Method for determining the residual moisture in a condensation dryer and condensation dryer for the same
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Solution Overview
Problem
Existing condensation dryers face challenges in accurately determining the final residual moisture content of laundry, leading to inefficiencies in drying processes and potential overdrying or underdrying, as current methods rely on indirect measurements and are influenced by load and initial moisture content.
Innovation Solution
A method involving a condensation dryer with a process air duct, equipped with sensors to measure relative humidity and temperature, which calculates absolute water loading and tracks its time profile to determine residual moisture content, allowing for precise control of the drying process by comparing it to a set value and adjusting accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect measurement methods (electrodes measuring electrical resistance) are used to determine moisture content, then the device complexity is reduced, but the measurement precision deteriorates because the method is influenced by load and initial moisture content
Solution Approach 1:
The patent introduces process air as an intermediary medium to indirectly measure the moisture content of laundry. By measuring the moisture content of the air that has contacted the laundry, the system obtains accurate moisture information without directly measuring the laundry itself, thus improving measurement precision while maintaining relatively simple device complexity
Solution Approach 2:
The patent replaces the electrical resistance measurement method with a humidity sensor-based measurement method. Instead of using electrodes to measure electrical resistance of laundry, the system uses humidity sensors to measure the moisture content of process air, which provides more accurate and reliable measurements independent of load conditions
2Productivity
If the drying process is terminated at a predetermined switch-off value based on electrical resistance, then the productivity is improved by reducing drying time, but the manufacturing precision deteriorates because it cannot achieve a specific final residual moisture content
Solution Approach 1:
The patent implements a feedback control system where the humidity sensor continuously monitors the moisture content of process air, and the control device adjusts the drying process parameters based on this feedback. This closed-loop control enables the system to achieve a specific target residual moisture content (manufacturing precision) while optimizing drying time (productivity) by terminating the process at the precise moment when the target is reached
Solution Approach 2:
The patent employs dynamic adjustment of drying parameters based on real-time moisture measurements. The control device can dynamically modify heating power, air circulation rate, and drying time according to the actual moisture content of laundry, allowing the system to adapt to varying loads and initial moisture conditions to achieve consistent final moisture content across different scenarios
3Ease of operation
If a fixed drying program is used without adapting to load and initial moisture content, then the ease of operation is improved, but the reliability deteriorates because the final residual moisture content cannot be accurately controlled
Solution Approach 1:
The patent enables the drying system to automatically determine and adapt to the actual load and initial moisture content conditions. The humidity sensor and control device work together to self-adjust drying parameters without user intervention, maintaining ease of operation while significantly improving reliability by ensuring accurate control of final residual moisture content for each specific drying scenario
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 precise control of the drying process, ensuring the desired residual moisture level is reached, optimizing energy efficiency and gentleness on laundry, while adapting to varying loads and initial moisture conditions.
Implementation Method 1
a heat exchanger in the process air duct for condensing water from warm, humid process air
Implementation Method 2
at least one humidity sensor is arranged... measuring a relative humidity H rel of the process air with the humidity sensor
Implementation Method 3
measuring a temperature T P of the process air with a temperature sensor
Implementation Method 4
process air is moved in a circuit by means of a fan
Data Source
Figure 1
AI summary
The invention relates to a method for operating a condensation dryer 1 with a process air duct 2, in which process air is moved in a circuit by means of a fan 6, a heater 4, a drum 3 with items of laundry placed therein, and a control device 8, in which process air duct 2 Heat exchanger 14 for condensing water from warm, humid process air and at least one humidity sensor 9,10 are arranged, with a drying process comprising the following steps: (a) measuring a relative humidity Hrel of the process air with the humidity sensor 9,10; (b) measuring a temperature TP of the process air with a temperature sensor 9,10; (c) determining an absolute water loading LW of the process air from the relative humidity Hrel taking into account the temperature TP, a relationship between a maximum water loading LWmax and the temperature TP stored in the control device 8 being used; (d) tracking the course of the water loading LW over time; (e) using the time profile of the water load Lw to determine a residual moisture content RW in the laundry items; (f) comparing the residual moisture RW with a specified residual moisture RWset; and (g) ending the drying process when the specified residual moisture content RWset is reached or fallen below. The invention also relates to a condensation dryer suitable for carrying out this method.