Wood Drying Control via Condensate Measurement

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Solution Overview

Problem

Wood drying processes in kilns often result in crack formation and deformation due to moisture gradients, and are inefficient with high energy consumption.

Innovation Solution

A method that controls the drying process by measuring the amount of condensed water to adjust between intense and soft drying phases, using control parameters for air flow, heating, and venting to minimize cracks and deformation, and optimize drying efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If intense drying is performed with high air flows, low relative humidity, and high temperature, then drying speed is improved, but crack formation and deformation occur due to moisture gradients

Engineering Contradiction:
Improvedrying speedVSAvoidwood quality (crack-free and deformation-free)
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The drying process dynamically adjusts air flow velocity and temperature based on real-time moisture content measurements. The system transitions from static drying conditions to dynamic control, where parameters are continuously modified to match the wood's drying state, preventing moisture gradients that cause cracks while maintaining efficient drying speed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

A feedback control system uses moisture content sensors to monitor the wood's drying progress and automatically adjusts drying parameters. The measured moisture content feeds back to the control system, which modifies air flow and temperature to prevent excessive moisture loss at the surface, thereby eliminating the root cause of crack formation while maintaining productivity.

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If soft drying is performed with lower air flows, higher relative humidity, and lower temperatures, then crack formation is minimized, but drying time increases significantly

Engineering Contradiction:
Improvewood quality (crack-free and deformation-free)VSAvoiddrying time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The system employs dynamic drying curves that adjust the aggressiveness of drying based on the wood's current moisture content. Early in the drying process when moisture content is high, softer drying conditions are applied. As drying progresses and moisture content decreases, the system intensifies drying parameters, achieving both high quality and reduced total drying time compared to traditional soft drying methods.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes drying parameters (air flow velocity, temperature, humidity) as functions of moisture content rather than maintaining constant parameters. This parameter transformation allows the system to optimize drying rate at each moisture level, preventing cracks during high-moisture phases while accelerating drying during low-moisture phases, thus reducing overall drying time.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If constant drying parameters are maintained throughout the drying process, then process control is simple, but efficiency is reduced and quality problems occur

Engineering Contradiction:
Improvecontrol system complexityVSAvoiddrying efficiency
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The control system implements feedback loops that automatically adjust drying parameters based on moisture content measurements. This automated feedback control achieves the benefits of complex adaptive drying schedules without requiring manual intervention or overly complicated control logic, maintaining reasonable system complexity while dramatically improving drying efficiency and quality.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The drying system is designed to self-regulate based on moisture content feedback. The control system automatically determines the appropriate drying parameters at each stage without external intervention, making the complex adaptive control transparent and easy to operate. This self-service capability achieves high efficiency drying while keeping the user interface simple.

Inventive Principle:
Principle #25Self-service

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 allows for efficient and high-quality wood drying with reduced risk of cracks and deformation, balancing drying speed with energy efficiency.

Implementation Method 1

a condenser (10) arranged in the compartment, such that water is condensed from the air within the compartment by heat exchanging with a cooler medium

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 2

a heater (8) arranged for heating the air within the compartment

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

at least one air circulator (2) creating a flow of air within the compartment (1)

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3093599B1Method for controlling drying of wood
Publication Date: 2020.05.13 COLDBAY
  • EP3093599B1 patent drawingFigure 1~2

AI summary

The present invention relates to a method for controlling drying of wood in a compartment. The method comprises receiving a measured value indicative of an amount of condense water derived from air circulating through the wood during the drying, determining a control parameter value based on the measured value, outputting the determined control parameter value for controlling the drying of wood.