Air Pollution and Meteorology

Crawford, T.V.

doi:10.3109/15563656908990939

Cited by 11 publications

(11 citation statements)

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“…The historical transition of cyclones development can be found in Crawford (1976), Storch (1979) and Ogawa (1984), where many old and interesting types of cyclones are discussed. The most standard construction of the returned flow type is composed of a cylindrical body with a fixed diameter and a conical part.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of cyclone geometry and its influence on performance parameters by computational fluid dynamics (CFD)

Martignoni

Bernardo

Quintani

2007

Braz. J. Chem. Eng.

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-Cyclone models have been used without relevant modifications for more than a century. Most of the attention has been focused on finding new methods to improve performance parameters. Recently, some studies were conducted to improve equipment performance by evaluating geometric effects on projects. In this work, the effect of cyclone geometry was studied through the creation of a symmetrical inlet and a volute scroll outlet section in an experimental cyclone and comparison to an ordinary single tangential inlet. The study was performed for gas-solid flow, based on an experimental study available in the literature, where a conventional cyclone model was used. Numerical experiments were performed by using CFX 5.7.1. The axial and tangential velocity components were evaluated using RSM and LES turbulence models. Results showed that these new designs can improve the cyclone performance parameters significantly and very interesting details were found on cyclone fluid dynamics properties using RSM and LES.

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Section: Introductionmentioning

confidence: 99%

Evaluation of cyclone geometry and its influence on performance parameters by computational fluid dynamics (CFD)

Martignoni

Bernardo

Quintani

2007

Braz. J. Chem. Eng.

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“…The analyses of the results of all these calculations were to help in the study. The numerical calculation for fluidization for gas velocity was defined via the formulae suggested by [4] , while on distributor was obtained through the formulae given by [10] , heat transfer tube was calculated through [8] , heat transfer coefficient and the film coefficient on the inside surface were calculated through the recommendation of [5] . .…”

Section: Resultsmentioning

confidence: 99%

“…Feed water and wall temperature: At 30°C for the water, the following characteristic data were obtained from thermodynamic steam table [8] : t ba = bed temperature = 800°C (between 750-950°C) t 0 = exit gas temperature = 330°C (not less than 175°C) [12] C = Specific of heat capacity of air = 1010J kgk Heat transfer coefficient: For turbulent gas flow, an empirical equation was recommended according to [5] : The tube chosen for this experiment was from stainless steel type 310 but carbon steel preferable austenitic steel such as 304, 316, 321, or 347 grades are also suitable. The pitch between pipe to pipe = 16 mm.…”

Section: Heat Transfer Tubesmentioning

confidence: 99%

Pneumatic and Hydraulic Systems in Coal Fluidized Bed Combustor

Saleh¹

2009

American Journal of Engineering and Applied Sciences

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Problem statement:This study designed the pneumatic and hydraulic systems in coal fluidized bed combustor. These are fluidization of silica sand bed material, Air distributor, centrifugal fan, electric motor power drive and surface heat exchanger. Approach: The effects of increased gas velocity on silica sand and the resultant drag force formed the basic equations in fluidization. Air distributor was introduced to achieve pressure drop across the beds. Results: The constructed centrifugal fan was driven by selected electric motor based on pressure and temperature changes in the reactor. The dimensions of the heat transfer tube were calculated from fluid flow and energy balance equations. The values obtained were as the follows: Fluidization velocity (1.54 m sec −1 ), gas velocity through orifice (29.52 m sec −1 ), the fan electric motor (2 KW, 3 ph at 1500 pm), the steam temperature obtained was 160°C from water ambient temperature of 30°C and tube length 22 m was coiled into levels in the combustor. Conclusion/Recommendation: Precise specifications of pneumatic and hydraulic systems will adequately address the environment concern of coal fired power supply as a method to address epileptic power supply in Nigeria.

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“…The concentration equation becomes thus simplified as in which d is the particle diameter, q is the amount of particle charge which had been discussed in detail in Crawford (1976), and C, is the Cunningham correction factor that is expressed as in which A is the mean free path of gas molecules. According to the standard model for the eddy viscosity and Fick's law of diffusion, we write the turbulent terms in Eq.…”

Section: Models For Concentration Fieldmentioning

confidence: 99%

The Characteristics of Ionic Wind and Its Effect on Electrostatic Precipitators

Liang

Lin

1994

Aerosol Science and Technology

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The ionic wind and turhulent flow field formed in a nonconsewative electric force field have long been recognized to have a significant effect on an electrostatic precipitator (ESP). To simulate the flow field in an ESP, one should include the electric force term in the momentum equation. We considered the flow field in an ESP to be a turhulent flow and applied two-and three-dimensional models of k-&-A and k+E to close turbulence. The SIMPLEX numerical scheme was applied to investigate the characteristics of the ionic wind and its influence on an ESP. The collecting efficiency of an ESP for a particle diameter of each grade was calculated to understand how the ionic wind interferes with the collecting efficiency. The results indicate that under normal operating conditions the effect of ionic wind is not pronounced. However, as the flow velocity becomes smaller, especially when the flow velocity is < 0.6 m/s, the ionic wind becomes pronounced and has a significant influence on the flow field and the collecting efficiency. The collecting efficiency is suhstantially diminished and the turhulent intensity is enlarged. When the main flow velocity is < 0.23 m/s, the collection efficiency may decrease about 12% owing to the ionic wind effect.

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Air Pollution and Meteorology

Cited by 11 publications

References 0 publications

Evaluation of cyclone geometry and its influence on performance parameters by computational fluid dynamics (CFD)

Evaluation of cyclone geometry and its influence on performance parameters by computational fluid dynamics (CFD)

Pneumatic and Hydraulic Systems in Coal Fluidized Bed Combustor

The Characteristics of Ionic Wind and Its Effect on Electrostatic Precipitators

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