Heat Exchanger Base Sheet Moisture Management
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Solution Overview
Problem
Conventional base sheets for total heat exchanger elements face challenges in achieving a balance between flame resistance, heat exchanging efficiency, moisture permeability, and cost-effectiveness, with issues such as rust formation, excessive moisture absorption, and fragility, particularly when using calcium chloride or high beating degrees.
Innovation Solution
A base sheet with a paper base material having a specific freeness range, controlled calcium chloride content, and inclusion of a blocking inhibitor, optimized to achieve low basis weight, high moisture permeability, and excellent flame and gas barrier properties, while maintaining mechanical strength and heat exchanging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If calcium chloride is added to improve flame resistance, then flame resistance is improved, but moisture absorption becomes excessive causing liquid sagging
Solution Approach 1:
The invention changes the chemical composition parameters by replacing calcium chloride with magnesium chloride hexahydrate, which has different hygroscopic properties. This parameter change allows achieving flame resistance without excessive moisture absorption that causes liquid sagging
Solution Approach 2:
The invention uses a readily available chemical compound (magnesium chloride hexahydrate) that can be easily incorporated into the paper base material, replacing the problematic calcium chloride while maintaining cost-effectiveness and productivity
2Reliability
If calcium chloride is used as desiccant, then flame resistance is improved, but rust occurs in equipment
Solution Approach 1:
The invention substitutes calcium chloride with magnesium chloride hexahydrate, which is equally effective for flame resistance but does not cause rust formation in paper machine equipment, calenders, and winders
Solution Approach 2:
The invention converts the harmful rust-causing property of calcium chloride into a beneficial solution by selecting magnesium chloride hexahydrate, which provides the same flame protection function without the harmful side effect of rust formation
3Reliability
If base sheet is increasingly beaten to improve gas barrier properties, then gas barrier properties are improved, but production efficiency decreases and base sheet becomes fragile
Solution Approach 1:
The invention extracts the need for excessive beating by incorporating magnesium chloride hexahydrate into the paper base material, which provides gas barrier properties through chemical composition rather than mechanical processing
Solution Approach 2:
The invention replaces the mechanical beating process with a chemical solution (magnesium chloride hexahydrate incorporation), substituting mechanical action with chemical composition to achieve gas barrier properties without reducing production efficiency or strength
4Reliability
If base sheet is increasingly beaten to improve gas barrier properties, then gas barrier properties are improved, but base sheet becomes fragile
Solution Approach 1:
The invention replaces the mechanical beating process with chemical incorporation of magnesium chloride hexahydrate, achieving gas barrier properties without the mechanical degradation that causes fragility
Solution Approach 2:
The invention changes the chemical composition parameter by adding magnesium chloride hexahydrate, which provides gas barrier properties while maintaining or improving mechanical strength through proper chemical bonding in the paper structure
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 solution results in a base sheet with enhanced moisture permeability, appropriate moisture absorption, and improved flame resistance and gas barrier properties, while maintaining a low basis weight, effectively addressing the limitations of existing technologies.
Implementation Method 1
a prescribed amount of calcium chloride is included in a paper base material to prepare a total heat exchanger element-use base sheet having increased flame resistance and gas/CO2 barrier properties
Implementation Method 2
a heat exchange ventilation device (heat exchanger) that can exchange heat between supplied air and discharged air
Implementation Method 3
A liner part of the total heat exchanger element can be used to exchange sensible heat (temperature) and latent heat (humidity) at the same time
Data Source
AI summary
The object of the present invention is to provide a base sheet for a total heat exchanger element such that the base sheet has a high moisture permeability and an appropriate rate of moisture absorption as well as excels in flame resistance and gas barrier properties while its basis weight is low. A base sheet for a total heat exchanger element comprising calcium chloride in a paper base material, characterized in that the paper base material comprises pulp with a freeness of from 200 to 600 ml as measured in accordance with JIS P 8121 except that a pulp collection amount is set to 0.3 g/L; the paper base material has a bone-dry basis weight of from 17 g/m2 to less than 23 g/m2; and content of the calcium chloride is from 6 g/m2 to less than 9 g/m2.