Study and testing of direct contact heat exchangers for geothermal brines. Phase II, August 1976--June 1977

Abstract

The analytical and experimental studies completed under this project have explored several aspects of geothermal binary power cycles and column type direct contact heat exchangers between geothermal brine and isobutane. A major improvement of the heat exchanger was developed by the combination of the preheater and boiler into a single continuous column. At East Mesa, this new direct contact heat exchanger was tested on geothermal brine in order to correlate the experimental heat transfer data with the theoretical model for use in designing larger plants. Experiments also involved a small radial inflow turbine to produce electricity which marked the first generation of electricity from geothermal brine using a binary cycle. In analytical studies, a comparison of the relationship between column diameter and droplet size was made for both Minard--Johnson and Sakiadis--Johnson model. The Letan--Kehat model for relating column height and temperature profile was analyzed and compared with experimental data. It appears that the experimental results are in good agreement with the theoretical models. A detailed design of a 250 Kw pilot plant incorporating the direct contact heat exchanger was completed. This design with estimated costs for it and a 500 Kw pilot plant is incorporated.