مطالعه عددي ميدان جريان و انتقال حرارت نانو سيال در كانال هاي موج دار در جريان آرام و آشفته

چكيده انگليسي :

Numerical Study of laminar turbulent Flow and Heat Transfer of Nano fluids in Wavy Channels Ehsan Abidi e abidi@me iut ac ir Date of Submission 2014 06 23 Department of Mechanical Engineering IsfahanUniversity of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Ahmad Sohankar asohankar@cc iut ac irAbstractIn this study numerical simulations were performed for laminar turbulent flow and heat transfer of nano fluidsin wavy channels as a main part of the plate heat exchangers The Reynolds numbers based on the inflowvelocity and the height of channel were chosen in the range of 200 1600 The numerical results were comparedwith the reported numerical results and good agreement was obtained A grid study was also performed witheight different mesh sizes to find the appropriate grid In order to improve the performance of the plate heatexchangers two passive heat transfer augmentation methods were employed including the corrugated wavy walls and adding nanoparticles to the base fluid In the first augmentation method the walls of channel arecorrugated and the effect of channel geometric parameters including wave amplitude wave length differentphase between the upper and lower wavy walls and wave shape on the characteristics of the flow field and heattransfer was investigated The scaled wave amplitude and wave length considered for this parameter study are inthe ranges of 0 1 0 5 and 1 1 4 4 respectively The angles of 0 90 and 180 are considered for different phasebetween the upper and lower wavy walls and the Sine Arc Triangle and TetraPak wave shapes are employed tocorrugate the walls of channel To study the results obtained Nusselt number pressure drop friction factor andalso a thermal parameter the relation between the key parameters of the velocity friction factor f and thermalboundary layers Nusselt numbers were provided to evaluate the optimized parameters of the wavy channel The results show that suitable scaled wave amplitude wave length and different phase between the upper andlower wavy walls of optimized wavy channel are 0 4 2 2 and 0 respectively Also results show that the wavychannel with TetraPak wave shape has the best performance in comparison with the other shapes considered Inthe second augmentation method the effect of adding the nanoparticles of Al2O3 CuO and TiO2 to water as thebase fluid with 1 5 volume fraction on the heat transfer enhancement of the optimized wavy channel wasstudied to choose the most appropriate nanofluid The results show that the heat transfer and pressure dropincrease as the Reynolds number the wave amplitude and the nanoparticle volume fraction increase The heattransfer rate of base fluid flow in the optimized wavy channel is 2 49 times more than the flow in the simplechannel without wave Also it was found that the water CuO nanofluid has the best performance between thenanofluids considered in this study where the heat transfer rate of flow of water CuO nanofluid with 5 volumefraction in the optimized wavy channel increased 23 compared with the base fluid flow KeywordsWavy channel Nano fluids Heat transfer enhancement Thermal performance parameter Numerical simulation plate heat exchangers

عبيدي، احسان

مطالعه عددي ميدان جريان و انتقال حرارت نانو سيال در كانال هاي موج دار در جريان آرام و آشفته

بهبود انتقال حرارت , ضريب عملگر گرمايي , حل عددي