The efficiency of short airlift pumps operating at low submergence ratios

An airlift pump operating at submergence ratios between 0.2 and 0.6 and usi ng water as the pumping liquid, has been investigated. Circular pipes of co nstant short length of 1 m and inner diameters of 3 and 5 cm were used as r iser tubes. The water flow rate measurements for various air flow rates all owed the study of the pumping efficiency as a function of the air flow rate , submergence ratio and certain geometrical parameters (riser tube diameter and injector design). The efficiency curves start from a zero efficiency a t a minimum air flow rate, then increase rapidly with the air flow rate up to an efficiency maximum. For higher air flow rates, the efficiency decreas es exponentially. Diagrams showing the influence of the riser tube diameter and injector design, are presented. Additionally, based on the experimenta l data, two equations are presented, which allow the prediction of the maxi mum efficiency and the corresponding water and air flow rates inside the ex perimental range.