Air-Conditioner Relay Unit Venting for Flammable Refrigerant Leaks
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Solution Overview
Problem
Existing air-conditioning apparatuses lack effective countermeasures to prevent refrigerant leakage into the outdoor unit housing, particularly when using flammable refrigerants, and do not adequately address the safety and energy efficiency concerns associated with such leaks.
Innovation Solution
The air-conditioning apparatus includes a refrigerant circuit with a compressor, flow switching device, and heat exchangers housed in an outdoor unit, a heat medium relay unit with a ventilation opening to discharge leaked refrigerant, and a separate indoor unit for heat exchange, ensuring safety and improved energy efficiency by maintaining refrigerant concentration below the Lower Flammability Limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a refrigerant circuit is configured to circulate combustible refrigerant between outdoor unit and heat medium relay unit, then heat exchange efficiency is improved, but refrigerant leakage into housing creates safety hazards
Solution Approach 1:
A heat medium (water or antifreeze solution) is introduced as an intermediary substance between the refrigerant and the indoor environment. The refrigerant exchanges heat with the heat medium in a heat exchanger, and the heat medium circulates through pipes to indoor units. This intermediary system prevents direct refrigerant contact with indoor spaces, containing potential leakage risks within the outdoor unit and heat medium relay unit housings.
Solution Approach 2:
The potentially harmful refrigerant is extracted from the indoor environment and confined to the outdoor unit and heat medium relay unit. By separating the refrigerant circuit from the indoor air handling system and using a heat medium as the transport fluid indoors, the refrigerant is removed from areas where leakage would pose safety risks to occupants.
2Use of energy by moving object
If heat medium circulation system is implemented between relay unit and indoor units, then energy efficiency is improved, but refrigerant leakage into relay unit housing remains unaddressed
Solution Approach 1:
The housing structure itself provides the safety function by incorporating ventilation openings that enable self-ventilation. When refrigerant leaks into the heat medium relay unit housing, the ventilation openings allow the leaked refrigerant to be discharged to the outdoor environment, maintaining refrigerant concentration below flammable limits without requiring additional active safety systems.
3Reliability
If ventilation openings are added to heat medium relay unit housing, then safety is improved by discharging leaked refrigerant, but device complexity increases
Solution Approach 1:
The ventilation openings in the heat medium relay unit housing serve multiple functions: they provide natural ventilation to discharge leaked refrigerant for safety, and also facilitates heat dissipation from the housing. This multi-functionality avoids the need for separate active ventilation systems, maintaining structural simplicity while achieving safety goals.
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 configuration effectively prevents refrigerant concentration buildup, preventing ignition and enhancing safety while reducing energy consumption by minimizing heat medium pipe lengths and conveyance power.
Implementation Method 1
a heat exchanger related to heat medium capable of exchanging heat between the refrigerant and a heat medium
Implementation Method 2
exchanging heat between the refrigerant and a heat medium that is different from the refrigerant
Implementation Method 3
a housing of the heat medium relay unit includes an opening allowing ventilation between a housing space of the heat exchanger related to heat medium and a space other than the housing space
Implementation Method 4
allowing ventilation between a housing space of the heat exchanger related to heat medium and a space other than the housing space
Data Source
Figure 1~2
Figure 3
Figure 3A
AI summary
To obtain an air-conditioning apparatus that is capable of preventing increase in refrigerant concentration inside a housing caused by refrigerant leakage inside the housing and increased its safety. A refrigerant circuit A device constituted by a compressor 10 that sends out a combustible refrigerant, a heat exchanger related to heat medium 15 that is capable of exchanging heat between the refrigerant and a heat medium different from the refrigerant, and other components that are connected by pipes, in which the refrigerant circuit A circulates the refrigerant; devices constititing a heat medium circulating circuit B configured to circulate the heat medium related to heat exchange in the heat exchanger related to heat medium 15. At least the compressor 10 and the like are housed in an outdoor unit 1, at least the heat exchanger related to heat medium 15 and the like are housed in a heat medium relay unit 3, and an indoor unit 2 is housed in a use side heat exchanger 26. The outdoor unit 1, the heat medium relay unit 3, and the indoor unit 2 are formed separately and can be disposed in separate positions. A housing of the heat medium relay unit 3 has an opening 61 that allows ventilation between the housing space of the heat exchanger related to heat medium 15 and the space outside the housing space.