GLEF direct-contact heat-exchanger program

A number of flash-binary cycles for the Salton Sea Known Geothermal Area have been evaluated leading to the identification of the optimum one. The brine coming from the well is separated in a flash tank producing a liquid and a vapor stream. The liquid is used in a direct contact preheater to bring the working fluid (isopentane) to the saturation point. The isopentane is then vaporized in a shell and tube heat exchangers by use of the flashed steam. The isopentane vapor is expanded in a turbine driving the generator, condensed in a surface condenser and finally returned to the preheater by the main feed pump. A review of the theoretical correlations available for the design of direct contact heat exchangers has been carried out as well as the design and fabrication of a test facility to evaluate the performance of direct contact heat exchangers under various conditions and to verify the cycle analysis. The results of the test data support the assumptions made in the system analysis and in particular, the terminal temperature differences established in the heat balance have been achieved. The column length calculation procedure has been tested and found satisfactory under the test conditions.