Steady and Transient Conjugate Heat Transfer in Rectangular Microchannel Heat Sinks PDF Download

Author: Kiran K. Ambatipudi
Publisher:
ISBN:
Category : Heat sinks (Electronics)
Languages : en
Pages : 230

View

Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description

Author: Phaninder Injeti
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
ABSTRACT: In this project we studied the effect of different parameters on heat transfer in two-dimensional microchannels, microtubes and also tube-in-block heat exchangers for various engineering applications. These included the use of flow restrictions to enhance local heat or mass transfer rate, enhancement of conjugate heat transfer with discrete heating and magnetic coolers (or heaters) associated with magnetic refrigeration system. The results of this research will help in designing the heating or cooling systems and selection of their appropriate geometrical dimensions and materials for specific applications. Types of problems studied in this project are: steady state analysis of forced convection around a restricted flow passage in a micro channel, effect of protrusions in a microtube or microchannel for conjugate heat transfer with uniform or discrete heating and transient analysis of heat transfer in trapezoidal microchannels under time varying heat source. For each of these problems a numerical simulation model was developed. The mass, momentum, and energy conservation equations were solved in the fluid region and energy conservation in the sold region to arrive at the velocity and the temperature distributions. Detailed parametric study was carried out for each problem. The parameters were shape and size of the restriction/protrusion, number of restrictions/protrusions, wall thickness, Reynolds number, solid materials and working fluids. The results showed that in microtubes the local value of Nusselt number increases at the restriction/protrusion and the global value for the whole tube is somewhat lower. For a two-dimensional microchannel, both the local Nusselt number at the restriction/protrusion as well as the global Nusselt number for the entire channel is higher. In the trapezoidal channels the results showed that with the increase in Reynolds number, the outlet temperature decreased and the average heat transfer coefficient increased. With an increase in magnetic field there was an increase in the solid fluid interface temperature and in turn the average heat transfer coefficient increased. With a decrease in the channel height and width there was an increase in the average Nusselt number in the channel.

Author: Satish Kandlikar
Publisher: Elsevier
ISBN: 9780080445274
Category : Science
Languages : en
Pages : 492

View

Book Description
&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.

Author: Lian Zhang
Publisher: Springer Science & Business Media
ISBN: 3662098997
Category : Technology & Engineering
Languages : en
Pages : 148

View

Book Description
Two-phase microchannel cooling is one of the most promising thermal-management technologies for future high-power IC chips. Understanding the boiling process and the two-phase-flow behavior in microchannels is the key to successful implementation of a microchannel heat sink. This book focuses on the phase-change phenomena and the heat transfer in sub-150 nm diameter silicon microchannels, with emphasis on thermal measurement and modeling, and the impact of small dimensions on two-phase flow regimes.

Author: Marc Robert Greenland
Publisher:
ISBN:
Category : Heat
Languages : en
Pages :

View

Book Description
In this study the heat transfer and hydrodynamic parameters were experimentally investigated for a single microchannel housed in a stainless steel solid base material for different aspect ratios in the laminar regime with water as the working fluid. The stainless steel base material had a low thermal conductivity (15.1 W / mK) which magnified the conjugative effects in order to better understand the heat transfer. Rectangular microchannels with a height and width of 0.64 mm x 0.41 mm for Test Section 1, 0.5 mm x 0.5 mm for Test Section 2 and 0.43 mm x 0.58 mm for Test Section 3 were considered. The overall width of the solid substrate was 1.5 mm and the length was 50 mm for all of the test sections. The aspect ratio of the channel and the solid substrate was kept equal. A constant heat flux of 10 W / cm2 was applied to the bottom outer wall of the test section. A sudden contraction inlet and a sudden expansion outlet manifold contained pressure ports, to measure the pressure drop across the test sections, and thermocouples measured the mean inlet and outlet fluid temperatures. Thermocouples were used to measure the outer top and side wall temperatures at four equally spaced positions along the axial direction. The amount of axial heat conduction was below 0.6 % for all of the test sections and therefore warranted the use of a two-dimensional conduction model to determine the heat transfer parameters at the fluid to solid interface based on the outer measured wall temperatures. The local Nusselt number decreased, along the axial direction but increased towards the exit for all of the test sections. The average Nusselt number increased with the flow rate and the critical Reynolds number for fully turbulent flow Test Section 1 was 1950, for Test Section 2 was 2250 and for Test Section 3 was 1650. The average Nusselt number was directly related to the perimeter of the microchannels two side walls and the bottom wall (not the top wall), and thus decreased as the aspect ratio of the channel increased. The experimentally determined Nusselt numbers were larger for all three test sections when compared to common acceptable correlations. The friction factor decreased with the flow rate and was smaller in magnitude when compared to conventional theories. The diabatic friction factor magnitudes were smaller than the adiabatic friction factors. The friction factor decreased as the aspect ratio decreased, where the aspect ratio was calculated by taking the maximum of the microchannels width or height, divided by the minimum of the two. The possibility of a relationship could exist between the Colburn j-factor and the friction factor when considering the results for Test Section 1 and Test Section 2 but the results for Test Section 3 were significantly different.

Author: Jose Raul Rujano Maldonado
Publisher:
ISBN:
Category : Heat sinks (Electronics)
Languages : en
Pages : 200

View

Book Description

Author: Srikanth Rangarajan
Publisher: CRC Press
ISBN: 1000752836
Category : Science
Languages : en
Pages : 223

View

Book Description
Phase-change Material based heat sinks and associated optimization remains a topic of great interest, as evident from the increasing number of citations and new applications and miniaturization. Often the multi objective perspective of such heat sinks is ignored. This book introduces the readers to the PCM based heat sinks and Multi objective optimization. The authors have also included interesting in house experimental results on the "Rotating heat sinks" which is a first of a kind work. Useful to budding thermal researchers and practicing engineers in the field, this book is also a great start for students to understand the cooling applications in electronics and an asset to every library in a technical university. Since this book not only gives a critical review of the state of the art but also presents the authors' own results. The book will encourage, motivate and let the reader consider pursuing a research career in electronic cooling technologies.

Author: Abram S. Dorfman
Publisher: John Wiley & Sons
ISBN: 1119320569
Category : Technology & Engineering
Languages : en
Pages : 458

View

Book Description
Applications of mathematical heat transfer and fluid flow models in engineering and medicine Abram S. Dorfman, University of Michigan, USA Engineering and medical applications of cutting-edge heat and flow models This book presents innovative efficient methods in fluid flow and heat transfer developed and widely used over the last fifty years. The analysis is focused on mathematical models which are an essential part of any research effort as they demonstrate the validity of the results obtained. The universality of mathematics allows consideration of engineering and biological problems from one point of view using similar models. In this book, the current situation of applications of modern mathematical models is outlined in three parts. Part I offers in depth coverage of the applications of contemporary conjugate heat transfer models in various industrial and technological processes, from aerospace and nuclear reactors to drying and food processing. In Part II the theory and application of two recently developed models in fluid flow are considered: the similar conjugate model for simulation of biological systems, including flows in human organs, and applications of the latest developments in turbulence simulation by direct solution of Navier-Stokes equations, including flows around aircraft. Part III proposes fundamentals of laminar and turbulent flows and applied mathematics methods. The discussion is complimented by 365 examples selected from a list of 448 cited papers, 239 exercises and 136 commentaries. Key features: Peristaltic flows in normal and pathologic human organs. Modeling flows around aircraft at high Reynolds numbers. Special mathematical exercises allow the reader to complete expressions derivation following directions from the text. Procedure for preliminary choice between conjugate and common simple methods for particular problem solutions. Criterions of conjugation, definition of semi-conjugate solutions. This book is an ideal reference for graduate and post-graduate students and engineers.

Author: Yuri B. Zudin
Publisher: Springer Science & Business Media
ISBN: 3540707255
Category : Science
Languages : en
Pages : 162

View

Book Description
Here is a new method for calculating heat transfer in coupled convective-conductive fluid-wall systems under periodical intensity oscillations in fluid flow. The true steady state mean value of the heat transfer coefficient must be multiplied by a newly defined coupling factor, which is always smaller than one and depends on the coupling parameters Biot number, Fourier number as well as dimensionless geometry and oscillation parameters. Includes characteristic solved problems, with tables and diagrams.