CFD study of heat transfer enhancement in double pipe heat exchanger with twisted tape inserts

In this work The performance of a double pipe heat exchanger with full length tight-fit twisted tape has been studied. Different twist ratios y=3D1.5, 2.0, 2.5 and 3.0 were selected for heat transfer enhancement. Reynolds number range is from 25000 to 92000 for air side (inner tube) with heavy fuel oil flow rates 0.1 kg/s for the shell side. Optimum design has been obtained through simulations using SOLIDWORKS PREMIUM 2016 software package. The inner and outer stainless-steel pipes nominal diameters were (4 and 6 in) with schedule 10 and 1.5m length. The results showed that the maximum enhancement is about 26.6%, 106.1% and 91.7% in heat transfer rate, Nusselt number and convection heat transfer coefficient respectively, as compared with the plain tube. Based on optimal results, for temperature of 600 K exhaust air, the application of double pipe heat exchanger with twisted tape by preheat heavy fuel oil could reduce the viscosity and that will reduce the pumping power required to pump the heavy fuel oil. Also could save 200,656 Mw annually by recovering heat from furnaces exhaust gases.