6991

6533

كارشناسي ارشد

تبديل انرژي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك

1390

پانزده، 104ص.: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

علي اكبر عالم رجبي، احمد صابونچي

مهدي نيلي احمد آبادي

27/6/91

محسن ثقفيان، محمدرضا سليم پور

1396/09/18

كتابنامه

مكانيك

مهندسي مكانيك

ID6533

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

An Experimental Investigation on the Effect of Longitudinal Flexible Filaments on Heat Transfer and Pressure Drop in the Pipe with Uniform Wall Temperature Omid Nematollahi o nematollahi@me iut ac ir Date of Submission 2012 03 05 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors Ali Akbar Alemrajabi rajabi@cc iut ac ir Ahmad Saboonchi ahmadsab@cc iut ac irAbstractHeat transfer enhancement has been widely used in recent years Heat exchangers with enhanced heattransfer work at a lower velocity or reduced driving force temperature and or smaller size Many waysexist to achieve these goals One of them is utilization of inserts Both heat transfer and pressure dropincrease by using inserts There are many types of inserts like twisted type wire coil wire mesh etc Some inserts are not beneficial due to their relatively high pressure drop In this study the effect of flexible filaments on enhancement of heat transfer and pressure drop isinvestigated Also a Performance Evaluation Criterion has been defined and applied to evaluate theeconomic benefit of these filaments In this project the effect of filaments on heat transfer andpressure drop in a tube of uniform wall temperature is investigated Steam is used as a heat source toobtain a uniform wall temperature and the working fluid in the tube is water The results are presentedin two regimes of flow i e laminar and turbulent The range of Reynolds number for laminar flow isfrom 600 to 2300 and for turbulent flow is from 3000 to 10000 Three kinds of filaments are used inthis project Polypropylen Polyester and Cotton Density of these filaments when dry is 0 91 1 39 and 1 55 respectively Filaments were installed in four array types in the pipe Furthermore experiments were carried out using three lengths of filaments The results of our experimental tests have shown that use of these flexible filaments leads to enhancedheat transfer and pressure drop whose extents depend on the type of filament array type and length offilament in the tube It was found that filaments with higher density have greater effect on heat transferand pressure drop Also filaments of shorter length are more effective Furthermore the more thenumber of filaments in an array the more effective on heat transfer and pressure drop is In additionheat transfer enhancement increases with increase in the diameter of filament Among the configurations investigated the array consisting of three cotton filament of 30 centimeterslength and distributed uniformly in the tangential direction has performed the best 51 increase in theNusselt number was observed when this arrangement was used in laminar flow Furthermore inturbulent flow the Nusselt number increases by 46 The Performance Evaluation Criterion P E C of 0 61 was achieved Keywords Internal flow Flexible filaments enhancement of heat transfer Inserts

علي اكبر عالم رجبي، احمد صابونچي

مهدي نيلي احمد آبادي

محسن ثقفيان، محمدرضا سليم پور