Two-phase flow in porous media with phase change: Steam injection and postdryout heat transfer.

摘要

Steam injection into a porous media was studied experimentally. The steam was injected into a uniform downward water flow in a porous channel. Water Reynolds number up to 100 was tested to investigate the underlying physics. Two steam injection rate bounds were detected for a given water flow rate and subcooling. The upper boundary is the steam injection rate where the steam zone grows without bound and the lower bound is the steam flow rate where a bubble is initiated. The bounds were determined for different porous channels and operating conditions. Chaotic oscillation of steam-water interface was observed in highly permeable channel for high water flow rate. The average Nusselt number was presented in terms of the Reynolds numbers and the Stefan number, based on measurement.; The steam injection problem was also attacked for Darcy flow. The governing equations were transformed using steam function and velocity potential as independent variables. The resulting energy equation was solved by integral method. The steam flow inside the steam zone was calculated numerically. The steam zone shape and location were determined by minimizing the mass flux error between the steam flow and water flow at the interface. The temperature and pressure distribution, local condensation rate along the steam-water interface and flow fields for both steam and water were calculated. The results were compared against the measured values and showed reasonable agreements.; Post-dryout behavior of a particulate debris bed was investigated numerically. A separate flow model using the concept of relative permeabilities and the Leverett function was used to describe two-phase flow and heat transfer in the bed. The saturation distribution, liquid and vapor pressures and flows were calculated when heat generation rate (decay rate) was less than a critical value called the 'dryout heat flux'. When the heat generation was greater than the dryout heat flux, a dry zone was defined by extrapolating the two-phase flow calculation. The maximum temperature in the bed, the melting heat fluxes, and the fractional contribution to heat transfer by radiation for various bed configuration were investigated.