Thermo-fluid Dynamic Analysis of a CSP Solar Field Line during Transient Operation

Concentrating Solar Power (CSP) technology allows to produce high temperature thermal energy from solar radiation. The thermal energy can be converted into electricity or it can be directly used for industrial processes. Most of the available simulation models of CSP plants evaluate the behavior of the solar field in stationary conditions, neglecting transient thermo-fluid-dynamic effects. Nevertheless, the study of the dynamic behavior of the solar field is a very challenging and interesting task and allows obtaining useful information for the design and the effective management strategies of CSP plants. This paper presents a thermo-fluid-dynamic analysis of a solar field line of the CSP plant currently under construction in Ottana, Sardinia (Italy), which uses thermal oil as heat transfer fluid. Dynamics of the system due to solar irradiance variations have been evaluated by using an axisymmetric unsteady 2D numerical model developed in Comsol to evaluate the oil temperature distribution along the receiver tube for different operating conditions. The results have been compared with those obtained with a simpler, non-stationary one-dimensional model, developed in Matlab environment. The comparative analysis show very similar results for the two models and demonstrate that the dynamic effects on the temperature distribution along the solar field line are not negligible.