Irfan Karagoz

Effects of flow and geometrical parameters on the collection efficiency in cyclone separators

A mathematical model has been developed for calculation of cut-off size and fractional efficiencies in cyclone separators, by taking into account the effects of flow, particle and geometrical parameters, and acceleration assuming that the mixture of fluid and particles is homogenous, and acceleration diminishes depending on the friction and geometry. Collection efficiency curves and cut-off size values predicted by the proposed model showed a good agreement with experiments over a wide range of inlet velocities for different types of cyclones. Comparison of the obtained results with semi empirical models available in literature also indicated that the present model may be used successfully for determination of the performance of a tangential inlet cyclone. Analyses of the effects of various parameters reveals that, in addition to flow and geometrical parameters, surface friction, vortex length and flow regimes play an important role on cyclone performance especially in small cyclones.

Modelling of the Pressure Drop in Tangential Inlet Cyclone Separators

This article introduces a new mathematical model that predicts the pressure drop in a tangential inlet cyclone. The model calculates the pressure drop from the frictional losses in the cyclone body, using a wall friction coefficient based on the surface roughness and Reynolds number. The entrance and exit losses are also included in the model by defining new geometrical parameters. The pressure drop coefficient is obtained as a function of cyclone dimensions and operating conditions. The model is validated by studying 12 different cyclones presented in the literature. Comparison of the model results with predictions and measurements published in the literature show that the new model predicts the experimental results quite well for a wide range of operating conditions covering a flow rate of 0.3–220 l/s and a temperature range of 293–1200°K, in different cyclones. The pressure drop coefficient is also examined in view of the outlet pipe diameter, friction coefficient, surface roughness, and Reynolds number.

A Novel Explicit Equation for Friction Factor in Smooth and Rough Pipes

In this paper, we propose a novel explicit equation for friction factor, which is valid for both smooth and rough wall turbulent flows in pipes and channels. The form of the proposed equation is based on a new logarithmic velocity profile and the model constants are obtained by using the experimental data available in the literature. The proposed equation gives the friction factor explicitly as a function of Reynolds number and relative roughness. The results indicate that the present model gives a very good prediction of the friction factor and can reproduce the Colebrook equation and its Moody plot. Therefore, the new approximation for the friction factor provides a rational, accurate, and practically useful method over the entire range of the Moody chart in terms of Reynolds number and relative roughness.

Effects of Surface Roughness on the Performance of Tangential Inlet Cyclone Separators

This study is carried out to investigate the effects of surface roughness on the flow field and cyclone performance. The flow inside the cyclone separator is modeled as a three-dimensional turbulent continuous gas flow with solid particles as a discrete phase. The continuous gas flow is predicted by solving the governing equations by using the Reynolds Stress turbulence model, and the modeling of the particle motions is based on a Lagrangian approach. The results of the numerical simulations are compared with experimental data as well as with the results of mathematical models. Analysis of computed results shows that increase of relative roughness due to corrosion, wear, or accumulation of particles on the inner walls considerably influences the tangential velocity, cyclone separation efficiency, and cyclone pressure drop especially for high inlet velocities. Decreases in cyclone collection efficiency and pressure drop with the increase in surface roughness are found to be more pronounced for high values of relative roughness.

Experimental and numerical investigation of pressure drop coefficient and static pressure difference in a tangential inlet cyclone separator

The aim of this study was to investigate the pressure drop coefficient and the static pressure difference related to the natural vortex length and to evaluate the results for gas-particle applications. CFD simulations were carried out using a numerical technique which had been verified previously. Results obtained from the numerical simulations were compared with the experimental data. Analysis of the results showed that the pressure drop coefficient decreases with the increasing inlet velocity, becoming almost constant above a certain value of the inlet velocity. The reason is that the effect of viscous forces decreases at high Reynolds numbers. The pressure drop coefficient also decreases with the increasing exit pipe diameter and decreasing exit pipe length.

Usability of cyclone separators as air filters in vehicles

This study deals with the use of cyclone separators as air filters in light or heavy duty vehicles. Cyclone separators were compared with the conventional air filters, which provide low particle collection efficiency with high pressure drop, and these characteristics are made worse by contamination. By taking into account the related studies in the literature, tangential inlet cyclones were considered in this comparison. The pressure drop and particle collection efficiency in the proposed tangential inlet cyclone were computed by using the mathematical models given in the literature. Comparison of the computed results of the cyclone with the conventional air filters demonstrated that the tangential inlet cyclones are advantageous because of low pressure drop and high particle collection efficiency and can be used as main or pre-filters in vehicles.

Experimental Investigation of the Natural Vortex Length in Tangential Inlet Cyclones

In this study, the natural vortex length has been investigated experimentally under the effects of inlet gas velocity, diameter, and insertion length of the vortex finder and surface friction in a special designed cyclone which has a double cylindrical body without cone. Experimental results show that, comparing to the other parameters, the height of the frictional surface and inlet gas velocity affect the natural vortex length considerably. The natural vortex length increases with the increase of inlet velocity and with the decrease of the height of the frictional surface. It was also observed that when the diameter of the vortex finder increases, the natural vortex length increases up to certain point and starts to decrease after that.

The Effects of Vortex Finder Dimensions on the Natural Vortex Length in a New Cyclone Separator

The shape and structure of the vortex formed inside a cyclone separator are very important for the cyclone efficiency, because they mainly govern the separation process. There are many geometrical and operational parameters affecting the vortex. This paper presents experimental results on the effects of the vortex finder dimensions and the surface friction on the vortex length. The cyclone used in this investigation is cylindrical with no conical bottom. The cyclone pressure drop and the vortex length are recorded for each test performed using different flow rates. The results reveal that an increase of the cyclone height, i.e., of the frictional surface, leads to a decrease of the vortex length. It was also shown that the diameter and length of the vortex finder adversely affect the vortex length.

Theoretical and experimental investigation of effect of valve timing on volumetric efficiency in an IC engine

Volumetric efficiency is a typical parameter that is effected by almost all constructive, aerodynamic and thermal parameters through a simple or complicated relation. In this study, the effect of valve timing, which is a highly dynamic parameter, has been investigated. Beside the original one, thirteen new camshafts have been produced without changing the angles that valves are open. New camshafts are then produced by shifting the valve-open period. All camshafts are used to determine volumetric efficiency at various engine speeds.

An investigation of external flows with various pressures and surfaces

Abstract Flow and convective heat transfer characteristics are considered by solving the mass, momentum and energy equations for two dimensional laminar and turbulent boundary layers at zero, favourable and adverse pressure gradients, including the influence of unheated starting length, surface curvature and free stream pressure gradients. The numerical predictions have been compared with approximate methods and experimental results. Results showed that Stanton numbers in laminar flat plates increased in all favourable pressure gradients and but increased only in moderate favourable pressure gradients of concave walls. On the other hand, Stanton numbers decreased both with adverse pressure gradients in laminar flow and with favorable pressures in tubulent flows.