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Computational fluid dynamics studies of dry and wet pressure drops in structured packings
Seyyed Hossein Hosseini,Saeed Shojaee,Goodarz Ahmadi,Mortaza Zivdar 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4
Computational fluid dynamics was used to study the hydrodynamic of structured packings. The results showed that the k–v was a suitable turbulence model for analyzing the flows in structured packings. A simple method was proposed for evaluating the liquid holdup based on the Iliuta and Larachi (2001)model [25], the calculated liquid film thickness in 2D framework, and the empirical correlation of Brito et al. (1994) [26]. The presented method can be used for estimating the wet pressure drop in 3D structured packings for loading region with good accuracy as well as computational economy. The process of liquid film formation was also discussed.
Seyyed Hossein Hosseini,Mahmood Reza Rahimi,Nader Azizi,Goodarz Ahmadi 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.3
The hydrodynamics of a vertically vibrating fluidized bed was studied using an Eulerian-Eulerian twofluid model (TFM) incorporating the kinetic theory of granular flow and including the frictional stress effects. Influences of frictional stresses, vibration amplitudes and frequency on behavior of the particles were studied. In the case with vertical vibration, the numerical results showed three regions of solid concentration along the bed height: a low particle concentration region near the bottom of the bed, a high concentration region in the middle of the bed, and a transition region at top of the bed. The accuracy of results was found to be closely related to the inclusion of the frictional stresses. Ability of the two-fluid model for predicting the hydrodynamics of vibrating fluidized beds was discussed and confirmed.
CFD simulation of gas-solid bubbling fluidized bed containing FCC particles
Seyyed Hossein Hosseini,Rahbar Rahimi,Mortaza Zivdar,Abdolreza Samimi 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.5
The hydrodynamics of a bubbling gas-solid fluidized bed of 57.4 μm FCC particles was simulated by using a state-of-the-art two-fluid model integrating the kinetic theory of granular flow for particulate phase stresses. The overestimation of the bed expansion was resolved by using a suitable scale factor in the drag model as suggested by McKeen and Pugsley (T.R. McKeen, T.S. Pugsley, Powder Technol., 129, 139 (2003)). This study showed that the method was appropriate in simulation of a gas-solid fluidized bed of Geldart A particles at high gas velocities (0.3 to 0.61 m/s). The reduction of computational time especially for simulation of large-scale systems was achieved. The time-averaged local voidage was compared with the experimental data and the trend of varying several parameters on the hydrodynamic of the bed was investigated. The simulation results showed both qualitative and quantitative agreement with the literature.
Intrinsic kinetics of the Fischer-Tropsch synthesis over an impregnated cobalt-potassium catalyst
Hossein Atashi,Mohsen Mansouri,Seyyed Hossein Hosseini,Mohammad Khorram,Ali Akbar Mirzaei,Masoud Karimi,Ghobad Mansouri 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.3
The optimal amount of 15 wt%Co/10 wt%K/Al2O3 catalyst was prepared using the impregnation technique in order to study the kinetics of the Fischer-Tropsch synthesis. The rate of synthesis was measured in a fixed-bed micro reactor with H2/CO feed ratio of 1-3 and space velocity in the range of 2,700-5,200 h−1 under reactor pressure of 8 bar and a temperature range of 210-240 oC. The experimental data were best fitted by a Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach rate in the form of −rCO=(k2K1PCOPH2)/(1+K1PCO). Furthermore, the data were fitted fairly well by a power law equation in the form of −rCO=kPCO 1.32PH21.42. The activation energies for LHHW approach model and power law equation were obtained as 138.5 kJ/mol and 87.39 kJ/mol, respectively.
Amir Hossein Alizadeh-Ghamsari,Amir Reza Shaviklo,Seyyed Abdullah Hosseini 한국축산학회 2023 한국축산학회지 Vol.65 No.4
This study was conducted to evaluate the effects of co-dried fish protein hydrolysate (CFPH) on broilers performance, intestinal microbiology, and cellular immune responses. Five hundred one-day-old (Ross 308) male broilers were allocated to four treatments with five replicates of 25 birds in a completely randomized design. The experimental treatments included four levels of CFPH (0% as the control, 2.5%, 5%, and 7.5%) in the isonitrogenous and isocaloric diets. During the experiment, body weight (BW) and feed intake (FI) were periodically recorded in addition to calculating average daily gain (ADG), feed conversion ratio (FCR), liveability index, and European broiler index (EBI). In addition, cellular immune responses were evaluated at 30 days of age. On day 42, ileal contents were obtained to examine the microbial population. Based on the findings, Dietary supplementation of 5 and 7.5% CFPH increased the percentage of the thigh while decreasing the relative weight of the gizzard compared to the control group. The highest relative length of jejunum was observed in birds receiving 2.5 and 5% CFPH, and its highest relative weight belonged to birds fed with 5% CFPH. The number of coliforms, enterobacters, and total gram-negative bacteria in the intestines of birds receiving CFPH was less than that of the control group. In general, the application of CFPH in broiler nutrition can decrease the level of soybean meal in diet and it can be considered as a new protein supplement in poultry production. It is suggested to study the incorporation of this new supplement in other livestock’s diets.
Three-dimensional CFD study of conical spouted beds containing heavy particles: Design parameters
Naimeh Setarehshenas,Seyyed Hossein Hosseini,Mohsen Nasr Esfahany,Goodarz Ahmadi 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5
The flow behavior of conical spouted beds containing heavy particles that occurs in chemical vapor deposition (CVD) was investigated using the computational fluid dynamics (CFD) approach. A fully Eulerian description of solid and gas phases flows in 3D was used in these simulations. The hydrodynamics parameters including particle velocity, solid flux, and solid volume fraction profiles at different bed levels were evaluated, and the overall behavior of solid particles in the beds was studied. The results showed close agreement with the corresponding experimental data. The effects of cone angle, static bed height, and cone bottom diameter on the hydrodynamic behavior of heavy particles were analyzed and the results were presented. In addition, the effects of flat wall of semi-conical spouted bed (halfcolumn) on the CFD results and performance of the spouted bed were investigated. The hydrodynamic results for the full bed were quite different from those for the half bed geometries. It was also found that the conical spouted bed with the angle of 45o leads to the roughly stable spouting compared to the 30o angle bed. The CFD model also showed that the conical-cylindrical spouted beds operating with heavy particles has the potential for periodic occurrence of choking in the spout zone.
Influence of gas exhaust geometry on flow pattern, performance, and erosion rate of a gas cyclone
Parvaz Farzad,Hosseini Seyyed Hossein,Bastan Ahmad Reza,Foroozesh Jamal,Babaoğlu Nihan Uygur,Elsayed Khairy,Ahmadi Goodarz 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7
The effect of gas exhaust shape on the performance, flow pattern, and erosion rate of a gas cyclone was investigated using a numerical model. The results show that the shape of the gas exhaust affects the movement of the vortex core in the gas cyclone. With a change in the shape of the exhaust gas, the axial and tangential velocities changed in the cyclone. The highest turbulent kinetic energy in cyclones was found in the gas exhaust region. The results showed that the diamond gas exhaust exhibited the highest turbulent kinetic energy among the other shapes. In the cases of diamond and square gas exhausts, the size of the Rankine vortex was decreased, leading to a reduction in the centrifugal force of the gas flow and, thereby, cyclone separation efficiency. The lowest erosion rate and highest separation efficiency were found for the cyclone with a circular gas exhaust.
A New AC/DC Converter for the Interconnections between Wind Farms and HVDC Transmission Lines
Nouri, Soheil,Babaei, Ebrahim,Hosseini, Seyyed Hossein The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3
In this paper, a new ac/dc converter is proposed for HVDC-connected wind farms. The proposed converter provides a suitable dc voltage for HVDC transmission systems. Each wind turbine is connected to two full bridge diode rectifiers. These rectifiers are connected to each other by three thyristors. Firing the thyristors at desired angles provides an adjustable dc voltage in the output of the converter. Simulation results show the efficiency of the proposed converter.
Reduced-phase dual-illumination interferometer for measuring large stepped objects.
Tayebi, Behnam,Jafarfard, Mohammad Reza,Sharif, Farnaz,Bae, Yoon Sung,Shokuh, Seyyed Hossein Hosseini,Kim, Dug Young Optical Society of America 2014 Optics letters Vol.39 No.19
<P>We present a reduced-phase dual-illumination interferometer (RPDII) that measures the topography of a sample with large step height variation. We experimentally demonstrate the basic principle and the feasibility of this novel single-shot quantitative phase imaging. Two beams of this interferometer illuminate a sample at different incident angles, and two phases of the different incident angles and their phase difference are simultaneously recorded using three spatial frequencies. The relative phase difference between two beams of an RPDII can be controlled by adjusting the angle such that the maximum phase difference is smaller than 2π, and thus there is no phase wrapping ambiguity in the reconstructed phase. One 4f optical system with a transmission grating is used to illuminate the sample with two collimated beams incident at different angles. The feasibility of this technique is demonstrated by measuring the thicknesses of two stepped metal layers with heights of 150 and 660 μm. Although the change in stepped height is more than 1000 times the wavelength of the laser used in our interferometer, the thicknesses of these two metal layers are successfully obtained without the use of an unwrapping algorithm.</P>