Solar-driven sodium thermal electrochemical converter coupled to a Brayton heat engine: Parametric optimization. (February 2021)

• Record Type: Journal Article
• Authors: Peng, Wanli; Gonzalez-Ayala, Julian; Su, Guozhen; Chen, Jincan; Hernández, Antonio Calvo
• Is Part Of: Renewable energy. Volume 164(2021)
• Page Start: 260
• Page End: 271
• Publication Date: 2021-02
• Subjects: Solar collector -- Sodium thermal electrochemical converter -- Brayton heat engine -- Irreversible loss -- Performance characteristic -- Parametric optimization; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2020.09.084
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: A novel high-efficiency device comprised of three subsystems, a solar collector, a sodium thermal electrochemical converter, and a non-recuperative Brayton heat engine, is modeled by taking into account the main internal and external irreversibility sources. The model extends previous works in which the heat waste of the electrochemical converter is used as heat input in a Brayton gas turbine to study its performance and feasibility when a solar energy input is added. The operative working temperatures of three subsystems are determined by energy balance equations. The dependence of the efficiency and power output of the overall system on the solar concentration ratio, the current density, the thickness of the electrolyte, and the adiabatic pressure ratio (or temperature ratio) of the Brayton cycle is discussed in detail. The maximum efficiencies and power output densities are calculated and the states of the maximum efficiency-power density are determined under different given solar concentration ratios. The parametric optimum selection criteria of a number of critical parameters of the overall system are provided and the matching problems of the three subsystems are properly addressed. It is found that under a solar concentration around 1350, the maximum efficiency and power output density of the proposed hybrid system can reach, respectively, 29.6% and 1.23 × 10 5 W/m 2 . These values amount approximately 32.7% and 156% compared to those of the solar-driven sodium thermal electrochemical converter system without the bottoming Brayton cycle. The Pareto front obtained from numerical multi-objective and multi-parametric methods endorses previous findings. Highlights: A solar-sodium thermal electrochemical converter-Brayton cycle system is studied. The parametric optimum criteria of main parameters are provided. Matching conditions between the subsystems are given. The efficiency and power output density are increased around 32.7% and 156%. The optimum energetic space given by the Pareto front is obtained.