Energy dissipation analysis of transient heat transfer for turbulent flow in a circular tube with baffle inserts

In this paper energy dissipation analysis was conducted to evaluate the performance of nine circular tubes with baffle plate inserts having different pitch to tube inlet diameter ratio and baffle orientation angle in the range of Reynolds number 3000 ⩽ Re ⩽ 20,000 for the case of constant heat flux. The characteristic parameters of the tubes are pitch to tube inlet diameter ratio H/D = 1, 2, 3 and baffle orientation angle β = 45, 90, 180°. Air having Prandtl number is 0.71 was used as working fluid, while stainless steel is considered as a pipe material. As an evaluation criteria of iE has been proposed by Sano et al., which is based on correlating the heat transfer coefficient and the dissipation energy in a fluid has been considered to evaluate transient forced convection. The data show that unsteady dissipation energy criterion for the baffled tubes is higher than smooth tube and the type of 9031 has been found as the most effective one.