Flat-plate solar collectors are one of the cleanest and most efficient heating systems available. Studies on the presence of covalently functionalized graphene (Gr) suspended in distilled water as operating fluids inside an indoor flat-plate solar collector (FPSC) were experimentally and theoretically performed. These examinations were conducted under different testing conditions namely 0.025%-wt., 0.05%-wt., 0.075%-wt., and 0.1%-wt., 0.5, 1, and 1.5 kg/min, 30, 40, and 50 °C, and 500, 750, and 1000 W/m2. Various techniques were used to characterize the functionalized nanofluids’ stability and morphological properties namely UV/Vis spectrophotometry, EDX analysis with a Scanning Electron Microscope (SEM), zeta potential, and nanoparticle size. The results showed that the collected heat improved as the percentage of GrNPs and the fluid mass flow rates increased, although it decreased as the reduced temperature coefficient increased, whereas the maximum increase in collector efficiency at higher concentration was 13% and 12.5% compared with distilled water at 0.025 kg/s. Finally, a new correlation was developed for the base fluid and nanofluids’ thermal efficiency as a function of dropped temperature parameter and weight concentration with 2.758% and 4.232% maximum deviations.
Previous studies have shown that the crosswind reduces the output power of a SCPP (solar chimney power plant) with the deflection of the plume at the exit and separation of wind flow there at the downstream. The present numerical investigation was focused on the effect of the stack configuration on the performance of a SCPP. In this paper, the SCPP of the prototype in Manzanares was simulated, where the Boussinesq approximation was used for solving the continuity, Navier-Stokes and energy equations by the standard k-epsilon turbulence model in finite volume method. Governing parameters are taken as oblique angles from 27° to 45° and wind velocity from 0 to 10 m s −1 . Investigation revealed that by changing the stack configuration, the performance of the SCPP could be improved. Numerical simulation of the conventional chimney was compared with the simulation data of the proposed altered chimney geometry (outlet bevel cutting) and observed that the throttling effect on the outlet of the chimney could be reduced. It was noticed that by changing the chimney oblique angle from 27° to 45°, the efficiency of the power plant was dropped. Further, the results illustrated that the oblique angle relies on the wind velocity and it needs to increase with the increase in the wind velocity to obtain a reasonable change in power output. The present investigation was further enhanced to incorporate a comparison of solar chimney power output in two cities (Kuala Lumpur and Kerman) for a better understanding of the effect of environment on constructing the solar tower power plant. The result shows that Kuala Lumpur is appropriated for the installation of SCPP although, the Kerman is suitable too, but the wind velocity in that city is higher than that in Kuala Lumpur.
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