Split Water-Refrigerant Heat Exchangers for Scaled Heat Pump Heaters

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Solution Overview

Problem

Heat pump water heaters face maintenance challenges due to scale accumulation in the water-refrigerant heat exchanger, which narrows the flow path and increases costs as the entire unit often needs to be replaced instead of just the affected heat exchanger.

Innovation Solution

The design includes two separate water-refrigerant heat exchangers, where the first heat exchanger can be replaced independently without replacing the second, allowing for easy and low-cost maintenance by separating their installation and operation within different chambers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the water-refrigerant heat exchanger is installed in a lower portion of the ventilation chamber covered by heat-insulating material and housed in a hard case, then the heat exchanger is protected and insulation is improved, but the heat exchanger becomes difficult to remove and replacement requires replacing the entire heat pump unit

Engineering Contradiction:
Improveheat exchanger protectionVSAvoidheat exchanger replaceability
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The patent divides the water-refrigerant heat exchanger into two separate units: a first water-refrigerant heat exchanger and a second water-refrigerant heat exchanger. This segmentation allows the first heat exchanger to be replaced independently without replacing the entire heat pump unit, resolving the contradiction between protection and replaceability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent places the first water-refrigerant heat exchanger in a different spatial location (upper portion of the ventilation chamber or outside the hard case) compared to the second heat exchanger (lower portion inside the hard case). This dimensional separation enables independent access and replacement of the first heat exchanger while maintaining the protective structure for the second heat exchanger.

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

2Reliability

If scale accumulates in the water-refrigerant heat exchanger, then heat exchange efficiency decreases and water flow rate is lowered, but replacing the entire heat pump unit incurs large maintenance costs

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidmaintenance cost
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

By segmenting the heat exchanger into two replaceable units, the patent enables cost-effective maintenance where only the affected first heat exchanger needs replacement rather than the entire heat pump unit, directly addressing the high maintenance cost issue.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent enables selective replacement of the first water-refrigerant heat exchanger when it accumulates scale, while the second heat exchanger continues to function. This selective discarding and recovery approach reduces maintenance costs compared to replacing the entire heat pump unit.

Inventive Principle:
Principle #34Discarding and recovering

3Productivity

If the water flow path is narrowed due to scale accumulation, then water flow rate decreases, but access to the heat exchanger for cleaning or replacement is difficult due to its installed position

Engineering Contradiction:
Improvewater flow rateVSAvoidaccessibility for maintenance
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent positions the first water-refrigerant heat exchanger in the upper portion of the ventilation chamber or outside the hard case, creating spatial separation from the second heat exchanger. This dimensional arrangement provides easy access to the first heat exchanger for maintenance operations while the second heat exchanger remains in its protected lower position.

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

Solution Approach 2:

By separating the heat exchanger into two independent units with different locations, the patent enables easy access to the first heat exchanger for cleaning or replacement operations, resolving the accessibility issue while maintaining the protective structure for the second heat exchanger.

Inventive Principle:
Principle #1Segmentation

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 enables the replacement of the first heat exchanger with minimal disruption to the second, reducing maintenance costs and extending the life of the system by allowing for targeted replacement of the affected component.

Implementation Method 1

a compressor configured to compress a refrigerant

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

a first water-refrigerant heat exchanger configured to exchange heat between the refrigerant and water; a second water-refrigerant heat exchanger configured to exchange heat between the refrigerant and water

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

exchange heat between the refrigerant and water

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

an evaporator configured to evaporate the refrigerant

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3299742B1Heat pump water heater
Publication Date: 2020.03.11 MITSUBISHI ELECTRIC CORP
  • EP3299742B1 patent drawingFigure 1
  • EP3299742B1 patent drawingFigure 2
  • EP3299742B1 patent drawingFigure 3~4

AI summary

A heat pump water heater includes: a compressor; a first water-refrigerant heat exchanger; a second water-refrigerant heat exchanger; refrigerant paths capable of forming a refrigerant circuit; and water channels including a flow channel, the flow channel leading hot water that has passed through the second water-refrigerant heat exchanger to the first water-refrigerant heat exchanger. The heat pump water heater is able to perform a heating operation. In the heating operation, the hot water heated in the second water-refrigerant heat exchanger is fed to the first water-refrigerant heat exchanger and the hot water further heated in the first water-refrigerant heat exchanger is supplied to a downstream side of the water channels. The first water-refrigerant heat exchanger is able to be replaced without replacing the second water-refrigerant heat exchanger.