شبيه سازي و محاسبه ضرايب انتقال جرم و حرارت در فوم هاي كاتاليستي مونوليتيك با استفاده از CFD

چكيده انگليسي :

108 Simulation and calculation mass and thermal coefficient in monolithic foam catalyst by CFD Mohammad Karimi Meysam Department of Materials Engineering June 26 2018 Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiAbstractThe chemical reaction rate is one of the important parameters on the production efficiency of achemical processes The use of catalysts is one of the methods which used to increase the ratespeed of chemical reactions For example they can be use in environmental pollution reductionprocesses The catalysts are made up from several components the base of catalyst have veryimportant role in their efficiency One of the main parameters in designing and selecting the base ofthe catalysts is their special surface area Hence open cell foam is an ideal choice for the base ofthe catalysts due to the high level of the surface area The main purpose of this study is simulateand calculate the coefficients of mass and heat transfer in catalytic foams for NOx gas eliminattion In the presence of oxygen and ammonia gas by Ffluent computing fluid dynamics software Thefirst Calculation of mass and heat transport coefficients was done in catalytic tube with squarecross section due to the complexity of the transfer phenomena in catalytic foams and the validationof the results Since the fluid velocity is one of the effective parameters in the transport phenomenain different catalysts the effect of the velocity of the fluid velocity 1 11 m s on the transitionportions was studied by the Ansys work bench software in the catalytic tube with the cross sectionis initially a square with a diameter of 6 mm and a length of 70 cm The results show that the fluidvelocity was affected by the conversion rate of nitrous oxide gas The catalytic reaction ofammonia gas with nitrogen monoxide with a constant ratio of ammonia gas and nitrous oxide0 85 at a flow inlet velocity of 3 m s the length of 30 cm from the reaction tube was completed Also by increasing the velocity to 11 m s at the end of the tube 5 of the input nitrogenmonoxide gas remains So using the mass transfer coefficients and the average displacementtemperature during the catalytic tube the Sherwood and Nusselt number equations were presentedin terms of Reynolds number which are Nu 0 7651Re0 2593 Sh 0 0023Re0 957 In order tovalidate the results of this study they were compared with experimental data and other simulationsof the researchers which is well matched The effect of the flow inlet velocity on the transportphenomena in the foam catalyst was investigated which is constructed by the geodecat software with 96 porosity and 500 micron pore diameter The results show that the high level and thegreater fluid involvement due to the geometric structure of the foam complete catalytic reactionwhen the inlet velocity of 3 m s with the same molar percentage of inlet gases in the catalytic tubeat a distance of 3 mm and the length of the foam has velocity of 11 m s at a distance of 7 mmfrom the foam length Also the equations for calculate the changes of the Sherwood number andthe Nusselt number were also presented by using the mass transfer coefficient and heat transferduring foam Sh 0 1841 Re0 92201 Nu 0 3624Re0 8385 Generally the results of comparisonbetween the catalytic foam and the catalytic tube showed that catalyst foams could be used withless length than catalytic tubes because of the high fluid involvement with catalytic walls Keywords Catalyst Computational Fluid Dynamics Fluid Flow Heat Transfer Mass Transfer

محمد كريمي، ميثم

شبيه سازي و محاسبه ضرايب انتقال جرم و حرارت در فوم هاي كاتاليستي مونوليتيك با استفاده از CFD

كاتاليست , ديناميك سيالات محاسباتي , جريان سيال , انتقال حرارت , انتقال جرم