Study On Heat Transfer Of A New Baffled Shell And Tube Heat Exchanger

Shell and tube heat exchanger is a kind of heat transfer equipment,is the key device of energy utilization,widely used in energy,medicine,electric power and chemical industry,its main role is to ensure the normal operation of industrial equipment.Baffle are key components in tube and shell type heat exchanger,and baffle plate is able to support the function of the heat transfer way,can the shell side of the divide space,and guide the direction of fluid flow,thereby allowing the fluid in the shell side way or lateral across the tube bundle repeatedly by the regulation,in order to enhance fluid turbulence degree,ascend in the shell side fluid in thermal efficiency,raise the heat transfer coefficient.At present,most of the heat exchangers used in industry are still arched baffle structure,which has uneven distribution of shell flow field and high resistance caused by flow dead zone.In view of these shortcomings,this paper designs a spherical lattice plate structure based on the lattice plate structure and combines the advantages of curved bow baffle.The main work and achievements are as follows:(1)The three-dimensional numerical model of the spherical lattice heat exchanger was established,and the mesh,boundary conditions and fluid domain were set up for the model.Numerical simulation of the model was carried out by FLUENT,and the simulation results were compared with the experimental results in the literature to verify the effectiveness of the model.The flow performance and heat transfer performance of patterned plate heat exchanger and spherical patterned plate heat exchanger are compared,and the pressure drop characteristics and heat transfer of the two are compared.According to the distribution of flow field,temperature field and pressure field at different shell side of two kinds of heat exchangers,the characteristics of spherical lattice heat exchangers are analyzed.(2)The influence of the key design parameters,such as the radius of curvature,the total opening Angle and the number of lobes,on the shell side pressure drop,heat transfer coefficient and comprehensive performance of the spherical lattice heat exchanger is studied in depth.When the curvature radius of the spherical lattice plate is small,its comprehensive performance is better.Under the same flow rate,the comprehensive performance is improved gradually with the increase of the opening Angle.When the number of plates is large,the heat transfer coefficient of the heat exchanger increases gradually,and the pressure drop of the shell side decreases monotonically.(3)According to the key design parameters of the spherical checkerboard,an orthogonal test with three factors and four levels was designed,A total of 16 models with different factor levels were numerically simulated.The range analysis method was used to evaluate the performance according to three different performance evaluation criteria,namely,the highest heat transfer coefficient,the lowest pressure drop and the best comprehensive performance.It is found that the primary and secondary order of the influence of each factor on the heat transfer coefficient is: total opening angle>flap number>radius of curvature;The order of primary and secondary effects on pressure drop is: total opening angle>number of lobes>radius of curvature.The primary and secondary order of influence on comprehensive performance is:number of lobes>total opening angle>radius of curvature.