Transient conjugated forced convection heat transfer in thick walled pipes and minipipes with time periodically changing convective boundary condition

Abstract

Transient conjugated heat transfer in thick walled pipes with thermally developing laminar flow is analyzed. Effects of axial fluid conduction as well as radial and axial wall conduction are involved. The problem is solved numerically in a two regional pipe, initially isothermal, for which the ambient temperature in the downstream region suddenly begins to change periodically in time. A parametric study is done to investigate the effects of five defining dimensionless parameters of the problem, which are namely; wall thickness ratio, wall-to-fluid thermal conductivity ratio, wall-to-fluid thermal diffusivity ratio, the Peclet number, the Biot number, and also the effect of the value of the angular frequency.