Prospective fully-coupled multi-level analytical methodology for concentrated solar power plants: General modelling

The complexity of the cascading solar-thermal-mechanical-electrical energy conversion in concentrated solar power (CSP) plants urges to develop an accurate and fast analytical methodology for on-site use. Herein, we propose a novel fully-coupled multi-level analytical methodology, where multi-dimensional model (0-1-2-3 Model) is developed to address the optical-hydraulic-thermal-elastic synergistic issue in CSP plants: (i) At system-level, the 0 Sub-Model reveals the heat-work transformation in power block in the view of thermodynamics; (ii) At loop-level, the 1 Sub-Model uncovers the collection, concentration and transformation of solar energy into the working fluid in the loop on account of 1D thermo-hydraulics; (iii) The 2 Sub-Model, employing 2D finite volume method (FVM), figures out the detailed circumferential temperature profile of receiver tubes in terms of composite heat transfer; (iv) At component-level, the 3 Sub-Model, using 3D finite element method (FEM), brings insight into the nonuniform-temperature-induced deformation of receiver tubes focusing on the thermo-elastics. The 0-1-2-3 Model enables both system-level performance prediction and component-level targeting insight in a remarkably high-efficient way with guaranteed accuracy. In comparison, the computational time of a full 3D model is 15 times longer than that of the proposed 0-1-2-3 Model for a typical 4-m heat collection element (HCE) and it goes up to 23 times longer for a 24-m loop section. To make the proposed model easily understood, a CSP plant with parabolic trough collector (PTC) and direct steam generation (DSG) technologies is applied. It was found that under the rated conditions, the energy and exergy efficiencies of the plant are 18.89% and 20.26%, respectively.