Dishwasher Drain Pipe Cooling to Preserve Condensation Drying
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Solution Overview
Problem
In dishwashers, the energy required to heat washing water is high, and the integrated passage of a drain pipe through the water tank can impair the drying efficiency by warming the condensation surface during the drying step.
Innovation Solution
A final pumping sequence is implemented at the end of the rinsing step, which includes pumping out rinsing water as waste water and filling the drain pipe section in the water tank with cold water, ensuring the condensation surface is cooled before the drying step, thereby preventing heating by residual waste water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the drain pipe is routed through the water tank to enable heat recovery from waste water, then energy consumption for heating washing water is reduced, but the drying efficiency deteriorates because the condensation surface temperature increases during the drying step
Solution Approach 1:
The system performs preliminary cooling of the drain pipe by filling it with cold water from the water tank before the drying step begins. This preliminary action removes the harmful heat from the drain pipe, ensuring that the condensation surface remains cold enough for efficient drying while still allowing heat recovery during the washing phases.
Solution Approach 2:
The system applies preliminary anti-action by introducing cold water into the drain pipe to counteract the heating effect that would otherwise occur during waste water pumping. This prevents the condensation surface from becoming too warm, thereby maintaining drying efficiency while still enabling heat recovery from waste water.
2Productivity
If cold water is filled into the water tank to cool the condensation surface for drying, then drying efficiency is improved, but the energy recovery from waste water is reduced because the water is already cooled
Solution Approach 1:
The system performs the cold water filling action at a specific time - before the drying step but after heat recovery from waste water has occurred. This timing ensures that heat recovery is maximized during the washing phase, and then the water is cooled for the drying phase, achieving both objectives.
Solution Approach 2:
The system uses periodic action by alternating between heat recovery mode (during washing) and cooling mode (before drying). The drain pipe is filled with cold water periodically at the transition from washing to drying, allowing the system to optimize for heat recovery during washing and for drying efficiency during the drying phase.
3Loss of energy
If waste water remains standing in the drain pipe section during the drying step, then heat is transferred to the water tank, but the condensation surface temperature increases reducing drying performance
Solution Approach 1:
The system performs preliminary cooling of the drain pipe with cold water before the drying step. This removes the heat that would otherwise be transferred to the water tank during drying, keeping the condensation surface temperature low for optimal drying performance while still allowing heat recovery during washing.
Solution Approach 2:
The system rushes through the heat transfer process by quickly filling the drain pipe with cold water before drying begins, minimizing the time that warm waste water could heat the water tank. This ensures that heat recovery occurs during washing, but the drying phase starts with a cooled drain pipe.
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 reduces the energy needed to heat washing water while maintaining or improving drying efficiency by ensuring the condensation surface is at a lower temperature, enhancing moisture condensation and drying results without additional time or energy requirements.
Implementation Method 1
the water stored in the water tank extracts heat from the waste water heated during a partial wash cycle of a wash cycle
Implementation Method 2
the water tank can in particular simultaneously serve to cool the wall section of the washing tank with which it is in thermally conductive contact during a drying step
Implementation Method 3
the wall section acts as a condensation surface for moisture in the washing container
Data Source
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AI summary
The invention relates to a dishwasher, in particular a household dishwasher (1), comprising a control device (8) for controlling a wash cycle for cleaning dishes by means of at least one dishwashing program (SP) stored in the control device (8), having a washing container (2) for accommodating the dishes to be washed during the wash cycle. Said dishwasher further comprises a water container (12) that is connected to the washing container (2) in a heat-conductive manner for storing water (W), in particular fresh water (FW), a valve array (13, 28) that can be controlled by way of the control device (8) for filling the washing container (2) with water (W), in particular with fresh water (FW), a drain pump (19) that can be controlled by the control device (8) for pumping waste water (AW) from the washing container (2) via a drain pipe (20), which passes through the water container (12). The dishwashing program (SP) is configured such that at the end of a rinsing cycle (KS), a final pumping sequence (SPS) is provided, comprising a dishwater pumpout step (SAS) for pumping out as wastewater (AW) dishwater (S) used during the rinsing cycle (KS) for acting upon dishes to be washed using the drain pump (19), a cold-water filling step (KE) for introducing a cold water volume into the washing container (2) by means of the valve array (13, 28), and a cold-water pumpout step (KA) for pumping out as waste water (AW) the cold water volume introduced during the cold-water filling step (KE) by means of the drain pump (19).