Energy and exergy assessment of organic Rankine cycle electricity generation with hot spring as the heat source in Aceh, Indonesia

Abstract

Aceh as one of Indonesian province has some hot springs potencies that can be utilized to generate electricity by organic Rankine cycle (ORC) system. This paper discusses energy and exergy assessment of ORC with hot spring as the heat source in Aceh, Indonesia. Energy and exergy assessment are utilized to evaluate ORC performance. The performance are evaluated from the hot springs that have temperature difference with cooling fluid temperature more than 40°C and the flow rate more than 30 liter/minute. Lokop-1 (93.5°C, 26.2°C, 3000 liter/minute), Lokop-2 (87°C, 27°C, 180 liter/minute), and Lokop-3 (76.5°C, 27°C, 60 liter/minute) are the hot springs location that meet the specified criteria. The working fluid and cooling fluid chosen in this study are R227ea and water. The cooling water temperature is assumed equal to the ambient air temperature. Theoretic electricity power, thermal efficiency, exergy efficiency, total exergy destruction, and exergy destruction rate in each equipment are evaluated in this research. The calculation results of the theoretic electricity power, thermal efficiency, and exergy efficiency, respectively, are Lokop-1 (168.3 kW, 7.77%, 7.21%), Lokop-2 (9 kW, 7.04%, 6.51%), and Lokop-3 (2.4 kW, 5.7%, 5.25%). Lokop-1 has the highest total exergy destruction. The exergy assessment from exergy destruction rate in each equipment show that the maximum exergy destruction occurs in the evaporator.