太阳能热发电用固体颗粒式空气吸热器内传热机理研究

Using the flowing solid particles as the absorbing material is an important means to solve the problem of easy destroy at high temperature of the current volumetric receiver. It is very important to do in-depth study on the heat transfer mechanism of solid particle air receiver under the heating condition of non-uniform and non-stable high concentrated solar radiation. Thus in this projects, the following research will done. The radiation characteristics of the solid particles will be tested and the scope and conditions of the Mie scattering theory and other approximation algorithms will be determined. By the research, the basic data of solid material radiation will be accumulated. The coupled heat transfer mathematical physics model and method of multi-process including the concentrated solar radiation spread, radiative heat transfer of high temperature solid particles and convective heat transfer between the solid particles and air will be carried out to calculate the mechanism of energy conversion of fluidized bed and free falling solid particle air receiver. The correctness of the theoretical model and numerical method will be verified by a lot of experiments on the solar furnace concentrating system and 1MW solar thermal power tower plant. The effects of characteristics of the solid particles and parameters of gas-solid two-phase flow on the mechanism of solid particle air receiver will be revealed by extensive numerical simulation. On the basis of above research, the thermal performance of the solar thermal power tower using solid particle air receiver will be simulated. By the research of this project, the solid theoretical foundation for large-scale application of the solid particle air receiver will be provided.

以流动的耐高温固体颗粒作为吸热材料是解决目前容积式空气吸热器高温易于毁坏的重要手段，深入研究非均匀非稳定的高倍聚聚太阳辐射能流加热条件下固体颗粒式空气吸热器内传热机理具有重要意义。本课题将细致研究固体颗粒的辐射特性, 确定Mie散射理论及其他近似算法的适用范围和条件，积累基础数据；开展固体颗粒流化床式和下落式两种典型空气吸热器内聚光辐射能的传播、固体颗粒高温辐射与传递、空气与固体颗粒间对流换热等多过程耦合传热的数学物理模型及求解方法研究，并研制小型吸热器在太阳炉聚光系统和1MW塔式太阳能热发电站中做大量实验验证模型和算法的正确性。进行大量数值模拟揭示固体颗粒特性、气固两相流动特征等参数对固体颗粒空气吸热器热性能的影响机理。并以此为基础，数值模拟固体颗粒式空气吸热器应用于塔式太阳能热发电站的热性能，为固体颗粒式空气吸热器大规模应用提供坚实理论基础。

本项目针对固体颗粒式空气吸热器内流动与传热的关键科学问题开展研究，涉及太阳能聚光、辐射传递、对流换热等多个学科领域，该项目的研究对促进相关学科发展具有一定的理论意义和实用价值。.本项目的主要工作包括：.（1）从单个固体颗粒在聚光辐射能流加热条件的下落过程吸热与换热规律，建立了完备的流动与换热过程数学物理模拟，模拟了不同直径的固体颗粒在相同条件下自由下落过程,分析了固体颗粒直径、固体颗粒热物理性能参数、加热能流密度等因素对辐射损失和对流损失的影响机制,获得了固体颗粒达到最终温度与下落距离间的相互影响规律。.（2）针对石英管束式固体颗粒空气吸热器内的辐射传递与空气换热特性，建立了高倍聚集太阳辐射能流加热条件下的颗粒吸热、辐射传递与固体颗粒与空气间换热过程的理论模型，获得了主要参数对颗粒流动过程和出口空气温度的影响规律，研制了室内冷态流化与太阳能聚光的热态实验系统，获得了太阳法向直射辐照度变化条件下该类型吸热器的运行特性。.（3）针对单根石英管内下落式固体颗粒吸热器内的辐射传递与换热特性研究，建立了完备的数值模拟模型，研制了单根石英管内下落式固体颗粒吸热器的冷态实验平台，掌握了主要参数对吸热器流动性能的影响特性。研制了太阳炉加热的单根石英管内下落式固体颗粒吸热器的热性能实验系统，获得了粒径0.5 mm和1mm碳化硅颗粒吸热器的动态传热特性。