Comparison between two solar feed water heating systems in thermal power plant

Abstract

Solar feed water heating using parabolic trough collectors may be integrated into an existing power plant to reduce the amount of extracted steam and increase power output. Two systems are possible. The first system requires a heat transfer fluid with a high boiling point and an oil-water heat exchanger in addition to parabolic trough collectors. The second system does not require a heat transfer fluid and an oil-water heat exchanger because steam is generated directly in absorber tubes of parabolic trough collectors. The objective of this paper is to use models of thermal power plant, parabolic trough collectors, oil-water heat exchanger, and feed water heater to compare the power outputs resulting from integrating both solar feed water heating systems into a thermal power plant. Numerical results obtained for a case study of a 50-MW power plant indicate that, in order for both systems to generate the same power outputs, the total heating surface area of the first system must be 3.48% more than that of the second system. Furthermore, if both systems have the same total heating surface areas, the second system will generate up to 0.26% more power output than the first system.