Maimoon Atif

Performance analysis of supercritical CO 2 Brayton cycles integrated with solar central receiver system

Solar thermal energy is a promising source of energy, especially for high intensive solar irradiation locations such as Saudi Arabia. Solar tower is considered the most promising concentrating solar power technologies in the future. On the other hand, supercritical carbon dioxide (sCO2) Brayton cycles have recently received attention by the researchers in the field due to the high thermal efficiency that can be attained from the cycle which can reach 50%. In this paper, thermodynamic analysis of a solar thermal tower system integrated with supercritical CO2 cycles is presented. A mathematical model was developed to achieve the objective of the present study. The first part of the model deals with generating a heliostat field in a conventional radial staggered configuration. The generated heliostat field is then evaluated for its optical performance. The heat collected through the heliostat field is redirected to the central receiver where the supercritical CO2 thermal cycles are integrated. Total net thermal heat and power generated from the thermal system are presented and discussed for Dhahran, Saudi Arabia.

Time Instant Optimization of a Heliostat Field Using a Heuristic Algorithm

Solar central receiver systems are viewed as one of the most promising concentrated solar power (CSP) technologies for power production, in which solar radiation is concentrated through large mirrors (heliostats) onto a central receiver. This is due to the fact that very high temperatures can be reached at the receiver and thus higher thermal efficiency can be achieved compared with other CSP technologies. Heliostat field layout optimization is an essential task for any solar central receiver system.In this paper, a heuristic algorithm, i.e. the differential evolution (DE), was employed to perform efficient optimization of the conventional radial staggered heliostat field layout using MATLAB. The model calculates all the required optical performance parameters at every step of the optimization process for each heliostat and consequently more reliable results are obtained as compared with many other optimization methods. Two cases were considered: one with single variable optimization and the other with multi-variable optimization. For the first case, the azimuthal spacing between the adjacent heliostats or the radial distance between the rows of heliostats were optimized independently and for the second case both of these variables were optimized simultaneously. Both cases were examined for high sun altitude angle and low altitude angle and a comparison study was performed between them to check their effect on the heliostat field efficiency. Finally, it was noted that varying the radial distance between the rows of the heliostats yields slightly better efficiency as compared with when optimizing the azimuthal spacing.Copyright