为得到易于直接应用的波纹型太阳能通风预热墙热效率简化数学表达式,建立太阳墙的仿真模型,引入高度比H*、特征厚度δ*、孔隙率σ、波纹凹凸度Lw、波纹度W*等5种结构参数,通过数值模拟研究其与近壁面雷诺数Re对太阳墙努塞尔特数σ、热传递系数He和压差值Pdrop的耦合影响关系。发现系统性能指标与Re间呈幂函数规律,与σ的对数和其他参数间则呈二次指数函数规律。利用LM优化算法求得计算式的经验系数,结果表明Nu和压差的简化计算结果与仿真模拟结果存在最大不超过6.85%的偏差。集热效率的简化计算结果与实验测试结果存在平均4.89%、最大6.69%的误差,相比传统计算方法所得的修正结果平均提高近10%的精度,数据吻合良好,可为工程设计提供参考。
Abstract
This paper establishes a numerical simulation model of the solar ventilation preheating wall in purpose of obtaining a simplify calculations method for the thermal efficiency that can be easily applied. Five structural parameters, such as height ratio H*, characteristic thickness δ*, porosity σ, corrugation concavity Lw, and corrugation degree W*, are introduced. The coupling relationship between them and the near-wall Reynolds number Re on the solar wall Nusselt number Nu, heat transfer coefficient Hε and differential pressure value Pdrop is investigated by numerical simulation. The system performance indexes present a power function law with respect to Re, and a quadratic exponential function law in relation to the logarithm of σ and other parameters. The calculated empirical coefficients are obtained using the LM optimization algorithm. The results indicate that the simplified calculation results of Nu number and differential pressure have a maximum deviation of 6.85% from the simulation results. The simplified calculation results of heat collection efficiency have an average error of 4.89% and a maximum error of 6.69% with the experimental test results. The accuracy of the corrected data is improved by nearly 10% on average compared with the corrected values achieved by the traditional calculation method. The results are in good agreement and provide a reference for engineering design.
关键词
太阳能 /
数值模拟 /
通风 /
预热墙 /
简化计算方法
Key words
solar energy /
numerical simulation /
ventilation /
preheating wall /
simplify calculations method
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基金
国家自然科学基金（52078408; 51878532）; 陕西省杰出青年基金（2020JC-43）
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