Assefa, Abebayehu (PhD)Bedru, Muaz2018-07-312023-11-182018-07-312023-11-182010-09http://etd.aau.edu.et/handle/12345678/10682Solar Central Tower systems have a single receiver placed on top of a tower surrounded by hundreds of mirrors (heliostats) which follow the apparent motion of the sun in the sky and which re-direct and focus the sunlight onto the receiver. The key elements of a solar tower system are the heliostats:- provided with a two-axis tracking system, the receiver, the steam generation system and the storage system. A fluid circulates through the receiver, collecting thermal energy at high temperatures, and flows to an insulated storage tank. Steam for the 10 MW turbines is made as needed by pumping the hot fluid to a heat exchanger. The receiver and energy storage fluid is a commercial molten potassium and sodium nitrate mixture. The number of heliostats will vary according to the particular receiver‟s thermal cycle and the heliostat design. The power plant analyzed in this paper has a capacity of generating 10MW electric power. The power cycle was modeled using EES to obtain the state point variables such as conductances of the heat exchangers, mass flow rates of steam and HTF, enthalpies, temperatures, pressures etc… at specified state points for steady state operation of the plant. These state point variables are used as reference inputs and/or parameters during system simulation using TRNSYS. The CRS was modeled in TRNSYS simulation studio using existing TRNSYS 16.0 components most of which are from STEC library release 3.0 packages. The CRS financial and economic analysis as well as different system component size and number was optimized using SAM. Without the incorporation of thermal storage, 788 heliostats with 97m2 area satisfies the power demand specified for this research but the addition of thermal storage increases the number of heliostats to 1200 with significant increase in initial system cost and decrease in levelized energy cost. A six hour capacity two tank thermal storage is incorporated with the power plant in order to avoid power transient during low and high DNI, to have power when there is no sunlight, to increase the capacity factor and to minimize the levelized cost of energy. The addition of a thermal storage extends the power plant operation to 16 hours with 13 hours of constant 10MW net electrical power output for a clear sunny day. The SAM analysis reveals that the ii addition of thermal storage in the system significantly increase the investment cost from $58,072,837.73 to $76,781,394.61 with minimizing effect of LCOE from 33.02 to 26.79 cents/kWh and increasing capacity factor from 17.3 to 30.0%enThermal Engineering StreamThesis