基于横纹管氨水溶液垂直管外降膜吸收性能的变化规律

Performance Variation of Aqua Ammonia Falling Film Absorption Outside Vertical Tube Based on Transversally Grooved Tube

针对三根不同尺寸规格的横纹管,通过实验研究提高其吸收效率,选择吸收性能最优的管型。实验结果表明,随着压差和管内冷却水流速的增大,溶液吸收氨气的量增加,管外溶液传质系数增大。当管外氨水溶液喷淋密度从小变大时,光滑管和横纹管的传质系数均先增加后减小,过程中出现了最大值。该系列实验的结果表明横纹管比相同工况的光滑管有更高的强化传热和传质能力,当溶液喷淋密度为479.6kg/(m.h)时,横纹管比光滑管的传质系数增大了97.8%。三组实验中均发现一个共同的规律,横纹管的传质系数随凹槽尺寸变化而改变,2号横纹管表现出更强的吸收氨气能力。该管凹槽宽度与横纹管外径的比值为0.0814。通过对凹槽内溶液流动模型分析,比较了溶液通过凹槽时掺混和涡流的流动形态,得出了不同尺寸规格横纹管吸收性能差异的一个原因。

A series of experiments are carried out to find approach which can enhance absorption efficiency for transversally grooved tube （TGT） with different sizes, and to choose an optimal tube type. The experiment results show that aqua ammonia can absorb more ammo- nia gas and the mass transfer coefficient becomes larger with the increase of pressure difference and velocity of cooling water inside tube. When sprinkle density of aqua ammonia outside tube increases, mass transfer coefficient increases firstly and then decreases, so an opti- mum exists. The group experiments results indicate that transversally grooved tube have better mass transfer ability than smooth tube. For example, when sprinkle density of solution is 479.6kg/（ m ~ h）, mass transfer coefficient of transversally grooved tube rise by 97.8% compared to smooth tube. A common law is discovered during three groups of experiment. Different sizes of TGT have different ability to absorb ammonia gas, and No. 2 tube is the best tube considering absorption efficiency. The ratio of groove width to diameter of this tube is 0. 0814. Flow patterns of blend and vortex flow are compared among three transversally grooved tubes with solutions flowing through grooves, and the reason why TGT with different sizes have different absorption efficiency is obtained.