Research On Application Of Kalina Cycle In The Hot Dry Rock Power Generation

HDR resource, exploited as heat rocks at temperature above150℃and a few kilometers below the earth’s surface, are one of the few environmental-friendly energy resources with vast potential. HDR power has broad prospects for develop, however conventional cycle with water as a working fluid used in HDR power would reduce efficiency, due to the endothermic process with fixed temperature of water does not match the exothermic process of low temperature heat source. In this paper, Kalina cycle with a mixture of ammonia as the working fluid is applied in the HDR power generation to improve the performance of power systems. Then the relevant theoretical researches were studied.By analysis of the characteristics of HDR geothermal resources and Kalina cycle, HDR power generation system based on Kalina cycle was established. Then according to the different levels of heat source temperature, the HDR power system was adjusted and optimized to get the simplified type. Then the structure, operation principle, main features, as well as the key technical points of the two cycle systems were analyzed. Aimed at the complexity of the calculation of physical property parameters of ammonia mixture, this paper established the calculation model of thermodynamic properties of system cycle considering the terminal temperature difference of the heat transfer in each heat exchanger, and compiled the calculation program of various state points and thermal performance of system cycle.Studies have shown that, for the first HDR power generation systems, the cycle thermal efficiency and power recovery efficiency gradually increased with the heat source temperature and concentration of working solution. But within the range of optional concentration of basic solution, cycle thermal efficiency and power recovery efficiency increased with the decrease of the concentration of basic solution. For simplified HDR power generation system, with the increase of the heat resource temperature, the cycle efficiency increased firstly and then decreased, and the geothermal heat recovery efficiency and power recovery efficiency dipped firstly and then increased gradually. The decrease of cooling water temperature is also beneficial to improve system performance. In addition, there is an optimal concentration to make the cycle thermal efficiency and power recovery efficiency of system maximum.