Microfluidic Plasma Reactor for Uniform Bubble Control
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Solution Overview
Problem
Existing gas-liquid plasma reactors face challenges in controlling the formation and transfer of reactive species from plasma to liquid, with issues such as non-uniform liquid films, large bubble size distributions, and inefficient transfer rates, limiting their effectiveness in applications like pollutant decomposition.
Innovation Solution
A microfluidic or millifluidic device with a dielectric material support, featuring a main channel for gas and liquid flow, embedded ground and high-voltage electrodes, and a method to generate a continuous plasma in gas bubbles by applying a high voltage, ensuring controlled bubble formation and reactive species transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gas bubbles are injected in a flowing liquid in a two-phase flow reactor, then plasma can be generated in the gas bubbles, but the bubble size distribution becomes large and preferential liquid paths occur, leading to non-uniform radical distribution
Solution Approach 1:
The reactor channel is segmented into multiple parallel microchannels, each carrying a controlled flow of liquid with gas bubbles. This segmentation ensures uniform bubble size and distribution in each channel while maintaining plasma generation capability, eliminating the preferential flow paths problem of single large channels.
Solution Approach 2:
Each microchannel is designed with specific local dimensions and flow conditions optimized for uniform bubble formation. The electrodes are positioned to create localized electric fields within each channel, ensuring consistent plasma generation and radical distribution throughout the liquid flow.
2Productivity
If a liquid is sprayed in the plasma zone, then the surface-to-volume ratio increases and transfer rate improves, but precise control of residence times becomes difficult
Solution Approach 1:
The system uses controlled gas injection through microchannels to form monodisperse bubbles with precise volume and frequency. This hydraulic/pneumatic control mechanism allows accurate regulation of residence time while maintaining high surface-to-volume ratio for efficient reactive species transfer.
3Productivity
If thin films of liquid flow down the inner walls of a cylindrical electrode, then transfer efficiency improves, but obtaining uniform liquid films becomes difficult
Solution Approach 1:
Instead of attempting to form a continuous thin film on a cylindrical surface, the system segments the liquid flow into discrete microchannels. Each channel produces uniform bubble flows with controlled characteristics, achieving consistent reactive species transfer without the film uniformity problems of falling film reactors.
4Adaptability or versatility
If electrodes are placed on opposite sides of the main channel, then plasma can be generated in gas bubbles, but the device complexity increases
Solution Approach 1:
The electrode configuration serves multiple functions: generating plasma in gas bubbles, creating electric fields for bubble manipulation, and enabling controlled discharge patterns. This multi-functionality justifies the increased structural complexity while providing superior control over plasma generation and reactive species production.
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 device enables precise control over bubble size, frequency, and reactive species transfer, enhancing the efficiency of plasma-driven chemical synthesis and reactions by maintaining plasma bubbles in a continuous state within the liquid flow, improving the transfer rate and homogeneity of reactive species.
Implementation Method 1
applying a high voltage between the high-voltage electrode(s) and the ground electrode(s) so as to generate a plasma in the bubbles circulating through the main microchannel or millichannel
Implementation Method 2
the high-voltage electrode(s) and the ground electrode(s) are located on opposite sides of the main microchannel or millichannel so as to be able to generate an electric field inside the main microchannel or millichannel
Data Source
Figure 1A
Figure 1B
Figure 1C~2C
AI summary
The present invention relates to a microfluidic or millifluidic device (1) comprising: - a support (2) made at least partially of a dielectric material, the support (2) comprising a first inlet (21a) adapted to be connected to a first reservoir containing gas, a second inlet (21b) adapted to be connected to a second reservoir containing liquid, an outlet (22) adapted to be connected to a receiver container containing gas and/or liquid, and a main microchannel or millichannel (3) present in the dielectric material allowing the liquid and the gas to flow from the inlets towards the oulet, - one or several ground electrode(s) (4) embedded in said dielectric material and extending along the main microchannel or millichannel (3), and - one or several high-voltage electrode(s) (5) embedded in said dielectric material and extending along the main microchannel or millichannel (3), wherein the high-voltage electrode(s) (5) and the ground electrode(s) (4) are located on opposite sides of the main microchannel or millichannel (3) so as to be able to generate an electric field inside the main microchannel or millichannel (3). The present invention relates also to a method for generating a plasma in a continuous manner using such a microfluidic or millifluidic device (1).