Multipass Membrane Contactor Layout to Prevent Dehumidification Condensation
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Solution Overview
Problem
Conventional membrane contactors in dehumidification systems face inefficiencies due to condensation on the gas side of the membrane, which hinders mass and heat transfer, and require large membrane surface areas for effective operation.
Innovation Solution
A contactor design featuring porous sidewalls with hygroscopic material flow through multiple contact modules and turbulence generators in air channels to enhance mass and heat transfer efficiency, while orienting air flow to prevent condensation and using a multipass flow path for the liquid desiccant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional membrane contactors are used with large membrane surface area, then dehumidification effectiveness is improved, but device complexity and space requirements increase
Solution Approach 1:
The contactor is divided into multiple contact modules arranged in series, where each module contains a membrane element. This segmentation allows the system to achieve high dehumidification effectiveness through multiple sequential contact stages rather than requiring a single large membrane surface, thereby reducing the overall membrane area needed while maintaining productivity
Solution Approach 2:
The patent transitions from a single-pass flow configuration to a multipass flow arrangement where liquid and gas flows are redirected through multiple contact modules in series. This dimensional change in flow path configuration increases the effective contact time and mass transfer efficiency, allowing smaller membrane surfaces to achieve the same dehumidification performance
2Productivity
If membrane contactors operate with aqueous fluid flow adjacent to hydrophobic membrane, then mass transfer of water vapor is improved, but condensation forms on the gas side of the membrane
Solution Approach 1:
The system pre-cools the aqueous fluid before it contacts the membrane, and pre-heats or conditions the gas stream to control its dew point. This preliminary conditioning of both phases prevents the temperature and humidity conditions that would lead to condensation on the gas side of the membrane, maintaining mass transfer efficiency without harmful condensation
Solution Approach 2:
The patent converts the potentially harmful condensation effect into a beneficial pre-cooling mechanism. By carefully controlling the operation, the slight cooling effect near the membrane is harnessed to improve the temperature gradient for mass transfer, while the multipass configuration ensures condensate is removed before it can accumulate and hinder performance
3Productivity
If single-pass flow path is used for liquid desiccant, then device complexity is reduced, but mass and heat transfer efficiency decreases
Solution Approach 1:
The liquid desiccant flow path is segmented into multiple passes through different contact modules, with each pass contributing to the overall mass and heat transfer. This segmentation of the flow path, achieved through manifold configurations that redirect flow between modules, increases efficiency without requiring complex external control systems
Solution Approach 2:
The multipass flow configuration serves multiple functions simultaneously: it increases mass transfer efficiency by providing multiple contact opportunities, distributes the liquid flow evenly across all membrane surfaces, and facilitates heat recovery between inlet and outlet streams. This multi-functionality achieves high efficiency while maintaining relatively simple device architecture
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 reduces membrane surface area requirements, improves mass and heat transfer efficiency, and minimizes condensate collection, leading to enhanced dehumidification performance by optimizing vapor pressure distribution and air flow mixing.
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
gases, such as water vapor for example, can be selectively removed or dissolved into the liquid
Implementation Method 4
Membrane contactors allow a gaseous phase and a liquid phase, to exchange mass and heat between the phases
Implementation Method 5
Membrane contactors allow a gaseous phase and a liquid phase, to exchange mass and heat between the phases
Data Source
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 sidewall that defines an internal space through which a hygroscopic material flows. Adjacent contact modules are fluidly coupled to form a multipass flow path for the hygroscopic material through the contactor.