D8.5.2 Exergy Analysis of the ASTEP system

This document covers the exergy analysis of the ASTEP system based on the simulation models developed in WP5 as well as using experimental data available from WP6.The objective of this analysis is to identify the irreversibility of the different components and to assess the inefficiencies of the system to propose different alternatives of optimization.To attain this objective, some simulations of the integrated ASTEP systems for MAN and AMTP cases were performed in some representative days and for whole year. The formulation used allows the identification of the inefficiencies of each component.The results of these simulations show that, as expected, the main contributor to the irreversibility of the system is the Sundial. Other important contributors are the heat exchangers, the chiller and the boiler and, when the storage system is almost full, the mixture that controls the temperature at the inlet of the demand side. In addition, further mixing and splitting processes were analysed and comparisons between the two systems were established.This task runs in parallel to those of WP5 aimed at the optimization of the system, so it has influenced in the decision of the final layout of each system, as it was highly conditioned by some constraints exposed in Deliverable D5.1 [1].After that, some results based on the data obtained in WP6 are presented for the exergy analysis of the SunDial and the Thermal Energy Storage system. The exergy analysis evidences a poor efficiency of the solar field and mirrors for the MAN system and significantly better (but still below expected) for the AMTP one; the good performance of the Thermal Energy Storage system during the heat transfer process; and the pronounced exergy losses due to the heat losses to the ambient.