Experimental evaluation of low head oxygenators

The overall mass transfer coefficient, G(20), for a single hole orifice pla te was evaluated in a series of experiments as affected by four geometric v ariables: orifice plate hole diameter (5, 10, 14, 19, and 22 mm), hydraulic head on the flooded plate (2.5, 5, and 13 cm), water fall height from the orifice to the receiving pool of water (30, 61, 91, and 122 cm), and the co llection pool depth (2.5, 8, 13, 25, and 41 cm). This is, in essence, the s implest form of a low head oxygenator (LHO). A regression equation was deve loped to predict G(20) as a function of these variables, their interactions , and squared terms. The hydraulic head above the flooded plate had no sign ificant effect (P < 0.10) on the overall mass transfer coefficient. It was determined that the contribution of the orifice hole solely to overall gas transfer was much less than previously assumed, suggesting that a much larg er percentage of gas transfer is due to the splashing and subsequent entrai nment as water droplets fall into the receiving pool of water. Practical im plications of the results are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.