Thermal equilibrium in transient conjugated forced-convection channel flow

The validity of the local thermal equilibrium assumption in transient conjugated forced-convection channel flow is investigated numerically. Axial conduction in both fluid and solid domains is included. It is found that five dimensionless parameters control the local thermal equilibrium assumption. These parameters are the thermal diffusivity ratio alpha(R), the Biot number Bi, the dimensionless channel length xi(max), the Peclet number Pe, and the solid-to-fluid total thermal capacity ratio C-R. The qualitative and quantitative aspects of the effects of these five parameters on the channel thermalization time are investigated.