CFD Analysis of Twisted Tube Heat Exchangers

Using of twisted tubes is one of the most promising technique to increase heat transfer between hot and cold fluids. In this study, the ratio of oval cross sections and number of twists in the Reynolds range of 1000 to 15000 were analyzed by computational fluid dynamics tools. The ratio of oval cross sections between 1 and 2.5 and the number of twists between 0 and 3 are considered for a case study. Basically, increasing the Reynolds number, increasing the cross section diameter ratio, and increasing the number of twists increase the Nusselt number and the friction factor simultaneously. In this case study, the ratio of oval cross sections 1.67 and the length of the twisted of 3 (0.6 m), reveal the best performance to achieve the optimal pressure drop and Nusselt number, respectively.