The effect of spray on the radiation transfer of concentrated solar irradiation in a novel designed solar steam generator

High-temperature steam is required to produce hydrogen with Solid Oxide Electrolysis Cells (SOEC), but generating steam can be power-consuming. Concentrated solar power is a good candidate for replacing electricity or fossil fuel in generating steam. This paper investigated the effect of spray on radiation transfer in a novel solar steam generator designed to utilize spray cooling to enhance heat transfer. The Monte Carlo ray-tracing technique, considering the absorption of droplets, absorption of water vapor, and multiple scattering of droplets, is employed to analyze the flux density at the focal plane and the spatial scattering power distribution of droplets. The results show that the total incident power transmittance is found to be in positive proportion to the mean droplet diameter while in reverse proportion to the spray volume fraction. Since the maximum difference in spectral transmittances is less than 1%, it is not feasible to adjust the wavelength for higher transmittance. The nozzle position seems highly affects the solar power distribution, and the central area is more affected than the outer area. Thus, increasing the spray volume fraction may uniform the flux density but reduce the transmittance. The spatial scattering power analysis indicates that increasing the droplet diameter can effectively improve the transmittance when the spray volume fraction keeps constant, which may be a solution when applied to a large-scale steam generator.