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The purpose of this paper is to develop a new vibration probe sensor for measurement of particle mass flow rate in gas–solid two phase flow.

A new vibration probe sensor based on polyvinylidene fluoride (PVDF) piezoelectric film is designed. The particle impact model according to Hertz contacting theory is presented. The average amplitude, standard deviation and spectral peak at the natural frequency of the probe (21.2 kHz) of the signals acquired through experiments are chosen as characteristic quantities for further analysis.

Through experimental study of relation between three characteristic quantities and the mass flow rate and air flow velocity, a good regularity is found in the average amplitude and the spectral peaks at natural frequency of the probe. According to the particle impact model, the structure of quantitative model is built and parameters of two models are calculated from experimental data. Additionally, tests are made to estimate mass flow rate. The average errors are 5.85 and 4.26 per cent, while the maximum errors are 10.81 and 8.65 per cent. The spectral peak at natural frequency of the probe is more applicable for mass flow rate measurement.

The sensor designed and the quantitative models established may be used in dilute phase pneumatic conveying lines of coal-fired power plants, cement manufacturing facilities and so on.

First, the new sensor is designed and the quantitative models are established. Second, the spectral peak at natural frequency of the probe is found that can be used for measurement of mass flow rate.

The purpose of this paper is to perform the computational fluid dynamics (CFD) simulation with experimental validation to investigate the particle segregation effect in abrupt and smooth shapes circulating fluidized bed (CFB) risers.

The experimental investigations were carried out in lab-scale CFB systems and the CFD simulations were performed by using commercial software BARRACUDA. Special attention was paid to investigate the gas-particle flow behavior at the top of the riser with three different superficial velocities, namely, 4, 6 and 7.7 m/s. Here, a CFD-based noble simulation approach called multi-phase particle in cell (MP-PIC) was used to investigate the effect of traditional drag models (Wen-Yu, Ergun, Wen-Yu-Ergun and Richardson-Davidson-Harrison) on particle flow characteristics in CFB riser.

Findings from the experimentations revealed that the increase in gas velocity leads to decrease the mixing index inside the riser. Moreover, the solid holdup found more in abrupt riser than smooth riser at the constant gas velocity. Despite the more experimental investigations, the findings with CFD simulations revealed that the MP-PIC approach, which was combined with different drag models could be more effective for the practical (industrial) design of CFB riser. Well agreement was found between the simulation and experimental outputs. The simulation work was compared with experimental data, which shows the good agreement (<4%).

The experimental and simulation study performed in this research study constitutes an easy-to-use with different drag coefficient. The proposed MP-PIC model is more effective for large particles fluidized bed, which can be helpful for further research on industrial gas-particle fluidized bed reactors. This study is expected to give throughout the analysis of CFB hydrodynamics with further exploration of overall fluidization.

A modelling approach of gas solid flow, considering different physical phenomenon such as fluid turbulence, particle turbulence and interparticle collision effects are presented. The approach is based on the two‐fluid model formulation where both phases are treated as continuum. This implies that the gas phase as well as the particle phase are weighted by their separate volumetric fractions. According to the experimental results and numerical simulations, the inter‐particle collision possesses a significant influence of turbulence level on particle transport properties in gas solid turbulent flow even for dispersed phase volume fraction (α<0.01). Comparisons in predictions have been depicted with inclusion of interparticle collision effect in the equation of particle turbulent kinetic energy and with exclusion of this effect. Experimental research has been conducted in a thermal power plant depicting higher erosion resistance of noncircular square sectioned coal pipe bends in comparison with those with circular cross section, the salient features of the experimental work are presented in this paper. Experiments have been conducted to determine, pressure drop in straight and curved portions of conduits conveying air coal mixtures in a thermal power plant. Validation of this experimental data with numerical predictions have been presented.

The purpose of this paper is to calculate the two‐dimensional (2D) centre position of objects with known shapes based on the reconstruction image of a square sensing area estimated with simulated and measured data by using electrical capacitance tomography (ECT).

A 2D electrostatic finite element model is used to calculate the capacitances between electrode pairs. A reconstruction algorithm with low computation time provides suitable images for subsequent image processing techniques. The results based on numerical data are verified by measurements.

It is possible to calculate the centre position of up to four rods (cross‐sectional area about 5 per cent of the measuring area) with an accuracy of 3 per cent in both coordinate directions related to the dimensions of the measuring area.

The paper presents an efficient method for position determination of several objects with known shape and uniform permittivity distribution by using ECT measurements with low‐cost electronic for industrial application.

Dynamic separator is an equipment having a rotor and static vanes and is used to separate solids from gas-solids flow based on size. Particle separation in a dynamic separator happens due to complex interchanges between multiple forces exerted in the separation zone. Currently, there is only limited knowledge concerning the working principles of separation. This paper aims to systematically study a dynamic separator using numerical models to get insights into particle separation.

The Lagrangian–Eulerian formulation is used to simulate gas-solid flow. Multiple frames of reference using stage interpolation are used to account for rotation. Periodic symmetry in the equipment is exploited to create a simplified numerical model. The predictions from the numerical model are compared against available experimental data.

The numerical results indicate that only when particle collision is included, the separation efficiency trend from the experiment is matched by numerical predictions. Further, it is shown that at the same range of rotor speeds where numerical results predict increased separation efficiency, the solid pressure due to particle collision also reaches its maximum value. The gas flow and particle behavior in the separator are explained in detail.

The importance of particle collision in separation is interesting because traditionally, particle separation is assumed to be influenced by three forces, namely, centrifugal force, drag force and gravity. The numerical results, however, point to the contribution by particle collision, in addition to the above three forces.

To present dynamical analysis of axisymmetric and three‐dimensional (3D) simulations of a nuclear fluidized bed reactor. Also to determine the root cause of reactor power fluctuations.

We have used a coupled neutron radiation (in full phase space) and high resolution multiphase gas‐solid Eulerian‐Eulerian model.

The reactor can take over 5 min after start up to establish a quasi‐steady‐state and the mechanism for the long term oscillations of power have been established as a heat loss/generation mechanism. There is a clear need to parameterize the temperature of the reactor and, therefore, its power output for a given fissile mass or reactivity. The fission‐power fluctuates by an order of magnitude with a frequency of 0.5‐2 Hz. However, the thermal power output from gases is fairly steady.

The applications demonstrate that a simple surrogate of a complex model of a nuclear fluidised bed can have a predictive ability and has similar statistics to the more complex model.

This work can be used to analyze chaotic systems and also how the power is sensitive to fluctuations in key regions of the reactor.

The work presents the first 3D model of a nuclear fluidised bed reactor and demonstrates the value of numerical methods for modelling new and existing nuclear reactors.

The average residence time of liquid flowing over the surface of a rotating cone was determined numerically. The development and propagation of the free surface flow was simulated using the volume of fluid (VOF) method. The numerical simulations were validated using laboratory experiments using soy‐oil as a model liquid, and approximate analytical solutions of the simplified governing equations. The numerical simulations revealed the importance of the cone rotation frequencies and the minor influence of the cone angles on the residence times. Higher liquid throughputs produced smaller residence times. As expected, an increasing cone size results in proportionally higher residence times. Furthermore, it was established that even for small cones with a characteristic diameter of, e.g. less than 1m, relatively high (∼1 kg/s) throughputs of liquid are possible. It appears that the combination of the decreasing layer thickness and the increasing size of the numerical grid cells with increasing radial cone coordinate hampers the numerical simulation of this system.

The objective of this study is to investigate several issues related to particle circulation within the TFB, including exploring an appropriate method to quantify particle circulation time, the effects of different operational parameters on particle circulation time, and the relationship between particle mixing and particle circulation.

The computational fluid dynamics coupled with the discrete element method (CFD-DEM) is applied to investigate the particle circulation characteristics of a tapered fluidized bed (TFB). An approach for defining particle circulation, which accounts for the horizontal motion of each particle, is proposed to estimate particle circulation time.

It is found that the overall particle circulation in a TFB could be accelerated by increasing air velocity and wall inclination angle, while an increase in particle size and an increase in inter-particle cohesive forces decelerate particle circulation; the increase in the open area ratio of the central region of the air distributor would decelerate the particle circulation. Moreover, the particle circulation time and mixing rate are independent variables that describe the flow dynamics of particles from different perspectives.

A large part of fluidized beds in industrial applications can be classified as TFB. This study presents a numerical method to obtain detailed knowledge about particle circulation in a TFB, which is essential for the design, optimization, and control of related processes.

The particle circulation in a TFB is important but rarely investigated, and it is hard to be quantified using existing experimental approaches. The proposed numerical workflow reveals the characteristics of particle circulation from a particle-scale perspective.

Rectangular fluidised beds are commonly used in industry, e.g. circulating fluidised bed (CFB) boilers. Apparently, no one has tried to imagine rectangular fluidised beds by electrical capacitance tomography (ECT). The purpose of this paper is to design a rectangular ECT sensor to understand the behaviour of a rectangular CFB riser.

A rectangular sensor with eight electrodes is adopted to obtain the capacitance data. The sensitivity map is simulated to calculate the grey level of pixels for visualisation using the linear back‐projection algorithm.

Experiments showed that the position of the objects in the riser can be obviously indicated and the central region of the object(s) has significantly higher grey level than other regions in the images using the rectangular ECT sensor.

It has a limitation in providing a higher resolution image.

The results obtained by the rectangular ECT sensor show that it is promising to study the characteristics of flow non‐uniformity in the fast fluidisation regime of CFB.

Without using square and circular ECT sensors, this is the first time a rectangular ECT sensor has been developed to study the unique problems of the characteristics of flow non‐uniformity in a rectangular CFB riser.

A consistent implementation of the general computational framework of unified second-order time accurate integrators via the well-known GSSSS framework in conjunction with the traditional Finite Difference Method is presented to improve the numerical simulations of reactive two-phase flows.

In the present paper, the phase interaction evaluation in the present implementation of the reactive two-phase flows has been derived and implemented to preserve the consistency of the correct time level evaluation during the time integration process for solving the two phase flow dynamics with reactions.

Numerical examples, including the classical Sod shock tube problem and a reactive two-phase flow problem, are exploited to validate the proposed time integration framework and families of algorithms consistently to second order in time accuracy; this is in contrast to the traditional practices which only seem to obtain first-order time accuracy because of the inconsistent time level implementation with respect to the interaction of two phases. The comparisons with the traditional implementation and the advantages of the proposed implementation are given in terms of the improved numerical accuracy in time. The proposed approaches provide a correct numerical simulation implementation to the reactive two-phase flows and can obtain better numerical stability and computational features.

The new algorithmic framework and the consistent time level evaluation extended with the GS4 family encompasses a multitude of past and new schemes and offers a general purpose and unified implementation for fluid dynamics.