Apparatus using a heat pump including a refrigerant leakage detector

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Solution Overview

Problem

In heat pump systems, refrigerant leakage into the water circuit can lead to discharge through both outdoor and indoor pressure relief valves, posing a risk of refrigerant entering indoor spaces.

Innovation Solution

A heat pump apparatus with a refrigerant flow switching device, an expansion device, and a refrigerant leakage detecting device, which switches the refrigerant flow and sets the expansion device to a closed state when leakage is detected, allowing early retrieval of refrigerant to prevent indoor contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pressure relief valve is installed in the indoor unit, then overpressure protection is provided, but refrigerant may leak into indoor space through the pressure relief valve when refrigerant enters the water circuit

Engineering Contradiction:

Improveoverpressure protectionVSAvoidrefrigerant leakage into indoor space

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The refrigerant leakage detecting device is installed in the water circuit to detect refrigerant contamination before it can be discharged into the indoor space through the pressure relief valve. When refrigerant is detected in the water circuit, the system proactively switches operations and retrieves the refrigerant, preventing the harmful discharge that would otherwise occur through the overpressure protection device.

Inventive Principle:

Principle #10Preliminary action

2Object-generated harmful factors

If refrigerant leaks into the water circuit, then refrigerant can be discharged through pressure relief valves, but this causes refrigerant to enter indoor spaces

Engineering Contradiction:

Improverefrigerant dischargeVSAvoidindoor space contamination

Core Design Contradiction:

Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

The system converts the potentially harmful situation of refrigerant in the water circuit into a beneficial outcome by using the refrigerant leakage detecting device to identify the contamination. This detection triggers operational switching that retrieves the refrigerant from the water circuit and redirects it through the refrigerant circuit, transforming a harmful leakage scenario into a controlled retrieval process that prevents indoor contamination.

Inventive Principle:

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

3Productivity

If the expansion device remains open during refrigerant leakage, then refrigerant continues to circulate, but this allows continuous leakage into the water circuit

Engineering Contradiction:

Improverefrigerant circulationVSAvoidrefrigerant leakage

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The refrigerant leakage detecting device provides continuous monitoring of the water circuit for refrigerant contamination. When refrigerant is detected, this feedback signal triggers the control device to switch operations and close the expansion device, thereby stopping the refrigerant flow that would otherwise continue to leak into the water circuit. This feedback mechanism dynamically adjusts system operation based on real-time detection data.

Inventive Principle:

Principle #23Feedback

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 system effectively detects and retrieves refrigerant leaks early, preventing its entry into indoor spaces and ensuring safer operation.

Implementation Method 1

a refrigerant leakage detecting device connected to the main circuit... When leakage of the refrigerant into the heat medium circuit is detected

Methodology Applied

Scientific EffectPressure measurement:

Implementation Method 2

a load-side heat exchanger... configured to cause a heat medium to flow via the load-side heat exchanger

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 3

The refrigerant circuit is allowed to perform a first operation in which the load-side heat exchanger is used as a condenser

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 4

a compressor... configured to circulate refrigerant

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 5

an expansion device... When leakage of the refrigerant into the heat medium circuit is detected, the expansion device is set to a closed state

Methodology Applied

Scientific EffectThrottling:

Data Source

PatentUS11248829B2Apparatus using a heat pump including a refrigerant leakage detector

Publication Date: 2022.02.15 MITSUBISHI ELECTRIC CORP

AI summary

An apparatus using a heat pump includes a refrigerant circuit and a heat medium circuit. The refrigerant circuit is capable of performing a first operation, in which a load-side heat exchanger is used as a condenser, and a second operation, in which the load-side heat exchanger is used as an evaporator. A main circuit of the heat medium circuit has a branching part and a joining part. An overpressure protection device and a refrigerant leakage detecting device are connected to the main circuit. The overpressure protection device is connected to a connection part located between the load-side heat exchanger and one of the branching part and the joining part, or at the load-side heat exchanger. When leakage of refrigerant is detected, the state of a refrigerant flow switching device is set to a second state, an expansion device is set to a closed state, and a compressor is operated.