Airlift Pump Research Articles

Perception of faunal circadian rhythms depends on sampling technique

Ecologists aim at disentangling how species vary in abundance through spatial and temporal scales, using a range of sampling techniques. Here, we investigated the circadian rhythm of seagrass-associated decapod crustaceans through three sampling techniques. Specifically, we compared the abundance, biomass and structure of seagrass-associated decapod assemblages between the day and night using a hand net, an airlift pump and baited traps. At night, the hand-net consistently collected a larger total abundance and biomass of decapods, what resulted in significant diel differences, which were detected for the total biomass, but not for the total abundance, when decapods were sampled through an airlift pump. Traps, however, collected a larger total abundance, but not total biomass, of decapods during the night. In summary, our perception of faunal diel rhythms is notably influence by the way organisms are sampled.

Experimental Investigation on the Integration of Raceway Pond and Airlift Pump for Microalgal Cultivation

This work proposed an integration of raceway pond and airlift pump (RWPAP) for microalgae cultivation. Therefore, the proposed reactor was evaluated under various configurations of liquid depth in the raceway reactor, air flow rates, two riser airlift pump diameter and two nozzle hole diameter. The minimum air flow rate necessary for circulating medium in the RWPAP reactor in addition to the liquid velocity in the reactor was investigated. These parameters as well as the power consumption were determined in order to achieve the maximum efficiency and effectiveness configuration. The maximum effectiveness configuration of the RWPAP system was achieved at the water depth 40 cm, air flow rate 0.83 L min -1 , injector hole diameter 0.5 mm and tube diameter 0.75 inch that produced the maximum ratio velocity to power consumption with near one tenth of power consumption of the maximum efficiency configuration. At these configurations, the microalga Dunaliella Salina was cultivated in the natural culture medium from the Maharlu Salt Lake, southeast of Shiraz, Iran in order to achieve commercialization and reduce cultivation cost and the results showed that the effectiveness configuration had better biomass productivity, CO 2 utilization efficiency, power consumption and water evaporation rate compared to another configuration. The effectiveness configurations gave comparable batch biomass productivity (0.096 g L -1 day -1 ) and 25.37% CO 2 utilization efficiency, but around five-times higher biomass productivity per unit power input (2.21 g W -1 day -1 ) than reported for the modified airlift reactors. Furthermore, the β-carotene content and composition of fatty acids were evaluated.

Constitutive Equations for a Simulator of Airlift Pump in a Large Diameter Pipe using Drift-Flux Model

Constitutive Equations for a Simulator of Airlift Pump in a Large Diameter Pipe using Drift-Flux Model

Impact of fish feed on airlift pumps in aquaculture systems

Airlift pumps are commonly used in aquaculture systems to circulate water and maintain critical gas levels. In production marine reuse systems, a significant decrease in airlift pump flowrate was visually observed immediately after feeding. In experimental systems without fish, it was found that feed additions of less than 10 mg/L decreased water flow by as much as 78% for diffuser injectors but only 10% for pumps with direct air injection. For both injector types, feed impact diminished over several hours but persisted longer in seawater than in freshwater. Video footage revealed increasing bubble coalescence with the addition of feed. The decrease in pump flow is likely attributed to water property changes due to compounds leaching out of the feed. This decrease in pumping rate has the potential to negatively impact water quality, system performance, and fish health.

Investigating the hydrodynamics of airlift pumps by wavelet packet transform and the recurrence plot

The hydrodynamics of airlift pumps at various gas superficial velocities were investigated using the wavelet packet transform and recurrence plot due to their capabilities for extracting the micro structures and determining the whole complexity in airlift pumps. For this purpose, the pressure fluctuations of an airlift pump were measured at various gas superficial velocities. The wavelet packet transform was first used to extract the integer approximation and detailed information from the pressure signals. Then, the energy distributions in each frequency band were calculated and the corresponding dynamical characteristics were obtained using a recurrence plot. It was found that the highest pumping efficiency under the slug-churn flow condition is caused by the highest mean pressure. In addition, the energy of the slug-churn flow regime has a dramatic increase in the frequency band of 31.25–62.5 Hz, due to the burst of big Taylor bubbles. In the low-frequency band (0–31.25 Hz), the pressure shows a chaotic behavior due to the turbulence of liquid flow. In the frequency band of 31.25–62.5 Hz, the pressure executes a transition from chaotic fluctuation in slug flow to periodic fluctuation in slug-churn due to the linear motion of small bubbles.

Investigating the flow characteristics of air-lift pumps operating in gas–liquid two-phase flow

Abstract Experiments were conducted to investigate the flow characteristics in the riser pipe and the suction pipe of airlift pump at a series of air flow rates and submergence ratios by using a high speed camcorder and a Laser Doppler Velocimetry system (LDV). A modified model was developed to predict the performance of airlift pump operating in gas–liquid two-phase flow. The results show that an unstable flow structure composed by a water falling film, a bubbly mixture, a water ascending film appearing alternately in riser pipe dominates the performance of airlift pump at large air flow rates. The bubbly mixture with a strongest capacity for pumping water first increases to its maximum and then slightly decreases. In suction pipe, the average velocity shows a flat profile and increases with increasing submergence ratio. Moreover, the predicted results of modified model are in good agreement with the experimental data in a margin of ± 12%.

Development of helical coil based fluidic diode pump for liquid pumping

The main selection criterion for pumps in reprocessing applications is the absence of any moving parts or the moving parts not having any direct contact with the process fluid. There are different types of fluidic pumps such as vortex diode, reverse flow diode, etc. In this work, a new design of helical coil fluidic pump has been developed and demonstrated. Helical coils are widely used in process industries as heat exchangers, reactors, motionless mixers, etc. It is for the first time that the authors are proposing the use of helical coil as a fluidic pump based on its inherent property of high pressure drop as compared to a straight tube.The main objective of this work is to develop an alternate pumping system for reprocessing applications to replace the conventional air lift pump. The helical coil based fluidic diode pump was made up of SS 304 seamless pipe (pipe inner diameter is 9.5 mm) with a 36 mm diameter of helical coil and pitch of 14 mm. In this work, friction factor for the given helical coil was measured from pressure drop experiments. This information was also useful for understanding the transition of the laminar to turbulent region. In order to propose the operating region, the pumping capacity was measured for the helical coil based fluidic pump at different operating conditions. Experimental results show that the proposed hardware is able to pump up to 54 dm3/h. Recommendations have been made for proposing an optimum design.

The effect of liquid temperature on the performance of an airlift pump

Airlift pumps are very simple devices consisting of a vertical riser tube which is partially immersed in the liquid to be pumped and into which air is injected at the base to produce an upward flow. These devices are characterized by higher reliability and low maintenance. They are used, especially, for pumping dangerous and polluted liquids. The objective of the present study is to evaluate the performance of a pump when hot liquids are handled and air humidification is not neglected. For this purpose, an air-lift pump was designed and tested. Experiments were performed for many operating conditions A theoretical model is proposed in this study taking into account the air humidification and liquid temperature. The proposed model has been compared with experimental data and some recognized models of literature. The proposed model is in good agreement with experimental results.

Performance study of humidification–dehumidification system operating on the principle of an airlift pump with tunable height

Abstract A new experimental set up for humidification–dehumidification operating on the principle of an air lift pump was experimented. Experimental work investigates the main operating parameters of a proposed desalination process working with an air humidification–dehumidification method. The principal objective of this investigation was the determination of the humid air behavior through single stage of an airlift humidification–dehumidification system. The experimental work studied the influence of the operating conditions such as the water temperature, the submerged ratio and the airflow rate on the performance of the setup. The experimental results show that the production rate of the system increases with the both increase of the brackish water temperature and the airflow rate. The productivity of the system is strongly affected by the brackish water temperature, airflow rate and slightly affected by the submerged ratio. Within the studied ranges, the maximum productivity of the system reached to 4.035 kg/h, at water temperature (Tw) = 85 °C and m ˙ a = 5 kg/h. A good agreement was achieved with productivity calculations.

Experimental Study of an Air Lift Pump

In this investigation the effect of submergence ratio and air jacket on the performance of the air lift pump has been studied. Three types of air jackets in addition to five levels of submergence ratios were used. Each air jacket has a number of drilled holes distributed uniformly at the perimeter of the inside pipe, where the total area of drilled holes was kept constant. It has been found that the water flux increases as the submergence ratio increased. Also it was found that the minimum air flux required to start discharging water from the pump decreases as the submergence ratio increases. Air jacket with a hole of 4 mm diameter, resulted the highest performance for the air lift pump.

Experimental and Numerical Simulation of an Airlift Pump with Conventional and Modified Air Injection Device

The effect of air injection device on the performance of airlift pump used for water pumping has been studied numerically and experimentally. An airlift pump of dimensions 42mm diameter and 2200 mm length with conventional and modified air injection device was considered. A modification on conventional injection device (normal air-jacket type) was carried out by changing injection angle from 90 (for conventional) to 22.5 (for modified). Continuity and Navier-Stokes equations in turbulent regime with an appropriate two-phase flow model (VOF) and turbulent model ( ) in two dimensions axisymmetry flow were formulated and solved by using the known package FLUENT version (14.5). The numerical and experimental investigations were carried out for both conventional and unconventional air-jackets at submergence ratio of 0.75 and air mass flow rate from 0.5, 2, 10, 50 and 85 kg/hr. Comparisons between the numerical and experimental results for both injection devices were made and fair agreements were found and the main results showed that the performance and maximum efficiency of airlift pump is increased for higher mass flow rate of injected air for the tested submergence ratio using unconventional airjacket performance with average enhancement were 9% and 10% for performance and maximum efficiency respectively.

Analytical and Experimental Investigation for the Effect of Air Injection Angle on the Performance of Airlift Pump

The effect of air injection angle on the performance of airlift pump used for water pumping has been studied analytically and experimentally. An airlift pump of dimensions 42mm diameter and 2200 mm length with conventional and modified air injection device was considered. A modification on conventional injection device (normal air-jacket type) was carried out by changing injection angle from 90 (for conventional) to 45 and 22.5 (for modified). Continuity and one-dimensional momentum balance for the flow field with basic principle of two-phase flow and expressions of slip ratio and friction factor as function of flow rates were formulated. The analytical and experimental investigations were carried out for both conventional and unconventional air-jackets at submergence ratios 0.75, 0.6 and 0.5 and air mass flow rate from 0.5 to 97kg/hr. The comparison between the analytical and experimental results shows agreement and the main results showed that the performance and maximum efficiency of airlift pump is increased for higher mass flow rate of injected air for all tested submergence ratio using unconventional air-jacket and the higher performance was associated with injection angle 22.5 , with average enhancement were 9% and 10% for performance and maximum efficiency respectively.

Development of a mobile airlift pump for scientific divers and its application in sedimentological underwater research

Development of a mobile airlift pump for scientific divers and its application in sedimentological underwater research

Taylor flow in intermediate diameter channels: Simulation and hydrodynamic models

The two-phase Taylor flow pattern has been studied extensively. However, limited information is available for flows in intermediate diameter channels (5≲Bo≲40, or 6mm≲D≲27mm for ambient gas–water flows), as found in air-lift and bubble pumps. Previous investigations have primarily evaluated Taylor flow models in terms of overall pressure drop, which incorporates hydrostatic and multiple hydrodynamic components. Thus, individual sub-models and sources of error could not be directly assessed. In this investigation, volume-of-fluid (VOF) based Taylor flow simulations are performed over a wide range of laminar and turbulent conditions in the intermediate Bond number regime (5<Bo<20, 250<Nf<1000, and 20<Rej<8100). Results are applied to individually evaluate hydrodynamic sub-models for bubble-region frictional pressure drop gradient (∇pf,b), slug frictional pressure drop gradient (∇pf,s), and flow transition pressure loss (Δptrans). Based on these results, recommendations are provided for selection of hydrodynamic sub-models. These hydrodynamic closure models are integrated with kinematic flow models to yield a complete intermediate Bond number Taylor flow formulation for which all submodels were independently validated. The resulting model achieves improved accuracy for predicting experimental liquid flow rates compared with previous Taylor flow models (81% of cases within 50% of measured flows rates).

Entropy analysis of buoyancy driven gas–liquid two-phase flow: Analytical and experimental approaches

Buoyancy-driven two-phase flow is widely utilized in numerous applications, namely for pumping and transport of corrosive industrial liquids, and waste, muddy, or hot water containing sediments as in mining. This pumping method benefits the advantage of transporting unusual fluids that are not easily carried by conventional pumping systems. The airlift pump is one these buoyancy-driven pumping methods. An experimental entropy analysis of an airlift pump is presented in this work. The entropy generation of a pump plays a substantial role in its performance. Analysis of such gas–liquid systems is similar to the problem of modeling two-phase flows. The objective of the paper is to propose a comprehensive entropy analysis method that considers all the effective parameters involved in the entropy generation of an airlift pump, i.e. gas–wall and water–wall frictions, phase interactions, and losses due to relative velocities. A theoretical model is proposed, and entropy generation of the airlift pump is calculated in different submergence ratios, on the basis of experimental data. The results are then compared with those obtained from the authors’ previous work, i.e. the thermodynamic approach. Finally, a complete investigation of the importance of each effective parameter is reported for different working conditions. It is concluded that the proposed model is capable of providing comparatively good values for the entropy generation on the basis of the design parameters like the phase flow rates, especially for the cases with submergence ratios above 0.5.

Growth comparison of microalgae in tubular photobioreactor and open pond for treating anaerobic digestion piggery effluent

The overwhelming interest in the use of microalgae to handle associated nutrient surge from anaerobic digestion technologies for the treatment of wastewater, is driven by the need for efficient nutrient recovery, greenhouse gas mitigation, wastewater treatment and biomass reuse. Here, the feasibility of growth and ammonium nitrogen removal rate of semi-continuous mixed microalgae culture in paddle wheel-driven raceway pond and helical tubular closed photobioreactor (Biocoil) for treating sand-filtered, undiluted anaerobic digestion piggery effluent (ADPE) was compared under outdoor climatic conditions between June and September 2015 austral winter season. Two Biocoils, (airlift and submersible centrifugal pump driven) were tested. Despite several attempts in using airlift-driven Biocoil (e.g. modification of the sparger design), no net microalgae growth was observed due to intense foaming and loss of culture. Initial ammonium nitrogen concentration in the Biocoil and pond was 893.03±17.0mg NH4+-NL−1. Overall, similar average ammonium nitrogen removal rate in Biocoil (24.6±7.18mg NH4+-NL−1day−1) and raceway pond (25.9±8.6mg NH4+-NL−1day−1) was achieved. The average volumetric biomass productivity of microalgae grown in the Biocoil (25.03±0.24mg AFDW L−1day−1) was 2.1 times higher than in raceway pond. While no significant differences were detected between the cultivation systems, the overall carbohydrate, lipid and protein contents of the consortium averaged 29.17±3.22, 32.79±3.26 and 23.29±2.15% AFDW respectively, revealing its suitability as animal feed or potential biofuel feedstock. The consortium could be maintained in semi-continuous culture for more than three months without changes in the algal composition. Results indicated that microalgae consortium is suitable for simultaneous nutrient removal and biomass production from piggery effluent.

Evaluation of the performance for an artificial deep pool (ADP) as an alternative fish shelter

A newly developed underground artificial deep pool (ADP) with a sediment barrier system and an airlift pump system is proposed as an alternative fish shelter at a pond during the dry season. The feasibility of the proposed ADP as an alternative fish shelter and habitat was evaluated based on both quantitative and statistical methods after monitoring the performance of the ADP over 10 months. The observation indicated that there is only a slight difference, if any, in water quality between the inside and the outside of the ADP. However, significant differences in the relative density of fish between the ADP and both the experimental and control ponds were observed. Whereas water column species, including Acheilognathus koreensis and Carassius carassius, were dominant in the ADP, insectivorous species, such as Zacco temminckii, were dominant in both the experimental and control ponds. Nonetheless, at low water levels, ADP can provide temporally and spatially stable shelters for fish, regardless of a factor of preference to ADP. These findings imply that the proposed ADP can be utilized as an alternative fish shelter suitable for lentic systems, and the ADP is also expected to help restoring fish species that are depleted in hostile habitats during the extended dry season.

Air injection methods: The key to a better performance of airlift pumps

This paper presents a comprehensive experimental investigation on the effect of air injection methods on the performance of airlift pumps. The effect of air–water two-phase flow patterns and the phase interaction is presented. The present airlift pump utilizes various air injectors specially designed to enable air injection radially, axially, dual (radial and axial), or with a swirl effect at the air inlet ports. In addition, two air injection modes including steadily and pulsating, at different injection frequencies, are investigated at different two-phase flow patterns. The results have shown that the performance of airlift pumps does not only depend on the design of air injector, but also on the dynamics of air injection method. The pulsating mode of air injection is found to control the intermittent flow pattern in the pump riser and consequently able to keep the pump operating within the best efficiency range. The maximum efficiency of the pulsating axial injection operating at a frequency of 1Hz has improved by 60% over that of typical steady axial injection and by 24% over that of steady dual injection. Furthermore, the performance of airlift pumps with dual injector is improved by synchronizing the injected air at both axial and radial injection ports. The improvement in this arrangement is attributed to the better utilization of available compressed air, reduction of axial air penetration and minimization of water reverse flow in the riser pipe.

TREATMENT CHARACTERISTICS AND OPERATIONAL PARAMETERS OF A NEWLY DEVELOPED REACTOR WITH SLUDGE SEPARATION FILTER AND AIRLIFT PUMP FOR CARBON AND NITROGEN REMOVAL

Nutrient removal from sewage is one of the most urgently required issues from the viewpoint of prevention of eutrophication and preservation of water quality for water supply system. Among several nutrient removal methods, biological treatment, which is a modified activated sludge system, is widely applied. However, biological nitrogen removal process, which consists of nitrification and denitrification steps, needs opposite operations at several stages such as necessity of oxyg en and requirement of electron donor of organic compounds. In this study, treatment characteristics of a reactor with both sludge separation filter and airlift pump are investigated. This reactor has sludge separation filter in the middle part and airlift pump that supplies oxygen and circulate liquid from aerobic zone to anoxic zone in order to cut down the required energy. From laboratory scale experiments, design and operational parameters are investigated and it is shown that NH4-N loading rate of 35 mgN/(L-media· hr) at aerobic zone and DO loading rate of less than 0.15 kgDO/(kgMLSS·d) to anoxic zone are required for stable treatment.

TREATMENT CHARACTERISTICS AND OPERATIONAL PARAMETERS OF A NEWLY DEVELOPED REACTOR WITH SLUDGE SEPARATION FILTER AND AIRLIFT PUMP FOR CARBON AND NITROGEN REMOVAL

Nutrient removal from sewage is one of the most urgently required issues from the viewpoint of prevention of eutrophication and preservation of water quality for water supply system. Among several nutrient removal methods, biological treatment, which is a modified activated sludge system is widely applied. However, biological nitrogen removal process, which consists of nitrification and denitrification steps, needs opposite operations at several stages such as necessity of oxygen and requirement of electron donor of organic compounds. In this study, treatment characteristics of a reactor with both sludge separation filter and airlift pump are investigated. This reactor has sludge separation filter in the middle part and airlift pump that supplies oxygen and circulate liquid from aerobic zone to anoxic zone in order to cut down the required energy. From laboratory scale experiments, design and operational parameters are investigated and it is shown that NH4-N loading rate of 35 mgN/(L-media･hr) at aerobic zone and DO loading rate of less than 0.15 kgDO/(kgMLSS･d) to anoxic zone are required for stable treatment.