ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels最新文献_第5页

Investigation of In-Air Droplet Generation in Confined PDMS Microchannels Operating in the Jetting Regime 射流状态下密闭PDMS微通道空气中微滴生成的研究

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7690

Pooyan Tirandazi, J. Healy, Julian D. Arroyo, C. Hidrovo

{"title":"Investigation of In-Air Droplet Generation in Confined PDMS Microchannels Operating in the Jetting Regime","authors":"Pooyan Tirandazi, J. Healy, Julian D. Arroyo, C. Hidrovo","doi":"10.1115/ICNMM2018-7690","DOIUrl":"https://doi.org/10.1115/ICNMM2018-7690","url":null,"abstract":"Liquid-in-air generation of monodisperse, microscale droplets is an alternative to conventional liquid-in-liquid methods. Previous work has validated the use of a highly inertial gaseous continuous phase in the production of monodisperse droplets in the dripping regime using planar, flow-focusing, PDMS microchannels. The jetting flow regime, characteristic of small droplet size and high generation rates, is studied here in novel microfluidic geometries. The region associated with the jetting regime is characterized using the liquid Weber number (Wel) and the gas Reynolds number (Reg). We explore the effects of microchannel confinement on the development and subsequent breakup of the liquid jet as well as the physical interactions between the jet and continuous gaseous flow. Droplet breakup in the jetting regime is also studied numerically and the influence of different geometrical parameters is investigated. Numerical simulations of the jetting regime include axisymmetric cases where the jet diameter and length are studied. This work represents a vital investigation into the physics of droplet breakup in the jetting regime subject to a confined gaseous co-flow. By understanding the effects that different flow and geometry conditions have on the generation of droplets, the use of this system can be optimized for specific high-demand applications in the aerospace, material, and biological industries.","PeriodicalId":137208,"journal":{"name":"ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128547611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

A Simplified Model for Species Transport in Very Large Scale Microfluidic Networks 超大尺度微流体网络中物种迁移的简化模型

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7663

A. Taher, B. Jones, P. Peumans, L. Lagae

{"title":"A Simplified Model for Species Transport in Very Large Scale Microfluidic Networks","authors":"A. Taher, B. Jones, P. Peumans, L. Lagae","doi":"10.1115/ICNMM2018-7663","DOIUrl":"https://doi.org/10.1115/ICNMM2018-7663","url":null,"abstract":"A novel modeling technique for fluid flow and species transport in very large scale microfluidic networks is developed with applications to massively parallelized microreactors. Very large scale integration (VLSI) of microfluidic circuits presents an attractive solution for many biological testing applications such as gene expression, DNA sequencing and drug screening, which require massive parallelization of reactions to increase throughput and decrease time-to-result. However, the design and modeling of VLSI microfluidics remains challenging with conventional 2D or 3D computational fluid dynamic (CFD) techniques due to the large computational resources required. Using simplified models is crucial to reduce simulation time on existing computational resources. Many microfluidic networks can be solved using resistance based networks similar to electrical circuits; however, simplified models for species transport (diffusion plus advection) in microfluidic networks has received much less attention.\u0000 Here, we introduce a simplified model based on resistance network based modeling for flow dynamics and couple it with a one-dimensional discretization of the advection-diffusion transport equation. The developed model was validated against CFD simulations using ANSYS Fluent for a flow network consisting of a 4 by 4 array of microreactors. It showed good agreement with 2D CFD simulations with less than 6% error in total pressure drop across the network for channels with a length to width ratio of 10. The error was only 3% for a channel length to width ratio of 20. The developed model was then used to optimize the design of a 100-microreactors network used for high purity cyclical loading of reagents. The reactor configuration with a minimum cycle time for reagent loading and unloading and minimum operating pressure were evaluated with the code. In theory, the simulation can be scaled to much larger reactor arrays after further optimizations of the code and utilizing parallel processing.","PeriodicalId":137208,"journal":{"name":"ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125578666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimization of Wettability Gradient for Enhancement of Thermal Performance of Micro Heat Pipes 提高微热管热性能的润湿梯度优化

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7666

Manjinder Singh, N. Datla, S. S. Bahga, S. Kondaraju

引用次数: 0

Evaluation of Liquid-Gas Two-Phase Flow Pressure Drop Signatures in Proton Exchange Membrane (PEM) Fuel Cell Flow Channels 质子交换膜燃料电池流道中液气两相流压降特征的评价

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7667

M. Mortazavi, Jingru Benner, Anthony D. Santamaria

引用次数: 4

Active Sensors for Gas-Liquid Mass Transfer Studies in Capillaries 毛细管气液传质研究的主动传感器

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7659

W. Krieger, R. Dinter, Georg K Wiese, S. Z. Horst-Meyer, N. Kockmann

{"title":"Active Sensors for Gas-Liquid Mass Transfer Studies in Capillaries","authors":"W. Krieger, R. Dinter, Georg K Wiese, S. Z. Horst-Meyer, N. Kockmann","doi":"10.1115/ICNMM2018-7659","DOIUrl":"https://doi.org/10.1115/ICNMM2018-7659","url":null,"abstract":"Gas-liquid and gas-liquid-solid reactions in microstructured devices are an active field in scientific research with many industrial applications. High surface-to-volume ratio as well as enhanced heat and mass transfer are advantageous making microstructured devices a promising technology to overcome mass transfer limitations. The implementation of traditional sensors and analytical methods is a drawback when investigating mass transfer phenomena within microstructured devices, since they disturb the flow and reactor characteristics. Offline measurement techniques provide limited insight into flow structure, while noninvasive online measurement techniques either cannot provide local results or require a sophisticated setup. In this work, a noninvasive ultrasonic sensor (SONOTEC, Germany) is used to measure particle concentration and bubble length in Taylor flow. Particle concentration and bubble detection is derived from the ultrasonic signal. Further, an Arduino based slider setup is developed, which is equipped with a computed-vision system to track bubbles in Taylor flow. This setup can be combined with optical analytical methods allowing for investigating the entire life time of a single bubble or liquid slug.","PeriodicalId":137208,"journal":{"name":"ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128094541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Flow Through Microchannels With Textured Walls: A Theory for Moderately Slow Variations 流动通过微通道与纹理壁:适度缓慢变化的理论

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7607

Mainendra Kumar Dewangan, S. Datta

引用次数: 0

Improving Liquid Supply Pathways on Graphene Oxide Coated Surfaces for Enhanced Pool Boiling Heat Transfer Performance 改善氧化石墨烯涂层表面的液体供应途径以提高池沸腾传热性能

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7714

A. Rishi, Anju Gupta, S. Kandlikar

{"title":"Improving Liquid Supply Pathways on Graphene Oxide Coated Surfaces for Enhanced Pool Boiling Heat Transfer Performance","authors":"A. Rishi, Anju Gupta, S. Kandlikar","doi":"10.1115/ICNMM2018-7714","DOIUrl":"https://doi.org/10.1115/ICNMM2018-7714","url":null,"abstract":"Graphene is a two-dimensional material that possesses excellent thermal properties and thus has gained an enormous attention in the applications of heat transfer. In this work, we demonstrate the enhancement of boiling heat transfer performance on substrate coated with graphene oxide and/or copper composites. The graphene oxide and/or copper composites were introduced on the substrate by two commonly used coating techniques-dip-coating and a two-step electrochemical deposition method. The focus of this paper is to compare the morphologies, surface properties such as wickability and porosity rendered by these coating methods and compare the resultant heat transfer coefficients and critical heat fluxes. The surfaces were characterized by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) techniques. Critical Heat Flux of 220 W/cm2 at the wall superheat of 14.8°C was achieved for the highest 2.5% GO-Cu electrodeposited chip, while CHF of 128 W/cm2 at the wall superheat of 13.2°C was achieved for the 5 minutes dip coated test surface.","PeriodicalId":137208,"journal":{"name":"ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels","volume":"114 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116496542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Evaporation From a Simulated Soil Pore: Effects of Relative Humidity 模拟土壤孔隙的蒸发:相对湿度的影响

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7628

P. Chakraborty, M. Derby

{"title":"Evaporation From a Simulated Soil Pore: Effects of Relative Humidity","authors":"P. Chakraborty, M. Derby","doi":"10.1115/ICNMM2018-7628","DOIUrl":"https://doi.org/10.1115/ICNMM2018-7628","url":null,"abstract":"Reduction of irrigation is a pressing issue in the food-water-energy nexus. Around two-third of global water withdrawals are used for irrigation in the areas with insufficient rainfall. In the U.S. Central High Plains, the Ogallala Aquifer is responsible for providing water for the production of corn, wheat, soybeans, and cattle; reducing the evaporation of water from soil provides an excellent opportunity to decrease the need for irrigation. In this paper, evaporation of sessile 4-μl water droplets from a single simulated soil pore was observed. Soil pores were created using three 2.35-mm hydrophilic glass or hydrophobic Teflon beads of the same size. The experiments were conducted at the same temperature (20° C) and two relative humidity levels, 45% and 60% RH. Evaporation times were recorded and the transport phenomena were captured using a high-speed camera. Relative humidity directly affected evaporation; evaporation times were lower at the lower RH. The glass surface had higher wettability and therefore the droplets were more stretched on the glass beads, more droplet-air areas were created and evaporation times were approximately 30 minutes at 60% RH. The Teflon surface was hydrophobic, for which air-water contact areas were lower, and evaporation times were longer — approximately 40 minutes at 60% RH. As evaporation progressed, a liquid island formed between two beads at both 45% and 60% RH in for glass and Teflon pores. The rate of decrease of the radius of the liquid island was shorter in Teflon than glass beads, which corresponded to lower evaporation rates from Teflon.","PeriodicalId":137208,"journal":{"name":"ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125413129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Effect of the Pressure Drop Oscillation on the Local Heat Transfer Coefficient in a Heated Horizontal Pipe 压降振荡对受热水平管内局部换热系数的影响

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7652

I. Park, M. Fernandino, C. Dorao

引用次数: 1

Transient Local Resolution of Flow Boiling in a Microchannel With a Streamlined Pin Fin

ASME 2018 16th International Conference on Nanochannels, Microchannels, and Minichannels Pub Date : 2018-06-10 DOI: 10.1115/ICNMM2018-7602

A. Parahovnik, Yingying Wang, Y. Peles

引用次数: 4