平板型太阳能集热器三维动态传热计算模型开发与应用

Development and Application of Three-dimensional Dynamic Heat Transfer Model for Flat Plate Solar Collectors

平板型太阳能集热器热性能受到环境、运行条件和设计因素的共同影响。本文在分析辐照、温度、风速、入射角度等多因素影响的基础上,建立平板型太阳能集热器部件与环境间导热、对流、热辐射等三维动态传热过程计算模型,开发快速差分求解算法并形成软件,应用于平板型集热器的瞬时传热过程分析和全年运行性能预测。通过在人工环境实验系统中进行不同环境条件多工况实验,计算集热效率与实测最大偏差为0.023,相对偏差为4.9%,集热器热性能分析速度和准确度大大提高。软件在考虑风速、入射角度、热惰性等因素后,全年单位面积辐照量4 941 MJ/m^(2)条件下,平板型太阳能集热器的单位面积集热量比依据瞬时效率曲线计算得到的集热量降低11.0%,可更准确地计算集热器在实际环境和运行条件下的热性能,为系统优化设计提供依据。

The thermal performance of flat plate solar collector (FPC) is affected by environmental factors,operating conditions,and design factors. Based on the analysis of impacts of multiple factors such as irradiation,temperature,wind speed,and incident angle,a three-dimensional dynamic heat transfer model for the heat conduction,convection,and heat radiation between FPC components and environment was established. A fast differential solution method and software were also been developed to analyze the transient heat transfer of FPC and predict its annual operation performance. Compared with experimental data under different environmental conditions in the artificial environment system,the maximum deviation of the heat collection efficiency is 0. 023,with a relative deviation of 4. 9%. The speed and accuracy of thermal performance analysis are greatly improved.Considering wind speed,incident angle,thermal inertia and other factors,the unit area heat gain of FPC calculated by this software is reduced by 11. 0% compared with the result based on the transient efficiency curve under an annual unit area irradiation exposure of 4,941 MJ/m^(2). It shows the software can provide a more accurate calculation of thermal performance of FPC in actual environment and operation conditions,offering evidence for system optimization design.