Hygroscopic Material Drying Control via Surface Temperature Feedback
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Solution Overview
Problem
Current drying methods for hygroscopic materials, such as wood, often result in undesirable deformations like crack formation, twisting, and residual internal stresses due to rapid drying, leading to lower product quality and increased production costs.
Innovation Solution
A method and apparatus that control the drying process by monitoring and regulating the dry bulb temperature, wet bulb temperature, and surface temperature of hygroscopic materials using a controlled drying medium with a contactless thermometer, ensuring a controlled evaporation rate to prevent deformations and optimize drying time and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast drying is applied to hygroscopic material, then productivity is improved, but manufacturing precision deteriorates due to surface drying before inner moisture migration
Solution Approach 1:
The method applies preliminary heating to the inner part of the hygroscopic material before surface drying occurs. By pre-heating the interior, moisture migration from the inner part to the surface is accelerated, ensuring that the material structure is prepared for the subsequent fast drying phase, thus preventing deformations while maintaining high productivity
Solution Approach 2:
The invention dynamically changes temperature parameters during the drying process. It uses multiple heating zones with different temperature profiles and adjusts them based on the drying stage, allowing the material to transition from a phase where inner moisture migrates to the surface to a phase where surface evaporation occurs, thereby resolving the contradiction between fast drying and preventing deformations
2Loss of time
If fast drying is applied to hygroscopic material, then drying time is reduced, but harmful factors increase due to tensile stress and capillary effect disruption
Solution Approach 1:
The method applies preliminary heating to the inner part of the hygroscopic material before surface drying occurs. By pre-heating the interior, moisture migration from the inner part to the surface is accelerated, ensuring that the material structure is prepared for the subsequent fast drying phase, thus preventing deformations while maintaining high productivity
Solution Approach 2:
The invention implements feedback control by continuously monitoring temperature and moisture content during drying. Based on this feedback, the heating power and drying conditions are automatically adjusted to maintain optimal stress levels, allowing fast drying while preventing harmful tensile stresses from developing
3Manufacturing precision
If conventional drying schedules are used, then manufacturing precision is maintained, but productivity is reduced due to slow drying
Solution Approach 1:
The drying process is segmented into multiple phases with different heating and drying intensities. The method divides the material into different zones (surface and interior) and applies different treatment regimens to each, allowing simultaneous achievement of high quality and fast drying by optimizing conditions for each segment
Solution Approach 2:
The invention transforms the static conventional drying schedule into a dynamic process that adapts in real-time. By continuously adjusting heating power, air flow, and humidity based on monitored material state, the system maintains manufacturing precision while significantly improving drying efficiency compared to fixed schedules
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 prevents unwanted deformations and internal stresses, optimizes drying time, and efficiently determines the equilibrium moisture content, thereby improving product quality and reducing energy consumption.
Implementation Method 1
moisture evaporation from the surface of the hygroscopic material
Implementation Method 2
the hygroscopic material's capillary effect vanishes and the water migration from the inner part of the hygroscopic material to its surface is interrupted
Data Source
Figure 1a~1h
Figure 2
Figure 3
AI summary
The invention relates to a method for drying hygroscopic material (2), comprising the steps a) supplying hygroscopic material (2) in a drying chamber (4) comprising a drying medium (6), b) supplying energy to the drying chamber (4), c) detecting the drying medium's (6) dry bulb temperature in the drying chamber (4) and providing an output signal for the detected dry bulb temperature, d) detecting the drying medium's (6) wet bulb temperature in the drying chamber (4) and providing an output signal for the detected wet bulb temperature, e) detecting the temperature of the hygroscopic material's (2) surface layer (11) and providing an output signal for the detected surface temperature and f) utilizing the output signal for the detected dry bulb temperature, the output signal for the detected wet bulb temperature and the output signal for the detected surface temperature as an indication of the hygroscopic material's (2) surface moisture content for regulating the properties of the drying medium (6). The invention also relates to an apparatus for drying hygroscopic material (2).