تحليل جريان و انتقال حرارت در مبدل هاي دو لوله اي موجدار

چكيده انگليسي :

Analysis of the Flow and Heat Transfer in the Double Pipe Corrugated Heat Exchangers Laleh Shamaei Shamaei laleh@gmail com Department of Mechanical Engineering Isfahan University of Technology Isfahan Iran Degree M Sc Language FarsiSupervisor Mohammad Reza Salimpour salimpour@cc iut ac irAbstract Heat transfer with the internal flow of the pipes and channels has vast industrial applications amongwhich heat exchangers are highly important Heat exchangers are generally a type of equipment thatexchange the heat between two fluids without their physical contact Increasing heat transfer in the heatexchangers can effectively save energy and material This can be only achieved by designing lighter andmore efficient heat exchangers So far plenty of methods have been proposed to improve the heat transfer in the heat exchangers Most of these methods are based on disordering and exchanging the boundary layer which is close to theheat transfer surface with the central stream to generate new boundary layer Using wavy pipes is one ofthe pathways employed to increase the heat transfer in the heat exchangers Sinusoidal tubes were found tobe considerably efficient for transferring heat in heat exchangers condensers and evaporators In this study heat transfer and pressure drop in the sinusoidal tubes with different profiles wereinvestigated Also the most effective profile which could provide the maximum heat transfer and theminimum pressure drop was finally determined In the first section two types of double pipe heat exchangers were simulated The first one had asimple internal tube while the second one possessed a wavy symmetric axial one Based on thesimulations a lower total heat transfer coefficient and a higher pressure drop were observed in wavydouble pipe heat exchangers compared to simple ones It can be therefore concluded that wavy exchangersdo not necessarily have better heat transfer features than simple ones The effect of slope and frequency ofthe internal tube on the heat transfer and pressure drop was consequently explored in wavy double pipeexchangers In order to achieve that the candidate profile was investigated at a constant total heat transferarea and the Reynolds number was changed with two methods The optimum geometry from heat transferperspective was then determined by investigating the trend of total heat transfer coefficient and pressuredrop In the first method a couple of geometry with similar heat transfer area was selected for the internaltube The analysis and comparison of these geometries exhibit that the pressure drop decreases withdecreasing the slope of the wavy tube Trend of the total heat transfer is inconsistent with the slopechanges though It primarily decreases with enhancing the slope and then at a certain point it starts toincrease In the second method optimization was performed using software called Design Exploration Optimization results indicate that the slope of the optimum geometry increases with enhancing theReynolds number Consequently wavy tubes with increasing Reynolds number seem to be highlyapplicable Keywords Heat exchangers wavy pipe straight pipe heat transfer coefficient pressure drop optimization

شمايي، لاله

تحليل جريان و انتقال حرارت در مبدل هاي دو لوله اي موجدار

لوله صاف , ضريب كلي انتقال حرارت , افت فشار , بهينه سازي