Dishwasher Outer Wall Heating to Prevent External Condensation

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Solution Overview

Problem

Domestic dishwashers with heat pump arrangements face issues with condensation on the outer walls, leading to moisture-related damage and aesthetic problems, as the evaporator is thermally coupled to the liquid tank, causing heat transfer that can result in condensation on the exterior.

Innovation Solution

Incorporating a means to heat the outer wall, such as a fan or heating element, to prevent condensation by maintaining the wall temperature above the dew point, and using a heat exchanger to further enhance heat transfer and efficiency, while ensuring the liquid tank remains a cold source for drying.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the evaporator is thermally coupled to the liquid tank to enable heat transfer for drying items, then the drying function is improved, but condensation occurs on the outer wall causing moisture damage and aesthetic problems

Engineering Contradiction:
Improvedrying functionVSAvoidcondensation on outer wall
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the thermal management system by introducing a separate heating means for the outer wall, independent from the evaporator-liquid tank heat transfer system. This allows the evaporator to continue cooling the liquid tank for drying while the heating means independently prevents condensation on the outer wall.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The heating means is activated in advance or simultaneously with the evaporator operation to preheat the outer wall or maintain its temperature above the dew point, preventing condensation before it can occur. This counteracts the cooling effect that would otherwise cause moisture accumulation.

Inventive Principle:
Principle #9Preliminary anti-action

2Loss of energy

If the evaporator cools the liquid tank to enable drying, then water vapor is condensed inside the receiving space, but the outer wall temperature drops causing external condensation

Engineering Contradiction:
Improvewater vapor condensation inside receiving spaceVSAvoidouter wall temperature
Core Design Contradiction:
Loss of energyVSTemperature

Solution Approach 1:

The patent applies local quality by creating different temperature zones: the liquid tank and receiving space are cooled for condensing internal moisture, while the outer wall is heated or maintained at a higher temperature to prevent external condensation. The heating means is specifically positioned to affect only the outer wall region.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The heating means acts as an intermediary between the cooled liquid tank and the external environment, preventing the cold from the liquid tank from propagating to the outer wall. This mediator maintains thermal separation between the internal cooling function and external temperature requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If a heating means is added to prevent condensation on the outer wall, then condensation is prevented, but the device complexity increases

Engineering Contradiction:
Improvecondensation preventionVSAvoidsystem structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The heating means is designed to serve multiple functions: it prevents condensation on the outer wall, and can potentially serve as part of the overall thermal management system for the dishwasher. This multi-functionality reduces the need for entirely separate systems and minimizes overall complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The heating means is integrated with the existing control system of the dishwasher, allowing it to be automatically controlled based on operating conditions. The system self-regulates to prevent condensation without requiring additional complex control mechanisms, using the dishwasher's existing intelligence.

Inventive Principle:
Principle #25Self-service

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

Effectively prevents condensation on the outer wall, minimizing moisture damage and maintaining the aesthetic integrity of the dishwasher's surroundings, while improving the compressor's efficiency and energy usage.

Implementation Method 1

an evaporator for evaporating a heat transfer medium

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

the evaporator being thermally coupled to a liquid tank of the household dishwasher

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 3

a compressor for compressing the heat transfer medium coming from the evaporator

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 4

a condenser for condensing the heat transfer medium coming from the compressor

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 5

the heat transfer medium coming from the compressor being liquefied using the condenser

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 6

at least one means with the aid of which the outer wall can be heated at least in sections in order to counteract condensation of water vapor on the outside of the outer wall

Methodology Applied
Scientific EffectHeating: Heating

Data Source

PatentEP3643217B1Preventing condensation of water vapor on an outside wall of a household dishwasher
Publication Date: 2021.07.28 BSH HAUSGERATE GMBH
  • EP3643217B1 patent drawingFigure 1
  • EP3643217B1 patent drawingFigure 2
  • EP3643217B1 patent drawingFigure 3a~3b

AI summary

A household dishwasher is proposed, comprising a receiving chamber (1) for receiving items to be washed (2) and a heat pump arrangement through which a heat transfer medium (3) flows during its operation, wherein the heat pump arrangement comprises at least an evaporator (4) for evaporating the heat transfer medium (3), a compressor (5) for compressing the heat transfer medium (3) coming from the evaporator (4) and a condenser (6) for condensing the heat transfer medium (3) coming from the compressor (5), wherein the evaporator (4) is thermally coupled to a liquid tank (7) of the household dishwasher, in particular arranged at least partially within a liquid tank (7) of the household dishwasher, which is arranged at least partially between the receiving chamber (1) and an outer wall (8) of the household dishwasher that delimits the household dishwasher to the outside.According to the invention, the household dishwasher has at least one means by which the outer wall (8) can be heated, at least in sections, in order to counteract condensation of water vapor on the outer surface (9) of the outer wall (8) facing away from the receiving chamber (1) and/or to evaporate any condensation present on the outer surface (9). Furthermore, a method for operating a household dishwasher is proposed.