Energy performance enhancement of solar thermal power plants by solar parabolic trough collectors and evacuated tube collectors ‐based preheating units

Abstract

Summary Solar steam power plant is the dominant technology in the category of solar thermal power systems. In steam power cycles, there is usually a couple of steam lines, extracted from medium‐pressure and low‐pressure turbines, to preheat the working fluid before the boiler. This although leads to an increase in the energy efficiency of the cycle, reduces the contribution of the turbine proportionally. Therefore, finding an alternative method of preheating the working fluid would be effective in further enhancement of the efficiency of the system. In this study, the feasibility of using solar collectors for the preheating process in a solar steam power plant is investigated. For this, parabolic trough solar collectors and evacuated tube solar collectors based on a wide range of different scenarios and configurations are employed. The plant is designed, sized and thermodynamically analyzed for a case study in Saudi Arabia where there is a large solar irradiation potential over the year. The results of the simulations show that, among all the considered scenarios, a power cycle aided by a set of parabolic trough collectors as the preheating unit is the best choice technically. This configuration leads to about 23% increased power generation rate and 6.5% efficiency enhancement compared to the conventional design of the plant.

Multi‐objective optimization of a novel supercritical CO 2 cycle‐based combined cycle for solar power tower plants integrated with SOFC and LNG cold energy and regasification

“…A significant advantage of using sCO 2 in comparison with helium Brayton cycle is that sCO 2 provides greater thermal efficiency at lower temperatures and allows for higher operating temperatures. 34 A preliminary thermodynamic assessment of three different sCO 2 power cycles integrated in a high-temperature solar tower system, working up to 800 C, was conducted by Binotti et al 36 In another research, solar thermal tower systems were powered by supercritical carbon dioxide (sCO 2 ) recompression Brayton cycles by Atif and Al-Sulaiman. 37 They generated a surround heliostat field layout utilizing a mathematical model subsequently adjusted for optical performance yearly employing differential evolution as an evolutionary algorithm.…”

“…Different heat transfer fluids (HTFs), including synthetic oils or nitrate salts, are often used to transfer solar energy from the receiver to the power block in the CSP plants. Nevertheless, these heat transfers fluids, due to their working temperature limitations can only be used in a temperature range (400°C for oil, 565°C for14 salts) that in conclusion will limit the performance of the plants 34,35 while the higher operating temperatures will result in higher system energy efficiency. A significant advantage of using sCO 2 in comparison with helium Brayton cycle is that sCO 2 provides greater thermal efficiency at lower temperatures and allows for higher operating temperatures 34 .…”

“…Nevertheless, these heat transfers fluids, due to their working temperature limitations can only be used in a temperature range (400°C for oil, 565°C for14 salts) that in conclusion will limit the performance of the plants 34,35 while the higher operating temperatures will result in higher system energy efficiency. A significant advantage of using sCO 2 in comparison with helium Brayton cycle is that sCO 2 provides greater thermal efficiency at lower temperatures and allows for higher operating temperatures 34 . A preliminary thermodynamic assessment of three different sCO 2 power cycles integrated in a high‐temperature solar tower system, working up to 800°C, was conducted by Binotti et al 36 In another research, solar thermal tower systems were powered by supercritical carbon dioxide (sCO 2 ) recompression Brayton cycles by Atif and Al‐Sulaiman 37 .…”