太阳能高倍聚光加热条件下单个固体颗粒下落过程传热特性  

Heat performance of single falling solid particle under high concentrated solar irradiation

作　　者：王天健[1] 白凤武[1] 杨贝[1] WANG TianJian BAI FengWu YANG Bei(Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China)

机构地区：[1]中国科学院电工研究所,中国科学院太阳能热利用及光伏系统重点实验室,北京100190

出　　处：《科学通报》2016年第28期3172-3180,共9页Chinese Science Bulletin

基　　金：国家自然科学基金(51376176)资助

摘　　要：下落式固体颗粒吸热器是指固体颗粒在吸热器中下落,同时被太阳光辐射加热,以得到高温固体颗粒.本文建立了单个固体颗粒下落的模型,模拟不同直径的固体颗粒在相同条件下自由下落过程,发现固体颗粒直径较大时,对流损失和辐射损失更小,下落高度能够达到的最大温度更高,所需受热的距离更长.空气流速对固体颗粒的最终温度没有影响,但会缩短固体颗粒在达到最终温度时的下落距离.改变热流密度的大小,发现固体颗粒所能达到的最终温度升高,达到最终温度所需的下落距离缩短.这些结果对下落式固体颗粒吸热器的实验和实际运行具有指导作用.Concentrated solar power tower plants are one of attractive renewable energy systems capable of not only generating electricity, but also driving chemical processes that require high temperature（〉1000 K） heat input. Solid particle receivers have been proposed as an approach for efficiently achieving higher temperatures. In a falling particle receiver nearly black particles are dropped inside a cavity to directly absorb the concentrated solar irradiation. Particles are lifted up to a tower receiver for solar heating and then back down to a hot storage on the ground. In this paper, a model of a single falling particle from the top is established, the Energy-Balance equation of the single particle is used to simulate this process. The main variable properties of the heat transfer process are the particle diameter, falling distance, air velocity, and the concentrated solar flux. On the basis of the simulation results, following valuable conclusions are obtained. It is concluded that convention and radiation losses decreases with the increase of particle diameter increases. Bigger particles are able to absorb more concentrated solar irradiation and get higher final temperature with longer heating distance. While for falling the same distance such as 0.5 m, smaller diameter of the particle leads to a higher particle temperature. For bigger particles whose diameter is 0.5 or 1 mm, the particle temperature increases with the falling distance and tend to a stable value. However, smaller particles with the diameter of 0.3, 0.2 or 0.1 mm there exist the peak particle temperature in the falling process and then drop to a stable value. For the calculated particle diameter range, the final temperature of the particle approaches to a stable value. Air velocity has no influence on the final temperature of the particle, but take effects on the distance at which the particle get to the final temperature. The final falling distance to get the stable temperature decreases with the increase of air velocity. The concentrated sol

关 键 词：太阳能热发电 下落式固体颗粒吸热器 单个固体颗粒下落 数值计算 温度变化 

分 类 号：TM615[电气工程—电力系统及自动化]