HVAC Refrigerant Pump-Down Control to Reduce Indoor Flammable Gas Risk
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
HVAC systems using flammable refrigerants face safety risks due to potential leaks, which can lead to fires and injuries, as these refrigerants can accumulate indoors and pose hazards to building occupants.
Innovation Solution
An HVAC system with controllers that determine the outdoor temperature and initiate a pump-down procedure to move flammable refrigerant from the indoor unit to the outdoor unit at the end of the air conditioning cycle, using a valve and compressor to prevent indoor accumulation and mitigate leak risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If flammable refrigerants are used to increase energy efficiency, then energy efficiency is improved, but safety risks worsen due to potential leaks and fire hazards
Solution Approach 1:
The patent extracts the flammable refrigerant from the indoor environment by implementing a pump-down procedure that moves all refrigerant to the outdoor condensing unit before the heating season begins. This separation removes the harmful element (flammable refrigerant) from the indoor space where it could cause fire hazards, while still allowing the system to use these efficient refrigerants during cooling operation.
Solution Approach 2:
The system performs a preliminary pump-down action before the heating season starts to ensure all flammable refrigerant is removed from indoor components. This advance preparation prevents potential fire hazards during the heating season when the system would be inaccessible or difficult to service, addressing the safety concern before it can manifest.
2Ease of operation
If refrigerant is stored indoors for easy access, then ease of operation is improved, but safety risks worsen due to accumulation of flammable gas
Solution Approach 1:
The patent removes flammable refrigerant from indoor storage locations by implementing a pump-down procedure that consolidates all refrigerant in the outdoor condensing unit. This eliminates the fire hazard of having flammable gas accumulated in the indoor furnace or air handler while still allowing rapid refrigerant access when needed through the outdoor unit.
Solution Approach 2:
The outdoor condensing unit serves as an intermediary storage location for the flammable refrigerant. By storing refrigerant outdoors rather than indoors, the system maintains accessibility for servicing while removing the refrigerant from the hazardous indoor environment, thus mediating between the need for accessibility and the need for safety.
3Object-affected harmful factors
If pump-down procedure is implemented to move refrigerant outdoors, then safety is improved, but device complexity worsens due to additional control mechanisms
Solution Approach 1:
The pump-down procedure leverages existing multi-functional components already present in the heat pump system. The four-way valve, which is already used for reversing between heating and cooling modes, is also utilized to redirect refrigerant flow during pump-down. The outdoor condensing unit's compressor and coil serve dual purposes as both the heating/cooling component and the pump-down storage location. This multi-functionality implements safety without requiring entirely new dedicated components.
Solution Approach 2:
The system performs self-service by using its own existing components to accomplish the pump-down procedure. The四通 valve (four-way valve) and outdoor compressor work together to automatically transfer refrigerant from indoor to outdoor locations without requiring external equipment or complex additional control systems. The system's inherent components are repurposed to achieve the safety function.
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 enhances safety by containing flammable refrigerants outdoors, reducing the risk of indoor leaks, fires, and property damage, thereby improving overall safety and risk management in HVAC systems.
Implementation Method 1
initiating operation of a compressor at an end of the air conditioning cycle to pump down a refrigerant to the outdoor coil
Implementation Method 2
initiate a closure of the valve coupled to the refrigerant line... to prevent indoor accumulation
Data Source
Figure 1
Figure 2
Figure 3
AI summary
In one embodiment, an HVAC system (100) includes an indoor unit (130) having a furnace (136), an outdoor heat pump unit (140) having a compressor (146) and an outdoor coil (144), a refrigerant line (160) coupled to the indoor unit (130) and the outdoor heat pump unit (140), and a valve (170) coupled to the refrigerant line (160). The HVAC system (100) further includes one or more controllers (122) operable to determine that the outdoor heat pump unit (140) is in operation during an air conditioning cycle. The controllers (122) are further operable to determine an outdoor temperature and compare the outdoor temperature to a predetermined temperature. The controllers (122) are further operable to initiate a closure of the valve (170) coupled to the refrigerant line (160) and initiate operation of the compressor (146) at an end of the air conditioning cycle to pump down a refrigerant to the outdoor coil (144) in response to comparing the outdoor temperature to the predetermined temperature.