Dryer Moisture Estimation Using Heater Power and Air Temperature
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Solution Overview
Problem
Existing methods for terminating a drying cycle based on moisture content in dryers are inefficient, often requiring manual user input, complex sensor installations, or additional expensive sensors, and fail to accurately measure moisture in bulky items or during static drying processes.
Innovation Solution
A method using a single temperature sensor to measure the air temperature linked with the laundry items, monitoring the power supplied by the heater to estimate moisture retention, and automatically terminating the cycle when a predetermined moisture level is reached, independent of the dryer's heating system type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conductibility sensors are used to measure moisture content, then moisture detection accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the moisture detection function from dedicated conductibility sensors and implements it using the existing temperature sensor combined with power consumption monitoring. This removes the need for complex sensor installations while maintaining moisture detection capability through indirect measurement of evaporation rate.
Solution Approach 2:
The patent introduces power consumption as an intermediary parameter to indirectly measure moisture content. Instead of directly measuring moisture with complex sensors, the system monitors the power required for evaporation, which serves as a mediator between the temperature sensor and the moisture detection goal.
2Measurement precision
If multiple temperature sensors are used to estimate moisture content, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent makes the existing temperature sensor multi-functional by combining it with power consumption monitoring to perform both temperature control and moisture detection functions. This eliminates the need for additional dedicated moisture sensors while maintaining accurate moisture estimation capability.
Solution Approach 2:
The patent merges the moisture detection function with the existing temperature sensing and control system. By combining temperature data with power consumption data, the system achieves moisture estimation using a single temperature sensor instead of requiring multiple sensors.
3Measurement precision
If manual user input for fabric type is required, then drying cycle accuracy is improved, but ease of operation decreases
Solution Approach 1:
The patent enables the system to automatically determine fabric type and drying parameters through power consumption monitoring and evaporation rate analysis. The system serves itself by inferring fabric characteristics from the drying process dynamics without requiring manual user input, thereby maintaining accuracy while improving ease of operation.
Solution Approach 2:
The patent changes the approach from static user-input-based fabric classification to dynamic parameter-based inference. By monitoring how power consumption and evaporation rate change during the drying process, the system automatically adapts to different fabric types without requiring predefined user input.
4Reliability
If drying cycle duration is extended to ensure complete drying, then drying completeness is improved, but energy consumption increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring power consumption and evaporation rate to determine when drying is complete. This real-time feedback allows the system to terminate the drying cycle at the optimal moment when moisture content reaches the desired level, ensuring completeness while avoiding unnecessary energy consumption from extended drying.
Solution Approach 2:
The patent applies partial action by extending the drying cycle only as much as necessary to achieve the desired moisture level, rather than using fixed extended durations. The system terminates drying immediately when the moisture target is reached, avoiding excessive energy consumption while ensuring sufficient drying completeness.
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 ensures accurate and automatic cycle termination with minimal sensor requirements, improving efficiency and reducing energy waste, particularly effective for bulky items and static drying processes, while maintaining consistent drying performance across different loads.
Implementation Method 1
uses a single temperature sensor to measure the air temperature linked with the laundry items
Implementation Method 2
monitoring the power supplied by the heater to estimate moisture retention
Implementation Method 3
monitoring the power supplied by the heater
Data Source
AI summary
The power P of the heater of a dryer is regulated in order to heat up the air used to dry washed articles placed in the drying chamber to a temperature close to a set point temperature TSET. The output signal of the regulator of the heater is used to estimate the moisture content of the fabrics and to terminate the drying cycle when a predefined moisture level is reached.