pipe maintains high pressure resistance for safe operation, while the bend portion incorporates a breakage-guide structure with locally reduced strength. This local quality differentiation allows the pipe to withstand normal operating pressures while providing a predetermined weak point for controlled failure and explosion prevention
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 solution effectively prevents explosions by allowing controlled release of refrigerant pressure and minimizing the spread of disproportionation reactions, ensuring safety during operation with HFO-1123.
Implementation Method 1
the bend portion comprising a breakage-guide structure having a pressure resistance lower than a pressure resistance of rest of the pipe
Implementation Method 2
a plate interposed between the breakage-guide structure and outside of the casing
Data Source
Figure 1~2
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AI summary
Provided is an outdoor unit for use in a refrigeration cycle apparatus circulating refrigerant mixture inclusive of 1,1,2-trifluoroethylene, the outdoor unit including: a casing; a pipe configured to allow the refrigerant mixture to flow through the pipe, the pipe being accommodated inside the casing and including a bend portion, the bend portion including a breakage-guide structure having a pressure resistance lower than a pressure resistance of rest of the pipe; and a plate interposed between the breakage-guide structure and outside of the casing.