Numerical Simulation And Optimization Of The Single-tube Heat Exchanger With Pin Finned Tube

As a high-effective special shape tube for enhanced heat transfer, the pin finned tube has many good characteristics such as extending the heat transfer surface, intensifying the fluid turbulence, enhancing the transfer coefficient, less shell-side fouling, and prevention of flow induced vibration. Because of the complicated configuration of the heat exchangers with pin finned tube, previous studies focused on their experiments and there are no many researches on their numerical simulations.The heat exchangers with pin finned tube have been simulated by means of FLUENT. By changing structural parameters and process conditions, this paper investigates flow behavior, heat transfer and resistance performance of shell-and-tube heat exchangers with pin finned tube. The main contents are as follows:Based on the analysis of portrait flow pin fin tube flowing characteristics, The heat exchangers with pin finned tube of orthogonality design were simulated using hot water (cold water) and diesel oil as heat-transfer medium, and the heat transfer performance curve obtained. From the result of orthogonality design, the sensitive degree diversity for four factor are educed. From the perspective of the total heat transfer coefficient, pin fin portrait distance among of four factors is the most sensitive. From the perspective of the comprehensive heat transfer performance, pin-fin length is the most sensitive, and in the future study of heat exchangers, the main work should be on changing the portrait distance or incline degree of pin fin can achieve the further optimize and compact purpose.Numerical simulations were conducted for hot water flowing in tube side of heat exchanger with diesel oil as heat-transfer medium flowing in shell side, utilizing three-dimensional model. Temperature field and heat transfer performances in shell side of the heat exchanger with two different specifications of straight-pin fin tub and angle of inclination 30 0, 45 0, 60 0- inclined-pin fin tub were simulated. Pressure drop is about 1.06~1.4 times greater than that at same flow condition and heat transfer enhancement of inclined-pin-fined tube is about 1.7~3 times greater than that of smooth tube heat exchanger. Pressure drop of straight-pin fin tub is about 1.1~3 times and heat transfer enhancement of straight-pin fin tub is about 2~3.6 times greater than that of smooth tube heat exchanger.At low velocity, heat transfer enhancement effect of the inclined-pin tube exchanger significantly reduces the flow resistance of the shell, and its comprehensive heat transfer performance is better, but as the velocity increases, the integrated heat transfer performance decreased rapidly, and gradually as light tubes. It shows the practical application should be taken into account to select the appropriate angle. Between 30 0and 45 0, there is a right angle, and its the integrated heat transfer performance is better and occupy less space.Through three different shapes of pin fin pins about the fin tube heat exchanger which are pressure dropâ–³p, the total heat transfer coefficient K, Composite heat transfer performance ho /â–³p, comparison of simulation results show that heat transfer and pressure drop performance of the drop-shaped pin fins are better than that of the circular pin fins and the elliptical pin fins. Heat transfer performance of the elliptical pin fins less than the drop-shaped and cylindrical pin fins, but the resistance of it is best among the three pin fin pins.