Experimental studies on bubble characteristics for R134a–DMF bubble absorber

Abstract

Experimental investigations have been carried out to visualize bubble behavior and effect of gas flow rate and liquid concentration on bubble characteristics of Tetrafluoro ethane (R134a) in liquid R134a–Dimethyl Formamide (DMF) solution in a glass absorber. Bubble behavior was studied in still as well as flowing solution. At lower gas flow rates, bubbles tend to be spherical due to the dominance of surface tension. At higher gas flow rates, bubbles tend to be hemispherical due to the dominance of inertia force. Bubble diameter during detachment increases with increase in gas flow rates. Also, the bubble diameter initially increases as the solution concentration increases up to 0.075kgkg−1 and then starts decreasing as the solution concentration increases further. At lower solution concentrations, effect of absorption driving potential (xeq−xl) is dominant than that of surface tension, due to this bubble diameter increases. When the solution concentration is increased further, effect of surface tension is dominant resulting in decrease in bubble diameter. Bubble diameter measured from the experiments is compared with that of the numerical model developed by the authors and other literature experimental correlations and it is found that the agreement is good. A correlation for bubble diameter during detachment is presented from the experimental studies, which can be useful for the design of R134a–DMF bubble absorber.