A thorough three-dimensional simulation of steam generating solar parabolic trough collectors, a benchmark of various methods’ accuracy

Investigations show that most simulations on solar parabolic trough collectors reported in the literature are one-dimensional or at least with a variety of simplifications. Indeed, for this collector type, due to the complex heat transfer elements as well as two-phase flow through the tubes, etc., such simplifications make the model fail to give an acceptable estimation of the circumferential temperature distribution of the walls, thermal stresses, heat losses, vapor volume fraction, etc. In this article, a detailed three-dimensional numerical modeling of solar parabolic trough collectors is presented. The results of this model are also compared to those given by an axisymmetric model and a one-dimensional nodal model to highlight the impacts of such a rigorous model on the accuracy of the final results. The results demonstrated that although the axisymmetric and nodal models show acceptable accuracy in predicting the temperature and enthalpy for the flow, they are quite incapable of precisely calculating the vapor volume fraction and heat loss rates. The discrepancy in the distribution of vapor volume fraction in different sections of the absorber tube causes significant temperature heterogeneity in the solid walls.