Energetic and exergetic analysis of a novel geothermal driven multi-generation system using n-pentane as working fluid

Abstract

In the present study, a geothermal driven multi-generation system for electric power, heating, cooling and hydrogen production is introduced. The proposed system is based on an organic Rankine cycle (ORC), where n-pentane is used as the working fluid. Within the study, it is aimed to evaluate the impact of geothermal source flow rate/temperature, ambient temperature and turbine inlet pressure on the energetic and exergetic performance of different system components. Besides, the overall first and second law efficiencies of the multi-generation system for different operating conditions are determined. In the investigated system, generated electricity can be partially used for domestic needs while the rest is proposed to be used for hydrogen production through an electrolysis process. Heat recovered from the ORC is also utilised for driving a single-effect absorption chiller (SEAC) for producing heating and cooling. The study results showed that the optimum mass flow rate and temperature of the geothermal source are 11.88 kg/s and 483.2 K, respectively. For the optimised operating conditions of the proposed multi-generation system, overall energetic and exergetic efficiencies were determined as 0.56 and 0.41, respectively.