Maximum Exergy Control of a Solar Thermal Plant Equipped with Direct Steam Collectors

Abstract

The performance of solar thermal power plants is strongly affected by the radiation intensity, which is subject to large variations depending on the weather conditions and on the time of the year. The control system of the solar thermal energy conversion plant must take into account such variable conditions, introducing correct thermodynamic relations pursuing the minimization of exergy destruction. The advantage of introducing direct-steam solar collectors with respect to the use of a separate heat transfer fluid in the primary circuit is also demonstrated. The model simulation predicts a performance improvement - compared to traditional control laws - ranging from 10 to 20% depending on the reference month.