Computational study of aeration for wastewater treatment via ventilated pump-turbine

Daskiran, Cosan; Riglin, Jacob; Schleicher, W. Chris; Öztekin, Alparslan

doi:10.1016/j.ijheatfluidflow.2017.11.006

Cited by 11 publications

(3 citation statements)

References 22 publications

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“…The results demonstrated that the dissolved oxygen level is higher in regions with intense vortex activities. Subsequently, Daskiran et al 16,17 applied a dissolved oxygen process to the rotating machinery. Herrmann-Heber et al 18 focused on the effect of hydrodynamic parameters on oxygen mass transfer during pulsed aeration in the numerical model.…”

Section: Introductionmentioning

confidence: 99%

Dissolution and evolution effects on pressure fluctuations in a space micropump

Ren

Hao

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part E:

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The purpose of this paper is to reveal the dynamic mass transfer effects between gas and liquid on pressure fluctuations in a space micropump using our proposed computational model of gas–liquid mass transfer. Complex dissolution and evolution processes were applied to achieve accurate dynamic gas–liquid mass transfer predictions in the micropump. The validation of experiments was conducted by measuring the performance characteristics of the micropump, and the mass transfer model was verified by a dissolved oxygen concentration experiment in plug discharge flow. Based on this, four conditions including unsteady single-phase, two-phase without mass transfer, dissolution, and coexisting dissolved–released flows calculations are discussed to clarify the frequency contents, generation reasons, and propagation law. Combined with entropy production analysis, the pressure fluctuation influenced by the dissolution and evolution is illustrated. The results exhibit that the evolution of the gas is located on the head of the long blade suction surface in the impeller. When a unidirectional gas-to-liquid dissolution process occurs, the fluctuating amplitude of the characteristic dominant 5 fn is significantly weakened; otherwise, when dissolution and evolution coexist, the amplitude is significantly promoted as the released gas increase the flow instability. In addition, the distributions of local high entropy production induced by mean and fluctuating velocity gradients overlap that of large mass transfer rates and high amplitude of the mixing frequency in the volute, exhibiting the relationship between entropy production, mass transfer, and flow instability. The current study provides a guidance that the dissolved gases’ concentration must be controlled strictly to avoid the evolution of gas for the safety and stability of the space hydraulic system.

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Section: Introductionmentioning

confidence: 99%

Dissolution and evolution effects on pressure fluctuations in a space micropump

Ren

Hao

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part E:

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“…Studies and research also include mathematical modeling of flow [23,24]. Numerical simulation of two-phase bubbly flow in the wake of NACA0015 hydrofoil is carried out under different conditions [25].…”

Section: Introductionmentioning

confidence: 99%

Hydraulic Turbine Performance Assessment with Implementation of an Innovative Aeration System

Bunea

Ciocan

Bucur

et al. 2021

Water

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The environmentally friendly concept in terms of water quality represents a condition for developing hydropower plants all around the world. Since 2017, hydropower has represented more than 70% of all renewable energy production and it is essential for the integration of the other renewable sources of energy and for regulation of the grid. To maintain the “green” label concerning the dissolved oxygen level (6 mg DO/L), the energy suppliers should respond to environmental concerns about the operation of hydropower plants. In the context of sustainable development, the ecological degradation of rivers is unacceptable due to the implementation of a hydropower plant on the watercourse. For deep reservoirs or tropical regions, the oxygen level in the water downstream of the hydropower plants may be low and affect the aquatic life for many kilometers downstream. This paper presents a new aeration system for discharged water from hydropower plants that provides water aeration with minimum energy consumption. The influence of the aeration process on the turbine operation and efficiency is analyzed. Experimental measurements are carried out on site on a small Francis turbine. The influence of the aeration process on the turbine mechanical performances (vibration level and relative displacement) and hydraulic performances (turbine efficiency, power output, and pressure fluctuation) is analyzed. The results showed that the impact of the aeration device implementation and operation over the energetic characteristics of the turbine is in the efficiency measurements accuracy range. The aeration through this device did not influence the turbine operation (vibration, level, or pressure fluctuations).

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“…They relied on a multi-adaptive regression spline algorithm to demonstrate that the airflow rate could be decreased by around 31% while keeping the quality of the water within the acceptable range. Numerical simulation methods were also employed by Daskiran et al [19], who developed a large eddy simulation model for a modular pump-turbine to analyse oxygen dissolution inside the draft tube. Kalenik et al [20] analysed the effects of air and water flow rates on the oxygen content of water oxygenated in a pipe aerator.…”

Section: Introductionmentioning

confidence: 99%

Effect of Rotational Speed of a Self-Aspirating Mixer on Oxygen Saturation in Water

Wróblewski

Skotnicka-Siepsiak

2020

Polish Maritime Research

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There are two categories of gas-liquid mixers: conventional and special-purpose. In theory, any conventional mixer can be applied to aerate a liquid, but fast-rotating devices are generally preferred. Special-purpose mixers (tubular, prismatic, cylindrical) have a hollow shaft, and operate by drawing gas from above the surface of the liquid and dispersing it inside the liquid. This process is referred to as aspirated aeration. In contrast, conventional mixers increase the pressure of the aspirated gas. Gas drawn from above the surface of the liquid flows through channels bored inside the shaft and the impeller, and is introduced to the liquid in this way. This article presents the results of an experiment investigating the aeration efficiency of a six-tube self-aspirating mixer at different rotational speeds. The experiment was conducted in a flow tank. The results indicate that self-aspirating mixers are effective devices for water aeration and mixing.

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Computational study of aeration for wastewater treatment via ventilated pump-turbine

Cited by 11 publications

References 22 publications

Dissolution and evolution effects on pressure fluctuations in a space micropump

Dissolution and evolution effects on pressure fluctuations in a space micropump

Hydraulic Turbine Performance Assessment with Implementation of an Innovative Aeration System

Effect of Rotational Speed of a Self-Aspirating Mixer on Oxygen Saturation in Water

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