Refrigerant Shutoff Circuit for HFO-1123 Air Conditioner Pressure Isolation
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Solution Overview
Problem
Refrigerants like HFC-32 and HFC-410A used in air conditioners have high global warming potentials, and those containing HFO-1123 can undergo disproportionation reactions under high-pressure and high-temperature conditions, leading to pressure rises that may cause refrigerant ejection into indoor spaces.
Innovation Solution
Incorporating a refrigerant shutoff mechanism in the air conditioner's circuit that shuts off refrigerant flow from the outdoor unit to the indoor unit when a disproportionation reaction occurs, using check valves or electromagnetic valves to prevent pressure propagation, and optionally including a refrigerant relief mechanism to release excess refrigerant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a refrigerant containing HFO-1123 is used to reduce global warming potential, then environmental impact is reduced, but the refrigerant may undergo disproportionation reaction under high-pressure and high-temperature conditions causing pressure rise and potential refrigerant ejection into indoor spaces
Solution Approach 1:
The refrigerant circuit is segmented into outdoor and indoor portions with a shutoff mechanism that divides the system. When disproportionation reaction occurs in the outdoor unit, the shutoff mechanism isolates the indoor unit, preventing pressure propagation while maintaining the use of environmentally friendly HFO-1123 refrigerant throughout the system.
Solution Approach 2:
A shutoff mechanism acts as an intermediary between the outdoor and indoor units. This intermediary component detects pressure changes from disproportionation reactions and automatically closes to block the harmful pressure wave, protecting the indoor unit while allowing the refrigerant system to continue using HFO-1123.
2Reliability
If a refrigerant shutoff mechanism is added to prevent refrigerant ejection during disproportionation reaction, then safety is improved, but device complexity increases
Solution Approach 1:
The shutoff mechanism is designed to operate automatically based on pressure differential across the valve. When pressure rises in the outdoor unit due to disproportionation reaction, the pressure difference automatically closes the shutoff valve without requiring external control systems, sensors, or power sources, thus maintaining safety while minimizing added complexity.
3Productivity
If the refrigerant circuit is configured to circulate refrigerant through the compressor, outdoor heat exchanger, indoor heat exchanger, and back to the compressor, then cooling efficiency is improved, but the propagation path for pressure rise from disproportionation reaction is extended
Solution Approach 1:
The shutoff mechanism is positioned in the refrigerant circuit to preemptively block the propagation path of pressure rise before it can reach the indoor unit. By placing the shutoff between the outdoor and indoor units, the system maintains its efficient circulation path for normal operation while having a pre-positioned barrier ready to stop harmful pressure propagation if disproportionation occurs.
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 solution reduces the likelihood of refrigerant ejection into indoor spaces and minimizes damage to indoor unit components by inhibiting the propagation of disproportionation reactions and pressure rises, even when HFO-1123 undergoes self-decomposition.
Implementation Method 1
the refrigerant contains a hydrofluorocarbon having a property of undergoing a disproportionation reaction... when a disproportionation reaction occurs in a portion of the refrigerant circuit within the outdoor unit
Data Source
AI summary
An air conditioner (1, 101) has a refrigerant circuit (10, 110) which is formed by connecting an outdoor unit (2, 102) and an indoor unit (3). The refrigerant circuit (10, 110) has a refrigerant sealed therein. The refrigerant contains a hydrofluorocarbon having a property of undergoing a disproportionation reaction. The refrigerant circuit (10, 110) includes a refrigerant shutoff mechanism (24, 41, 43, 46, 47, 48) that shuts off a flow of the refrigerant from the outdoor unit (2, 102) side to the indoor unit (3) side when the refrigerant in a portion of the refrigerant circuit (10, 110) within the outdoor unit (2, 102) meets a predetermined condition.