تحليل عددي و بررسي تجربي انتقال حرارت نانو سيال آب/آلومينا در مبدل هاي حرارتي دو لوله اي ، پوسته لوله اي و صفحه اي

چكيده انگليسي :

Numerical and Experimental Investigation on Al2O3 Water Nanofluid Heat Transfer in the Double Pipe Shell Tube and Plate Heat Exchangers Mahboobeh Akhtari m akhtari k@yahoo com 2012 03 06 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Masoud Haghshenas Fard haghshenas@cc iut ac irAbstractRecently applications of nanofluids for enhancment of heat transfer performance of thermal systems havebeen improved There are many published works dealing with studies of nanofluids heat transfer in verysimple geometrical configurations e g circular channels and tubes But there are a few publishedexperimental and numerical works related to heat transfer of nanofluids in the heat exchangers In thisstudy heat transfer of the Al2O3 water nanofluid with 0 2 and 0 5 volume fractions flowing in doublepipe shell tube and plate heat exchangers counter flow under laminar flow conditions investigatedexperimentally Effects of hot and cold mass flow rates temperature and nanoparticle volume fractions onthe overall heat transfer coefficient and heat transfer rate of the nanofluids have been investigated Furthermore Al2O3 water nanofluid with 0 2 and 0 5 volume fractions was used in plate heatexchanger to evaluate the nanofluid type effects on the forced convective heat transfer Finally theperformance of heat exchangers is compared together The results of the experiments showed that the heattransfer rate and overall heat transfer coefficients of nanofluid are higher than those of the base fluid distillated water and overall heat transfer coefficient increases with increasing the nanoparticlesconcentration Also heat transfer rate and overall heat transfer coefficients of nanofluid increase with anincrease in the flow rate of the nanofluid and cold water and nanofluid temperature in all of the heatexchangers Compared with pure water the results indicated that the heat transfer performances ofnanofluid with 0 5 nanoparticle volume concentrations in the double pipe shell tube and plate heatexchangers are higher than those of water by about 7 6 12 7 and 16 9 respectively In plate heatexchanger overall heat transfer coefficient of Al2O3 water nanofluid with respect to Al2O3 water wasmore in the same concentrations The average increasing in the overall heat transfer coefficient of Al2O3 water nanofluid with respect to Al2O3 water with 0 2 and 0 5 volume fractions was 5 6 and4 4 respectively The overall heat transfer coefficients of nanofluid in the plate heat exchanger are higherthan shell tube heat exchanger and in the shell tube heat exchanger is higher than double pipe heatexchanger The average increasing in overall heat transfer coefficient for Al2O3 water nanofluid with0 5 volume fraction in 50 C for plate heat exchanger with respect to shell tube heat exchanger is29 9 and for shell tube heat exchanger with respect to double pipe heat exchanger is 22 8 Simulationof double pipe and shell tube heat exchangers carried out by means of the processes in FLUENT version12 1 numerically The GAMBIT software has been used for geometry and mesh generation The overallheat transfer coefficients predicted by CFD simulation were compared with the experimental results It wasobserved that the CFD results are in the good agreement with experimental data In nanofluid with 0 5 concentration the average relative error between experimental data and CFD results for the double pipeheat exchanger is 11 7 while for the shell tube heat exchanger is 15 6 It is shown that thecomputational fluid dynamics is a reliable tool for investigation of heat transfer of nanofluids in the variouskinds of heat exchangers Key words nanofluid heat transfer overall heat transfer coefficient heat exchanger simulation

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تحليل عددي و بررسي تجربي انتقال حرارت نانو سيال آب/آلومينا در مبدل هاي حرارتي دو لوله اي ، پوسته لوله اي و صفحه اي

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