Hydrodynamic and thermal aspects of two-phase flow through porous media

Analytical models proposed for flow regime transition and drag forces allow theoretical predictions of void fractions and pressure gradients as functions of gas and liquid flow velocities. Application of the models in counter-current flow results in a reconciliation of conflicting observations reported by different authors regarding data behavior prior to flooding. Counter-current flooding limits can be predicted theoretically by the present models. The models are also employed to predict flow characteristics in two-dimensional flows through porous media with stratification.;Single phase heat transfer from a body surrounded by a non-heated porous medium is studied experimentally. It is found that permeability of the surrounding porous medium has little influence on single phase heat transfer. Data at low Reynolds number suggest that correlations available in the literature may be deficient. An alternate correlation similar to the Dittus-Boelter equation is obtained.;Experiments are performed to determine boiling heat fluxes from a body embedded in a liquid saturated porous medium under different surface conditions. It is found that an increase in surface roughness results in an increase in boiling heat fluxes. The presence of the non-heated particles results in a slight enhancement in film boiling. The enhancement in film boiling coefficient is found to vary inversely with diameter of the non-heated particles. The presence of particles also results in early nucleation and higher heat fluxes at low superheats. In fully developed nucleate boiling, the dependence of heat flux on superheat becomes weaker in the presence of particles. Maximum heat fluxes are found to increase with increasing diameter of the particles. The limiting mechanism for a partially wetted surface is found to occur at the heating surface. With increasing surface wettability the limiting mechanism is found to be counter-current flooding in the porous medium at small particle diameter. Transient quenching data indicate that surface temperature of the heated body is not necessarily uniform, especially near the maximum heat flux. As such, maximum heat fluxes obtained during quenching may not be representative of steady state values for large bodies with low thermal conductivity.