بررسي تجربي انتقال حرارت جابجايي اجباري نانو سيال درجريان آرام درون كانال با سطح مقطع هاي مختلف در شرايط دماي ثابت ديواره

چكيده انگليسي :

Experimental investigation of nanofluid laminar flow heat transfer through conduits with different cross sections by uniform wall tempreture Amir dehshiri parizi a dehshiri@me iut ac ir Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi M R Salimpour Assoc Prof salimpour@cc iut ac ir M Saghafian Assist Prof saghafian@cc iut ac ir Abstract Energy costs have soared rapidly in the last decade and there is tremendous need for new kinds of heating cooling fluids to improve heating system performance and reduce equipment size and energy consumption Study of thermal characteristics for laminar fully developed flow thruogh conduits with different cross sections is significant in design of heat exchangers The primary objective of the heat exchanger designer is to work with geometeries that yield 1 a high value of heat transfer area to volume ratio 2 a high value of heat transfer coefficient and 3 a corresponding low value of friction factor Nanofluids are a new phenomenon of working fluids with high thermal potential used for industrial applications such as construction of compact heat exchangers It seems we can achive the primary objective of the heat exchanger designs by using of non circular cross sections instead of circular cross section and using of nanofluids instead of conventional fluids Therfore in this study we investigate experimental laminar forced convective heat transfer of nanofluid through conduits with different cross sections We study the effects of different parameters such as cross section shape circle square rectangle and triangle Reynolds number 500 2400 and volume concentration of nanoparticles in suspension 0 2 and 0 5 on heat transfer by designing and assembling of an experimental aparatus Very good agreement between experimental data and Seider Tate equation results for distilled water were obtained which emphasizes the accuracy of experiments Experimental results indicate that the Nusselt number increases with increment of Reynolds number and volume fraction of TiO2 nanoparticles For a specific range of Reynolds number the Nusselt numbers of Nano fluid are higher than those of the base fluid for all cases This illustrates that adding a few amount of nano powder can improve Nusselt number in conduits The average enhancement of 5 84 7 37 7 21 and 7 18 for volume fraction of 0 5 and average enhancement of 2 74 3 17 3 20 and 3 36 for volume fraction of 0 2 were observed in conduits with circular square rectangle and triangle cross sections respectively Experimental data express that Nusselt number of circular case for all range of Reynolds number at specific volume fraction is higher than that of other three cases and Nusselt number of square and rectangle are higher than that of triangle case For example at Reynolds number of 2000 for nanofluids at 0 5 volume fraction of TiO2 nanoparticles the Nusselt number is 10 41 10 08 9 91 and 8 85 for circular square rectangle and triangle cross section respectively For a specific Reynolds number and volume fraction of TiO2 nanoparticles the Nusselt number of fluids flow through conduit with circular cross sections is more than that of conduits with square rectangle and triangle cross sections The relative enhancement of Nusselt number of working fluids flow through conduit with circular cross section is less than that of conduits with square rectangle and triangle cross section This behavior indicates that heat lost in sharp angles is reduced Keywords heat transfer TiO2 water nanofluid different cross section uniform wall temperature PDF created with pdfFactory trial version www pdffactory com

دهشيري پاريزي، امير

بررسي تجربي انتقال حرارت جابجايي اجباري نانو سيال درجريان آرام درون كانال با سطح مقطع هاي مختلف در شرايط دماي ثابت ديواره

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