Parametric Optimization and Adaptable Comparison of Power Generation Cycle for Medium- and Low-temperature Geothermal Energy

Abstract

A novel Kalina cycle coupled absorption heat transformer (KC-AHT) is proposed in this paper. The temperature of geothermal tail water of Kalina cycle, as an example in Husavik, Iceland, is about 80℃, which is used to district heating continue. But for general regions, 60℃ is enough as the heat source of district heating. In the premise of satisfying district heating, some measures can be adopted to decrease the temperature of geothermal tail water for the target to improve the power output. Consequently, the energy contained by geothermal tail water can be recycled using KC-AHT to decrease the thermal pollution caused by geothermal tail water and increase the power output. In order to expedite the calculation and study of KC-AHT under various boundary conditions, the engineering equation solver (EES) software package is used, and the simulation result is validated. The result shows that the generator inlet temperature of basic solution is increased from 64.6℃ to 73.2℃, which leads to the net power output of KC-AHT increases by 6.8% and 14.9% than that of Kalina cycle in reference and Kalina power plant in Husavik, Iceland, respectively. Besides, the parametric study shows that the best ammonia concentration of basic solution is 0.9 in general regions, not 0.82 in Iceland, the temperature of final tail water and cooling water has a large effect on the power output, the optimum turbine inlet pressure and ammonia concentration are existent to guarantee the highest net power output under a certain condition.