Experimental Study on Oxygen Mass Transfer Characteristics by Plunging Hollow Jets
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RESEARCH ARTICLE-CIVIL ENGINEERING
Experimental Study on Oxygen Mass Transfer Characteristics by Plunging Hollow Jets Munish Kumar1
· N. K. Tiwari1 · Subodh Ranjan1
Received: 15 May 2020 / Accepted: 17 September 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract Aeration by plunging water jets is an effective and economical method of transferring oxygen into the receiving pool of water. A dispersion of air bubbles occurs underneath the pool surface as a high-velocity liquid jet plunges on the water surface after being ejected from a particular fall height. The present study aims to investigate the impact of jet velocity, jet length, water depth and jet thickness of plunging hollow jets in oxygenating the water in the aeration tank. Empirical correlations are proposed for the determination of volumetric oxygen transfer coefficient based on jet velocities and jet kinetic powers. Moreover, the oxygen transfer capacity of single hollow jet, double hollow jet and a dual jet (combined hollow and solid) is tested by keeping a nearly constant jet flow area through the jet openings. The observations recorded from the experimental analysis lead to the development of predictive relationships for estimating the values of volumetric oxygen transfer coefficient in terms of basic jet variables. Keywords Single hollow jet · Double hollow jet · Jet length · Oxygen transfer · Jet velocity
1 Introduction Air–water interfaces are generated by the formation of air bubbles as a high-velocity water jet after passing through atmospheric air plunges and penetrates into a water pool. Interfacial area produced by the surface impact and penetration of plunging water jet may contribute in insertion of ambient air as well as enhancing the level of oxygen into the water. Aeration and mixing of the water pool is largely dependent upon the submergence and expansion of the bubble plume, and thus, a large turbulence is required for the perfect mixing and generating large air–water interfacial area. Aeration with plunging jets has many advantages over the other aeration equipment. Plunging jet aerators are energy efficient, simple in design, construction and operation and require low maintenance. In contrast to other conventional aeration sys-
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Munish Kumar [email protected] N. K. Tiwari [email protected] Subodh Ranjan [email protected]
1
Department of Civil Engineering, National Institute of Technology, Kurukshetra, Haryana, India
tems, plunging jet aerators do not need any air compressor and external stirring or agitation device for aeration and mixing, free of operational difficulties such as clogging in air diffusers, free of the limitation of speed and submergence of rotor and size of tank etc. [1, 2]. Due to these advantages, plunging jets are favourable and used in the processes of heat, mass and momentum transfer. Some of the important applications include aeration and floatation in the treatment of water and wastewater, biological-aerated filter, fermentation, bubble floatation of minerals, the co
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