5452

5112

كارشناسي ارشد

مهندسي شيمي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي شيمي

1389

چهارده،77ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

محسن نصر اصفهاني، نسرين اعتصامي

13/7/89

ارجمند مهربان،مسعود حق شناس

مهندسي شيمي

ID5112

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Experimental Investigation of Pool Boiling Heat Transfer of Nanofluid under Electric Field Maryam Sheikhbahai m sheikhbahai@ce iut ac ir Submitted April Department of Chemical Engineering Isfahan University of Technology Isfahan Iran Assoc Prof Mohsen Nasr Esfahany mnasr@cc iut ac ir Assist Prof Nasrin Etesami netesami@cc iut ac ir Abstract In this study pool boiling heat transfer coefficient and critical heat flux CHF of nanofluid in saturated condition on horizontal thin wire in the presence of DC electric field was studied experimentally at atmospheric pressure A mixture of Ethylene Glycol deionized water in volume fraction was used as base fluid Fe O nanoparticles used in and volume fraction concentrations Results show that low concentrations of nanofluid did not change boiling heat transfer coefficient But at concentration reduction was observed in boiling heat transfer coefficient The most enhancement of critical heat flux was about at volume fraction nanofluid Scanning Electron Microscopy SEM observation subsequent to the pool boiling experiment revealed that a porous layer of nanoparticle was deposited on heating surface during nucleate boiling of nanofluid In order to investigate the role of the nanoparticle surface coating on pool boiling heat transfer pool boiling parameters of base fluid was measured using a nano coated heater prepared by pool boiling of nanofluid on a bare heater The results show the layer is the main reason of changes in pool boiling parameters of nanfluid This layer significantly improves the surface wettability as shown by the reduction of the contact angle on the nanofluid boiled surfaces compared with the base fluid boiled surface Effects of electrohydrodynamic on pool boiling parameters were investigated by using two different electrode configuration needle and rod electrode by applying high voltage about kV separately Electrohydrodynamic increased the pool boiling heat transfer coefficient of nanofluid about at high concentrations up to volume fraction in the presence of rod electrode but it has no obvious effect on nanofluid boiling heat transfer coefficient at low concentration The critical heat flux of nanofluid was not affected by applying DC electric field Keywords pool boiling heat transfer coefficient critical heat flux nanofluid electrohydrodynamic

محسن نصر اصفهاني، نسرين اعتصامي

ارجمند مهربان،مسعود حق شناس