Downward heat transfer in heat-generating boiling pools

Abstract A model for heat transfer from the horizontal base of a volume heated boiling pool is proposed. Because of the density difference caused by volume boiling between the bulk fluid and the fluid near the base, the lighter two-phase fluid causes movement of the bulk fluid in the upward direction and causes a negative pressure gradient along the base plate of the pool. This negative pressure drives returning subcooled singlephase liquid in the boundary layer along the base plate. The analysis for the laminar case provides the definition of equivalent Grashof number for the combined (or opposing) two-phase and temperature driven natural convection along the base plate. The turbulent boundary layer is analyzed by assuming a two-layer model in which the inner layer is characterized by viscous and conduction terms and the outer layer by mean convection terms. The similarity analysis of the governing equations yields universal profiles for temperature and velocity and the scaling laws for the inner and outer layers. An asymptotic matching of the temperature profile in the overlap region leads to a heat transfer law that correlates the available experimental data on a volume heated boiling pool satisfactorily.