Test Plan for Heat Cycle Research Program, Phase I Supercritical Cycle Tests

The 60 kW Heat Cycle Research Facility (HCRF) provides a means of examining different concepts and components associated with the generation of electrical power from a geothermal resource using a binary power cycle. In this power cycle the heat or energy in a hot geothermal fluid is transferred to a secondary working fluid. This working fluid is vaporized in the heat exchange process and the vapor is in turn expanded through a turbine which drives a generator producing electrical power. the heat or energy in the vapor leaving the turbine is transferred to a circulating cooling water in the condenser where the working fluid is condensed to a liquid which can be pumped back to the heaters, completing the cycle. This waste heat load in the condenser is in turn transferred from the cooling water to the atmosphere in a cooling tower. The HCRF allows the different components described in the cycle above to be tested as well as the basic cycle itself. This cycle may vary in that the heaters, condenser, cooling system, pumps, etc. may differ in number and type, however the basic cycle does not change significantly. During this sequence of tests, the HCRF is operated using a supercritical vapor generator and a vertical condenser where the condensation occurs inside of the tubes as opposed to the shell side more commonly used in these applications. In addition to providing the data to be used to evaluate the design of these heat exchangers, these supercritical tests provide cycle and component performance data with both single component working fluids and working fluids comprised of different mixtures of hydrocarbons. The use of these mixtures promises to improve cycle performance, in terms of watt-hours per pound of geothermal fluid, provided the countercurrent flow paths can be maintained between the fluids in both the condenser and the heaters. The supercritical heaters and the condenser to be used in this series of tests were designed to provide the desired countercurrent flow paths