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Khairy Elsayed - One of the best experts on this subject based on the ideXlab platform.

  • influence of the Inlet cross sectional shape on the performance of a multi Inlet Gas cyclone
    Powder Technology, 2021
    Co-Authors: Nihan Uygur Babaoglu, Farzad Parvaz, Seyyed Hossein Hosseini, Khairy Elsayed, Goodarz Ahmadi
    Abstract:

    Abstract The influence of Inlet cross-sectional shape on the flow pattern, pressure drop, and cut-off diameter of a Gas cyclone was studied using the CFD model. Accordingly, five different Inlet cross-sectional shapes, namely, circle, ellipse, rectangle, square, and trapezoid, for the double-Inlet Gas cyclone were studied. It was observed that the maximum tangential velocity was about 1.95 times the corresponding Inlet velocity for primary and secondary rectangle Inlets. Furthermore, the computed tangential velocity in the cyclone with the primary and secondary rectangle Inlets (R-R) was considerably greater than those obtained by the other Inlet shapes. In this case, the axial Gas velocity reached its highest values at the bottom of the vortex finder and the cyclone center. It was also determined that the Inlet shape significantly affected the cyclone pressure drop. The Circle-Square and the Rectangle-Ellipse configurations of Inlet cross-sectional shape generated, respectively, the lowest pressure drop and the highest efficiency.

  • analysis and optimization of multi Inlet Gas cyclones using large eddy simulation and artificial neural network
    Powder Technology, 2017
    Co-Authors: Lakhbir Singh Brar, Khairy Elsayed
    Abstract:

    Abstract The present study is aimed at optimizing the performance of multi-Inlet Gas cyclones. The current contribution is threefold. First, a design of experiments (DoE) has been conducted for three variables viz. the flow rate through the secondary Inlet, the (square) cross-sectional area of the secondary Inlet and the location of the top of the main Inlet from cyclone roof. Second, the numerical simulations are performed using large eddy simulation (LES) to predict the Euler number, cut-off size and the collection efficiency for different combinations of the independent variables. The CFD simulation results are used to train an artificial neural network for three responses, namely the Euler number, the cut-off diameter and the overall collection efficiency. Moreover, the simulation results explain how the variations of the design variables affect the flow pattern and performance. Furthermore, the fitted surrogate model demonstrates that the most significant factors are the ratio of flow rates and the area ratio. Third, single-objective and multi-objective optimization studies are carried out using artificial neural network. The optimum design results in better performance than the conventional cyclones.

Xiaobing Liu - One of the best experts on this subject based on the ideXlab platform.

  • transport performance improvement of a multiphase pump for Gas liquid mixture based on the orthogonal test method
    Processes, 2021
    Co-Authors: Guangtai Shi, Zongku Liu, Xiaobing Liu, Binxin Wang
    Abstract:

    To improve the transport performance of a rotodynamic multiphase pump for a Gas–liquid mixture, we took the head and efficiency index at rated flow rate with 15% Inlet Gas volume fraction as the indices, and used the orthogonal test design method and CFD technology to optimize. We selected the blade shroud angles at the leading edge and trailing edge, and axial length of the impeller, as well as the Inlet incidence angle and blade number of the diffuser, and a total of five factors were used for the orthogonal test. The weight function was used to determine the final trial protocol. The results showed that the blade shroud angle at the trailing edge had the greatest influence on the head and efficiency indices. Under the rated flow rate with a 15% Inlet Gas volume fraction, the head and efficiency of the optimized pump were increased by 2.81 m and 5.6%, respectively, in comparison to the base pump. After the optimization, the partial fast-speed regions at the Inlet of the impeller passage and the partial low-pressure regions on the blade suction side of the impeller disappeared, the accumulation of the Gas phase on the blade suction side at the impeller outlet was suppressed, and the pumping performance of the impeller using the Gas–liquid mixture was improved greatly. This study provides an important theoretical basis for the optimization and design of a multiphase pump.

  • Transport Performance Improvement of a Multiphase Pump for Gas–Liquid Mixture Based on the Orthogonal Test Method
    'MDPI AG', 2021
    Co-Authors: Guangtai Shi, Zongku Liu, Xiaobing Liu, Binxin Wang
    Abstract:

    To improve the transport performance of a rotodynamic multiphase pump for a Gas–liquid mixture, we took the head and efficiency index at rated flow rate with 15% Inlet Gas volume fraction as the indices, and used the orthogonal test design method and CFD technology to optimize. We selected the blade shroud angles at the leading edge and trailing edge, and axial length of the impeller, as well as the Inlet incidence angle and blade number of the diffuser, and a total of five factors were used for the orthogonal test. The weight function was used to determine the final trial protocol. The results showed that the blade shroud angle at the trailing edge had the greatest influence on the head and efficiency indices. Under the rated flow rate with a 15% Inlet Gas volume fraction, the head and efficiency of the optimized pump were increased by 2.81 m and 5.6%, respectively, in comparison to the base pump. After the optimization, the partial fast-speed regions at the Inlet of the impeller passage and the partial low-pressure regions on the blade suction side of the impeller disappeared, the accumulation of the Gas phase on the blade suction side at the impeller outlet was suppressed, and the pumping performance of the impeller using the Gas–liquid mixture was improved greatly. This study provides an important theoretical basis for the optimization and design of a multiphase pump

  • Effect of the Inlet Gas Void Fraction on the Work Performance of the Multiphase Pump at Different Cavitation Stages
    'MDPI AG', 2021
    Co-Authors: Guangtai Shi, Xiaobing Liu, Yue Dan, Zekui Shu
    Abstract:

    The Inlet Gas void fraction (IGVF) has a great effect on the power performance of the multiphase pump, and the effect is even greater under the cavitation condition. To reveal the effect of the IGVF on the cavitation evolution and the work performance of the multiphase pump at different cavitation stages, the cavitation flow was calculated numerically for the pump under different Inlet Gas void fractions (IGVFs) of 0%, 10% and 20%. Meanwhile, the numerical simulation method was verified experimentally. The results showed that the increase of the IGVF could improve the cavitation performance of the multiphase pump and inhibit the increasing rate of the vapor. With the aggravation of the cavitation, the output power of the impeller decreased gradually under different IGVFs. In addition, the variation trend of the output power and the net energy gained by the fluid within each domain were exactly the same. At the same time, the position of better work performance was located in the impeller fore area at the critical and serious cavitation stages, while when the cavitation developed to the fracture cavitation, the position of better work performance moved to the impeller back area. At the fracture cavitation stage, the main work region of the multiphase pump moved from the back area to the fore area of the impeller with the increase of the IGVF. The research results are of great significance in improving the performance of the multiphase pump

  • effect of the Inlet Gas void fraction on the tip leakage vortex in a multiphase pump
    Renewable Energy, 2020
    Co-Authors: Guangtai Shi, Zongku Liu, Hong Yang, Xiaobing Liu
    Abstract:

    Abstract Inlet Gas void fraction (IGVF) played an important role on the flow characteristics in a multiphase pump. To reveal the effect of Inlet Gas void fraction on the flow characteristics in the tip clearance, a combination of numerical simulation and experiment was carried out and the reliability of numerical method was verified by comparing with the experimental data of the flow field by using high-speed photography. The results showed the accumulated Gas was mainly at the impeller Inlet near the pressure side (PS), tip clearance near the tip and the suction side (SS). When the IGVF increased, there was an obvious stratified structure and the separated vortex in the tip clearance. Compared to the water case, the Gas caused the tip leakage flow velocity to decrease from the blade Inlet to the streamwise coefficient of 0.2, and to increase from the streamwise coefficient of 0.2 to the blade trailing edge. At the same time, the IGVF had a significant influence on the tip leakage vortex (TLV) structure and trajectory, and the streamlines and vorticity distribution corresponding to the wake and the TLV were changed. Moreover, the flow characters and the structure of the TLV were more complicated under Gas-liquid condition.

  • A Review of Design Considerations of Centrifugal Pump Capability for Handling Inlet Gas-Liquid Two-Phase Flows
    MDPI AG, 2019
    Co-Authors: Qifeng Jiang, Xiaobing Liu, Yaguang Heng, Weibin Zhang, G Bois
    Abstract:

    Most of the pumps working under two phase flows conditions are used in petroleum industry applications, like electrical submersible pumps (ESP) for hydrocarbon fluids, in chemistry, nuclear industries and in agriculture for irrigation purposes as well. Two-phase flows always deteriorate overall pump performances compared with single flow conditions. Several papers have been published aiming to understand flow physics and to model all the main mechanisms that govern Gas pocket formation and surging phenomena. These mechanisms depend on the pump type, the impeller geometry, the rotational speed, design and off-design liquid flow rate conditions, the volumetric Gas fraction, the fluid properties and the Inlet pressure. In the present paper, a review on two phase performances from various centrifugal pumps designs is presented, mainly based on experimental results. The main focus is devoted to detect the significant geometrical parameters that: (1) Modify the pump head degradation level under bubbly flow regime assumption; (2) Allow single stage centrifugal pumps keep working under two-phase flow conditions with high Inlet void fraction values before pump shut down, whatever the pump performance degradations and liquid production rates should be. Because most of the published experimental studies are performed on dedicated laboratory centrifugal pump models, most of the present review is based on air-water mixtures as the working fluid with Inlet pressures close to atmospheric conditions. The following review supposes that Gas phase is considered as a non-condensable perfect Gas, while the liquid phase is incompressible. Both phases are isolated from external conditions: neither mass nor heat transfer take place between the phases

Xu Yang - One of the best experts on this subject based on the ideXlab platform.

  • Leakage Loss Study of a Synchronal Rotary Multiphase Pump With a Full Range of Inlet Gas Volume Fractions
    2020
    Co-Authors: Xu Yang, Yao Qin
    Abstract:

    The working performance of the synchronal rotary multiphase pump (SRMP), alike other types of positive-displacement multiphase pumps, is strongly affected by leakage loss. In this paper, the leakage loss in the SRMP with a full range of Inlet Gas volume fractions (GVFs) was theoretically and experimentally investigated. The leakage flows in the SRMP were modeled as the one-dimensional Gas-liquid flows through narrow gaps. Two types of leakage flow models, homogeneous leakage flow model (HLFM) and separated leakage flow model (SLFM), were developed. The experimental work was conducted to measure the volumetric flow rate of the SRMP using the mixtures of air and N32 oil as working fluids under various Inlet GVFs and differential pressures. Comparisons between the simulated and experimental pump flow rates showed that both the accuracies of the HLFM and SLFM related to the Inlet GVF. In addition to the differential pressure, the leakage loss of the SRMP was affected by the Inlet GVF. The leakage flow rate increased with the Inlet GVF due to the changes in physical properties of the Gas-liquid leakage flow. Parametric analysis showed that leakage loss in the SRMP can be effectively reduced by reducing the rotor radial clearance without much effect on its mechanical efficiency, whereas the optimum geometric parameters of the rotor and cylinder must be calculated by means of the optimization study with consideration of both the leakage loss and friction loss

  • theoretical and experimental study of a synchronal rotary multiphase pump at very high Inlet Gas volume fractions
    Applied Thermal Engineering, 2017
    Co-Authors: Xu Yang
    Abstract:

    Abstract Theoretical and experimental analyses are performed to investigate the pumping behaviour of a synchronal rotary multiphase pump (SRMP) at very high Inlet Gas volume fractions (GVFs). A comprehensive SRMP model is developed to predict the pump performance at very high Inlet GVFs, including the steady-state behaviours and the transient distributions of interesting variables during pump operation. The experimental work is implemented using N32 oil and air as the working fluids to measure the global performance parameters of the SRMP at the Inlet GVFs of 91–98% and different differential pressures. The SRMP model is validated by comparison of the simulated and experimental results. The results show that the Inlet GVF has a significant effect on the pump behaviour. At a given differential pressure, the leakage loss increases dramatically with the Inlet GVF, which results in a significant decrease in the volumetric flow rate of the SRMP. Because of the large proportion of shaft power wasted by the high-pressure back flow, the SRMP exhibits lower pump efficiency at the higher Inlet GVFs.

John T S Irvine - One of the best experts on this subject based on the ideXlab platform.

  • experimental and modeling study of high performance direct carbon solid oxide fuel cell with in situ catalytic steam carbon Gasification reaction
    Journal of Power Sources, 2018
    Co-Authors: Bin Chen, Houcheng Zhang, Peng Tan, Guangming Yang, John T S Irvine
    Abstract:

    Abstract In this paper, 2D models for direct carbon solid oxide fuel cells (DC-SOFCs) with in situ catalytic steam-carbon Gasification reaction are developed. The simulation results are found to be in good agreement with experimental data. The performance of DC-SOFCs with and without catalyst are compared at different operating potential, anode Inlet Gas flow rate and operating temperature. It is found that adding suitable catalyst can significantly speed up the in situ steam-carbon Gasification reaction and improve the performance of DC-SOFC with H2O as Gasification agent. The potential of synGas and electricity co-generation from the fuel cell is also evaluated, where the composition of H2 and CO in synGas can be adjusted by controlling the anode Inlet Gas flow rate. In addition, the performance DC-SOFCs and the percentage of fuel in the outlet Gas are both increased with increasing operating temperature. At a reduced temperature (below 800 °C), good performance of DC-SOFC can still be obtained with in-situ catalytic carbon Gasification by steam. The results of this study form a solid foundation to understand the important effect of catalyst and related operating conditions on H2O-assisted DC-SOFCs.

Haosheng Zhou - One of the best experts on this subject based on the ideXlab platform.

  • dem les of coal combustion in a bubbling fluidized bed part i Gas particle turbulent flow structure
    Chemical Engineering Science, 2004
    Co-Authors: Haosheng Zhou, Gilles Flama, Daniel J Gauthie
    Abstract:

    Abstract The Gas and particle motions in a bubbling fluidized bed both with and without chemical reactions are numerically simulated. The solid phase is modelled as Discrete Element Method (DEM) and the Gas phase is modelled as 2-D Navier–Stokes equations for 2-phase flow with fluid turbulence calculated by large Eddy simulation (LES), in which the effect of particles on subgrid scale Gas flow is taken into account. The Gas/particle flow structure, the mean velocities and turbulent intensities can be predicted as a function of several operating parameters (particle size, bed temperature, and Inlet Gas velocity). The lower the Inlet Gas velocity, the higher the ratio of particle collision. The distributions of the particle anisotropic velocity show that the particles have no local equilibrium, and the distribution of Gas kinetic energy corresponds to the distribution of Gas-particle coupling moment in the fluidized bed. An intensive particle turbulent region exists near the wall, and the Gas Reynolds stress is always much higher than the particle stress. The presence of the large reactive particles in the fluidized bed may affect significantly the Gas and particle velocities and turbulent intensities. The effects of the bed temperature and Inlet Gas velocity on the Gas particle flow structure, velocity, and turbulent intensity are also studied.

  • dem les of coal combustion in a bubbling fluidized bed part i Gas particle turbulent flow structure
    Chemical Engineering Science, 2004
    Co-Authors: Haosheng Zhou, Gilles Flamant, Daniel J Gauthier
    Abstract:

    Abstract The Gas and particle motions in a bubbling fluidized bed both with and without chemical reactions are numerically simulated. The solid phase is modelled as Discrete Element Method (DEM) and the Gas phase is modelled as 2-D Navier–Stokes equations for 2-phase flow with fluid turbulence calculated by large Eddy simulation (LES), in which the effect of particles on subgrid scale Gas flow is taken into account. The Gas/particle flow structure, the mean velocities and turbulent intensities can be predicted as a function of several operating parameters (particle size, bed temperature, and Inlet Gas velocity). The lower the Inlet Gas velocity, the higher the ratio of particle collision. The distributions of the particle anisotropic velocity show that the particles have no local equilibrium, and the distribution of Gas kinetic energy corresponds to the distribution of Gas-particle coupling moment in the fluidized bed. An intensive particle turbulent region exists near the wall, and the Gas Reynolds stress is always much higher than the particle stress. The presence of the large reactive particles in the fluidized bed may affect significantly the Gas and particle velocities and turbulent intensities. The effects of the bed temperature and Inlet Gas velocity on the Gas particle flow structure, velocity, and turbulent intensity are also studied.