Heat-Transfer Characteristics of Liquid Sodium in a Solar Receiver Tube with a Nonuniform Heat Flux

• Main Authors: Jing Liu, Yongqing He, Xianliang Lei
• Format: Article
• Language: English
• Published: MDPI AG 2019-04-01
• Series: Energies
• Subjects: solar-power tower; liquid sodium; solar salt; Hitec; heat flux
• Online Access: https://www.mdpi.com/1996-1073/12/8/1432

This paper presents a numerical simulation on the heat transfer of liquid sodium in a solar receiver tube, as the liquid sodium is a promising heat-transfer candidate for the next generation solar-power-tower (SPT) system. A comparison between three mediums&#8212;solar salt, Hitec and liquid sodium&#8212;is presented under uniform and nonuniform heat-flux configurations. We studied the effects of mass flow rate (<i>Q_m</i>), inlet temperature (<i>T_in</i>), and maximum heat flux (<i>q_o</i>_max), on the average heat-transfer coefficient (<i>h</i>) and the friction coefficient (<i>f</i>) of the three mediums. The results show that the <i>h</i> of liquid sodium is about 2.5 to 5 times than other two molten salts when <i>T_in</i> is varying from 550 to 800 K, <i>Q_m</i> is 1.0 kg/s, and <i>q_o</i>_max is 0.1 MW/m². For maximum heat fluxes from 0.1 to 0.3 MW/m², the <i>h</i> of liquid sodium is always an order of magnitude larger than that of Hitec and Solar-Salt (S-S), while maintaining a small friction coefficient.