Evaluation of cross-contamination in indirect thermal storage system in concentrated solar plants

Abstract

Solar concentration technology is fully dispatchable due to the use of thermal energy storage systems, in particular, commercial parabolic trough power plants use indirect storage systems based on molten salts. This system includes a heat exchanger to transfer energy between the thermal oil from the solar field and the salts used in storage. In addition, some content of water is considered by cross-contamination in the steam generator of the power block. This study analyses the compatibility between both fluids in the event of cross-contamination in the equipment. The degree of compatibility between a triphasic system made up of a mixture of sodium nitrate and potassium nitrate salts (60:40), heat transfer fluid (DP:DPO), and water, when they were subjected to 390 ºC for a period of 312 h (two weeks). The study shows how thermal oil undergoes complete thermal-oxidative degradation without high impact on the composition of the salts.

This work was partially funded by the Ministerio de Ciencia e Innovación de España (ITC-20111061-FEDER- Innterconecta- Composol) (PID2021-123511OB-C31 - MCIU/AEI/FEDER, UE), by the Ministerio de Ciencia e Innovación (TED2021-132216A-100), and by the Ministerio de Ciencia, Innovación y Universidades de España - Agencia Estatal de Investigación (AEI) (PID2021-123511OB-C31 - MCIN/AEI/10.13039/501100011033/FEDER, UE). The authors at University of Lleida would like to thank the Catalan Government for the quality accreditation given to her research group (2021 SGR 01615). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia