Effect of Wall Conduction on Combined Free and Forced Laminar Convection in Horizontal Tubes

Abstract

Combined free and forced laminar convection in ducts is encountered in a wide variety of engineering applications, including heat exchangers designed for viscous fluids in chemical processes, solar collectors, food industries, and biomedical engineering. In many engineering applications, the boundary conditions for thermal convection in ducts cannot be considered uniform either for wall temperature or heat flux. In the thermally fully developed flow, the effect of peripheral wall conduction may be introduced by the nonuniform peripheral wall heat flux in noncircular ducts and also introduced simultaneously by the secondary flow in rectangular channels, or by the secondary flow alone in circular tubes. This paper investigates the effect of peripheral wall conduction on combined free and forced laminar convection in hydrodynamically and thermally fully developed flow in horizontal circular tubes with uniform heat input axially. A finite-difference power-law scheme is employed to solve the problem.