Advanced Modeling of CSP Plants with Sensible Heat Storage: Instantaneous Effects of Solar Irradiance

Abstract

A flexible model for concentrated solar thermal power plants with two tank active direct storage system is developed on gPROMS platform. Eutectic mixture of potassium and sodium nitrates salt melt is used as heat transfer fluid and storage medium. The solar radiation data obtained from a weather station, during 10 years in the city of Isfahan are used. It is showed that the Bird’s clear sky model well represents the normalized weather data. The storage system is designed to feed the boiler for 15 hours in the absence of sun. The model predicts the instantaneous effects of solar irradiance change and calculates variable with time parameters of the CSP plant; namely, the salt melt flow rates through receiver and boiler, and tank levels during 24 hr. The results indicate that a collector surface area of 35 m 2 and 250Kg mixture of nitrate salts, per 1 KW electricity generation, is necessary. With respect to the “variable with time” nature of solar irradiance, the role of storage tanks to damp fluctuations in process parameters of a CSP plant is further quantified. A 2500 Kg of heat storage material eliminates variable collector surface area need of 100 m 2 to 1500 m 2 or equivalently, eliminated increasing boiler temperature greater than 1000 o C.