Solar linear Fresnel collector using molten nitrates as heat transfer fluid

The use of molten nitrates as heat transfer fluid in a solar Fresnel Linear Concentrator is proposed. A system specifically designed to work with molten nitrates is presented, with an analysis of its optical and thermal properties and the discussion of advantages and disadvantages with respect to existing systems.

Research highlights
► A solar Fresnel linear plant that uses a molten nitrates mixture as heat transfer fluid is proposed and analysed; the system adopts glass-covered evacuated receivers and a secondary reflector.
► The main differences with respect to existing Fresnel systems, and with respect to molten salt trough plants, are illustrated and discussed.
► A secondary reflector developed for this application is presented and its properties are discussed; the secondary reflector distributes a large fraction of the radiation in the upper part of the receiver, allowing to exploit all the receiver surface.
► The optical simulation (using an accurate ray-tracing algorithm) and the thermal simulation of the system are illustrated, calculating the efficiency with respect to the most important parameters (incidence angle, radiation intensity); the overall year efficiency for a locality in the south of Italy is computed.