Ayse Sarimeseli

Sedimentation of particles in developed turbulent flow in rough pipes

Abstract Sedimentation of particles on a pipe wall in developed turbulent flow is a rather common phenomenon in industrial processes. Various experimental investigations showed that the sedimentation velocity of particles is greatly affected by the roughness height and the friction factor. In this article, new expressions to calculate the friction factor and the sedimentation velocity of the particles in turbulent flow in rough pipes are suggested for the range of the Reynolds number, 10 4 ≤Re≤10 7 and the range of the dimensionless relaxation time, 10 −1 ≤ τ + ≤10 2 , respectively. Comparisons of the suggested equations in this work with the published experimental data from the literature show good agreement.

Modeling of Drop Coalescence in Isotropic Turbulent Flow

Coalescence of drops in fully developed turbulent flow depends on the size of drops and the properties of the flow. By comparing the size of drops with the Kolmogoroff length scale, collision frequencies of drops have been determined. If λ>λ0, then the collision frequency of drops in a gaseous medium is given as ωc∼(ϵR/a2)1/3 and for λ<λ0, it is given as ωc∼(ϵR/νc)1/2 in a liquid medium. New expressions for the fluctuation, thinning, and breaking of the intervening film between drops that is formed due to collisions were also suggested. At various Re and Mo numbers, for the calculation of maximum stable sizes of drops, some equations are suggested. In order to evaluate coalescence and break up rates a new dimensionless number, , is introduced. This number is defined as the ratio of the energy of the turbulent flow to surface energy. As a result of the coalescence of drops, evolution of the distribution function with time is determined from the solution of the Focker‐Planck equation. Comparisons of the calculated drop sizes with the experimental data reported in literature showed good agreement.

Deposition of Dispersed Particles in Isotropic Turbulent Flow

Particle deposition in turbulent flow depends on diffusional migrations and gravitational forces. However, the rate of this process occurs differently in vertical and horizontal flows. Therefore, some new expressions were suggested for these two types of flow in this article. Moreover, impact of the coalescence and break‐up phenomena on deposition was investigated. Suggested equations were compared with the experimental data taken from the literature and a good agreement was recorded.

Rheological Properties of Asphalt-Plastic Blends

Abstract In this article, the flow type of two different asphalt-plastic blends has been determined. One of these blends was prepared from the mixture of asphalt-cement that has a penetration degree of 60–70 (AC60-70) and low-density polyethylene (LDPE), and the other was prepared from the mixture of asphalt-cement that has a penetration degree of 150–200 (AC150-200) and low-density polyethylene (LDPE). Also, a model of the variation of the blend viscosity with temperature and concentration has been developed. It was found that this model is in a good agreement with the experimental data obtained and the relative error is calculated as 10–15%.

Effect of Some Process Parameters on the Separation of the Dispersed Ferrous Impurities Using Cycled Electromagnetic Filter

Electromagnetic filters (EMFs) can be effectively used for the cleaning of both industrial and domestic disposals such as waste water having low concentration and micron size of dispersed particles that show magnetic characteristics. In this work, we investigated the effect of some parameters of the filtration process, external magnetic field density, size of the filter matrix elements, filter length, filtration velocity, viscosity of the suspension, and number of the cycle on the separation efficiency of micron-sized particles that can be magnetized in an external magnetic field. It has been found that filtration efficiency decreased with increasing filtration velocity and suspension viscosity. Furthermore, the filter matrix elements geometry, pH value of the medium, and number of the cycling processes affected the cleaning efficiency. Recycling the suspension to the filter body allowed the cleaning process to be made in a smaller filter size with a high quality factor.

Determination of Drop Sizes in Annular Gas/Liquid Flows in Vertical and Horizontal Pipes

Measurement of drop sizes play vital role in applications dealing with gas/liquid flow mixtures. In the present work, drop sizes in vertical and horizontal pipe flows were determined using Malvern 2600HSD system that applies laser diffraction method. From the analysis of the experimental data obtained at two different pipe orientations, two separate expressions were developed to determine Sauter mean diameter, d 32. Except for the 20 m/s superficial gas velocity in vertical flow case, a good agreement was found between the developed expressions and the experimental data.

An Experimental Study on Rheological Properties of Pestil Blends

The rheological and sensory properties kind (apricot, grape and mulberry molasses) blends were studied pestil (rollband) syrup of apricot, mulberry and grape at 25, 40, 50 and 70°C, rheological properties kind of pestil syrup (untreatment and treatment with sulphurapricot molasses) blends were studied using sugar concentrations of 0%, 5% and 10%. The empirical power law model fitted the apparent viscosityrotational speed data. All blends exhibited pseudoplasticbehavior. The syrup content and temperature influenced the flow behavior and consistency index values. Temperature sensitivity of the consistency index was assessed by applying an Arrhenius-type equation. Ea values ranged from 326,65 to 175,86 J mol s-1 as syrup content varied from apricot, grape to mulberry, respectively. Arrhenius constant, k, however, correlated with mouthcoating.

Effect of the Magnetization Properties of the Granular Beds and the Operating Parameters on the Removal Ferrous Particles From the Waters by Using Magnetic Filter

In this article, magnetizing properties of different packed beds constructed from magnetic balls, pieces of rods, and chips were investigated in order to determine their effect on the magnetic filters’ performance. Magnetizing curves obtained from the results show that the magnetization of packed beds constructed from magnetic balls is stronger than of those constructed from pieces of rods and/or chips. Effects of the external magnetic field intensity, filter length, and recycle number on the effectiveness of magnetic filtration of both solutions were also investigated. We found that corrosion particle capturing capacity of the filter from water medium in the filter increases by amplifying external magnetic field intensity, raising filter length, and recycle number until the filter is overloaded.

Effect of Surfactants on the Particle Capture Mechanism in an Electromagnetic Filter

In this article, effects of the parameters of the filtration process and surfactants on the effectiveness of the separation of particles have been investigated. Water samples containing corrosion particles (rust) of low concentrations were mixed with a typical domestic type of detergent passed through an electromagnetic filter. It was found that the capturing capacity of the particles in the filter increased as the external magnetic field, filter length and the detergent concentration of the suspension increase, but the increase in diameter of the filter elements gave an opposite effect. Furthermore, it was recorded that the pH value of the suspension changes the efficiency of magnetic filter.

Estimation of Magnetization Properties of the Ferromagnetic Poly-Granular Beds

In this article, magnetizing properties of the packed beds that are constructed from the mixture of the ferromagnetic spheres of various sizes, pieces of wires and chips are investigated both experimentally and theoretically in order to determine the effect of the volumetric packing factor on the magnetizing properties of the bed. The average magnetizing curve has been determined by maintaining the external homogeneous magnetic field (H) higher than 150 kA/m.