Dishwasher Latent Heat Reservoir for Wash Heating and Drying

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Solution Overview

Problem

Existing dishwashers with latent heat storage devices and heat pumps face inefficiencies in heat management during wash and dry cycles, as they either overcool the latent heat storage or require complex air handling systems to condense moisture effectively.

Innovation Solution

A dishwasher design that uses a heat pump to extract heat from a latent heat storage device and transfer it to the process liquid in the wash phase, and then circulates a fluid between the tub and the latent heat storage device during the dry phase to condense moisture, utilizing separate heat exchangers for efficient heat transfer and condensation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If complex air handling systems are used to condense moisture during drying, then drying efficiency improves, but device complexity increases

Engineering Contradiction:
Improvedrying efficiencyVSAvoidair handling system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The invention extracts and utilizes the latent heat from the storage device to cool surfaces for condensation, separating the condensation function from complex air handling systems. This extraction approach achieves effective moisture removal using a simplified system that leverages the thermal energy already stored in the latent heat device

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The latent heat storage device serves dual purposes: it provides cooling during the wash phase and subsequently provides the thermal energy needed for condensation during drying. This self-service capability eliminates the need for separate complex air handling systems, as the same thermal storage system performs both cooling and condensation functions

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

This approach allows for efficient heating of the wash liquid and effective drying by recycling heat back into the latent heat storage device, promoting condensation of moisture from the process air, thus optimizing energy use and drying efficiency.

Implementation Method 1

heat is extracted from the latent heat store with the heat pump and this heat is supplied to the process liquid

Methodology Applied
Scientific EffectHeat pump heat transfer: Heat Exchanger

Implementation Method 2

a latent heat store (14) for storing heat. A latent heat store is a heat store that can be cooled or heated via a phase transition, so that part of the heat or cold can be stored as latent heat

Methodology Applied
Scientific EffectLatent heat storage via phase transition: Phase Change

Implementation Method 3

a fluid is pumped between a first area on or in the tub and a second area on or in the latent heat storage device

Methodology Applied
Scientific EffectHeat exchanger heat transfer: Heat Exchanger

Implementation Method 4

This cools a wall of the vat, causing water to condense out of the process air

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP2322072B1Dishwasher with a latent heat reservoir
Publication Date: 2013.12.18 V-ZUG AG
  • EP2322072B1 patent drawingFigure 1~2
  • EP2322072B1 patent drawingFigure 3

AI summary

The dishwasher has a tub (1) receiving a washing product and process fluid e.g. water, and a latent-heat accumulator (14) storing heat. A controller (20) is designed such that heat pumps (7-10) extract heat in a process phase of the latent-heat accumulator and guide the process fluid. A pump (15) circulates process fluid between a region (16) at or in the tub and a region (17) at or in the latent-heat accumulator in another process phase. Heat exchangers (18, 19) are thermally coupled with an inner chamber of the tub and the latent-heat accumulator. An independent claim is also included for a method for controlling a dishwasher.