太阳能粒子吸热器光热耦合动态热输运特性与调控机制研究

Concentrated solar power fluidized bed particle receiver can obtain both high temperature thermal energy collection and storage, which is a most promising technology in solar thermal power field. Because of high concentrated radio and non-uniform time varying characteristics of solar irradiation, inconstant ambient conditions and complex non-linear component of gas-solid two phase flow, the thermal energy transport process of particle receiver is characterized by unsteady and multi-physical fields couple. To realize the performance control of the receiver, it is necessary to study the key scientific problem, which can be described as the time delay effect of particle heat transfer process and its coupled responding mechanism with multi-physical fields thermal energy transport characteristics. This project will focus on the fluidized bed particle receiver. Based on dynamic characteristic experiment of particle heat transfer processes, and the multi scale analytical model with the so called hierarchy modeling and optical-thermal couple, the responding mechanism of thermal transport process in unsteady input and multi-physical fields will be analyzed deeply. In further, the restrain mechanism for particle thermal delay effect will be revealed at the random fluctuation of input heat sources. On this basis, the synergistic controlling mechanism of thermal energy transport characteristics for receiver can be explored under overall working condition, so that a combined design method considering material properties, system structure, and controllable operating parameters can be proposed under multi-physical fields couple. The investigation will provide a feasible theory method and technical support for the safe and efficient operation of solar particle receiver.

聚光型太阳能流化床粒子吸热器兼具高温集热和储热功能，是太阳能热发电领域前沿技术。高倍聚光太阳辐射能流的非均匀时变特性、多变环境条件以及气固两相流复杂非线性体系，使得粒子吸热器热输运过程呈现非稳态多物理场耦合的传热特征。为实现吸热器性能调控，需要研究“粒子传热过程的时滞效应及其与多物理场热输运特性的耦合响应机制”这一关键科学问题。本项目拟通过粒子集热过程的动态特性实验，以及“分层建模、光热耦合”的多尺度数值模型对太阳能流化床粒子吸热器展开研究，深入分析非稳态多物理场条件下热输运过程的响应规律，揭示粒子热迟滞特性对热源波动的平抑机理；在此基础上，探索吸热器热输运的性能协同调控机制，形成多物理场耦合作用下贯穿材料性能-吸热器结构-可控参数的统一调控方法。本项目的开展将为太阳能吸热器的安全高效运行提供可行的理论方法和技术支撑。

目前具有工程应用价值的传热流体和储热材料，往往不能兼具高热传导性能和高比热系数的优势，造成蓄、放热速率和储能能力之间的矛盾甚至双重短板。太阳能集热器内采用固体颗粒或粒子介质，与流化床技术相结合，可以兼具集热和储热功能，从而显著简化系统、降低建设成本、提高运行的安全性，为解决现有储热技术瓶颈提供了的新途径。. 本项目基于气固交叉逆流技术提出一款新型高温、高效、稳定粒子吸热器设计方案，并开展性能实验和理论分析研究。设计并搭建可视化气固逆流式流化床冷态实验模型并对其宏观流动特性及其影响因素展开探究，包括不同操作工况、进气布置方式、颗粒直径和管道结构的影响机制。提出了密相气固逆流式流化床粒子吸热器结构并搭建了单管实验室级别高温实验测试平台。在高温、大温差运行环境下探究了密相气固交叉逆流体系非线性热输运规律。基于计算颗粒流体力学和颗粒解析直接数值模拟方法建立设备尺度和颗粒尺度数值模型。通过设备尺度模型模拟了密相气固逆流式流化床粒子吸热器内颗粒流动过程，获得了气固流型与颗粒轴向速度在管内的轴/径向分布，基于实时固含率信息分析了上升气泡的生成频率与时间分率。本项目的开展将为太阳能吸热器的安全高效运行提供可行的理论方法和技术支撑。.