Integration of a parabolic-trough solar field with solid-solid latent storage in an industrial process with different temperature levels

Abstract

The aim of this work is to analyse the integration of solar industrial process heat with novel latent heat storage systems by means of a representative case study that has a demand profile with different temperature levels. To that end, an innovative thermal storage system is proposed to support the contribution of the solar field to the industrial heat demand. The storage system considered is based on the latent heat of the solid–solid transition of pentaglycerine and it seems particularly interesting for industrial applications with space limitations and low temperature differences. Additionally, it may suppose further advantages in terms of corrosion, degradation and low cost of raw material. Thermal tests have confirmed the suitability of pentaglycerine as storage material for such applications. In this case study, a solar field with parabolic-trough collectors coupled to a pasteurization process has been considered. To analyse the expected behaviour of the proposed system, a simulation model has been developed in TRNSYS. This model defines, for the first time in the literature, a complete set of operation modes and control strategies specific to concentrating solar collectors for industrial process heat applications with latent storage, able to deal with the required variable temperature levels. Annual simulations have been performed using locations and meteorological data of Graz (Austria) and Plataforma Solar de Almería (Spain). The simulation results show that the percentage of annual heat demand covered with solar energy could be increased from 20% to 27% in Graz or from 40% to 52% in the PSA by using 3 h of latent heat storage.