100 MWe. For power plants operating in the arid Southest region, an annual average daytime dry bulb temperature of 23°C and a wet bulb temperature of 12°C were assumed for the present study. These assumptions correspond to a condenser pressure of 1.8" Hg and in general result in a 2.5% improvement in performance compared to that of Reference 1. Wet cooling towers were considered throughout. The major tradeoff factor between the heat transport subsystem and the Rankine power plant is the magnitude of the temperature rise in the collectors (△Tc). The flow rate in the heat transport network is inversely proportional to ATc. As ATc decreases, the flow rate increases and the pipe diameter must be enlarged to maintain acceptable pressure drops and to control pumping power. Also, the larger the pipe diameter, the greater the heat leak and required wall thickness. Therefore, as ATc is decreased, the total cost of the energy transport network is increased. Conversely, for energy transport systems 1, 3 and 4 of Table 6, as ATc is decreased while maintaining the maximum temperature constant, the higher is the average temperature at the hot side of the steam generator. The Rankine plant performance, as with any heat engine, increases with increasing average hot side temperature.' Thus, as ATc decreases, the Rankine plant performance improves (i.e., efficiency increases). This tends to improve system efficiency and reduce collector cost. Based on the maximum fluid temperature chosen in Section 3.2.1.2, the Tc was varied and the most appropriate heat engine operating conditions were chosen. This Rankine engine performance was then combined with the heat transport subsystem costs in Section 4.2 to choose the optimum system design. The water energy transport subsystem (system 1) has a 315°C outlet temperature. The inlet water temperature,was varied from 200°C to 290°C and the optimum Rankine plant performance was then evaluated. The pinch point in the steam
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