Dishwasher Tub Wall Cooling to Prevent Drying-Phase Mist

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Solution Overview

Problem

Conventional dishwashers experience inefficiencies in the drying phase due to mist formation when the temperature difference between the tub center and the cooled wall is too high, leading to reduced drying rates and re-moistening of dishes.

Innovation Solution

The dishwasher's control system manages the cooling device to maintain a temperature difference of 1-10°C between the tub center and the cooled wall, with optimal results at 2-6°C, by increasing the cooling capacity in steps or continuously during the drying phase, ensuring efficient condensation and moisture removal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the cooling device is activated to cool the tub wall during the drying phase, then moisture condensation on the wall is improved, but mist formation occurs when the temperature difference is too high, reducing drying efficiency

Engineering Contradiction:
Improvedrying efficiencyVSAvoidmist formation
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The invention controls the temperature difference parameter between the tub center and cooled wall to remain within a specific range (1-10°C). By dynamically adjusting the cooling capacity to maintain this temperature difference, the system optimizes condensation efficiency while preventing mist formation that occurs when the temperature gradient is too steep.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The control system continuously monitors the temperature difference between the tub center and the cooled wall, and dynamically adjusts the cooling device's capacity in response. This feedback mechanism ensures the temperature difference remains within the optimal range, preventing mist formation while maintaining effective condensation throughout the drying phase.

Inventive Principle:
Principle #23Feedback

2Productivity

If the temperature difference between tub center and cooled wall is increased to enhance condensation, then drying rate improves, but mist formation occurs leading to re-moistening of dishes

Engineering Contradiction:
Improvedrying rateVSAvoidre-moistening of dishes
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention maintains the temperature difference parameter within an optimal window (1-10°C) rather than maximizing it. This controlled parameter range ensures sufficient temperature gradient for effective condensation and drying rate, while preventing the excessive gradient that causes mist formation and subsequent re-moistening of dishes.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The cooling capacity is adjusted to provide just sufficient cooling to maintain the temperature difference within the optimal range, rather than applying maximum cooling. This partial action approach achieves effective condensation and drying without creating the excessive temperature gradient that leads to harmful mist formation.

Inventive Principle:
Principle #16Partial or excessive action

3Productivity

If the cooling capacity is increased continuously during the drying phase, then the temperature difference is maintained within the optimal range, but energy consumption increases

Engineering Contradiction:
Improvedrying efficiencyVSAvoidcooling energy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The cooling capacity is made dynamic rather than static, being continuously or stepwise adjusted during the drying phase to maintain the temperature difference within the optimal range. The control system modulates the cooling power based on the current temperature conditions, providing just sufficient cooling to prevent mist formation while avoiding excessive energy consumption.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention dynamically changes the cooling capacity parameter throughout the drying phase to maintain the temperature difference within the optimal range (1-10°C). By adjusting this parameter in response to changing temperature conditions, the system achieves consistent drying efficiency without unnecessarily high energy consumption.

Inventive Principle:
Principle #35Parameter changes

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 approach significantly enhances drying efficiency by preventing mist formation, ensuring effective condensation on the wall and reducing drying time while maintaining a high drying result.

Implementation Method 1

a cooling device, e.g. in the form of a fan, is activated to cool at least one wall of the tub or an exchange surface with the tub air

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 2

the hot process air in the tub first absorbs moisture from the dishes

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

reaches the cooled wall by convection or diffusion, where it releases the moisture

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 4

reaches the cooled wall by convection or diffusion, where it releases the moisture

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 5

the hot process air in the tub first absorbs moisture from the dishes and then e.g. reaches the cooled wall by convection or diffusion, where it releases the moisture

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP2848180B1Dishwasher with cooled tub wall
Publication Date: 2016.05.25 V-ZUG AG
  • EP2848180B1 patent drawingFigure 1~2
  • EP2848180B1 patent drawingFigure 3

AI summary

In a dishwasher, at least one wall (4) of the tub (1) is cooled during the drying phase in order to accelerate the condensation of water from the process air. This ensures that the temperature of the wall (4) is no more than 10°C below the center temperature of the tub (1). In this way, extensive fogging, which can impair the drying process, can be avoided.