Relations for Thermodynamic Properties of Saline Solutions for Geothermal Brine Processes Calculations

Abstract

Simple analytical expressions are introduced for representing the variation of saturated geothermal brine pressure and density with temperature and the enthalpy and enthalpy with both pressure and temperature. Curve fitting techniques were used to select the values of the constants involved to achieve the best agreement with available data for saline solutions over the temperature range from 26.6°C (80°F) to 330°C (626°F) and for salt contents up to 35% by weight. The results have been incorporated into a computer program which can be sued for estimating the effect of dissolved salts in geothermal fluid processes. Ideal cycle calculations show that cycle thermal efficient are not seriously affected b y salt concentration. Useful work output per unit of brine flow is, however, reduced by approximately 15 to 20 percent for the higher saline concentrations.