Dynamic 6E analysis of direct steam generator solar parabolic trough collector power plant with thermal energy storage

Abstract

The present study discusses the generation of electricity through solar Rankine cycle thermal power plants by direct steam-generating collectors. This solar thermal power plant is modeled on the production of a net power of 50 MW. Modeling has been done by coding in the MATLAB environment and weather conditions of Qom city. A two-tank indirect heat storage system has been used to prevent the power generation cycle from failing when there is no solar energy. The design of a two-tank heat storage system to store the heat generated by direct steam generator collectors is the novelty of this research. Power generation continues in the discharge mode until the heat stored in the heat storage system is finished. An auxiliary boiler must also be used in the discharge mode to bring the steam condition to the desired condition for the high-pressure steam turbine inlet. In previous studies, analyses have been performed for the cycle without a heat storage tank and steady state conditions. For the first time in this research, this power plant's design is done transiently, hour by hour throughout the year, and reported. The heat storage system is designed to generate 6 h of 50 MW of electricity in the sun's absence. But according to the transient analysis, the amount of heat storage varies from day to day depending on the daylight hours of the same day, and therefore the amount of discharge hours per day is different. For each component of the power generation cycle, exergy, exergoeconomic, exergoenvironmental, emergoeconomic, and emergoenvironmental analysis as 6E analysis have been performed. The results are reported transiently hour by hour throughout the year, as well as the monthly average. The results showed that improving the boiler to reduce irreversibility and exergy destruction is an important matter that can improve both the environment and the plant economically. As a result of exergy analysis, the average monthly total exergy efficiency of the power plant varies between 70 and 85% during the year. The average monthly exergy efficiency of the solar field in the four months of May, June, July, and August is about 39 to 40%.