Solar thermal organic rankine cycle as a Renewable energy option

Abstract

The objective of the paper is to study the feasibility of an Organic Rankine Cycle (ORC)driven by solar thermal energy as a renewable energy option for small and medium sizedcommercial usage, power generation of less than 10MW. ORC is principally aconventional Rankine Cycle that uses organic compound as the working fluid instead ofwater and it is particularly suitable for low temperature applications. Appropriate organiccompound includes refrigerants and azeotropes. The ORC and the solar collector aresized according to the solar flux distribution in Malaysia. According to MalaysiaMetrological Department, Kota Kinabalu has the highest yearly average of solar radiationin the country for year 2003, for this reason it is chosen for the location of study. Thepower generation system consists of two cycles, the solar thermal cycle that harness solarenergy and the power cycle, which is the ORC that generates electricity. The solar thermalcycle circulates heat transfer fluid (HTF) in the cycle and harness thermal energy from the sun and transfers it to the organic compound in the ORC via a heat ex changer.Components in the power cycle or ORC include an ORC turbine for power generation, acondenser for heat rejection, a pump to increase the pressure and a heat ex changer. The HTF selected in this analysis is Therminol VP3, which is currently used for commercial solar thermal applications. For this research, 2 organic compounds were analyzed, R123 and iso butane. These two compounds are optimized for selection.