Dishwasher Drying Time Control Using Temperature Gradient Detection
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Solution Overview
Problem
Conventional dishwashers with inherent heat drying methods run a fixed drying cycle regardless of load, leading to inefficient energy use and inadequate moisture sensing due to saturated conditions, which does not account for varying loads and environmental factors.
Innovation Solution
A method that regulates drying time by recording and analyzing temperature profiles between items and a condensing surface to detect the completion of drying, allowing for automatic detection and premature termination of the drying process, thus optimizing energy use based on load without complex sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed drying cycle is used regardless of load, then adequate drying is achieved for large loads, but energy is wasted on small loads
Solution Approach 1:
The drying cycle duration is made dynamic rather than fixed. The control unit adjusts the drying time based on real-time temperature measurements and load detection, allowing the system to adapt the drying process to the actual moisture content and thermal mass of the dishes, thereby eliminating energy waste on small loads while ensuring adequate drying for large loads
Solution Approach 2:
A feedback mechanism is implemented using temperature sensors to continuously monitor the drying process. The control unit receives temperature data and adjusts the drying cycle termination based on whether the measured temperature reaches predefined thresholds that indicate sufficient drying, replacing the fixed-time approach with an adaptive control strategy
2Use of energy by moving object
If moisture sensors are used to detect drying completion, then drying can be optimized for small loads, but the system becomes technically complex and costly
Solution Approach 1:
Instead of using complex moisture sensors directly, the invention employs temperature as an intermediary parameter to indirectly detect drying completion. The temperature behavior of the dishes and surrounding air during the drying cycle provides sufficient information to determine when drying is complete, avoiding the need for expensive and complex moisture detection devices
Solution Approach 2:
The invention replaces the mechanical/electronic moisture sensing system with a thermal measurement system. By monitoring temperature changes and thermal behavior during drying, the system achieves moisture detection functionality using simpler and more cost-effective temperature sensors and control logic
3Use of energy by moving object
If the drying cycle is shortened for small loads, then energy is saved, but drying may be insufficient for large loads
Solution Approach 1:
The drying cycle duration is dynamically adjusted based on load detection. The control unit extends the drying time for large loads and shortens it for small loads, ensuring that each drying cycle is optimized for the specific amount of dishes present, thereby preventing both energy waste and insufficient drying
Solution Approach 2:
The system changes the time parameter of the drying cycle based on the detected load size. By adjusting the drying duration as a variable parameter rather than keeping it fixed, the system can optimize energy consumption for small loads while maintaining sufficient drying time for large loads
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 enables efficient energy use by ending the drying cycle when complete, ensuring adequate drying regardless of load, and reducing energy consumption by avoiding over-drying, especially with smaller loads.
Implementation Method 1
a heating device supplies heat to the interior of the washing chamber, but the moisture is not removed. This increases the temperature of the air inside the washing chamber
Implementation Method 2
A cold surface increases drying performance. The moisture from the indoor air can condense on it, whereby the moisture absorption capacity of the indoor air is maintained or increased
Implementation Method 3
detecting a feature characterizing the degree of evaporation of water from the surface of the items to be washed
Data Source
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AI summary
The invention relates to a method for controlling a drying time in a dishwasher comprising a washing compartment for receiving items to be washed, the items to be washed being heated to a defined initial temperature (T0) which is above the temperature of a condensation surface communicating with the washing compartment. The method according to the invention comprises the following steps: (a) detecting a temperature gradient of a characteristic temperature (T) during the drying of the items to be cleaned, (b) using the temperature gradient of the characteristic temperature to detect a property that is characteristic of the degree of evaporation of water on the surface of the items to be cleaned (28a, 28b).