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A qualitative study of mixing a fluid inside a mechanical mixer with the effect of thermal buoyancy

Hassouni Souad, Laidoudi Houssem, Makinde Oluwole Daniel, Bouzit Mohamed, Boumediene Haddou

Archives of Thermodynamics

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2023

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Vol. 44, no 1

105--119

EN

This paper is concerned with the rotational motion of the impeller and the thermal buoyancy within a mechanical mixer. The task was investigated numerically using the ANSYS-CFX simulator. The programmer is based on the finite volume method to solve the differential equations of fluid motion and heat transfer. The impeller has hot surfaces while the vessel has cold walls. The rotational movement of the impeller was controlled by the Reynolds number, while the intensity of the thermal buoyancy effect was controlled by the Richardson number. The equations were solved for a steady flow. After analyzing the results of this research, we were able to conclude that there is no effect of the values of Richardson number on the power number. Also, with the presence of the thermal buoyancy effect, the quality of the fluid mixing becomes more important. The increasing Richardson number increases the value of the Nusselt number of the impeller.

2

3D simulation of incompressible flow around a rotating turbulator: Effect of rotational and direction speed

Zoubai Elhadi, Laidoudi Houssem, Tlanbout Ismail, Makinde Oluwole Daniel

Archives of Thermodynamics

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2023

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Vol. 44, no 2

139--157

EN

This paper presents new results for the dynamic behaviour of fluid around a rotating turbulator in a channel. The turbulator has a propeller form which is placed inside a flat channel. The research was carried out using 3D numerical simulation. The rationale of the experiment was as follows: we put a propeller-turbulator inside a flat channel, and then we insert a water flow inside the channel. The turbulator rotates at a constant and uniform speed. The main points studied here are the effect of the presence of turbulator and its rotational direction on the flow behaviour behind the turbulator. The results showed that the behaviour of flow behind the turbulator is mainly related to the direction of turbulator rotating. Also, the studied parameters affect coefficients of drag force and power number. For example, when the turbulator rotates in the positive direction, the drag coefficient decreases in terms of rotational speed of the turbulator, while the drag coefficient increases in terms of rotational speed when the turbulator rotates in the negative direction.

3

Bed dynamics during drum granulation

Heim A., Gluba T., Obraniak A.

Physicochemical Problems of Mineral Processing

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2004

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Vol. 38

167--176

EN

Results of investigations of a granulated bed dynamics during agglomeration in rotating drums were discussed. The investigations were carried out in granulators with continuous wetting of the bed with water, thus making no difference whether the wetting time or bed moisture content was assumed as an independent variable. The variable parameters were: drum diameter D ranging from 0.25 to 0.4 m, drum filling with raw material k in the range from 5 to 20% of inner drum volume and rotational speed of the drum n = 10 to 32 rpm. During granulation the torque value was measured on the granulator shaft. Every minute a sample was taken from the drum, the angle of natural repose of the product, and its bulk density were determined. A dimensionless equation describing the bed dynamics during granulation process was proposed.

PL

W pracy przedstawiono wyniki badań dotyczących dynamiki granulowanego złoża podczas prowadzenia procesu aglomeracji w bębnach obrotowych. Badania prowadzono w granulatorach przy ciągłym nawilżaniu złoża wodą, co powodowało, że przyjęcie jako zmiennej niezależnej czasu nawilżania bądź wilgotności złoża było tożsame. Jako parametry zmienne stosowano: średnicę bębna D od 0.25 do 0.4 m, stopień wypełnienia bębna surowcem k w zakresie 5-20% objętości wewnętrznej bębna, prędkość obrotową bębna w zakresie n=10-32 obr/min. Podczas granulacji mierzono wartości momentu obrotowego na wale aparatu. W stałych odstępach czasowych równych 1 min. pobierano z bębna próbki, na podstawie których określano kąt naturalnego usypu uzyskanego produktu, a także jego gęstość nasypową. W pracy zaproponowano równanie kryterialne opisujące dynamikę złoża w trakcie procesu granulacji.