预冷式蒸发空冷器管外传热模型的研究

Study on the fin tube-outside heat transfer model of the precooled type evaporative air cooler

预冷式蒸发空冷器的换热管是蒸发空冷光管与干式空冷翅片管的耦合,若翅片管管外传热膜系数采用传统的干式空冷器传热模型计算,将带来较大的误差。用SPSS软件对预冷式蒸发空冷器传热实验数据进行了线性回归分析,得到了翅片管管外给热膜系数的最佳数学模型,对回归模型进行了综合评价和检验,模型的拟合优度为0.88;对比考察了实验系统干运行和湿运行时的传热性能,当只考虑迎风速度对翅片管管外给热系数的影响时,对应模型的拟合优度由干运行时的0.804下降到湿运行时的0.639。研究结果表明:湿式部分对干式部分的传热性能有较大的影响;空气迎风速度对翅片管管外给热膜系数的影响最显著,其次为介质进口温度和空气出口温度;建立的传热模型与实验数据具有较好的相关性,为预冷式蒸发空冷器的优化设计和操作提供了依据。

The coupling of the evaporative air-cooled bare tube bundle and the air-cooled fin tube bundle is employed in the precooled type evaporative air cooler.However,it may cause some error by using the traditional heat transfer model of the dry-type air cooler to calculate the fin tube-outside heat transfer coefficient.In this work,the linear regression analysis to the experimental data was carried out with SPSS software.The optimal mathematical model for fin tube-outside heat transfer coefficient was obtained.Through the evaluation and test of regression model,the goodness of fit was found to be 0.88.The heat transfer performance of the experimental system was also studied through the comparison of dry running and wet operation.When the effect of the air velocity on the fin tube-outside heat transfer coefficient was only considered,the goodness of fit decreased from 0.804 in the dry running to 0.639 in the wet operation.The results indicate that the heat transfer performance of the dry part is affected by the wet part.The fin tube-outside heat transfer coefficient is significantly affected by air velocity,followed by the process fluid inlet temperature and the air outlet temperature.The established heat transfer model has a good correlation with the experimental data,and provides the basis for the optimal design and operation of the precooled type evaporative air cooler.