Download or read book Simulation of Three dimensional Laminar Flow and Heat Transfer in an Array of Parallel Microchannels written by Justin Dale Mlcak and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer and fluid flow are studied numerically for a repeating microchannel array with water as the circulating fluid. Generalized transport equations are discretized and solved in three dimensions for velocities, pressure, and temperature. The SIMPLE algorithm is used to link pressure and velocity fields, and a thermally repeated boundary condition is applied along the repeating direction to model the repeating nature of the geometry. The computational domain includes solid silicon and fluid regions. The fluid region consists of a microchannel with a hydraulic diameter of 85.58[mu]m. Independent parameters that were varied in this study are channel aspect ratio and Reynolds number. The aspect ratios range from 0.10 to 1.0 and Reynolds number ranges from 50 to 400. A constant heat flux of 90 W/cm2 is applied to the northern face of the computational domain, which simulates thermal energy generation from an integrated circuit. A simplified model is validated against analytical fully developed flow results and a grid independence study is performed for the complete model. The numerical results for apparent friction coefficient and convective thermal resistance at the channel inlet and exit for the 0.317 aspect ratio are compared with the experimental data. The numerical results closely match the experimental data. This close matching lends credibility to this method for predicting flows and temperatures of water and the silicon substrate in microchannels. Apparent friction coefficients linearly increase with Reynolds number, which is explained by increased entry length for higher Reynolds number flows. The mean temperature of water in the microchannels also linearly increases with channel length after a short thermal entry region. Inlet and outlet thermal resistance values monotonically decrease with increasing Reynolds number and increase with increasing aspect ratio. Thermal and friction coefficient results for large aspect ratios (1 and 0.75) do not differ significantly, but results for small aspect ratios (0.1 and 0.25) notably differ from results of other aspect ratios.

Download or read book Numerical Simulation of Fluid Flow and Heat Transfer in Microchannels with Three dimensional Microstructures written by Olawale Olanrewaju and published by . This book was released on 2007 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulations of Laminar Transitional and Turbulent Flow and Heat Transfer in Continuous and Interrupted plate Channels written by Kelechi Ezeji and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The long-term goal of this research is to contribute to the development of mathematical models and numerical solution methods for use as cost-effective tools in procedures for designing the next generation of compact and ultra-compact heat exchangers (core heat transfer area density exceeding 700 m^2/m^3 and 3000 m^2/m^3, respectively). Such heat exchangers are expected to play a major role in ongoing worldwide efforts to propose novel energy conversion systems. The desire to participate in such efforts is the main motivation for this work. Attention in this work was focused on rectangular offset strip-fin plate-fin core configurations. Over the last 50 years, there have been many efforts to increase the compactness of such cores. However, increasing compactness reduces the hydraulic diameter and (hence) the Reynolds number, for the same average velocity, which can lead to turbulent-to-laminar transition. These consequences of increasing compactness bring up the issue of its effect on the rate of heat transfer for a fixed pumping power. The rectangular offset strip-fin plate-fin configuration causes starting, interrupting, and restarting of both velocity and thermal boundary layers, and also possible unsteadiness and vortex shedding; and these thermofluid features bring up the issue of maximizing heat transfer for specified heat transfer surface area and fixed pumping power.The main goal of this research was to contribute to the resolution of the first of the aforementioned two issues, in a highly cost-effective manner. Thus, fins of negligible thickness and flow passages of large cross-sectional aspect ratio were assumed, and attention was limited to steady two-dimensional fluid flow and heat transfer phenomena. Air was the fluid of choice, and it was assumed that its thermophysical properties remained essentially constant. Furthermore, the Eckert number was much less than one in the problems considered here, so viscous dissipation could be ignored.Elliptic and parabolic mathematical models of developing fluid flow and heat transfer in continuous parallel-plate channels and arrays of regular staggered plates were considered. Three different low-Reynolds-number turbulence models (all capable of predicting turbulent-laminar transition with reduction in Reynolds number) were selected for comparative assessment. These mathematical models were solved using two-dimensional elliptic (2DE) and parabolic (2DP) finite volume methods (FVMs): the 2DE FVM was an adapted version of an in-house code; the 2DP FVM was specially formulated and implemented for this work, retaining the momentum equation in the direction transverse to the main flow (a novel feature of the proposed method). Mathematical models of fully developed fluid flow and heat transfer in pipes and parallel-plate channels were also considered and solved using one-dimensional FVMs. The results were compared to those yielded by available empirical correlations and also experimental data. Finally, one of the three low-Reynolds-number turbulence models and the 2DP FVM were used to simulate fluid flow and heat transfer in three actual rectangular offset strip-fin plate-fin cores of compact heat exchangers.For fully developed flows, all three low-Reynolds-number turbulence models considered in this work gave results that showed excellent agreement with those yielded by available empirical correlations and also experimental data. For developing fluid flow and heat transfer, the 2DP results compared very well with the 2DE results; however, the 2DP FVM executed 700 to 12,000 times faster than the 2DE FVM for comparable computational grids. In simulations of developing fluid flow and heat transfer in continuous-plate channels and regular arrays of staggered plates, only one of the three low-Reynolds-number turbulence models gave good results. The details of the models, numerical methods, and results, and also some recommendations, are presented and discussed in this thesis." --

Download or read book Advances in New Heat Transfer Fluids written by Alina Adriana Minea and published by CRC Press. This book was released on 2017-03-16 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heat transfer enhancement has seen rapid development and widespread use in both conventional and emerging technologies. Improvement of heat transfer fluids requires a balance between experimental and numerical work in nanofluids and new refrigerants. Recognizing the uncertainties in development of new heat transfer fluids, Advances in New Heat Transfer Fluids: From Numerical to Experimental Techniques contains both theoretical and practical coverage.

Download or read book Master s Theses Directories written by and published by . This book was released on 2007 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Education, arts and social sciences, natural and technical sciences in the United States and Canada".

Download or read book Microscale and Nanoscale Heat Transfer written by C.B. Sobhan and published by CRC Press. This book was released on 2008-06-12 with total page 317 pages. Available in PDF, EPUB and Kindle. Book excerpt: Through analyses, experimental results, and worked-out numerical examples, Microscale and Nanoscale Heat Transfer: Fundamentals and Engineering Applications explores the methods and observations of thermophysical phenomena in size-affected domains. Compiling the most relevant findings from the literature, along with results from their own re

Download or read book Numerical Simulation of Laminar Flow and Heat Transfer in Two Dimensional Channels written by Paul D. Hancock and published by . This book was released on 1992 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1994 with total page 1036 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Issues in Mechanical Engineering 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 2526 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Mechanical Engineering / 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Mechanical Engineering. The editors have built Issues in Mechanical Engineering: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Mechanical Engineering in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Mechanical Engineering: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Heat Transfer and Fluid Flow in Minichannels and Microchannels written by Satish Kandlikar and published by Elsevier. This book was released on 2006 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: &Quot;This book explores flow through passages with hydraulic diameters from about 1 [mu]m to 3 mm, covering the range of minichannels and microchannels. Design equations along with solved examples and practice problems are also included to serve the needs of practicing engineers and students in a graduate course."--BOOK JACKET.

Download or read book Three dimensional Numerical Simulation of Fluid Flow and Heat Transfer in Fin and tube Heat Exchangers at Different Flow Regimes written by Leslye Paniagua Sánchez and published by . This book was released on 2014 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis aims at unifying two distinct branches of work within the Heat Transfer Technological Center (CTTC). On one side, extensive experimental work has been done during the past years by the researchers of the laboratory. This experimental work has been complemented with numerical models for the calculation of fin and tube heat exchangers thermal and fluid dynamic behavior. Such numerical models can be referred to as fast numerical tool which can be used for industrial rating and design purposes. On the other hand, the scientists working at the research center have successfully developed a general purpose multi-physics Computational Fluid Dynamics (CFD) code (TermoFluids). This high performance CFD solver has been extensively used by the co-workers of the group mainly to predict complex flows of great academic interest. The idea of bringing together this two branches, comes from the necessity of a reliable numerical platform with detailed local data of the flow and heat transfer on diverse heat exchanger applications. Being able to use local heat transfer coefficients as an input on the rating and design tool will lead to affordable and accurate prediction of industrial devices performance, by which the center can propose enhanced alternatives to its industrial partners. To accomplish these goals, several contributions have been made to the existing TermoFluids software which is in continuous evolution in order to meet the competitive requirements. The most significant problematics to adequately attack this problem are analyzed and quite interesting recommendations are given. Some of the challenging arising issues involve the generation of suitable and affordable meshes, the implementation and validation of three dimensional periodic boundary condition and coupling of different domains with important adjustments for the study of cases with different flow physics like time steps and thermal development. Turbulence is present in most of engineering flows, and refrigeration evaporator heat exchangers are not an exception. The presence of many tubes (acting like bluff bodies for the flow) arranged in different configurations and the fact that the flow is also confined by fins, create complex three dimensional flow features that have usually turbulent or transition to turbulent regime. Therefore, three dimensional turbulent forced convection in a matrix of wall-bounded pins is analyzed. Large Eddy Simulations (LES) are performed in order to assess the performance of three different subgrid-scale models, namely WALE, QR and VMS. The Reynolds numbers of the study were set to 3000, 10000 and 30000. Some of the main results included are the pressure coefficient around the cylinders, the averaged Nusselt number at the endwalls and vorticity of the flow. The final part of the thesis is devoted to study the three dimensional fluid flow and conjugated heat transfer parameters encountered in a plate fin and tube heat exchanger used for no-frost refrigeration. The numerical code and post processing tools are validated with a very similar but smaller case of a heat exchanger with two rows of tubes at low Reynolds for which experimental data is available. The next analysis presented is a typical configuration for no-frost evaporators with double fin spacing (for which very few numerical data is reported in the scientific literature). Conjugated convective heat transfer in the flow field and heat conduction in the fins are coupled and considered. The influence of some geometrical and flow regime parameters is analyzed for design purposes. In conclusion, the implementations and general contributions of the present thesis together with the previous existent multi-physics computational code, has proved to be capable to perform successful top edge three dimensional simulations of the flow features and heat transfer mechanisms observed on heat exchanger devices.

Download or read book Numerical Simulation of Unsteady Three Dimensional Fluid Flow and Heat Transfer Occurring in Open Channel Forehearths written by Yun Shang Lin and published by . This book was released on 1985 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microchannels and Minichannels ICMM2004 written by Satish G. Kandlikar and published by . This book was released on 2004 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Analysis of Wavy Microchannel Systems written by Roxana Durantes Sandoval and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, numerical simulations of the convective heat transfer on single-phase fluid flow wavy microchannel exposed to a heat flux are presented. First, a methodology based on local and global energy balances in the device instead of the commonly used Nusselt number is proposed to investigate the heat transfer enhancement in these systems. Then, to reduce the computational cost, an examination of the validity of two-dimensional approximations of three-dimensional is performed. A systematic approach is used to determine when the two-dimensional approximation for different channel width values departs from the three-dimensional original model and at what width values it isreasonable to make a two-dimensional simplification. For comparison, a two-dimensional model is also built and solved. The governing equations for an incompressible laminar flow and conjugate heat transfer are solved for representative models, under steady state and several operating conditions, by the finite element method. Results show that theaveraged energy-balance methodology enables higher accuracy than that based on the Nusselt number since neither heat transfer coefficients nor characteristic temperatures are needed. For the two-dimensional approximation, as the width is increased beyond 15 mm in width, results in the three-dimensional model tend to approach the ones of thetwo-dimensional model. Two-dimensional models require less memory and computational time, and they can have some advantages when performing parameter optimization.

Download or read book Direct Numerical Simulations of Three dimensional Flow and Augmented Heat Transfer in a Symmetrically Grooved Channel with Constant Temperature Walls written by Robert J. Faulkner and published by . This book was released on 1997 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Three Dimensional Laminar and Turbulent Convection in Separated Flow written by Magesh Thiruvengadam and published by . This book was released on 2008 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Three-dimensional laminar and turbulent separated flow and heat transfer in plane symmetric sudden expansion and plane backward facing step is examined in this dissertation. In Papers I, II, and III, simulations of 3-D laminar forced convection in plane symmetric expansion is studied...In Paper IV, 3-D turbulent flow measurements using Laser Doppler Velocimeter are made in a backward facing step flow and the three velocity components and the Reynolds stresses are measured in the separated and redeveloping flow region...In Paper V, the 2-D behavior of a thin film that is shear driven by turbulent air flow is simulated"--Abstract, leaf iv.

Download or read book Development of the Three dimensional Finite Analytic Method for Simulation of Fluid Flow and Conjugate Heat Transfer written by Ramiro Humberto Bravo and published by . This book was released on 1991 with total page 900 pages. Available in PDF, EPUB and Kindle. Book excerpt: