PERFORMANCE STUDY OF SOLAR THERMAL BINARY POWER CYCLES

Abstract

The purpose of this study is to evaluate the performance of solar thermal binary power generating system. The system will consist of two cycles, which is solar superheated steam cycle and the organic Rankine cycle. Three organic fluids, isobutane, R123 and R245fa will be used in the study and will be compared with R134a. The primary heat energy is captured from solar energy is used for superheated steam power cycle. The rejected heat from condenser of the steam cycle is used as heat input for the organic Rankine cycle. The temperature differences in the condenser of steam cycle and evaporator of the organic Rankine cycle range from 10°C to 15°C. The total work is produced by the two turbines from these two cycles. The performance is measured based on work and efficiency of the cycles. For organic Rankine cycle, it is found that refrigerant R123 gives the highest efficiency among refrigerant R245fa, R134a and isobutane. It was found that, the maximum work from the combination of the two cycles is from solar steam/isobutane which can produce 613.22 kJ/kg work. This combination of solar Rankine cycle and organic Rankine cycle produce 542.4 kJ/kg and 70.82 kJ/kg maximum works respectively. Both of these solar superheated Rankine cycle and organic Rankine cycle achieve 19.76 % and 16.87 % efficiency respectively.