Closed-form modeling of direct steam generation in a parabolic trough solar receiver

Solar thermal power is a promising and ever-growing source of carbon-free electricity. To date, analysis and design tools for solar thermal power generation with parabolic troughs are mathematically complex. We have developed a model of a solar parabolic trough, which advances the simulation of direct steam generators by describing their performance as a function of both time and axial position in closed form. We validate the model by comparing its predictions with data from the Direct Solar Steam (DISS) project, obtaining good agreement both temporally and spatially. The model predicts the profiles of fluid temperature, enthalpy, and quality as well as the lengths of each of the three different phase regions in the absorber. The formulation also yields the temperature profiles of the glass envelope and absorber wall. We further present the response to variable insolation. We propose this model as an engineering tool useful for preliminary modeling, sensitivity analyses, and benchmark solutions for more detailed studies of solar parabolic trough direct steam generators.