Two-phase Transport Phenomena in Microfluidic Devices - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Two-phase Transport Phenomena in Microfluidic Devices write by Cheng-Chieh Hsieh. This book was released on 2003. Two-phase Transport Phenomena in Microfluidic Devices available in PDF, EPUB and Kindle.
Transport Phenomena in Microfluidic Systems
Transport Phenomena in Microfluidic Systems - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Transport Phenomena in Microfluidic Systems write by Pradipta Kumar Panigrahi. This book was released on 2016-02-15. Transport Phenomena in Microfluidic Systems available in PDF, EPUB and Kindle. Fully comprehensive introduction to the rapidly emerging area of micro systems technology Transport Phenomena in Micro Systems explores the fundamentals of the new technologies related to Micro-Electro-Mechanical Systems (MEMS). It deals with the behavior, precise control and manipulation of fluids that are geometrically constrained to a small, typically sub-millimeter, scale, such as nl, pl, fl, small size, low energy consumption, effects of the micro domain and heat transfer in the related devices. The author describes in detail and with extensive illustration micro fabrication, channel flow, transport laws, magnetophoresis, micro scale convection and micro sensors and activators, among others. This book spans multidisciplinary fields such as material science and mechanical engineering, engineering, physics, chemistry, microtechnology and biotechnology. Brings together in one collection recent and emerging developments in this fast-growing area of micro systems Covers multidisciplinary fields such as materials science, mechanical engineering, microtechnology and biotechnology, et al Comprehensive coverage of analytical models in microfluidics and MEMS technology Introduces micro fluidics applications include the development of inkjet printheads, micro-propulsion, and micro thermal technologies Presented in a very logical format Supplies readers with problems and solutions
Transport Phenomena in Microfluidic Devices [microform]
Transport Phenomena in Microfluidic Devices [microform] - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Transport Phenomena in Microfluidic Devices [microform] write by Liqing Ren. This book was released on 2004. Transport Phenomena in Microfluidic Devices [microform] available in PDF, EPUB and Kindle. Both experimental and numerical studies about the transport phenomena in microfluidic devices are presented in this thesis. The transport phenomena of interest are pressure driven flow and electroosmotic driven flow with a Reynolds number on the order of unit, and the associated mass transport phenomena. The studied microfluidic devices include fused silicon capillaries, in-house made glass microchannels and a glass chip with a crossing-linked microchannel etched into its surface. The hydraulic diameter ranges from 20 mum to 200 mum. The on-chip sample injection processes are studied both experimentally and numerically. Fluorescent dyes are employed here as the sample and the sample injection (loading and dispensing) processes on a microfluidic chip are visualized using an in-house developed laser visualization system and techniques. The experimentally measured sample injection process is compared with the numerical simulation results. Reasonable agreements were found between the model predictions and experimental measurements. The model is further developed in order to improve the simulation accuracy and save significant computation time as compared with the previous model. A general model capable of simulating general on-chip injection processes is finally developed to make the numerical analysis tools complete. This general model considers the electrical conductivity difference present at microfluidic applications, which is not considered normally due to its complexity. The electroosomotic flow is commonly applied in microfluidic devices as a pump, therefore, the flow rate determination is of particular interest. An experimental setup and corresponding data acquisition system are developed to measure electroosmotic flow rate by employing solution displacement process and current monitoring technique. A theoretical model is developed to improve the accuracy of this technique. A numerical model is developed to simulate this displacing process and to obtain flow rate. Good agreements between numerical simulations and experimental measurements verified the developed model. The electrokinetic transport phenomena of pressure driven flow in microchannels are studied based on a simultaneous solution to the developed pressure driven flow model. It is found that the flow characteristics of microchannels differ significantly from that in macrosized devices showing high viscous effects. The numerical results are compared with the experimental measurements and good agreement verified the developed model.
Phase Separation in Two-phase Microfluidic Heat Exchangers
Phase Separation in Two-phase Microfluidic Heat Exchangers - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Phase Separation in Two-phase Microfluidic Heat Exchangers write by Milnes P. David. This book was released on 2011. Phase Separation in Two-phase Microfluidic Heat Exchangers available in PDF, EPUB and Kindle. Two-phase microfluidic heat exchangers have the potential to meet the large heat dissipation demands of high power electronics and computing systems. Two-phase cooling systems face practical challenges brought on by the growth and advection of the vapor phase in the confined geometries, which lead to large pressure drops, increased thermal resistance and the formation of detrimental flow instabilities. One proposed solution to these issues is phase separation, whereby the vapor is locally separated from the two-phase flow through a porous hydrophobic membrane. This dissertation describes a series of studies conducted to develop an understanding of the factors that influence vapor separation and its impact on the hydraulic and thermal characteristics of two-phase heat exchangers. Flow phenomena are a critical component in developing this understanding of phase separation. High speed visualization of adiabatic and diabatic vaporizing flows was carried out in a single 124[Mu]m by 98[Mu]m copper microchannel with a 65[Mu]m thick, 220nm pore diameter hydrophobic PTFE membrane wall. During adiabatic air-water flow, wavy-stratified and stratified flow dominated lower liquid velocities, while plug and annular type flows dominated at the higher velocities. Analysis found that air removal could be improved by increasing the venting area, increasing the trans-membrane pressure or using thinner, high permeability membranes. Diabatic water-vapor experiments with mass flux velocities of 140 and 340 kg/s-m2 and exit qualities up to 20% found that stratified type flows dominate at lower mass fluxes while cyclical churn-annular flow became more prevalent at the higher mass-flux and quality. The observed flow regimes are hypothesized to play a significant role in determining the pressure drop and heat transfer coefficient during flow boiling. To study the impact of various geometric and membrane factors on the performance of a phase separating microchannel heat exchanger dissipating 100W of heat, a numerical model incorporating vapor separation and transport during two-phase flow boiling in a microchannel was developed. The impact of substrate thermal conductivity and thickness, membrane permeability and thickness, liquid channel density, liquid and vent channel diameter and vent-to-liquid channel diameter ratio was studied and compared for a standard non-venting heat exchanger, a vapor venting heat exchanger and a non-venting heat exchanger occupying the same increased volume as the venting heat exchanger. The numerical study found that the venting heat exchanger had improved pressure drop and device temperatures for all tested conditions when compared against a standard heat exchanger but only under very limited conditions when compared against the volumetrically equivalent non-venting heat exchanger. The study indicates that the best venting heat exchanger performance is achieved when the membrane conductance is of the same order or higher than that of the microchannel; this can be achieved through the use of thin high permeability membranes coupled with small hydraulic diameter microchannels. Finally, a study was conducted to explore the fabrication methods to build a vapor separating heat exchanger and to quantify the operating performance of multichannel silicon and copper phase separating devices. A copper parallel microchannel heat exchanger with nineteen 130[Mu]m square microchannels was built and tested at heat fluxes of up to 820 kW/m2 and water mass fluxes of between 102 and 420 kg/s-m2. Normalized pressure drop was improved by as much as 60% and average substrate temperature by a maximum of 4.4°C between the non-venting control and vapor venting device under similar operating conditions. Comparison between the experimental results and simulation predictions found higher than expected pressure drop improvements at higher mass fluxes and poorer heat transfer coefficients at the lowest mass flux. Based on the flow phenomena study these discrepancies are believed to be due to the mass flux and vapor quality dependent two-phase flow structures. The encouraging experimental and numerical results motivate further study into phase separation methods, materials and flow physics. The development of a high performance phase separating heat exchanger, with the thermal benefits of two-phase boiling flow and the hydraulic benefits of single-phase liquid flow, would strongly enable the adoption and application of two-phase heat exchangers to provide effective and efficient cooling for next generation high power computing systems.
Micro- and Nanoscale Fluid Mechanics
Micro- and Nanoscale Fluid Mechanics - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Micro- and Nanoscale Fluid Mechanics write by Brian J. Kirby. This book was released on 2010-07-26. Micro- and Nanoscale Fluid Mechanics available in PDF, EPUB and Kindle. This text focuses on the physics of fluid transport in micro- and nanofabricated liquid-phase systems, with consideration of gas bubbles, solid particles, and macromolecules. This text was designed with the goal of bringing together several areas that are often taught separately - namely, fluid mechanics, electrodynamics, and interfacial chemistry and electrochemistry - with a focused goal of preparing the modern microfluidics researcher to analyse and model continuum fluid mechanical systems encountered when working with micro- and nanofabricated devices. This text serves as a useful reference for practising researchers but is designed primarily for classroom instruction. Worked sample problems are included throughout to assist the student, and exercises at the end of each chapter help facilitate class learning.
