Thermodynamic Analysis and Sizing of a Small Scale Solar Thermal Power System Based on Organic Rankine Cycle

Abstract

This paper presents the feasibility analysis of a small-scale low-temperature solar organic Rankine cycle power system. The heat transfer fluid for running the organic Rankine cycle system is hot water with a temperature of 120 °C provided by an array of evacuated tube solar collectors. The performance of the solar organic Rankine cycle system was investigated using two different working fluids over a wide range of the evaporation temperature. Technical and economic indicators such as the required solar collector aperture area, the total heat transfer surface area of the heat exchangers and the volume flow ratio between the outlet and inlet of the expander are among the key parameters used to evaluate the solar organic Rankine cycle. Thermolib toolbox 5.2 in conjunction with MATLAB/Simulink was used to predict the variation of the system performance. The results showed that the solar organic Rankine cycle system is able to achieve an overall system efficiency of 6.75% using a relatively low-temperature heat source. The results also showed that the solar organic Rankine cycle system requires smaller evacuated tube solar collector and heat exchanger areas when R245fa is used as the working fluid.

Keywords

• organic rankine cycle
• solar energy
• organic fluids
• evacuated tube solar collector
• low temperature heat sources
• thermolib.