7564

7036

كارشناسي ارشد

مهندسي شيمي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي شيمي

1391

دوازده،70ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

محسن نصر اصفهاني

ابراهيم شيراني

15/12/91

احمدرضا پيشه ور، مسعود حق شناس فرد

مهندسي شيمي

ID7036

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

CFD Analysis of Al2O3 water Nanofluid Taylor Flow in 2D Microchannels Considering Liquid Film Nader Afshar n afshar@cc iut ac ir Date of Submission November 28 2012 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mohsn Nasr Esfahany mnasr@cc iut ac irAbstract In this thesis Taylor flow also called slug flow of nanofluid Al2O3 water 1 vol in rectangularmicrochannels with high aspect ratio was investigated using FLUENT software 4 types of different inletconfigurations were considered to investigate hydrodynamics and heat transfer In first geometry air wasentered vertically and the nanoflid was entered horizontally In second geometry nanofluid was enteredvertically and air was entered horizontally In third geometry air and nanofluid both were entered verticallyand in fourth geometry air and nanofluid were entered in 120 angle The results are presented ashydrodynamic results and heat transfer results In hydrodynamic results slug and bubble lengths liquidfilm properties pressure drop and gas void fraction were studied and the results were compared withprevious correlations presented by other researchers There are very high deviations between the resultsbased on the previous correlations and the presented results in liquid film thickness slug and bubble lengthsand gas void fraction Results show that pressure drop is constant across a unit cell in microchannel In thisthesis two theoretical equations were presented to predict gas void fraction and period of Taylor flow Proposed equations predict measurements accurate to 3 for gas void fraction and 4 for slug period Investigation of velocity vectors specified that two vortices exist in front of bubbles and in the tail Thevortex which exist in bubble tail results in an inverse flow In heat transfer results the Nusselt number in aunit cell and the local Nusselt number in all geometries were investigated and compared Investigation oftemperature contour in a unit cell shows that the hottest point on the wall is where the back vortex exists Also the lowest Nusselt number in a unit cell is observed at the same point First geometry showed thegreatest Nusselt number and the Nusselt number has an inverse relationship with unit cell length Boundaryadaption method was used to simulate liquid film which is the fast method among the other methods usedby previous researchers and specified that the pressure drop has an 80 deviation without consideringliquid film in simulations Use of nanofluid instead of water as the liquid phase in Taylor flow couldenhance heat transfer coefficient Nanofluid of Al2O3 water 1 vol was used and simulated as ahomogenous liquid in this thesis The influence of using nanofluid was studied and determined a 10 increase in Nusselt number compared to water The hydrodynamic and thermal properties were consideredtemperature dependant in present simulation while previous researchers considered constant properties intheir simulations Keywords Taylor flow slug flow nanofluid microchannel CFD

محسن نصر اصفهاني

ابراهيم شيراني

احمدرضا پيشه ور، مسعود حق شناس فرد