The present study provides and examines an experimental and CFD simulation to predict and accurately quantify the individual phase holdup. The experimental findings demonstrated that the increase of solid beads has a significant influence on the (U_mf), as comparatively small glass beads particles require a low (U_mf) value, which tends to increase as the diameter of the beads increases. Besides that, the expansion ratio is proportional to the velocity of the liquid. Even though, the relationship becomes inversely proportional to the diameter of the beads. The liquid holdup was found to increase with increasing liquid velocity, however, the solid holdup decreased. The Eulerian–Eulerian granular multiphase flow technique was used to predict the overall performance of the liquid–solid fluidized beds (LSFBs). There was a good agreement between the experimental results and the dynamic properties of liquid–solid flows obtained from the CFD simulation, which will facilitate future simulation studies of liquid–solid fluidized beds. This work has further improved the understanding and knowledge of CFD simulation of such a system at different parameters. Furthermore, understanding the hydrodynamics features within the two-phase fluidization bed, as well as knowing the specific features, is essential for good system design, enabling the systems to perform more effectively.

An experimental investigation was conducted to examine, for the first time, the influences of using different designs of tube arrangements on the local heat transfer coefficient (LHTC) in a bubble column (with a diameter of 0.13 m) equipped densely with a bundle of tubes. The effect of using two different designs of tube arrangements has been examined for a broad range of gas flow rates using a sophisticated heat transfer technique. The obtained results indicate that the LHTC increases significantly with increasing the gas velocity, regardless of the design and installation of the tubes in the column. Additionally, the shape of the LHTC’s profiles alters considerably by the presence of a bundle of tubes and their arrangements. Moreover, the results indicate that the square tube pitch arrangement provides uniform heat transfer profiles, which enhance the performance of the bubble column reactor by 30%. Furthermore, the heat transfer profiles were found to be varied with the axial height of the column. The new experimental results obtained in this investigation will provide experimental reference data for creating and validating a mathematical model for predicting LHTCs. In addition, this will facilitate this kind of reactor’s design, scale-up, and operation.

Gas–liquid-solid fluidized beds are broadly utilized in the petrochemical, pharmaceutical, refining, food, biotechnology, and environmental industries. Due to complex phenomena, such as the particle-particle, liquid-particle, particle-bubble interactions, complex hydrodynamics, and heat transfer of three-phase (gas-liquid-solid) fluidized beds, they are incompletely understood. The ability to accurately predict the essential characteristics of the fluidized-bed system, such as hydrodynamics, individual phase mixing, and heat transfer parameters, is necessary for its successful design and operation. This paper investigates the pressure drop, minimum fluidization velocity, phase holdup, heat-transfer coefficient of a fluidized bed reactor, heat transfer studies, CFD simulation, and the effect of these parameters on the extent of fluidization. Many variables (fluid flow rate, particle density and size, fluid inlet, and bed height) affect the fluidizing quality and performance of the fluidization process. The hydrodynamics parameters, mixing of phases, and the behavior of heat transfer with various modes of fluidization were investigated to predict hydrodynamics parameters. Several publications have demonstrated the utility of (CFD) in explaining the hydrodynamics, heat, and mass transfer of fluidized beds. Principles of measurement, details of the experimental configurations, and the applied techniques by various researchers are also presented. Feng's model was statistically validated using experimental data that was both time-averaged and time-dependent. Furthermore, this model successfully predicted the instantaneous flow structures, which should provide strategies for the best design, scale-up, and operation in fluidized bed columns. The divergence between the simulated and observed values can be reduced by better understanding the fluidized bed's nature.

Spouted bed reactors (SBRs) are highly valued for their effectiveness in chemical and biochemical processes due to their mixing and heat transfer capabilities. Understanding the heat transfer mechanisms in these reactors is necessary. This research delves into the heat transfer behavior of SBRs, which plays a role in enhancing their performance under operational conditions. The study conducted experiments to measure the heat transfer coefficient (HTC) at varying gas velocities (ranging from 0.32 to 0.74 m/s) at radial positions (r/R = 0, ±0.28, ±0.56, and ±0.85) and axial levels (H/D = 0.8, 2.1, and 3.5) within the spouted bed (SB) column using a technique, for the assessment of local heat transfer coefficients (LHTCs). The results we obtained revealed the velocity of the gas, its radial position in the reactor, and its axial height. For instance, higher gas speeds led to heat transfer efficiency and variations in radial positions highlighted how the reactor’s shape influences heat transfer dynamics. It’s worth noting that increasing the gas speed from the lowest to the level tested resulted in a 25% increase in heat transfer coefficients. These discoveries provide insights for improving the design and performance of SBRs with ranging applications in industries that rely on effective heat transfer processes.

To improve the design and scale-up processes of bubble column reactors (BCRs), it is necessary to characterize the hydrodynamics by means of flow regime behavior. This study examines the impact of industrial heat exchangers and superficial gas velocities on flow regimes, pressure drop, and gas holdup in BC and SBC. A simulated Fischer–Tropsch bubble column is constructed. The experimental study utilized a Perspex column with a diameter of 0.14 m. Moreover, 18 copper tubes with a 0.16 m diameter are fitted into the bubble column. The selection of tubes in SBC was carried out in accordance with TEMA recommendations to ensure optimal heat dissipation. These tubes were made to resemble the industrial Fischer–Tropsch reactor by covering 25% of the bubble column’s cross-sectional area. In order to enhance the measurement and comprehension of the hydrodynamics within the reactor, this study employs a method measured the total gas hold-up and detected pressure fluctuations using three differential pressure transducers (Keller type PA 21Y/4). The column was equipped with a perforated plate air distributor, and glass beads were used as the solid phase. The gas distributor is constructed of porous polyethylene with pore sizes of 0.5 mm and plate thicknesses of 3 mm. To comprehend and assess the impact of tube configuration on the pressure drop; gas holdup; and regime transition velocities, the experimental data were recorded across a broad range of superficial gas velocities (i.e., 0.036–0.27 m/s). The findings suggest that higher superficial gas velocities result in amplified pressure fluctuations, with a recorded increase of 0.108 to 0.15 bar in pressure drop at a gas velocity of 0.27 m/s in the air-water system. Equipping the bubble/slurry bubble column with an industrial heat exchanger to the bubble/slurry bubble column resulted in a modest increase in pressure drop of around 0.042 bar, which disrupted the uniform flow and delayed regime transitions. Furthermore, the inclusion of solids leads to a 10% decrease in gas holdup, while the heat exchanger only slightly improves it by 5%. Drift flux analysis is a helpful tool for determining transition points. In the case of U-shaped heat exchanger tubes, the transition velocities can be altered by 1.7 m/s in BC. The results of this investigation will offer an exhaustive understanding of fluid dynamics as well as guidance in the design of reactors for extremely exothermic processes.

This study examines the impact of equipping a real heat exchanger in a slurry bubble column SBC on instantaneous and local heat transfer coefficients IHTC and LHTC, as well as the overall heat transfer coefficient U, employing advanced heat transfer techniques. The experiments were conducted in a 0.15 m inner diameter Plexiglas SBC with varying gas flowrates Ug (0.14–0.35) m/s at several radial sites along the column’s diameter (±0.18, ±0.46, and ± 0.74) and three axial locations (H/D = 2, 3 and 4). To simulate the industrial Fischer–Tropsch bubble column reactor FT-BCR, a real heat exchanger consisting of 18 copper tubes, each with a diameter of 0.16 m, were vertically installed, occupying 25% of the column cross-sectional. Glass beads with an average size of 150 μm were used loading up to 40% volume to represent the solid phase. The results demonstrated that both, LIHTC and U, showed significant decreases with increasing gas flow rates at all radial and axial positions. Moreover, the LIHTC near the wall notably decreased compared to the central zone by about 82% at the radial location and about 74% at the axial location. The obtained results and data contribute to understanding the impact of vertical tubes on heat transfer in a slurry bubble column reactor SBCR. Furthermore, the data obtained can validate reactor models, computational fluid dynamics CFD programs, and simulations, thereby improving the design and scale-up of these reactors.