Parallel-plate diffusion gas dehumidifier for particle sampling
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Solution Overview
Problem
Conventional dehumidifiers used in particulate sampling systems interfere with the measurement of particulate content by obstructing the gas flow and capturing particles, leading to inaccurate measurements due to the presence of water vapor in the gas stream.
Innovation Solution
A membrane diffusion gas dehumidifier is designed to minimize the impact on particulate matter by using a water-permeable membrane and a vacuum system to create a water vapor concentration gradient, allowing for effective removal of water vapor while maintaining high particle retention and minimizing flow obstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional dehumidifiers are used to remove water vapor from the gas stream, then water vapor removal efficiency is improved, but particle capture increases and measurement accuracy deteriorates
Solution Approach 1:
A hydrophobic porous membrane is introduced as an intermediary between the gas stream and the dehumidification process. The membrane selectively allows water vapor to pass through while blocking particulate matter, enabling dehumidification without particle capture. The membrane acts as a mediator that separates the water removal function from the particle measurement function.
Solution Approach 2:
The invention employs a hydrophobic porous membrane with specific pore sizes that allow water vapor molecules to pass through while preventing larger particulate matter from entering the dehumidification chamber. The porous structure provides selective permeability based on particle size and hydrophobicity, resolving the contradiction between water removal and particle preservation.
2Productivity
If conventional bundled-tube dehumidifiers are used, then water vapor removal capability is improved, but gas flow obstruction increases and particle collection is hindered
Solution Approach 1:
The invention uses a thin hydrophobic porous membrane instead of bulky bundled tubes. This thin film structure provides minimal resistance to gas flow while maintaining effective dehumidification capability. The membrane's thin profile allows smooth gas flow through the system without the obstructions caused by conventional tube bundles.
3Measurement precision
If the measuring device is operated at temperatures of 30°C or lower to improve sensitivity, then detection capability is improved, but water vapor condensation on sensing hardware increases
Solution Approach 1:
The dehumidification process is performed preliminarily before the gas stream reaches the temperature-sensitive sensing hardware. By removing water vapor upstream through the hydrophobic membrane, the system prevents condensation issues at lower operating temperatures without compromising detection sensitivity.
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 enables accurate measurement of particulate content by reducing water vapor interference while maintaining high particle retention, ensuring efficient dehumidification without significant particulate loss or obstruction in the gas flow.
Implementation Method 1
membrane diffusion gas dehumidifier
Implementation Method 2
create a water vapor concentration gradient
Implementation Method 3
vacuum system to create a water vapor concentration gradient
Data Source
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AI summary
A parallel-plate diffusion gas dehumidifier has a treatment zone having at least one water-permeable membrane. The gas dehumidifier includes an untreated gas inlet, a treatment zone bounded by water-permeable membranes, a support structure for the membranes, access to a source of vacuum, and a dehumidified gas outlet. The cross section of the treatment zone maybe provided in various shapes, for example, rectangular. The gas dehumidifier inlet and outlet include flow transitions that minimize the obstruction of particles passing through the dehumidifier. The dehumidifier may be used in particle sampling systems to dehumidify the sample gas prior to introducing the sample gas to a mass measuring device and mass flow controller. Methods of operating the gas dehumidifier and the particle sampling system are also provided.