Abstract
Experiments were performed to study the effect of jet angle of hollow jet aerators on oxygen transfer of water. Three jet angles of 30°, 45° and 60° were used to produce hollow jets impingement on the water in the pool. Results from experimental study showed a significant effect of hollow jet angle on volumetric oxygen transfer coefficient (KLa) at higher jet velocities. Standard oxygen transfer efficiency (SOTE) of 60° hollow jet aerators is observed higher with low-kinetic-power jets, but at higher kinetic power, 30° hollow jet aerator is observed to be the best in terms of SOTE. Moreover, modeling performance of the experimental data is evaluated by training and testing of the models, and empirical equations derived from multiple linear and multiple nonlinear regression techniques are compared with artificial neural network approach. The results of the present study are also compared with the previous studies of plunging jet aerators.
Highlights
Jet aeration occurs in many natural and practical situations involving pouring and filling of molten liquids, free fall of water from weir crest, breaking waves in sea and lakes, flowing water in rivers and canals, aerobic wastewater treatment and industrial processes, e.g., flotation of minerals, fermentation, cooling system in thermal industries, mixers in chemical industries (Sene 1988; Bin 1993; Deswal and Verma 2007a)
The current study investigates the oxygenation performance of hollow jet aerators of different jet inclination angles, and modeling techniques are employed to predict volumetric oxygen transfer coefficient of hollow jets
The oxygenation performance is encouraging with hollow jet angle of 30o compared to the other angles, still, the angle is envisaged to be not so effective with deep aeration pools, the reason being that the larger expansion of jet results in shallow penetration into the pool and reduces the jet activity at the lower section of the tank
Summary
Jet aeration occurs in many natural and practical situations involving pouring and filling of molten liquids, free fall of water from weir crest, breaking waves in sea and lakes, flowing water in rivers and canals, aerobic wastewater treatment and industrial processes, e.g., flotation of minerals, fermentation, cooling system in thermal industries, mixers in chemical industries (Sene 1988; Bin 1993; Deswal and Verma 2007a). Plunging jet aerators achieve both aeration and mixing (Van de Sande and Smith 1975), and the contact area. Ahmed (1974) and van de Donk (1981) researched over inclination angles of jet and found that oxygen transfer coefficient was weakly influence by angle of impact. Tojo et al (1982) findings on inclination angle of two cylindrical nozzles ranged from 45° to 90° were significantly different from above studies and indicated that the jet impact angle of the nozzles considerably influences the oxygen transfer rate of a jet mixer, and the author suggested an optimum inclination angle of 6 0o for efficient oxygen transfer and mixing. Ohkawa et al (1986) experimented over inclined jets having angles of 45° and 60° and found no significant influence of inclination angle on oxygen transfer Tojo et al (1982) findings on inclination angle of two cylindrical nozzles ranged from 45° to 90° were significantly different from above studies and indicated that the jet impact angle of the nozzles considerably influences the oxygen transfer rate of a jet mixer, and the author suggested an optimum inclination angle of 6 0o for efficient oxygen transfer and mixing. Ohkawa et al (1986) experimented over inclined jets having angles of 45° and 60° and found no significant influence of inclination angle on oxygen transfer
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