Heat Pump Release Box Design to Isolate Flammable Refrigerant Leakage

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Solution Overview

Problem

Heat pumps using flammable refrigerants like R290 pose a risk of hazardous events due to refrigerant leakage into indoor units, which can ignite electrical and electronic components.

Innovation Solution

A release box is integrated into the indoor unit housing to isolate and vent gaseous refrigerant away from ignition sources, featuring a design with a gas inlet connected to air purge valves and a vent to the outside, along with a drainage system to separate and drain liquid refrigerant, minimizing the risk of ignition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If refrigerant R290 is used in the heat pump, then the global warming potential and ozone depletion potential are reduced, but the risk of hazardous events due to flammability increases

Engineering Contradiction:
Improveglobal warming potential and ozone depletion potentialVSAvoidflammability hazard
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

A release box is introduced as an intermediary component between the heat medium circuit and the indoor unit housing. This release box receives gaseous refrigerant through a gas inlet connected to air purge valves and directs it safely outside through a vent, preventing direct contact between flammable refrigerant and ignition sources within the indoor unit housing.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The indoor unit housing is functionally segmented by introducing a separate release box. The release box creates a dedicated pathway for refrigerant discharge that is spatially separated from the main housing containing electrical and electronic components. This segmentation isolates the flammable refrigerant handling function from potential ignition sources.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If air purge valves are used to release gas from the heat medium circuit, then air is removed from the system, but gaseous refrigerant may also exit and enter the indoor unit housing

Engineering Contradiction:
Improveair removal functionVSAvoidrefrigerant leakage into housing
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The release box merges multiple functions: it serves as both an air purge outlet and a refrigerant containment/venting system. The gas inlet of the release box is connected to the outlet of air purge valves, combining the air removal function with the refrigerant safety function in a single integrated component.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The release box acts as an intermediary between the air purge valves and the indoor unit housing. It intercepts gaseous refrigerant that would otherwise enter the housing through the air purge valve outlet, and redirects it safely outside through the vent.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 release box effectively prevents the ignition of leaked refrigerant by isolating it from potential ignition sources and ensures safe discharge of gaseous refrigerant outside the unit, while also preventing liquid refrigerant from being discharged through the vent.

Implementation Method 1

The space further has a vent (venting opening) to an outside of the indoor unit housing for guiding gas released from the at least one air purge valve to the outside of the indoor unit housing

Methodology Applied
Scientific EffectGas venting:

Implementation Method 2

The release box is open or has an opening at a front side and the mounting opening in the lateral side wall of the indoor unit housing is closed from the outside of the indoor unit housing by a cover having a grille

Methodology Applied
Scientific EffectPhase separation:

Data Source

PatentEP4575351A1Heat pump
Publication Date: 2025.06.25 DAIKIN EURO
  • EP4575351A1 patent drawingFigure 1
  • EP4575351A1 patent drawingFigure 2~3
  • EP4575351A1 patent drawingFigure 4

AI summary

The present disclosure relates to a heat pump comprising a refrigerant circuit (10) connecting a heat source heat exchanger (12), an expansion valve (14), a usage side heat exchanger (16) and a compressor (18), the refrigerant circuit being accommodated in an outdoor unit housing (2); a heat medium circuit (20) connecting the usage side heat exchanger (16), a pump (22) and a load (29), the heat medium circuit further comprising at least one air purge valve (25, 27) having an outlet for releasing at least gas from the heat medium circuit (20), the air purge valve (25, 27) being accommodated in an indoor unit housing (3), and a release box (40) defining a space (48) having a gas inlet (52, 53) connected to the outlet of the at least one air purge valve (25, 27), and a vent (64) to an outside of the indoor unit housing (3) for guiding gas released from the at least one air purge valve (25, 27) to the outside of the indoor unit housing (3).