Web Drying Air Flow Ratio Optimization
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Solution Overview
Problem
Existing material web dryer arrangements face inefficiencies in energy usage and quality impairment due to high fresh air supply and exhaust air discharge, with limited potential for further improvement in efficiency without compromising web quality.
Innovation Solution
The air mass flow in the air dryer's supply line is increased 3 to 10 times greater than the exhaust air flow from the radiation dryer, optimizing the ratio of recycled air to exhaust air, which reduces the mass and temperature of air discharged, enhancing energy efficiency and drying effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If fresh air supply and exhaust air removal are reduced to increase energy efficiency, then energy efficiency improves, but air temperature and moisture content increase excessively
Solution Approach 1:
The patent recovers heat from exhaust air by directing it through heat exchangers that preheat the incoming fresh air supply. This allows the system to maintain reduced fresh air supply and exhaust air removal (improving energy efficiency) while still controlling the temperature and moisture content of air contacting the material web, as the recovered heat is utilized productively rather than wasted.
Solution Approach 2:
The patent changes the parameters of the air supply by preheating it using heat recovered from exhaust air. This parameter change (increasing supply air temperature through heat recovery) allows the system to operate with lower volumes of fresh air while maintaining effective drying temperatures, thus improving energy efficiency without excessively increasing air temperature or moisture content.
2Loss of energy
If fresh air supply and exhaust air removal are reduced to increase energy efficiency, then energy efficiency improves, but moisture content increases excessively
Solution Approach 1:
The patent recovers both heat and moisture management benefits from exhaust air through heat exchangers. By preheating incoming fresh air with exhaust air, the system reduces the total volume of fresh air needed while maintaining proper moisture content control, as the heat recovery process allows for more efficient moisture evaporation and removal with smaller air volumes.
Solution Approach 2:
The patent changes the temperature parameter of the supply air through heat recovery, which indirectly controls moisture content. By increasing supply air temperature via heat exchangers, the system achieves better moisture evaporation efficiency with reduced air volumes, thus improving energy efficiency while preventing excessive moisture accumulation.
3Loss of energy
If air mass flow in supply line is increased 3 to 10 times greater than exhaust air flow from radiation dryer, then energy efficiency increases from 53% to 64%, but system complexity increases
Solution Approach 1:
The patent merges the air duct systems of the radiation dryer and convective dryer by connecting their supply and exhaust lines. This integration allows the system to achieve the optimized air mass flow ratio (3:1 to 10:1) and improved energy efficiency (53% to 64%) without proportionally increasing complexity, as the systems share common infrastructure rather than operating as completely separate units.
Solution Approach 2:
The patent creates a multi-functional air handling system where the same air duct infrastructure serves both the radiation dryer and convective dryer. The air supply and exhaust systems perform multiple functions - supplying air to both dryers, recovering heat from both exhaust streams, and maintaining optimized air flow ratios - which achieves high energy efficiency while limiting complexity growth through functional integration.
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 configuration significantly increases the material web dryer's efficiency from 53% to 64% while minimizing the impact on web quality, allowing for more effective drying with reduced air discharge temperatures and increased drying surface area.
Implementation Method 1
The radiation dryer has a relatively high power density, i.e. it can transfer a relatively large amount of heat to the material web, so that the water in it can evaporate well.
Implementation Method 2
The air dryer transfers a smaller amount of heat to the material web. However, it is able to support the material web without contact.
Implementation Method 3
Heated air from the radiation dryer is collected by the air dryer and, if necessary, blown onto the material web after being heated again.
Data Source
Figure 1
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AI summary
The arrangement (1) has an air dryer (5) comprising an exhaust pipe (17) that is connected with an air supply duct (16) of an air guiding system (24). A radiation dryer (4) has another air guiding system (25) comprising another exhaust pipe (9) connected with the air supply duct of the former air guiding system. An air mass flow (m1) in the air supply duct during operation of the arrangement is 3 to 10 times greater than a mass air flow (m2) in the later exhaust pipe. The radiation dryer has infrared modules arranged under a cover.