【作者】 张立强；

【导师】 赵景利；

【作者基本信息】 河北工业大学 ， 化工过程机械， 2004， 硕士

【摘要】 本文以水和5％～40％的碳酸钾溶液为工作介质，对伞板式降膜蒸发器的传热性能进行了实验研究。首先对伞板的传热情况进行了理论分析，得出了伞板蒸发侧传热系数的计算式。通过恒壁温实验探讨了传热温差、液膜雷诺数、普朗特数这些主要因素对伞板式降膜蒸发器传热性能的影响，通过对以上影响因素的分析，得出了此种结构的蒸发器特别适用于小温差情况下的蒸发，而且特别适用于热敏性物料的蒸发等特性。同时通过对实验数据的处理，得出了伞板降膜蒸发侧传热系数的实验关联式，此关联式预测的传热系数与实验值吻合良好，误差基本在10％以内。 同时本文还对伞板式降膜蒸发器在小流量下产生的液膜破裂情况进行了理论分析以及实验研究。在实验条件下得出了伞板式降膜蒸发器小流量下液膜破裂的实验关联式，此关联式表明极限热通量随临界雷诺数增大而增大，在相同的临界雷诺数下，伞板蒸发器的极限热通量大于直板形蒸发器的极限热通量。表明此结构的蒸发器在小流量的情况下液膜不易破裂。更多还原

【Abstract】 The heat transfer performance of the umbrella-plate falling film evaporator was studied, water and concentration of 5%-40% potash was used as medium in this paper. At first, by theoretically analyzing the instance of heat transfer on the umbrella-plate evaporator. The formula of the heat transfer coefficient on the evaporation side in the umbrella-plate could be obtained. The influence of difference in temperature, Reynolds number of film and Prandtl number to the heat transfer performance on the evaporation side was discussed via the uniform wall temperature experiments. By analyzing above influence factors, The character of umbrella-plate evaporator which is fit for evaporation under little difference in temperature and fit for evaporating heat sensitivity materiel could be obtained. The experimental correlation formula of the heat transfer coefficient on the evaporation side in the umbrella-plate was obtained. The predicated heat transfer coefficient through the formula was finely accord with the experimental result, and the error was basically under 10%.By theoretical analysis and experimental investigation to the exasperate position of the heat transfer in the umbrella-plate falling film evaporator, The exasperate experimental formula of the heat transfer was obtained. With the same Reynolds, The high-point heat flux density of umbrella-plate evaporator is higher than vertical-plate evaporator could be observed from above formula, which maked out that with little Reynolds liquid film was not easy to break.更多还原