Flows and Heat Exchange in a Geothermal Bed in the Process of Extraction of a Vapor–Water Mixture from It

Abstract

With the use of the finite-difference method, a nonstationary nonlinear problem on the heat and mass transfer in a geothermal bed in the process of extraction of a vapor–water mixture from it was solved numerically with regard for the heat exchange between the bed and the surrounding rocks. The results obtained were analyzed and compared with the results of earlier investigations. It was established that the heat exchange between the bed and its roof and bottom influences the heat and mass transfer in the neighborhood of a producing well in it. It is shown that this heat exchange increases somewhat the pressure (temperature) of the phase transition of the heat-transfer medium and changes its saturation with water. At the stage of stationary heat and mass transfer in the bed, this change leads to a decrease in the water saturation of the heat-transfer medium, i.e., to an additional evaporation of water from it. However, at the stage of substantially nonstationary heat and mass transfer in the bed, the pattern is more complex: within certain time intervals, the heat exchange in separate regions of the bed decreases the content of vapor in the heat-transfer medium (increases its saturation with water). Moreover, in both the cases of absence and presence of heat exchange between the bed and the surrounding rocks, the distributions of the water saturation of the heat-transfer medium in the bed executes damped oscillations and, in so doing, approaches the stationary state.