Indirect Heat Pump Refrigerant Leakage Detection With Valve Isolation
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Solution Overview
Problem
In indirect air-conditioning systems, the risk of flammable refrigerants leaking from the primary circuit into the secondary circuit exists due to potential damage or deterioration of intermediate heat exchangers, leading to increased pressure and potential leaks into the room, posing a fire hazard.
Innovation Solution
A heat pump apparatus with a leakage detecting device that monitors pressure changes in the secondary circuit and automatically closes valves to prevent refrigerant flow from the primary circuit into the secondary circuit, thereby preventing leaks into the room.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an indirect air-conditioning system uses a plate heat exchanger or double pipe heat exchanger as an intermediate heat exchanger, then heat exchange efficiency between the flammable refrigerant and heat medium is improved, but the intermediate heat exchanger may be damaged due to freezing or deterioration over time, allowing refrigerant to leak into the secondary circuit
Solution Approach 1:
The leakage detecting device continuously monitors the secondary circuit for signs of refrigerant intrusion before significant leakage can occur. By detecting refrigerant in the secondary circuit early through sensors that monitor fluid composition or pressure changes, the system can trigger valve closure to prevent the refrigerant from reaching the room, thus addressing the reliability concern while maintaining the efficient heat exchange design
2Object-affected harmful factors
If the intermediate heat exchanger is damaged allowing refrigerant to mix with the heat medium, then the flammable refrigerant may leak into the room from welded seams or joints, but installing additional detection and prevention mechanisms increases device complexity
Solution Approach 1:
The patent introduces a leakage detecting device as an intermediary monitoring system that detects refrigerant in the secondary circuit and triggers valve closure. This mediator approach provides safety without requiring complete system redesign, balancing the fire hazard concern with acceptable device complexity by using sensors and control logic rather than fundamentally changing the heat exchanger design
Solution Approach 2:
The system implements feedback through the leakage detecting device that continuously monitors the secondary circuit and provides real-time information to the control system. When refrigerant is detected, the feedback loop triggers automatic valve closure to prevent leakage into the room, creating a closed-loop safety mechanism that addresses fire hazards with minimal added complexity
3Reliability
If flammable refrigerant leaks from the primary circuit into the secondary circuit, then pressure in the secondary circuit increases and refrigerant may leak into the room, but implementing continuous monitoring and automatic valve closure increases energy consumption
Solution Approach 1:
The leakage detecting device operates autonomously, continuously monitoring the secondary circuit for refrigerant presence without requiring external intervention. The system self-activates when refrigerant is detected and automatically closes the valves, providing safety through self-monitoring and self-action while minimizing energy consumption by only activating high-power components (valves) when necessary rather than running them continuously
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
Effectively prevents refrigerant leaks from entering the secondary circuit and subsequently into the room, mitigating the risk of creating an explosive atmosphere and ensuring safety.
Implementation Method 1
a plate heat exchanger or a double pipe heat exchanger is used as an intermediate heat exchanger that exchanges heat between the flammable refrigerant circulated through the primary circuit and the heat medium circulated through the secondary circuit
Implementation Method 2
A heat pump apparatus with a leakage detecting device that monitors pressure changes in the secondary circuit
Data Source
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AI summary
In a heat pump apparatus of an indirect type including a primary circuit on a heat source side and a secondary circuit on a load side, a refrigerant in the primary circuit is prevented from leaking through the secondary circuit. An air-conditioning apparatus 100 includes a leakage detecting device 13 that detects leakage of the refrigerant circulated through a refrigerant circuit, serving as the primary circuit, from an intermediate heat exchanger 5 into a water circuit 10, serving as the secondary circuit, and a controller 14 that closes valves 8a and 8b arranged on both sides of the intermediate heat exchanger 5 in the water circuit 10 to prevent water containing the refrigerant from flowing beyond the valves 8a and 8b when the leakage detecting device 13 detects the leakage.