| The heat exchanger is a kind of industrial equipment that can transfer energy betweenmultiple fluids.It has been widely used in metallurgy,steelmaking,nuclear power,power system,chemical industry since the 19 th century.But with the heat exchanger heat transfer efficiency,its fatigue life and safety performance has gradually attracted people’s attention.The study on the structure of the heat exchanger and the influence of the heat exchanger flow field on the temperature field and the stress and strain field are significant.Therefore,the study of fatigue life under fluid induced vibration load is a very interesting research topic.In this paper,a shell-and-tube heat exchanger is used as the research object.The finite element method and the thermo-hydrodynamic coupling method are used to analyze the velocity field,pressure field and temperature of the shell-and-tube heat exchanger with different flow rates.Field and JF factors,and the flow field results are transmitted to the stress-strain field for analysis to assess the fatigue life of the heat exchanger.In the simulated heat exchanger shell flow field found that the standard heat exchanger A shell flow,the faster,the faster the faster the dead zone,while the pressure loss and the maximum pressure will be more and more,the integrated JF factor Do not choose to choose a larger flow and in the heat exchanger baffle spacing selection should use 120 mm.The results show that the pressure loss,fluid velocity and heat transfer coefficient of the spiral baffle heat exchanger B increase with the increase of shell flow,but the JF factor But in the reduction,from the overall safety and heat transfer effect is not appropriate to choose a larger shell flow.With the increase of pitch,heat transfer coefficient and pressure loss are reduced,JF factor is increasing,the appropriate selection of large pitch spiral baffle to strengthen the heat transfer.During the flow field analysis of the C series of different baffles,the maximum speed,pressure loss and heat transfer coefficient of the shell section were increased with the increase of the flow rate in the C series baffle plate heat exchanger.But JF factor showed a downward trend,should not use a larger flow.In the baffle notch height selection,0.30 D notch height of the overall heat exchanger heat loss and heat transfer coefficient more in line with engineering practice,JF factor is also the highest.In the analysis of the temperature field and the stress and strain field of the heat exchangers A and B,the temperature difference between the two is not significant,but because of the high temperature medium of the tube,the temperature around the tube bundle is high and the thermal stress is easy to cause fatigue.The heat transfer capacity of the helical baffle is better from both heat fluxes.From the stress-strain cloud,it can be seen that the stress area is mainly concentrated in the tube bundle of the heat exchanger,the shell stress is very small.It can be seen that the strain of the spiral baffle heat exchanger is smaller than that of the bow baffle heat exchanger.According to the Manson-Coffin formula,the fatigue life of the spiral baffle heat exchanger B is longer,which can provide reference for the industrial improvement of the heat exchanger structure.In summary,the shell and tube heat exchanger is not suitable to select a larger inlet flow,and the baffle height and spacing between the existence of interrelated,through the introduction of the objective function can determine the best solution;the same time,Plate heat exchanger overall heat transfer performance and pressure loss are ideal,in the fatigue life is better than the traditional bow baffle heat exchanger. |
