Effect of surface roughness in microchannels on heat transfer

Download

index.pdf

Date

2008

Author

Turgay, Metin Bilgehan

Metadata

Show full item record

Item Usage Stats

293
views

123
downloads

In this study, effect of surface roughness on convective heat transfer and fluid flow in two dimensional parallel plate microchannels is analyzed by numerically. For this purpose, single-phase, developing, laminar fluid flow at steady state and in the slip flow regime is considered. The continuity, momentum, and energy equations for Newtonian fluids are solved numerically for constant wall temperature boundary condition. Slip velocity and temperature jump at wall boundaries are imposed to observe the rarefaction effect. Effect of axial conduction inside the fluid and viscous dissipation also considered separately. Roughness elements on the surfaces are simulated by triangular geometrical obstructions. Then, the effect of these roughness elements on the velocity field and Nusselt number are compared to the results obtained from the analyses of flows in microchannels with smooth surfaces. It is found that increasing surface roughness reduces the heat transfer at continuum conditions. However in slip flow regime, increase in Nusselt number with increasing roughness height is observed. Moreover, this increase is found to be more obvious at low rarefied flows. It is also found that presence of axial conduction and viscous dissipation has increasing effect on heat transfer in smooth and rough channels.

Subject Keywords

Mechanical engineering.

URI

http://etd.lib.metu.edu.tr/upload/12610253/index.pdf
https://hdl.handle.net/11511/18343

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Analysis of single phase convective heat transfer in microtubes and microchannels Çetin, Barbaros; Yüncü, Hafit; Department of Mechanical Engineering (2005) Heat transfer analysis of two-dimensional, incompressible, constant property, hydrodynamically developed, thermally developing, single phase laminar flow in microtubes and microchannels between parallel plates with negligible axial conduction is performed for constant wall temperature and constant wall heat flux thermal boundary conditions for slip flow regime. Fully developed velocity profile is determined analytically, and energy equation is solved by using finite difference method for both of the geometr...
Analysis of single phase convective heat transfer in microchannels with variable thermal conductivity and variable viscosity Gözükara, Arif Cem; Güvenç Yazıcıoğlu, Almıla; Department of Mechanical Engineering (2010) In this study simultaneously developing single phase, laminar and incompressible flow in a micro gap between parallel plates is numerically analyzed by including the effect of variation in thermal conductivity and viscosity with temperature. Variable property solutions for continuity, momentum and energy equations are performed in a coupled manner, for air as a Newtonian fluid. In these analyses the rarefaction effect, which is important for the slip flow regime, is taken into account by imposing slip veloc...
Transient dynamic response of viscoelastic cylinders enclosed in filament wound cylindrical composites Şen, Özge; Turhan, Doğan; Department of Engineering Sciences (2005) In this study, transient dynamic response of viscoelastic cylinders enclosed in filament wound cylindrical composites is investigated. Thermal effects, in addition to mechanical effects, are taken into consideration. A generalized thermoelasticity theory which incorporates the temperature rate among the constitutive variables and is referred to as temperature-rate dependent thermoelasticity theory is employed. This theory predicts finite heat propagation speeds. The body considered in this thesis consists o...
Numerical analysis of natural convective heat transfer through porous medium Aylangan, Benan; Yüncü, Hafit; Department of Mechanical Engineering (2006) In this thesis, natural convective heat transfer through an impermeable and fluid saturated porous medium is investigated numerically. A FORTRAN based code is developed and used in order to present the outputs of the applied model and the assumptions. The solutions of flow fields and temperature fields are presented within the medium. Moreover, Nusselt number variations for different values of Darcy, Prandtl, and Rayleigh numbers, and some other thermodynamic properties are investigated and presented. Compa...
Numerical simulation and analytical optimization of microchannel heat sinks Türkakar, Göker; Okutucu Özyurt, Hanife Tuba; Department of Mechanical Engineering (2010) This study has two main objectives: The performance evaluation of existing microchannel heat sinks using a CFD model, and the dimensional optimization of various heat sinks by minimizing the total thermal resistance. For the analyses, the geometric modeling is performed using the software GAMBIT while the thermal analysis is performed with FLUENT. The developed model compares very well with those available in the literature. Eight different metal-polymer microchannel heat sinks are analyzed using the model ...

Citation Formats

M. B. Turgay, “Effect of surface roughness in microchannels on heat transfer,” M.S. - Master of Science, Middle East Technical University, 2008.