气相添加剂对纳米溴化锂溶液传质特性影响的实验研究

发布时间：2018-01-22 00:11

本文关键词： 溴化锂溶液纳米异辛醇传质　出处：《北京建筑大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文主要研究了气相异辛醇添加剂对纳米溴化理溶液降膜传质特性的影响根据异辛醇的分子结构,从固液界面、气液界面两个角度分析了异辛醇强化传质的机理。从微观和宏观角度分析了Marangoni对流产生的条件、过程和机理。并解释了气相添加异辛醇与液相添加异辛醇相比的不同和优势。根据液相添加异辛醇时纯溴化锂溶液、只添加纳米的溴化锂溶液、添加分散剂的纳米溴化锂溶液的表面张力变化,运用Gibbs吸附公式和希什科夫斯基经验公式,计算了不同成分溴化锂溶液异辛醇的饱和吸附量,并且得出了添加分散剂的纳米溴化锂溶液异辛醇吸附量减小的计算结果。将不同质量的液相异辛醇加入到水蒸气发生器中,并控制和计算了进入吸收器中气相异辛醇的含量。运用溴化锂传质性能试验台,对气相异辛醇添加剂对纳米溴化理溶液降膜传质特性进行了实验研究。研究了不同吸收压力、不同流量下添加纳米粒子和异辛醇以气相方式进入吸收器时溴化锂溶液降膜吸收水蒸气的相对浓度差、水蒸气吸收速率、传质系数等传质特性,并用传质强化比addF表征了气相异辛醇所引起的Marangoni对流对传质的影响。实验结果表明气相添加异辛醇和纳米粒子对溴化锂溶液吸收水蒸气的能力起到了促进作用。促进作用与降膜流量、吸收压力、异辛醇添加量之间有一定的规律。当吸收压力为1.6Kpa时,水蒸汽发生器中添加1%异辛醇时的传质系数是纯溴化锂溶液的1.74倍,是纳米溴化锂溶液的1.32倍。addF随流量呈先增大,后减小趋势。根据水蒸气的吸收速率导出了异辛醇在吸收发生时的吸附量,并与第二章所计算的饱和吸附量值和传质强化比addF变化趋势相吻合,即addF并不是随着传质系数的增长而增长,并认为是流量增大对Marangoni对流的抑制和异辛醇的覆盖作用削弱了溴化锂溶液对水蒸气的吸收强化程度。
[Abstract]:The effect of gas phase isooctyl alcohol additive on the falling film mass transfer characteristics of nanometer brominated solution was studied according to the molecular structure of isooctanol from the solid-liquid interface. The mechanism of enhanced mass transfer by isooctanol was analyzed from two angles of gas-liquid interface, and the conditions of Marangoni convection were analyzed from both microscopic and macroscopic angles. Process and mechanism. The differences and advantages of gas phase addition of isooctanol and liquid phase addition of isooctanol were explained. According to the pure lithium bromide solution when isooctanol was added in liquid phase, only nanometer lithium bromide solution was added. The surface tension of nanometer lithium bromide solution with dispersant was changed. The saturated adsorption capacity of iso-octanol in lithium bromide solution with different components was calculated by using Gibbs adsorption formula and Hishkovsky's empirical formula. The calculation results of the reduction of iso-octanol adsorption amount in nanometer lithium bromide solution with dispersant were obtained. Different liquid phase isooctanol was added to the water vapor generator. The content of gaseous isooctanol in the absorber was controlled and calculated. The falling film mass transfer characteristics of gaseous isooctyl alcohol additive on nanometer brominated solution were studied experimentally and the different absorption pressures were studied. The relative concentration difference of water vapor absorption rate of water vapor absorption rate mass transfer coefficient and so on when lithium bromide solution drops film into absorber with different flow rate and iso-octanol are added into the absorber in gas phase. The effect of Marangoni convection induced by gaseous isooctanol on mass transfer was characterized by mass transfer enhancement ratio (addF). The ability to play a catalytic role. Promote the role of falling film flow. When the absorption pressure is 1.6Kpa, the mass transfer coefficient of 1% isooctanol in the steam generator is 1.74 times that of the pure lithium bromide solution. The amount of iso-octanol adsorbed in the presence of iso-octanol was derived according to the absorption rate of water vapor, which was 1.32 times as much as 1.32 times of nano-lithium bromide solution and then decreased with the flow rate. It coincides with the change trend of saturated adsorption volume and mass transfer enhancement ratio (addF) calculated in chapter 2, that is, addF does not increase with the increase of mass transfer coefficient. It is considered that the inhibition of Marangoni convection and the coverage of isooctyl alcohol with the increase of flow rate weaken the enhancement of water vapor absorption in libr solution.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ131.11;TB383.1

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