Performance evaluation of a direct vapor generation supercritical ORC system driven by linear Fresnel reflector solar concentrator

For the purpose of getting higher system efficiency at high temperature and avoiding the complex two-phase problem, the performance of a direct vapor generation (DVG) supercritical organic Rankine cycle (SORC) system driven by linear Fresnel reflector (LFR) concentrator was evaluated in the paper. The detailed procedure for modeling the LFR concentrator and SORC process through the EES environment was presented. The method to select suitable supercritical organic working fluids for middle-high temperature (150 °C-350 °C) was also indicated. The results showed that coupling the supercritical and DVG technology not only decreases the irreversibility at evaporator, it also reduces the heat loss and cost of system and allows obtaining higher overall efficiency. With the increasing of inlet temperature before turbine, the overall efficiency increases. In addition, the results demonstrated that supercritical cycle can be seen as a way to increase the maximum operating temperature. The results of the present work implied that cyclohexane is the best choice of organic working fluid for SORC system with an overall efficiency of 19.65%.