Impact of Weather Conditions Variability on External Receivers in Real-world Direct Steam Generation Solar Power Tower Plants

Abstract

Solar power tower plants are promising to decarbonize electricity production, where solar power is concentrated to heat the working heat transfer fluids effectively. However, due to atmospheric effects and cloud cover, such power varies spatially and temporally during the diurnal cycle. Therefore, estimating the net solar thermal power gained by receiver tubes in terms of time and location is highly significant. This research set the foundation for developing the heat irradiance equation as a function of time on external receiver absorbing tubes in the Ivanpah I plant using the solarpilot tool. Furthermore, a modified Gaussian distribution is derived for the incident heat flux over the tube circumference. Compared to the proposed distribution, it is found that both the uniform and basic Gaussian distributions employed in former computational fluid dynamics simulations would result in about 57.1% overestimation of the total solar power received. Multisegment correlations are also established for the temporal profile of axisymmetric heat flux on each side of the receiver. A thorough thermodynamic analysis procedure is also developed and applied under real-world weather conditions to exhibit the potential of the proposed scheme to handle such complicated computations comprehensively and cost-effectively. Based on the proposed procedure, an in-house matlab code is built to numerically predict the instantaneous heat losses from the north-facing evaporator panel tubes and their corresponding steam productivity. The results reveal that the onset of nucleate boiling takes up to 2 h from sunrise to reach, with 70% of the tube length required to start evaporation, which lasts to the rest of the tube. However, superheating can be established once solar intensity is strong enough around midday, occupying up to 12.9% of the tube length. The current research has paved the way for future detailed computational fluid dynamics (CFD) investigations of external solar power receivers and has significance in ensuring such systems' reliability and longevity.