Hydrodynamics of an external-loop airlift reactor with inserted membrane

Kojić, Predrag; Popović, Sanja; Tokic, Milenko; Šijački, Ivana M.; Lukić, Nataša; Jovičević, Dragica Z.; Petrović, Dragan Lj.

doi:10.1590/0104-6632.20170342s20150399

Cited by 8 publications

(7 citation statements)

References 53 publications

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“…Therefore, with coalescence prevention in the riser, driving force for liquid circulation decreased due to a large number of small bubbles that represent the resistance to circulation [42].…”

Section: Figurementioning

confidence: 99%

“…The results showed that the increase of the surface tension gradient, as a consequence of alcohol addition, has a strong impact on hydrodynamics and mass transfer characteristics of airlift reactor. The increase of surface tension gradient corresponds to the increase of the number of carbon atoms in alcohol molecule [42][43][44]. Alcohol addition has a remarkable effect on the gas holdup.…”

Section: Figurementioning

confidence: 99%

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Numerical study of the hydrodynamics and mass transfer in the external loop airlift reactor

Kojić

Krulj

et al. 2022

CI&CEQ

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The objective of this study was to investigate the hydrodynamics and the gas-liquid mass transfer coefficient of an external-loop airlift reactor (ELAR). The ELAR was operated in three cases: different inlet velocities of fluids, different alcohols solutions (water, 0.5% methanol, 0.5% ethanol, 0.5% propanol and 0.5% butanol) and different concentration of methanol in solutions (0%, 0.5%, 1%, 2% and 5%). The influence of superficial gas velocity and various diluted alcohol solutions on hydrodynamics and gas-liquid mass transfer coefficient of the ELAR was studied. Experimentally, the gas hold-up, liquid velocities and volumetric mass transfer coefficient values in the riser and the downcomer were obtained from the literature source. A computational fluid dynamics (CFD) model was developed, based on two-phase flow, investigating different liquids regarding surface tension, assuming the ideal gas flow, applying the finite volume method and Eulerian-Eulerian model. The volumetric mass transfer coefficient was determined using CFD model, as well as artificial neural network model. The effects of liquid parameters and gas velocity on the characteristics of the gas-liquid mass transfer were simulated. These models were compared with appropriate experimental results. CFD model successfully succeed to simulate the influence of different alcohols regarding the number of C-atoms on hydrodynamics and mass transfer.

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Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Numerical study of the hydrodynamics and mass transfer in the external loop airlift reactor

Kojić

Krulj

et al. 2022

CI&CEQ

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“…Waste generation prediction models have been developed with increasing frequency recently. So far, various models have been used to predict waste generation, such as expert systems, evolutionary programming, artificial neural networks (ANN), multiple linear regression, central composite design and combinations of these tools [19][20][21][22]. In this research, ANN will be used because compared to other models, neural networks are relatively insensitive to incomplete information and therefore allow coping with higher degrees of uncertainty.…”

Section: Introductionmentioning

confidence: 99%

“…ANN are mathematical models of information processing that function similarly to the human brain and are used to solve artificial intelligence problems. ANN are non-linear tools that use a set of input parameters from which the interconnected elements are calculated, while one or more output parameters represent the final result [22,23].…”

Section: Introductionmentioning

confidence: 99%

Prediction of the Production of Separated Municipal Solid Waste by Artificial Neural Networks in Croatia and the European Union

et al. 2022

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Given that global amounts of waste are growing rapidly, it is extremely important to determine what amount of waste will be generated in the near future. Accurate waste forecasting is also important for planning and designing a sustainable municipal solid waste (MSW) management system. For that reason, there is a need to build a model to predict the amount of MSW generated in the near future. Based on previous research, artificial neural networks (ANN) show better results in predicting waste generation compared to other mathematical models. In this research, an ANN model using the iterative algorithm Broyden–Fletcher–Goldfarb–Shanno (BFGS) for the prediction of MSW fractions, based on the socio-demographic characteristics, economic and industrial data obtained in Croatia and summarized data of the member states of EU (EU-27 from 2020), showed good predictive capabilities. The coefficient of determination during the training cycle for the output variables; household and similar waste (HHS), paper and cardboard waste (PCW), wood waste (WW), textile waste (TW), plastic waste (PW) and glass waste (GW) were 0.993; 0.997; 0.999; 0.997; 0.998; and 0.998, respectively, while reduced chi-square, mean bias error, root mean square error, mean percentage error, average absolute relative deviation and sum of squared errors were found low. In this paper, Yoon′s method of interpretation shows the relationships between socio-demographic data and the amount of generated waste. The results indicate that the lowest level of education shows a negative impact on observed waste-types calculations, with a relative impact between −9.889 and −4.467%. The most pronounced positive impact on the calculation of HHS, PCW, WW, TW, PW and GW was observed for year variable, gross domestic product, exports of goods and services, imports of goods and services, wages and salaries, secondary income, arrivals in collective accommodation establishments, overnight stays in collective accommodation establishments and exports of petroleum and petroleum products to partner countries, with a relative influence of 4.063–7.028; 2828–4851; 5240–6197; 5.308–6.341; 4290–4810; 4533–5805; and 4.345–4.493, respectively. The obtained results indicate that the amount of HHS waste at the EU-27 level in 2025 will decrease by approximately 18% compared to the data from 2018. The quantities of other observed recyclable types of waste will increase by 34% for PCW, 310% for WW, 40% for TW, 276% for PW and about 67% for GW. The amount of waste generated provides the basic information needed to plan, operate and optimize the waste management system. It could also help in the transition to an environmentally friendly and economically profitable circular economy. The model created in this research could also help with the system of separate waste collection, which would lead to more efficient recycling and the achievement of the set goals for recycling 55% of municipal waste by 2025.

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“…Restriction orifice has a strong impact on the hydrodynamics of EL-ALR by changing hydrodynamic resistance (6). Several authors investigated the effect of hydrodynamic resistance and found that the increase in the resistance is also accompanied by an increase in the riser gas holdup (7,8). Due to complex interrelations between the hydrodynamics, mass transfer, mixing, design and operating variables, modeling of airlift reactors is extremely complicated (1).…”

Section: Introductionmentioning

confidence: 99%

Influence of the geometry on the riser gas holdup in an external-loop airlift reactor: empirical and neural network modelling

Lj.

Aleksandar

2018

ACTA PERIOD TECHN

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Experimental studies on the effect of geometrical characteristics (restriction orifice free area and sparger configuration) on the riser gas holdup of an external-loop airlift reactor have been conducted in this paper. The impact of the addition of non-coalescing media, such as n-butanol, was also investigated. In general, the decrease in the restriction orifice free area led to a substantial increase (up to 90%) in the riser gas holdup. The addition of n-butanol effected gas holdup to a lesser extent, as it increased the gas holdup in the range of 4-15%, depending on the restriction orifice free area. On the other hand, the impact of the sparger type was observed only at lower gas velocities, for which the sinter plate increased the gas holdup up to 20% in comparison to the single orifice. The paper also presents an empirical correlation for the estimation of the riser gas holdup with an average relative error of 7%. Finally, a neural network model with an average relative error of 2.4% was proposed.

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Hydrodynamics of an external-loop airlift reactor with inserted membrane

Cited by 8 publications

References 53 publications

Numerical study of the hydrodynamics and mass transfer in the external loop airlift reactor

Numerical study of the hydrodynamics and mass transfer in the external loop airlift reactor

Prediction of the Production of Separated Municipal Solid Waste by Artificial Neural Networks in Croatia and the European Union

Influence of the geometry on the riser gas holdup in an external-loop airlift reactor: empirical and neural network modelling

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