A Thermal-Hydraulic Model for the Stagnation of Solar Thermal Systems with Flat-Plate Collector Arrays

Stagnation is the transient state of a solar thermal system under high irradiation where useful gain zero. Both flat-plate collectors with selective absorber coatings and vacuum-tube exhibit stagnation temperatures far above saturation temperature glycol-based heat carriers within range typical pressures. Therefore, always associated vaporization propagation vapor into pipes circuit. It therefore essential to design in such way that never reaches components cannot withstand temperatures. In this article, thermal-hydraulic model based on integral form two-phase mixture drift-flux correlation presented. The applicable meander-shaped tubes coatings. Experimental data from experiments two systems, which are identical except for optical properties coating, allowed comparison simulations carried out same boundary conditions. one features conventional highly while other thermochromic exhibits significantly lower temperature. Comparison simulation results experimental shows good conformity. This implemented an open-source software tool called THD dimensioning systems. latest version THD, updated by enables planners achieve cost-optimal systems ensure failsafe operation predicting steam initial conditions worst-case scenarios.