Multiscale analysis and modeling of multiphase chemical reactors

Experimental and numerical simulation of lignite chemical looping gasification with phosphogypsum as oxygen carrier in a fluidized bed

This twelfth volume of Annual Review of Heat Transfer marks the beginning of an expanded editorial team that is committed to maintaining the fine tradition of this series by providing improved and timely communications on new and important developments in the field of heat transfer. The theory and practice of heat transfer have been significantly broadened in recent years, particularly in biomedical engineering and biotechnology, micro- and nano-technologies, energy-efficient processes and systems, and in materials technologies such as laser and plasma processing. While continuing to feature advancements in the fundamentals of heat transfer, the editors will give special attention to presenting state-of-the-art reviews on topics of interest in such rapidly evolving areas of technology. The present volume starts with a review of the advances and challenges in micro and miniaturized heat pipes, which are being used for heat dissipation in many modern communication and computing systems. The second article deals with heat transfer in low energy plasmas used for microelectronic manufacturing, while the third article reviews heat transfer and phase-change during high-power, pulsed laser ablation of metals, as in thin film deposition, micro-machining and the synthesis of nanomaterials. Processing of thermoplastic, matrix composite materials, which involves complex, multi-scale heat and mass transfer, is considered in the fourth article, the next two articles deal with heat transfer in crystal growth, a precursor for electronic and opto-electronic device fabrication. The first of these articles treats convective instabilities under various growth conditions, while the second article considers the effects of an applied magnetic field on growth phenomena, associated hydrodynamics and the control of flow instability. The last article of this volume reviews the fundamentals of interferometric tomography and application of the technique to three-dimensional temperature measurement. The editors would like to thank the participating authors for their valuable contributions, to Begell House for editorial assistance, to Nancy Hughes of UC Berkeley and Alina Stroia of SUNY Stony Brook for their secretarial help, and to the thermal science and processing community for their continued support and input.

Chapter 3 - Rate laws

Reduction kinetics of cobalt oxide powder by methane in a fluidized bed reactor

Fluidized bed reactors (FBR) are widely used in chemical engineering, as well as for raw materials processing because of the excellent heat and mass transfer in a fluidized bed. A new FBR was developed for plasma assisted synthesis and coating of granular solid materials by integration of the FBR simultaneously into two different microwave cavities: a microwave plasma cavity and a chemical vapor deposition (CVD) cavity, where microwave radiation is used to heat the granular material. With such a FBR, a systematic study of plasma activation of the granular material on the chemical reaction taking place at the surface of the granular material is possible. The interaction of the fluidized particles with the microwave field influences the ignition, as well as the stability of the microwave plasma significantly. As compared to a single stage CVD-FBR or a single stage plasma enhanced (PE-FBR) coating performance and process control is significantly improved by the newly developed dual-zone circulating PE-CVD-FBR.

The gas phase pyridine synthesis process is usually carried out in a fluidized bed reactor. The contact efficiency between the reactants and the catalysts has great influence on the reactor performance. In this paper, three fluidized bed reactors with different flow patterns were used to investigate the contact efficiency. The superficial contact efficiency index (SCEI) was defined and used in this paper to quantify the contact efficiency inside these reactors. To obtain the values of the SCEI, the ideal reactor model was constructed. The results showed that the SCEI average value decreased as the flow pattern shifted from fast fluidization to bubbling fluidization; these values were 0.86, 0.55, and 0.19 for the fast fluidized bed reactor, turbulent fluidized bed reactor, and bubbling fluidized bed reactor, respectively. An empirical correlation was proposed in this paper to predict the SCEI under different operating conditions. The model prediction results agreed well with experimental results with an average prediction error of 8%.

Multi-fluid modeling biomass fast pryolysis with particle shrinkage model for complex reaction kinetics

Advancements of the Fluidized Bed Fenton (FBF) Technology for wastewater treatment: Mechanism, mass and heat transfer

Electro-fermentation offers a promising strategy to upgrade organic molecules from food waste into sustainable fuels that can help decarbonize the global transportation sector. Despite its potential for decarbonization, the electro-fermentation of food waste into transportation fuel precursors such as medium chain carboxylates (MCCs) is underexplored and requires improvements in rates and selectivity.This study aims to boost the rates and selectivity of food waste electro-fermentation into MCCs using a fluidized bed reactor containing powdered activated carbon (PAC) coupled with rumen microbes enriched for microbial chain elongation. Two electrochemical H-cell reactors—R1 (control) and R2 (with PAC)—were tested under varying cathodic and anodic potential using synthetic food waste (10 g COD/L) as the substrate. R2 significantly outperformed R1, particularly at -0.8 V vs Ag/AgCl, achieving a caproic acid concentration of 6.14 ± 0.69 g COD/L—more than double that of R1 (2.54±0.57 g COD/L). Enhanced electrochemical activity and reaction kinetics in R2 were attributed to PAC’s role in expanding biofilm surface area and facilitating electron transfer. Genomic microbial community analysis revealed distinct spatial distributions across the system, especially on electrodes and PAC particles. Advanced characterization of the extra-cellular polymeric substrates (EPS) showed significant increases in EPS production and the formation of redox-active compounds in the presence of PAC.Overall, these findings highlight the ability of fluidized bed reactors with chain-elongating organisms to improve the rates and selectivity of MCC production from food waste during electro-fermentation. This technology offers a promising pathway for organic waste valorization into sustainable transportation fuels, supporting a circular carbon economy. Efforts towards testing new reactor operation modes, expanding the portfolio of products, and implementing new types of waste biomass streams are ongoing.

Mathematical Model and Advanced Control for Gas-phase Olefin Polymerization in Fluidized-bed Catalytic Reactors

Modeling of chemical reactors — XXII Effect of simultaneous heat and mass transfer inside and outside of a pellet on reaction rate — II

The purpose of this paper is to examine absorbance for the removal of the Red Congo using wheat husk as a biological pesticide. Several experiments have been conducted with the aim of configuring breakthrough data in a fluidized bed reactor. The minimum fluidized velocities of the bed were found to be 0.031 mm/s for mish sizes of (250) µm diameter with study the mass transfer be calculated KL values. The results showed a well-fitting with the experimental data. Different operating conditions were selected: bed height (2, 5 and 10) cm, flow rate (90, 100and 120) ml/sec and particle diameter (250, 600, 1000) µm. The breakthrough curves were plotted for Congo Red, Values showed that the lower the bed, the lower the number of adsorbents and the potential of the weak bed to condense the density of the solution, which also increases the flow rate and will increase the mass transfer rate.

Modeling of autothermal reforming of methane in a fluidized bed reactor with perovskite membranes

Model of transport and chemical kinetics in a solar thermochemical reactor to split carbon dioxide

Dechlorination of polychlorinated phenols on bimetallic Pd/Fe catalyst in a magnetically stabilized fluidized bed