Vivek V. Buwa’s research while affiliated with Indian Institute of Technology Ropar and other places

... Significant research efforts are also being made to simulate the local liquid distribution in the trickle bed using the continuum (Eulerian) method. 30 While it is known that the Eulerian CFD models can predict the overall liquid holdup and pressure drop reasonably well, the ability of such CFD models to predict the local liquid holdup is not established and is limited by the availability of the measurements on the local liquid distribution. Therefore, it is important to have simultaneous measurements of overall as well as local liquid distribution for a wide range of operating conditions for the development and rigorous validation of the CFD models. ...

Reference:

Experimental characterization of dynamics of bed‐scale liquid spreading in a trickle bed

... Another study focused on the effect of the local bubble behaviors (β gas-inlert , gasinert solid phase momentum exchange using different drag models) on heterogeneous reaction rate, gas phase temperature, and gas compositions. With a high β gas-inlert , the mixing content of coal and inert solid phase increases, resulting in a high content of H 2 and CO (Parvathaneni et al. 2023). Bubble containing various combustible gas (H 2 , CO, and CH 4 ) were mainly found in the lower part of the gasifier . ...

Reference:

Catalytic coal gasification: mechanism, kinetics, and reactor model

... Thus far, various numerical and experimental approaches have been employed to investigate the two-phase hydrodynamics inside a trickle bed. Particle-resolved Computational Fluid Dynamics (CFD) methods, such as the Volume of Fluid (VOF) method [5][6][7][8][9][10] and Euler-Euler methods, [11][12][13] are a couple of popular numerical approaches to model and investigate trickle beds. 14 An appropriate experimental technique that can provide local information on the two-phase flow texture and hydrodynamics inside a trickle bed can greatly help validate and develop such computational models. ...

Reference:

Magnetic resonance imaging of trickle flow

... A tapered FB with an increase in the cross section from bottom to top is considered unlike the cylindrical FB in FIOR and FINMET processes. For a similar operating flow rate, due to less injection area in a tapered FB than in a cylindrical FB, the gas velocity is high in the tapered FB. 45,46 Due to this, in the tapered FB, iron ore with a wide size distribution can be homogenously fluidized with a lower elutriation rate than in the cylindrical FB. 47 Cyclones with a dip-leg are present in the FB, and the transport disengagement height is optimized to minimize elutriation and heat loss. 44 The hematite fine ore typically in the mean size range of 1− 2 mm (maximum size up to 8 mm) is pneumatically charged into the Stage-I FB (i.e., R4) reactor and conveyed to the next stages 48,49 (see Figure 8). ...

Reference:

Iron-Ore Reduction in Fluidized Beds: Review of Commercial Technologies, Status, and Challenges

... This is being used in the measurement of scalar concentration fields in fluid flows which can be resolved both spatially and in time [1][2][3]. The technique is widely used and is being adopted in many fields including but not limited to investigation of reacting flows [4], study of heat transfer characteristics [5], fluorescent thermometry using LIF [6,7], eduction of 3D time resolved concentration field [8,9] and simultaneous momentum and concentration measurement [10][11][12] to name a few. The scalar whose concentration is to be measured is 'tagged' with a small amount of a suitable fluorescent dye (e.g. ...

Reference:

Analysis of an Accurate Iterative Technique with Attenuation Compensation in Planar Laser Induced Fluorescence

... From a hydrodynamic standpoint, these simulation studies provide insightful analysis that helps to optimize, design, and run fixed-bed reactors. Besides these, for the area of multiphase flow CFD simulations, the development of PRCFD has provided an excellent modeling tool for detailed simulations of hydrodynamics in the structure of packed packing [23][24][25][26]. In addition, as a precise modeling tool for PRCFD simulations of packed bed hydrodynamics, it has been utilized for comparative analyses with other methods and measurement techniques, such as pore network modeling [27], Magnetic Resonance Imaging (MRI) [28], and Particle Image Velocimetry (PIV) regarding packed bed hydrodynamics [29]. ...

Reference:

Particle-resolved computational fluid dynamics simulation of the heat transfer in fixed-bed reactors for heterogeneous catalysis: A review

... Ambekar et al.'s PRCFD simulations indicated that local velocity and second-order quantities, such as strain rate and vorticity, predicted by both RANS (with various eddy-viscosity models) and LES, are in reasonable agreement with DNS predictions. Specifically, ε-based RANS models, which focus on turbulent dissipation per unit mass, show good agreement with DNS, while ω-based RANS models, which focus on turbulent dissipation per unit volume, significantly under-predict turbulence quantities by several orders of magnitude due to their inadequacy in handling strongly wall-dominated flows [67]. As for ε-based RANS models, the realizable k-ε RANS model with enhanced wall treatment provides higher accuracy compared to the standard k-ε model, as it improves the turbulent viscosity coefficient and turbulent stress predictions, and can adapt to a wider range of y + value, especially for resolving viscous sub-layer region. ...

Reference:

Particle-resolved computational fluid dynamics simulation of the heat transfer in fixed-bed reactors for heterogeneous catalysis: A review

... where ðÀP si I þ s si Þ is the formation of the fluctuation energy due to shear in the solid phase and H si is the energy dissipation rate due to collision between solid particles and estimated as follows: 38,39 ...

Reference:

Numerical investigation on solids settling in a non-Newtonian slurry inside a horizontal flume

... A tapered FB with an increase in the cross section from bottom to top is considered unlike the cylindrical FB in FIOR and FINMET processes. For a similar operating flow rate, due to less injection area in a tapered FB than in a cylindrical FB, the gas velocity is high in the tapered FB. 45,46 Due to this, in the tapered FB, iron ore with a wide size distribution can be homogenously fluidized with a lower elutriation rate than in the cylindrical FB. 47 Cyclones with a dip-leg are present in the FB, and the transport disengagement height is optimized to minimize elutriation and heat loss. 44 The hematite fine ore typically in the mean size range of 1− 2 mm (maximum size up to 8 mm) is pneumatically charged into the Stage-I FB (i.e., R4) reactor and conveyed to the next stages 48,49 (see Figure 8). ...

Reference:

Iron-Ore Reduction in Fluidized Beds: Review of Commercial Technologies, Status, and Challenges

... This value then decreases to 40 kg m −2 s −2 at L/D = 6.5. Jain et al. [51] conducted a study of a chimney distributor element as well as a bubbling cap distributor element. The distributor plates are the most important devices for achieving the most optimal distribution of the gas-liquid mixture over the catalytic bed. ...

Reference:

Computational Fluid Dynamics for Modeling of Hydrotreating Fixed-Bed Reactors: A Review