**4. Conclusions**

**Figure 5.** Effect of air flow rate on removal amount.

102 Heat and Mass Transfer - Advances in Modelling and Experimental Study for Industrial Applications

**Figure 6.** Effect of liquid flow rate on removal amount.

Since the interfacial fluid flow could be provoked by the surface tension gradient, the volatile matter was used as an additive in this study to discuss the effect of additive on mass transfer performance. Therefore, not only experimental mass transfer rates for water vapor absorption into the TEG solutions under different operating conditions were reported but also mass transfer performance with and without adding additives were also compared in this study. The removal amount of H<sup>2</sup> O increased with the higher TEG concentration and liquid flow rate; however, the removal amount of H<sup>2</sup> O decreased with the lower liquid temperature and air flow rate. Besides, the interfacial disturbance that resulted from addition of surface additive made the absorption ability of the TEG solution with ethanol higher than that without ethanol. According to the following deductions, the mass transfer performance was enhanced by adding ethanol to the TEG solution. The first is that the vaporizing ethanol would result in the surface tension gradient to form the interfacial disturbance, and the probability of gas-liquid contact is increased. The second is that the surface tension gradient would result from the vaporization of ethanol, and the formed surface tension gradient would prompt the TEG solution thin film to spread on the packing surface more widely. Therefore, the better removal amount of H<sup>2</sup> O for the TEG solution with ethanol was demonstrated by the experimental results in this study.
