Heat Pump Air Passage Layout for Refrigerant Leak Discharge

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Solution Overview

Problem

In air conditioning apparatuses, refrigerant leaks can lead to stagnation within the casing and localized increases in indoor refrigerant concentration due to inadequate discharge and diffusion of leaking refrigerant, particularly when using flammable refrigerants like R32, HFO-1234yf, HFO-1234ze, R290, or R1270.

Innovation Solution

A heat pump apparatus design featuring a load unit with a heat medium circuit chamber, a fan system that draws indoor air, and an air passage isolated from the heat medium circuit chamber, where the air inlet is positioned lower than the air outlet, allowing for vertical air flow and effective discharge of leaking refrigerant through the air outlet, preventing stagnation and diffusion of refrigerant indoors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If flammable refrigerant (R32, HFO-1234yf, HFO-1234ze, R290, or R1270) is used to achieve low GWP, then global warming potential is reduced, but flammability risk increases requiring caution for refrigerant leakage

Engineering Contradiction:
Improveglobal warming potentialVSAvoidflammability risk
Core Design Contradiction:
Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of refrigerant leakage (flammability risk) into a beneficial outcome by designing a ventilation system that actively discharges leaking refrigerant. The air outlet positioned above the air inlet creates upward airflow that captures and removes leaked refrigerant, transforming the potential hazard into a controlled discharge process that prevents accumulation.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces air as an intermediary medium to safely transport and discharge leaked refrigerant. The ventilation system uses air flow generated by the air inlet and air outlet configuration to carry away refrigerant molecules, creating a safe transfer mechanism that prevents direct contact between leaked refrigerant and flammable environments.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If refrigerant leakage occurs, then refrigerant concentration increases indoors, but inadequate discharge and diffusion allow stagnation and localized concentration increases

Engineering Contradiction:
Improverefrigerant discharge effectivenessVSAvoidlocalized refrigerant concentration
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent addresses the two-dimensional problem of refrigerant dispersion by introducing a vertical dimension through the air outlet positioned above the air inlet. This vertical arrangement creates three-dimensional airflow patterns that enhance refrigerant capture and discharge, preventing localized accumulation by utilizing vertical air movement in addition to horizontal dispersion.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent implements preliminary action by pre-positioning the air outlet above the air inlet to create favorable airflow conditions before leakage occurs. This pre-configured vertical arrangement ensures that when leakage happens, the airflow is already optimized to capture and remove refrigerant, preventing stagnation before it can occur.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If air inlet and air outlet are positioned at the same height, then device structure is simplified, but refrigerant discharge and diffusion effectiveness is reduced

Engineering Contradiction:
Improveair passage configurationVSAvoidrefrigerant discharge efficiency
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent applies asymmetry by deliberately positioning the air outlet at a different height than the air inlet, creating an asymmetric vertical arrangement. This asymmetric configuration optimizes refrigerant discharge by utilizing natural convection currents and creating favorable airflow patterns that enhance refrigerant removal efficiency, accepting the increased structural complexity as necessary for improved safety performance.

Inventive Principle:
Principle #4Asymmetry

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 design effectively prevents refrigerant stagnation within the casing and reduces localized indoor refrigerant concentration, enhancing safety by ensuring the flammable refrigerant is quickly discharged and diffused, thereby minimizing the risk of forming flammable concentration regions.

Implementation Method 1

a fan, an air inlet configured to suck indoor air therethrough, an air outlet formed at a different height position from a height position of the air inlet, and configured to blow indoors the air sucked through the air inlet, and an air passage formed between the air inlet and the air outlet

Methodology Applied
Scientific EffectAir flow: Convection

Data Source

PatentEP3199883B1Heat pump apparatus
Publication Date: 2021.05.26 MITSUBISHI ELECTRIC CORP
  • EP3199883B1 patent drawingFigure 1
  • EP3199883B1 patent drawingFigure 2
  • EP3199883B1 patent drawingFigure 3

AI summary

A load unit includes a water circuit chamber configured to accommodate at least a part of a water circuit configured to allow water to flow therethrough, a fan, an air inlet formed at a height positioned different from that of the air inlet and configured to suck indoor air therethrough, an air outlet configured to blow indoors the air sucked through the air inlet, and an air passage formed between the air inlet and the air outlet so as to be isolated from the water circuit chamber. A load-side heat exchanger is provided in the air passage.