تحليل تجربي انتقال حرارت جريان نانو سيال در لوله موجدار

چكيده انگليسي :

Experimental Study on Heat Transfer of Nanofluid Flow inside a Corrugated Tube Kia golmohammadi k golmohammadi@me iut ac ir Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiM R Salimpour Assoc Prof salimpour@cc iut ac irM Saghafian Assist Prof saghafian@cc iut ac irAbstractIn this study heat transfer and pressure drop characteristics of water TiO2 nanofluid flow inside a corrugated tube isinvestigated The boundry condition is uniform wall temperature For this purpose a test apparatus was designedand assembled The length of test section was 93 cm with internal diameter of 7 71 mm and outer diameter of 9 52mm First the data were obtained for distilled water in the plain tube Later various test runs were performed fortwo nanoparticle concentrations 0 1 0 5 two corrugation depth e di 0 0648 0 103 two corrugation pitch p di 0 917 1 297 and two corrugation width w di 0 363 0 492 in a wide range of Reynolds numbers 3000 Re 15000 Experimental results showed the experimental values of the Nusselt number and friction factorfor the plain tube are in good agreement with the values predicted by empirical equation and the average deviation isabout 3 25 and 7 3 respectively For distilled water and nanofluid flows Nusselt number enhances withincreasing Reynolds number Also adding nanoparticles causes heat transfer enhancement which is due to theincrease in the thermal conductivity As found the nanofluid with TiO2 concentrations of 0 1 and 0 5 volumegives mean Nusselt numbers higher than those of the base fluid around 1 6 and 3 4 respectively The heat transferin transversely corrugated tube is more than that in helically corrugated tube Also Nusselt number enhances withthe increase of corrugation depth and corrugation width especially in larger Reynols numbers and the decrease ofcorrugation pitch to diameter ratio As can be seen the effect of nanoparticles on heat transfer of corrugated tubewith higher corrugation depth and corrugation width and lower corrugation pitch is further The friction factordecreases with increasing Reynolds Number and increases with increasing volume concentration The nanofluidwith concentrations of 0 1 and 0 5 by volume gives mean friction factors higher than those of the base fluid byaround 1 9 and 4 8 respectively Also the friction factor in transversely corrugated tube is more than that ofhelically corrugated tube and the friction factor increases with the increase of corrugation depth and decrease ofcorrugation pitch and corrugation width especially in larger Reynols numbers But for all corrugated tubes addingnanoparticles causes slight increases in friction factor compared with the plain tube in the range of presentexperiments For all corrugated tubes the thermal performance factor remains more than unity and increases up toabout 6000 Re and then reduces But with increase of corrugation width thermal performance increases forReynolds number more than about 12400 Also this factor have better performance for higher corrugation depthsand corrugation widths and lower corrugation pitches Moreover the highest performance is about 2 44 whichachieved for 0 5 of nanoparticles concentration inside the corrugated tube with e 1 2 mm p 7 mm and w 2 8 mmat Reynolds number of about 6000 Keywords heat transfer pressure drop nanofluid flow corrugated tube uniform wall tempretur

گل محمدي، كيا

تحليل تجربي انتقال حرارت جريان نانو سيال در لوله موجدار

افت فشار , دماي ديواره ثابت