Outdoor Unit Pipe Breakage Guide for HFO-1123 Explosion Relief
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Solution Overview
Problem
The refrigerant 1,1,2-trifluoroethylene (HFO-1123) is prone to explosion in high-temperature and high-pressure states due to chain disproportionation reactions, posing a safety risk in refrigeration cycle apparatuses.
Innovation Solution
Incorporating a breakage-guide structure with lower pressure resistance than the rest of the pipe at bend portions within the outdoor unit of the refrigeration cycle apparatus, which allows for controlled discharge of the refrigerant mixture when pressure abnormally increases, preventing chain reactions and explosions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HFO-1123 is used as refrigerant, then GWP is reduced to less than 1 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 patent applies preliminary action by pre-installing a breakage-guide structure at the bend portion of the refrigerant pipe before abnormal pressure occurs. This structure is designed in advance to break at a specific pressure threshold, preventing chain disproportionation reactions before they can spread. The breakage-guide structure acts as a pre-positioned safety mechanism that activates automatically when pressure exceeds safe levels, thereby preventing explosions without requiring real-time detection or control systems.
2Strength
If the pipe is made with high pressure resistance to contain HFO-1123, then safety is improved, but the ability to prevent chain reactions through controlled breakage is reduced
Solution Approach 1:
The patent applies local quality by creating a localized weak point (breakage-guide structure) at the bend portion of the pipe, while the rest of the pipe maintains high pressure resistance. The breakage-guide structure has deliberately reduced thickness or structural integrity compared to the main pipe body, creating a local difference in mechanical properties. This allows the pipe to be strong enough to contain normal operating pressures while having a predetermined location that will fail first under abnormal pressure conditions, directing the breakage to a controlled location away from critical components.
3Reliability
If a breakage-guide structure is added to the pipe, then explosion prevention is improved, but device complexity increases
Solution Approach 1:
The patent applies merging by integrating the breakage-guide structure directly into the bend portion of the refrigerant pipe as a unified component. Rather than adding a separate safety device or complex control system, the breakage-guide structure is formed as part of the pipe itself during manufacturing. This could be achieved by varying the wall thickness during pipe forming or by creating a localized structural feature at the bend. The integration of the safety function into the existing pipe structure minimizes additional complexity while maintaining effective 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 the spread of disproportionation reactions and subsequent explosions, ensuring safety even when using HFO-1123, by allowing controlled release of refrigerant pressure and minimizing scattering of debris.
Implementation Method 1
a breakage-guide structure having a pressure resistance lower than a pressure resistance of rest of the pipe; when the pressure of the refrigerant mixture abnormally increases, the pipe is broken at the breakage-guide structure portion
Data Source
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.