Scaling Up of the Geometrically Similar Unbaffled Circular Tank Surface Aerators

Abstract

The present investigation is concerned with the development of scale-up equations for the oxygen transfer coefficient, k, and the power number, P O , for unbaffled circular tank surface aerators under geometrically similar conditions, with the purpose of designing energy efficient aerators. It has been found for the present aerators that k and P O are uniquely related to a parameter, X, governing the theoretical power per unit volume and which is defined as Fr , where Fr and Re are the impellers' Froude and Reynolds numbers, respectively. Empirical correlations between k and X, as well as P O with X are developed for the range of experiments conducted. Based on such experimental results, procedures to design energy efficient aeration systems have been demonstrated and it was found that smaller sized aerators are more energy efficient and economical when compared to bigger sized tanks, while aerating the same volume of water, by maintaining the same input power to the tanks irrespective of their size. It has been also demonstrated that substantial amounts of energy can be saved if the aeration tanks run at higher input power.

Mesoporous Silica from Rice Husk Ash

“…Reynolds and Froude number can be grouped as, X= F 4/3 R 1/3 [10]. The parameter, X can simulate the power number in any shaped surface aeration tanks [11][12]. The term P/ρN 3 D 5 is denoted as power number.…”

Shape effect on optimal geometric conditions in surface aeration systems

“…Rao [10] has developed an optimal geometric condition for square shaped surface aeration systems. There exist numerous references on circular or cylindrical surface aeration systems [13][14][15][16][17][18][19]. Rao et al [18] and Rao and Kumar [19] have adopted the square tank optimal geometric conditions in their experiments.…”

“…There exist numerous references on circular or cylindrical surface aeration systems [13][14][15][16][17][18][19]. Rao et al [18] and Rao and Kumar [19] have adopted the square tank optimal geometric conditions in their experiments. Because of not having certain optimal geometric conditions, researchers have used certain guidelines [15] for the circular baffled and unbaffled systems.…”

Energy Dissipation and Shear Rate with Geometry of Baffled Surface Aerator

“…Many types of aerators are used in practice, such as cascade, spray nozzles, diffused or bubble aerators and surface aerators. Among them surface aerators are popular because of their comparable efficiency and ease in operation [2][3][4]. Surface aeration systems are most frequently used in aerobic biological reactors to supply microorganisms with oxygen and to mix the fermentation broth [5].…”