Fine Cellulose Fiber Ventilation Sheet for Moisture-Air Separation
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Solution Overview
Problem
Existing energy recovery ventilation sheets face challenges in achieving both high air permeability resistance and moisture permeability, which are essential for effective energy recovery in building ventilation systems, due to limitations in material properties such as fiber diameter, density, and thickness.
Innovation Solution
A multilayered structure comprising fine cellulose fiber nonwoven fabric layers with specific fiber diameters, densities, and thicknesses, optimized through a papermaking method and subsequent treatments, to enhance permeability resistance and moisture permeability, and potentially incorporating additional fibers and treatments for durability and flame retardancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ordinary microporous film, paper or nonwoven fabric is used for energy recovery ventilation sheets, then moisture permeability is improved, but air permeability resistance deteriorates (air penetration occurs)
Solution Approach 1:
The invention uses a hydrophilic porous polymer fiber nonwoven fabric with specific pore structure that allows water vapor molecules to pass through while blocking air molecules. The pore size and distribution are controlled to achieve selective permeability based on molecular size differences between water vapor and air.
Solution Approach 2:
The invention changes the physical and chemical parameters of the nonwoven fabric by selecting specific fiber materials with hydrophilic properties and controlling the basis weight, thickness, and pore structure. These parameter adjustments enable the material to exhibit both high moisture permeability and high air permeability resistance simultaneously.
2Object-affected harmful factors
If a polymer coating is applied to the surface of porous sheets to prevent air penetration, then air permeability resistance is improved, but moisture permeability deteriorates
Solution Approach 1:
The invention extracts and eliminates the polymer coating layer from the energy recovery ventilation sheet structure. By removing this coating, the sheet maintains its natural hydrophilic properties and moisture permeability while achieving air permeability resistance through the optimized nonwoven fabric structure itself, rather than relying on a surface coating.
3Object-affected harmful factors
If hydrophobic polymer materials are used for energy recovery ventilation sheets, then air permeability resistance is improved, but moisture permeability and thermal conductivity deteriorate
Solution Approach 1:
The invention changes the fundamental material parameter from hydrophobic to hydrophilic by selecting porous polymer fibers with hydrophilic properties. This material selection enables the sheet to maintain high moisture permeability and thermal conductivity while achieving adequate air permeability resistance through structural optimization rather than relying on hydrophobicity.
Solution Approach 2:
The invention utilizes the porous structure of hydrophilic polymer fiber nonwoven fabric to achieve selective permeability. The pore size, distribution, and connectivity are controlled to allow water vapor transmission while restricting air flow, eliminating the need for hydrophobic materials.
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
The multilayered structure demonstrates superior air permeability resistance and moisture permeability, enabling efficient energy recovery and humidity retention, thus improving the performance of energy recovery ventilators in reducing energy consumption and enhancing indoor air quality.
Implementation Method 1
a gas-impermeable energy recovery ventilation element arranged in a corrugated shape allows sensible heat to migrate while dividing into fresh outside supplied air that has been exchanged by ventilation and contaminated interior discharged air
Implementation Method 2
simultaneously allowing latent heat retaining water to pass from the discharged air to the supplied air by allowing permeation of humidity
Implementation Method 3
a multilayered structure comprising at least one fine cellulose fiber nonwoven fabric layer... with a permeability resistance of 2000 s/100 ml or more
Data Source
AI summary
Provided is a multilayered structure comprising at least one fine cellulose fiber nonwoven fabric layer made of a fine cellulose fiber, wherein the multilayered structure is characterized in that the mean fiber diameter of the fine cellulose fiber forming the fine cellulose fiber non-woven fabric layer is 0.005 to 0.5 μm, and the mean thickness of the multilayered structure is 10 to 200 μm, the density thereof is 0.10 to 0.90 g/cm3, and the permeability resistance thereof is 2000 s/100 ml or more. Also provided are an energy recovery ventilation sheet made of this multilayered structure, an energy recovery ventilation element using this energy recovery ventilation sheet as a partitioning material for partitioning two types of air flow of different temperature and/or humidity, and a energy recovery ventilator using this energy recovery ventilation element.