Fabrication And Hydrogen Production Performance Investigation Of Multi-Scale Microchannel

With the development of fuel cell technology,the hydrogen production technology of micro-reactors has received more and more attention.Relative to the breakthrough of catalytic material technology,the design and manufacture of microchannel structures have gradually become an obstacle to mobile hydrogen production technology.In this paper,a multi-scale microchannel reaction carrier plate was designed and manufactured according to the reaction requirements of methanol reforming for hydrogen production,which was used to improve the loading performance of the catalyst and the heat and mass transfer performance of the channel,thereby improving the hydrogen production performance of the microchannel.The main research contents are as follows:(1)In this paper,the basic theoretical analysis of the effect of each scale structure in the multi-scale microchannel on the performance of the micro-reactor was carried out,and then a multi-scale microchannel carrier plate structure was proposed according to the requirements of the reaction process on the carrier structure.The key dimension parameters such as surface structure and rib structure were preliminary designed.(2)In order to process the microgroove structure on the surface of the microchannel,a new method of electrode wire low-frequency assisted WEDM was proposed,and the influence of processing parameters such as pulse-on,pulse-off,average current and vibration frequency on the microgroove structure formation was studied.By using the low-frequency vibration of the Φ180 μm electrode wire,a fine microgroove array structure was directly processed on the surface of the carrier plate,which improved the processing efficiency of the microgroove structure on the surface of the carrier plate.(3)The microchannel carrier plates with surface submicrostructure and surface microgroove structure were processed by WEDM,respectively,and the catalyst loading performance was experimentally studied.The experimental results show that,compared with the surface submicrostructure,the microgroove structure can significantly improve the catalyst loading strength on the surface of the carrier plate.(4)Through numerical simulation,the influence of geometric parameters(shape,size,spacing,inclination angle)of microchannel rib structure on the heat and mass transfer performance of microchannel was studied.The simulation results showed that the mixing effect produced by the rib structure can significantly improve the heat and mass transfer performance of the microchannel,and the reasonable rib structural parameters do not significantly increase the pressure drop loss of the fluid while enhancing heat and mass transfer.Among them,microchannels with trapezoidal rib structure show the best heat and mass transfer performance.(5)The effect of various scale structures on the performance of hydrogen production was studied through the methanol steam reforming hydrogen production experiment.The test results showed that both the surface microgroove structure and the rib structure were beneficial to improve the microchannel hydrogen production performance.The rib structure has a greater influence on the performance of hydrogen production.When the gas hourly space velocity is 48757 ml/(g·h),the methanol conversion rate of the microchannel with rib structure is 25.2%higher than that of the ordinary rectangular microchannel.In addition,the hydrogen production performance of microchannels with different structures is compared,and the results show that multiscale microchannels exhibit the best hydrogen production performance.When the gas hourly space velocity is 43340 ml/(g·h),the methanol conversion rate is 32.4%higher than that of the ordinary rectangular microchannel.