Development of an automated design and off-design radial turbine model for solar organic Rankine cycle coupled to a parabolic trough solar collector

Abstract

Most of solar organic Rankine cycle (ORC) studies treat expansion machines as ideal machines operating with constant efficiencies. Expansion machines play vital role on the system design and performance. In fact, the system performance is substantially affected by changing turbine operating conditions or geometric parameters as proven in the current study. The current study presents an automated radial turbine model. The model encompasses design point sub-model, off-design sub-model and ORC-PTC sub-model. The radial turbine sub-model is validated against experimental data. Solar irradiance in Hail city, Saudi Arabia, is utilized to investigate the feasibility of the proposed model. The results showed that turbine operating conditions and design parameters affect the solar ORC performance considerably. For instance, increasing the evaporation pressure by 100 kPa resulted in 17.5% smaller turbine. When the turbine pressure ratio increased from 1.5 to 4.5, the PTC efficiency decreased by 1.7%, while the solar ORC efficiency increased by 200%. On 6th of July 2022, in Hail city, the proposed model presented a maximum net power output and thermal efficiency of 2.15 kW and 8.78%, respectively, at noon time.