Numerical Simulation Of Flow And Heat Transfer Of Fluid In Tube-side And Shell-side Of Helical Corrugated Tube

As an important equipment of heat exchange,heat exchanger plays an important role in industrial production.It is of great significance to change the structure of heat exchanger and study the new heat transfer tube for saveing energy and improving the efficiency of energy utilization.The helical convex structure of the helical corrugated tube can change the flow and heat transfer of the fluid in the tube side and the shell side.The helical corrugated tube with reasonable structural parameters can enhance the heat transfer.First,the geometric model of smooth tube,helical corrugated tubes with different structural parameters(helical convex height H and helical protrusion distance P)and corrugated tube with the same parameters of helical corrugated tube are established in this paper.The mesh of the fluid region and the solid region of the geometric model is meshed,and the grid independent verification of the mesh of the helical corrugated tube is verified.The 859500 grid is decided for numerical simulation.The calculation results of the smooth tube are compared with the empirical correlation,and the RSM model is selected as the calculated turbulence model.Then,the numerical simulation is carried out on the basis of the established geometric model to calculate the Nusselt number Nu,the resistance factor f and the comprehensive heat transfer factor?of the inner and outer fluid of the helical corrugated tube and the smooth tube,and to find the difference of the flow and heat transfer between the helical corrugated tube and the smooth tube.The results show that the heat transfer performance and flow resistance of the internal and external fluid in the spiral tube pipe will increase with the increase of H.When the P is 20 mm,the maximum value of Nu and f of the fluid inside the tube is increased by 60.5%and 152.9%,while of fluid outside the tube is increased by 70.8%and 256.7%with the H changing.The heat transfer performance and flow resistance of the internal and external fluid in the helical corrugated tube will increase with the decline of P.When the H is 1.5mm,the maximum value of Nu and f of the fluid inside the tube is increased by 52.4%and 128.3%,while of fluid outside the tube is increased by 56.6%and 124.5%with the P changing.The numerical simulation is also carried out on corrugated tube,witch have the same parameters of H and P with helical corrugated tube.It is found that the heat transfer performance and flow resistance of the internal and external fluid of corrugated tub are higher to a certain extent than that of the helical corrugated tube.When the Re_i is higher than 7500,the comprehensive heat transfer performance of the internal fluid of the helical corrugated tube is higher than that of the corrugated tube.For the shell side,the comprehensive heat transfer performance is2.3%to 5.8%higher than that of the helical corrugated tube.Last,analyze the velocity distribution,temperature distribution,pressure distribution and turbulent kinetic energy distribution of fluid in tube side and shell side of the helical corrugated tube,and also analyze the synergism of the velocity field and the temperature gradient field of the tube side fluid and the shell side fluid,and further study the influence of fluid inlet Reynolds number(Re_i and Re_o)and the helical corrugate parameters(P and H)to flow and heat transfer,and then to reveal the mechanism of heat transfer enhancement.