Mathematical Model for Calculating Oxygen Mass Transfer Coefficient in Diffused Air Systems

K. Al-Ahmady, Kossay

doi:10.33899/rengj.2011.26795

	Mathematical Model for Calculating Oxygen Mass Transfer Coefficient in Diffused Air Systems
Al-Rafidain Engineering Journal (AREJ)
Article 9, Volume 19, Issue 4, 2011, Pages 43-54 PDF (0 K)
DOI: 10.33899/rengj.2011.26795
Author
Kossay K. Al-Ahmady^*
Abstract
Abstract The key element in developing an analytical or mathematical procedure is to determine the main factors that possess potential importance in oxygen transfer process. In this paper, the factors that affect the oxygen mass transfer coefficient (KLa) in activated sludge units are determined. A dimensional analysis procedure is adopted to develop a mathematical model, which can be used for calculating these factors. A very high accurate model with a correlation factor of (98.889 %) is obtained from this analysis. The solution of the model shows that: The main dimensionless groups which controlling the oxygen mass transfer in this units are: Reynolds number, Froude number, the ratio of bubbles diameter to length of its bath in water, the ratio of water depth in the tank to tank length, and the ratio of diffusers area to tank area. Each of the Reynolds number and the ratio of area of diffusers to the area of tank have positive effect on the oxygen mass transfer coefficient. Increasing any of airflow rates, the area of diffusers coverage in the tank and the length of the path of bubbles in water significantly increase the oxygen mass flow rate while this ability can also be increased by decreasing the diameter of bubbles in the system.
Keywords
KEYWORDS; diffused air; oxygen transfer; dimensionless analysis; modeling

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