- 學位論文
添加低表面張力溶劑於吸收式除濕系統探討其對二氧化碳的吸收效能之影響
Effects of the Absorption of Carbon Dioxide by Adding a Low Surface Tension Solvent into the Absorption Dehumidification System
摘要
除了密度、黏度之外，表面張力也為物質的重要特性之一。當添加低表面張力且具揮發性之有機溶劑於吸收式除濕系統中，強制造成氣-液界面形成表面張力梯度，會提升質傳的性能。 添加低表面張力且具揮發性的有機溶劑於溶液界面時，由於工作溶液與添加溶劑的表面張力不一，所以產生了表面張力梯度，低表面張力的液體會向高表面張力的液體方向流動，下層液體向上補充，造成了對流的現象，我們稱此種對流為Forced Marangoni convection。當系統產生Marangoni convection時，可以促進氣-液表面更新效應，進而促進質傳性能的提升。 Marangoni effect 被應用在除濕系統中，可提升除濕性能。然而，對於室內空氣品質而言，除了溼度需要控制，室內空氣品質如二氧化碳的濃度也是重要的因素之一。綜合以上原理，在吸收式除濕系統中添加微量的乙醇，探討Marangoni效應是否可應用在提升二氧化碳的除去量，以達到除濕系統可同時去除二氧化碳的一機二用的理想，減少能源消耗。實驗的參數包括空氣及液體流量、工作溶液的溫度以及濃度以及進口空氣的溼度，並且比較有無添加乙醇之系統，對二氧化碳去除量的差異，以證明界面擾動現象對於系統之不可忽略的影響。
並列摘要
Surface tension is an important property of materials as well as density and viscosity. People found that when we add the solvent which is low surface tension and easily faded away into absorption dehumidification system, force the surface tension gradient forming on the interface of gas and liquid. The mass transfer rate will increase. Adding low surface tension surfactant into the working solution of absorption dehumidification system, there is a difference of surface tension difference between working solution and solvent. The surface tension gradient occurs. Higher surface tension liquid attracts low ones, and the bottom liquid will be replaced to the top. This phenomena is called “Marangoni convection”. While there is Marangoni convection in the system, it can accelerate the surface renew of gas and liquid and the mass transfer rate is increased. Marangoni effect can be applied into dehumidification system, and it can also increase the efficiency of dehumidification. However, for the indoor air quality point of view, besides humidity, the concentration of carbon dioxide is an important index for indoor air quality. In this study, we applied the principles above, adding a small amount of ethanol into the absorption dehumidification system. We want to know that whether the Marangoni effect can be applied into the increasing of the absorption of carbon dioxide or not. We may use one absorption dehumidification system to reduce not only moisture but also carbon dioxide.Thee are two functions in one machine and reduce energy consumption. The experimental parameters include gas and liquid flow rates, the concentration and temperature of working solution, and the humidity of inlet air. We also discussed the effect of the system with and without adding ethanol. By this experiment, we know that there is a significant effect of the interface turbulence in the absorption system with adding a low surface tension surfactant.