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thermal-entrance-lengths
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Analysis of micro channel heat sink performance
, Article 2005 SEM Annual Conference and Exposition on Experimental and Applied Mechanics, Portland, OR, 7 June 2005 through 9 June 2005 ; 2005 , Pages 1911-1918 ; 0912053909 (ISBN) ; Salehi, M ; Khiabani, R. H ; Sharif University of Technology
2005
Abstract
In the present research a numerical investigation has been made to evaluate the results of analytical approach in the analysis of micro channel heat sink (MCHS) which is increasingly used in the cooling of high heat dissipating electronic devices. In this regard the effects of geometrical and flow parameters affecting the absolute thermal resistance of MCHS have been analyzed. The effect of using different fluids in the value of the thermal resistance is considered as well. The accuracy of analytical method in predicting heat transfer and fluid flow regimes in micro channel is checked in comparison with numerical method. The effects of hydraulic and thermal entrance lengths of these systems...
Transient and steady-state forced convection to power-law fluids in the thermal entrance region of circular ducts: Effects of viscous dissipation, variable viscosity, and axial conduction
, Article Energy Conversion and Management ; Volume 51, Issue 5 , May , 2010 , Pages 1065-1074 ; 01968904 (ISSN) ; Memari, M ; Sharif University of Technology
2010
Abstract
A numerical study was conducted on the transient behavior of a hydrodynamically fully developed, laminar flow of power-law fluids in the thermally developing entrance region of circular ducts with taking into account the effects of viscous dissipation, axial conduction, and variations of viscosity with temperature. In this regard, the unsteady-state thermal energy and momentum equations were solved numerically using a finite-difference method, whereas the steady-state thermal energy equation with constant wall heat flux as the boundary condition was solved analytically as the initial condition of the former. The numerical procedure used in the present work was validated with an analytical...
Simulation of thermally developing laminar ow in partially filled porous pipes under wall suction
, Article Scientia Iranica ; Volume 23, Issue 6 , 2016 , Pages 2641-2649 ; 10263098 (ISSN) ; Seyyed Hashemi, M. H ; Sharif University of Technology
Sharif University of Technology
Abstract
This study numerically investigates uid ow and heat transfer enhancement of a two-dimensional developing laminar ow in an axisymmetric pipe with partially filled porous material attached to the wall. The effects of porous layer in the range of 0 ≤ δ=R < 1 and Darcy number in the range of 10-6 ≤ Da ≤ 10-4 are investigated. It is found that thermal entrance length increases with porous layer thickness and is longer than a plain pipe. In addition, the dependence of Nusselt number on the thickness of the porous layer is not monotonic. A critical value of the porous layer thickness exists at which the Nusselt number value reaches the minimum. As the porous layer is thickening, more uid is pushed...
Heat transfer enhancement in annular flow with outer grooved cylinder and rotating inner cylinder: review and experiments
, Article Applied Thermal Engineering ; Volume 120 , 2017 , Pages 257-268 ; 13594311 (ISSN) ; Nakhchi, M. E ; Sharif University of Technology
Abstract
This experimental work is an attempt to identify the most significant parameters influencing heat transfer enhancement in annular flow with outer grooved cylinder and rotating inner cylinder. This type of flow known as Taylor-Couette flow has many industrial applications such as electrical power generators and rotating machineries. A comprehensive review of the previous works on flow regimes, heat transfer and pressure drop in grooved channels is provided. The experiments are conducted based on four different factors including Taylor number, 0
Numerical study of heat transfer between shell-side fluid and shell wall in the spiral-wound heat exchangers
, Article International Journal of Refrigeration ; Volume 120 , December , 2020 , Pages 285-295 ; Afshin, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Heat transfer between heat exchangers and the surrounding environment, referred to as heat-in-leak, is a crucial phenomenon in the cryogenic applications which can substantially degrade the heat exchanger performance. Present research is organized to investigate the mechanism of heat transfer between the shell-side fluid and the shell wall of spiral wound heat exchangers (SWHEs) to determine the heat transfer coefficient used in the heat-in-leak calculations. The heat transfer characteristics are studied using computational fluid dynamics (CFD) tools. First, 20 dissimilar SWHE models with respect to the geometrical parameters are built and then numerically simulated at different Reynolds...
Transient forced convection with viscous dissipation to power-law fluids in thermal entrance region of circular ducts with constant wall heat flux
, Article Energy Conversion and Management ; Volume 50, Issue 4 , 2009 , Pages 1062-1068 ; 01968904 (ISSN) ; Mohammadi, A. A ; Sharif University of Technology
2009
Abstract
A numerical investigation was conducted on the transient behavior of a hydrodynamically, fully developed, laminar flow of power-law fluids in the thermally developing entrance region of circular ducts taking into account the effect of viscous dissipation but neglecting the effect of axial conduction. In this regard, the unsteady state thermal energy equation was solved by using a finite difference method, whereas the steady state thermal energy equation without wall heat flux was solved analytically as the initial condition of the former. The effects of the power-law index and wall heat flux on the local Nusselt number and thermal entrance length were investigated. Moreover, the local...