Gradient Membrane Contactor for Balanced Dehumidification Transfer
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Solution Overview
Problem
Conventional membrane contactors in dehumidification systems face inefficiencies due to unbalanced heat and mass transfer rates, leading to suboptimal performance, as well as issues with condensation and independent control of gas and liquid flows.
Innovation Solution
A dehumidification contactor design featuring porous membranes with varying permeability and thermal conductivity along the air flow path, allowing for controlled heat and mass transfer rates by incrementally changing membrane properties from inlet to outlet, ensuring balanced transfer rates and maximizing dehumidification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional membrane contactors are used with uniform membrane properties, then the structure is simple and easy to manufacture, but the heat and mass transfer rates are unbalanced, leading to suboptimal dehumidification performance
Solution Approach 1:
The patent applies local quality by varying the permeability and/or thermal conductivity of the membrane along the flow path. Different sections of the membrane have different properties: sections closer to the inlet have lower permeability and/or thermal conductivity, while sections closer to the outlet have higher permeability and/or thermal conductivity. This gradient structure balances the heat and mass transfer rates throughout the contactor, optimizing dehumidification performance without requiring overly complex external systems.
2Temperature
If the heat transfer rate is increased to improve heat transfer efficiency, then heat transfer performance improves, but the temperatures of the hygroscopic material stream and air stream equalize quickly, decaying the mass transfer potential
Solution Approach 1:
The patent applies parameter changes by systematically varying the thermal conductivity and permeability parameters of the membrane along the flow path. By making thermal conductivity decrease and/or permeability increase from inlet to outlet, the membrane controls the local heat and mass transfer rates. This gradient in parameters ensures that heat transfer does not occur too rapidly at the inlet, preserving the temperature difference and mass transfer potential throughout the contactor length.
3Productivity
If the mass transfer rate is increased to improve dehumidification performance, then water removal efficiency improves, but the heat of absorption diminishes the temperature difference between streams, decaying the heat transfer potential
Solution Approach 1:
The patent applies local quality by creating a gradient in membrane permeability from inlet to outlet. Sections near the inlet have lower permeability to limit excessive mass transfer and heat of absorption effects, while sections near the outlet have higher permeability to maximize water removal. This spatial variation in permeability quality balances the trade-off between maintaining temperature difference for heat transfer and achieving high water removal efficiency.
4Productivity
If condensation is prevented by controlling operating conditions, then dehumidification performance is maintained, but the ability to independently vary gas and liquid flows over wide ranges is limited
Solution Approach 1:
The patent applies self-service by designing the membrane with built-in gradient properties that automatically balance heat and mass transfer rates regardless of the specific operating conditions. The varying permeability and thermal conductivity create a self-regulating system where the membrane adapts to different flow rates of gas and liquid independently. This internal gradient structure provides inherent protection against condensation while allowing wide independent variation of flow rates, eliminating the need for complex external control systems.
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 design optimizes heat and mass transfer rates, enhancing dehumidification performance by controlling transfer rates and surface area usage, thereby improving the efficiency of the dehumidification process.
Implementation Method 1
Because the membrane is hydrophobic, the membrane will not allow liquid water to pass through the pores into the gas side of the membrane
Implementation Method 2
By adjusting the vapor pressure of the gas in contact with the membrane, gases, such as water vapor for example, can be selectively removed or dissolved into the liquid
Implementation Method 3
Membrane contactors allow a gaseous phase and a liquid phase, to exchange mass and heat between the phases
Data Source
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AI summary
A contactor configured for use in a dehumidification system is provided including a plurality of contact modules. Each contact module has a porous membrane that defines an internal space through which a hygroscopic material flows. A membrane property of the porous membrane of at least one contact module is substantially different than the other membranes of the plurality of contact modules.