Air-lift pumps characteristics under two-phase flow conditions

International Journal of Heat and Fluid Flow (Impact Factor: 1.78). 02/2009; 30(1):88-98. DOI: 10.1016/j.ijheatfluidflow.2008.09.002

ABSTRACT Air-lift pumps are finding increasing use where pump reliability and low maintenance are required, where corrosive, abrasive, or radioactive fluids in nuclear applications must be handled and when a compressed air is readily available as a source of a renewable energy for water pumping applications. The objective of the present study is to evaluate the performance of a pump under predetermined operating conditions and to optimize the related parameters. For this purpose, an air-lift pump was designed and tested. Experiments were performed for nine submergence ratios, and three risers of different lengths with different air injection pressures. Moreover, the pump was tested under different two-phase flow patterns. A theoretical model is proposed in this study taking into account the flow patterns at the best efficiency range where the pump is operated. The present results showed that the pump capacity and efficiency are functions of the air mass flow rate, submergence ratio, and riser pipe length. The best efficiency range of the air-lift pumps operation was found to be in the slug and slug-churn flow regimes. The proposed model has been compared with experimental data and the most cited models available. The proposed model is in good agreement with experimental results and found to predict the liquid volumetric flux for different flow patterns including bubbly, slug and churn flow patterns.

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Available from: Wael H. Ahmed, Aug 10, 2015
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    • "The kinematic viscosities for air and water are 1.655 Â 10 –5 m 2 /s and 0.895 Â 10 À6 m 2 /s, respectively . The experimental study of Kassab et al. [6] "
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    ABSTRACT: The present study investigates a hierarchy of models for predicting the performance of air-lift pumps. Investigated models range from simplified one-dimensional analytical models to large eddy simulation (LES). Numerical results from LES and from two differ-ent analytical models are validated against experimental data available from the air-lift pump research program at Alexandria University. Present LES employs the volume of fluid (VOF) method to model the multiphase flow in the riser pipe. In general, LES is shown to provide fairly accurate predictions for the air-lift pump performance. Moreover, numerical flow patterns in the riser pipe are in good qualitative and quantitative agree-ment with their corresponding experimental patterns and with flow pattern maps avail-able in the literature. On the other hand, analytical models are shown to provide results that are of surprisingly comparable accuracy to LES in terms of predicting the pump per-formance curve. However, due to the steady one-dimensional nature of these models, they are incapable of providing information about the different flow patterns developing in the riser pipe and the transient nature of the pumping process. [DOI: 10.1115/1.4027473]
    Journal of Fluids Engineering 11/2014; 136(11):111301. DOI:10.1115/1.4027473] · 0.94 Impact Factor
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    • "Also, they concluded that the performance of the airlift pump for lifting solid particle and liquid strongly depends on the flow pattern in which the pump operates. Kassab et al. (2009) evaluated the performance of a pump experimentally and introduced a theoretical model to optimise the operating parameters of the pump. They concluded that the airlift pump will lift the maximum amount of liquid if it is operated in the slug or slug-churn regimes. "
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    • "Previous laboratory experiments [12] [13] with water and air showed that the increasing the size of the injected bubbles can improve the efficiency. Most of the work that has been done on air lift pumps involves the usage of an upriser pipe with constant diameter [14] [15] [16]. Therefore not much information is available on effect of a tapered upriser pipes on two phase pump performance. "
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    ABSTRACT: Two phase lifting pumps are devices with the ability of lifting liquid phase by injecting the gas phase. Parameters which affect the performance of these pumps are divided into two groups. The first group contains design parameters such as diameter of the pipe, tapering angle of the upriser pipe and the submergence ratio which is the ratio of immersed length to the total length of the upriser. The second group includes operating parameters, such as the gas flow rate, bubble diameter, bubble distribution and inlet gas pressure. In this research, the performance of two phase lifting pump is investigated numerically for different submergence ratios and different diameter of the upriser pipe. For this purpose the two phase pump with a riser length of 914 mm and different diameters (6, 8 and 10 mm), and seven tapering angles (0°, 0.25°, 0.5°, 1°, 1.5°, 2° and 3°) are numerically modeled and analyzed. Different submergence ratios are used, namely: 0.4, 0.6 and 0.8. The numerical results are compared with the existing experimental data in the literature showing a reasonable agreement. The results indicate that decrease in size of the bubble diameter increases mass flow rate of liquid at constant submergence ratios. The present study reports the improved performance of this pump with decrease in bubble size and increase in angle of tapered upriser pipe. Moreover, the results show that the tapered upriser pipe with 3° tapering angle gives the highest efficiency at nearly all submergence ratios. Further, the highest efficiency of the pump is shown to be at the largest submergence ratio, namely 0.8.
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