Key Operating Parameters Research Articles

Numerical Study of Dry Reforming of Methane in Packed and Fluidized Beds: Effects of Key Operating Parameters

Replacing the conventionally used steam reforming of methane (SRM) with a process that has a smaller carbon footprint, such as dry reforming of methane (DRM), has been found to greatly improve the industry’s utilization of greenhouse gases (GHGs). In this study, we numerically modeled a DRM process in lab-scale packed and fluidized beds using the Eulerian–Lagrangian approach. The simulation results agree well with the available experimental data. Based on these validated models, we investigated the effects of temperature, inlet composition, and contact spatial time on DRM in packed beds. The impacts of the side effects on the DRM process were also examined, particularly the role the methane decomposition reaction plays in coke formation at high temperatures. It was found that the coking amount reached thermodynamic equilibrium after 900 K. Additionally, the conversion rate in the fluidized bed was found to be slightly greater than that in the packed bed under the initial fluidization regime, and less coking was observed in the fluidized bed. The simulation results show that the adopted CFD approach was reliable for modeling complex flow and reaction phenomena at different scales and regimes.

Optical Logic Gates Based on Z-Shaped Silicon Waveguides at 1.55 μm.

In the last ten years, silicon photonics has made considerable strides in terms of device functionality, performance, and circuit integration for a variety of practical uses, including communication, sensing, and information processing. In this work, we theoretically demonstrate a complete family of all-optical logic gates (AOLGs), including XOR, AND, OR, NOT, NOR, NAND, and XNOR, through finite-difference-time-domain simulations using compact silicon-on-silica optical waveguides that operate at 1.55 μm. Three slots, grouped in the shape of the letter Z, make up the suggested waveguide. The function of the target logic gates is based on constructive and destructive interferences that result from the phase difference experienced by the launched input optical beams. These gates are evaluated against the contrast ratio (CR) by investigating the impact of key operating parameters on this metric. The obtained results indicate that the proposed waveguide can realize AOLGs at a higher speed of 120 Gb/s with better CRs compared to other reported designs. This suggests that AOLGs could be realized in an affordable manner and with improved outcomes to enable the satisfaction of the current and future requirements of lightwave circuits and systems that critically rely on AOLGs as core building elements.

Human Factors in the Development of the Hydraulic System of the Powered Roof Support

The growing demand for mineral resources, including hard coal, requires the continuous improvement and development of technologies to improve safety, productivity and performance. The implementation of automation and digitization in mines has been ongoing for several years. Machinery and equipment development and improvement is also ongoing. The authors discuss the development and improvement of powered roof support, which is a critical part of the longwall system. The powered roof support is responsible for the safety of equipment and people working in the longwall. It supports the face and immediate roof and moves the longwall system forward as the shearer removes the coal and the roof collapsing (goafing) behind the shields. The aim of this study was to examine the human factors involved in the development and improvement of the hydraulic support system of powered roof support. The research was carried out among employees in hard coal mines using mainly surveys. The research allowed the authors to examine and analyze the information provided by the miners concerning powered roof support in the era of Industry 4.0 (the Fourth Industrial Revolution). According to the research findings, miners expect improvement in the reliability of the powered roof support, and they want the key operating parameters, especially the required load capacity, to be monitored in real-time so adjustments and improvements can be made. The results of the research point out the needs and expectations of miners. Their opinions should determine the direction and any research gaps into powered roof support.

A Novel, Low-Cost, Position-Sensitive Neutron Detector to Support Thick-Target Inverse Kinematics Experiments for Nuclear Data Measurements

High quality nuclear data lie at the heart of accurately modelling stellar systems and terrestrial nuclear reactors. However, some key reaction cross sections have large uncertainties, which limit such models in predicting isotopic abundances and other aspects of stellar evolution, along with key operational parameters for nuclear reactors. Reactions involving neutrons are particularly difficult to measure experimentally in laboratories, not least due to the unique challenges involved when detecting neutrons. We present a new approach to measuring nuclear reactions involving neutrons by exploiting the Thick-Target Inverse Kinematics (TTIK) approach. For such measurements, a new detector called ATTIKUS (A Thick-Target Inverse Kinematics detector by Universities in Sheffield) is under construction. Here we present designs and Geant4 Monte-Carlo simulations of the detector. The simulations indicate that a neutron position reconstruction resolution of 10 cm is obtainable and demonstrate how this device could be applied to the 13C(α,n) reaction, which is considered to be the main neutron source for the s-process in low-mass Asymptotic Giant Branch stars. In the TTIK method, the emission position of the neutron (the nuclear interaction position in a gaseous target) is directly linked to the centre-of-mass energy of the reaction. Therefore, a position resolution will translate into an energy resolution, depending on the beam-target combination. The inverse reaction, 16O(n,α), causes a large uncertainty in calculating the effective neutron multiplication factor, Keff in nuclear reactors, so improvements are required here.

A Rock Mass Strength Prediction Method Integrating Wave Velocity and Operational Parameters Based on the Bayesian Optimization Catboost Algorithm

Tunnel Boring Machines (TBMs) have been the main equipment for tunneling and underground construction due to their high safety performance and tunneling efficiency. However, the unknown and changing geological conditions during construction pose a challenge to TBM construction. As one of the essential parameters of rock properties, accurate acquisition of uniaxial compressive strength (UCS) is crucial for TBMs to adapt to changing ground conditions in a timely manner. Therefore, this study proposes a Catboost intelligent model based on Bayesian Optimization to predict UCS. Rock mass are velocity information and key TBM operational parameters are used as model input variables. The Gaussian data augmentation method is used to compensate for the difficulty of obtaining field data in large quantities. The Zhujiang Delta Water Resources Allocation Engineering field data are used in the model, and the obtained evaluation indicators MAPE, RMSE, VAF and a20-index are obtained as 9.91%, 499.38 MPa, 90.7% and 0.95, respectively. In addition, another project is selected to verify the applicability of the model. The validation results also confirm that the model is valid and reliable when applied to practical engineering.

Recent advances in biological hydrogen production from algal biomass: A comprehensive review

Clean fuels play a crucial role in the industrialized world's efforts to combat greenhouse gas emissions. Among the cleanest fuels available, hydrogen stands out as it produces water as a byproduct during combustion. To ensure the sustainable generation of clean fuels, it is imperative to produce hydrogen from environmentally friendly and renewable sources. Biological processes present a promising avenue for the production of hydrogen from affordable and sustainable bio-resources, including biomass and solar energy, using diverse techniques such as direct/indirect photolysis, photo-fermentation, dark-fermentation, and Microbial electrolysis cell. This comprehensive study delves into various aspects of biological hydrogen production, encompassing discussions on microorganisms, different types of substrates and their concentrations, the role of chemical additives, and key operational parameters like temperature, pH, agitation, and insights into hydrogenase and nitrogenase properties. For light-dependent processes, the study also explores the influence of illumination systems. Furthermore, the research examines different configurations of biological processes, integrating light, dark, and photo-fermentation in two- and three-component systems. By investigating these critical factors, the study aims to shed light on optimizing biological hydrogen production. The findings offer valuable insights for advancing the sustainable and efficient utilization of clean fuels in the global effort to mitigate greenhouse gas emissions.

An investigation into the thermo-fluid behavior of volumetrically heated cavities irradiated from the side

Radiation induced natural convection has been extensively researched due to its rife presence in numerous natural flows. Recently, it has seen renewed and resurged interests in context of understanding the photo-thermal energy conversion and its redistribution in direct absorption solar collectors (DASCs). The present work serves to further this objective; in particular, convection induced by direct interaction of the fluid and radiation (irradiated from side) has been critically and comprehensively investigated. In addition to DASCs, the present study has significant applications in various other fields such as nuclear power plants, building design, and laser fusion. A detailed mechanistic theoretical modeling framework has been developed to quantify the impact of various fluid properties and incident flux parameters; viz., Rayleigh number (102 to 108 in the laminar regime), Prandtl number (0.01–1000), optical thickness (0.1–100), convective heat loss from the transmitting wall (controlled in the simulation by varying the modified Biot number, Bi* from 0 to 5), aspect ratio (0.1–10). Furthermore, in addition to magnitude of the incident flux, its distribution (i.e., whether uniform or linearly varying) has also been dealt with. Another distinguishing aspect of the study is the use of the “heatlines” to visualize the flow of energy as it occurs during convection caused due to volumetric heating. Detailed analysis reveals that, while a conduction dominated regime is apparent at Ra ≤ 102, a transition regime occurs at 103 ≤ Ra ≤ 104, and convection is the domineering mechanism when Ra > 104. At higher Rayleigh numbers, the pattern of heatlines begins to resemble that of the streamlines. Nature of the flux distribution at the side wall (along the depth direction) significantly impacts the temperature distribution. Furthermore, there exits an optimum value of optical thickness (for a given Rayleigh number), which ensures minimum heat loss and maximum useful energy gain. Overall, through the present work, we have been able to decipher key design and operational parameters (and quantify their impacts) which dictate the momentum and heat transport in side-irradiated volumetrically heated cavities.

Copper recovery from printed circuit boards leaching solution with bioelectricity generation using microbial fuel cell

Recovery of valuable metals via leaching printed circuit boards (PCBs) has gained moment recently. This work studied the Microbial fuel cell (MFC) performances for recovery of Cu from a Cu2+ solution by examining key operating parameters. A dual-chamber MFC with 6cm × 6cm × 7cm dimensions was constructed. Both anode and cathode electrodes were made of a carbon cloth sheet. The anodic and cathodic chambers were separated by a Nafion membrane. The highest Cu recovery efficiency was 99.7% after 240h batch mode operation, yielding 102 mW/m2 MFC power density output using 1g/L Cu2+ solution as the catholyte (initial pH 3) and an anolyte containing 1g/L sodium acetate inoculated with a sludge from a wastewater treatment plant's anaerobic pond, with 2cm distance between the electrodes made of polyacrylonitrile polymer. The highest open circuit voltage, current density (based on cross-section cathode area) and power density with an external load of 1 kΩ was 555mV, 347mA/m2 and 193 mW/m2, respectively. Additionally, recovery of Cu in the leachate of PCBs using sulfuric acid leaching after 48h was performed and the highest Cu recovery was 50% in 48h.

Molybdenum Carbide/Ni Nanoparticles Embedded into Carbon Nanofibers as an Effective Non-Precious Catalyst for Green Hydrogen Production from Methanol Electrooxidation.

Molybdenum carbide co-catalyst and carbon nanofiber matrix are suggested to improve the nickel activity toward methanol electrooxidation process. The proposed electrocatalyst has been synthesized by calcination electrospun nanofiber mats composed of molybdenum chloride, nickel acetate, and poly (vinyl alcohol) under vacuum at elevated temperatures. The fabricated catalyst has been characterized using XRD, SEM, and TEM analysis. The electrochemical measurements demonstrated that the fabricated composite acquired specific activity for methanol electrooxidation when molybdenum content and calcination temperature were tuned. In terms of the current density, the highest performance is attributed to the nanofibers obtained from electrospun solution having 5% molybdenum precursor compared to nickel acetate as a current density of 107 mA/cm2 was generated. The process operating parameters have been optimized and expressed mathematically using the Taguchi robust design method. Experimental design has been employed in investigating the key operating parameters of methanol electrooxidation reaction to obtain the highest oxidation current density peak. The main effective operating parameters of the methanol oxidation reaction are Mo content in the electrocatalyst, methanol concentration, and reaction temperature. Employing Taguchi's robust design helped to capture the optimum conditions yielding the maximum current density. The calculations revealed that the optimum parameters are as follows: Mo content, 5 wt.%; methanol concentration, 2.65 M; and reaction temperature, 50 °C. A mathematical model has been statistically derived to describe the experimental data adequately with an R2 value of 0. 979. The optimization process indicated that the maximum current density can be identified statistically at 5% Mo, 2.0 M methanol concentration, and 45 °C operating temperature.

Guiding the optimization of membraneless microfluidic fuel cells via explainable artificial intelligence: Comparative analyses of multiple machine learning models and investigation of key operating parameters

Membraneless microfluidic fuel cells (MMFCs) offer great potential for clean energy production, but their expense and tedious optimization process have limited their wider use. Machine learning (ML) algorithms have shown promise in improving the optimization of MMFCs, but the “black box” nature of these models has caused uncertainty and limited their adoption. To address this, we conducted the first study that implements the explainable artificial intelligence (XAI) approach to gain in-depth insights into multiple ML optimization models' predictions and the impacts of operating parameters on MMFCs' performance. Among 27 investigated models that are generated based on nine ML and three bio-inspired evolutionary algorithms, the combination of a decision tree and the particle swarm optimization algorithm is the most effective model that satisfied all criteria of high time efficiency (execution time = 3.194 s), accuracy (squared correlation coefficient = 0.999), and optimum power density identification (0.278 mWcm−2). The ML-optimized power density is 239.024% increased, which is 3.4 times higher than the average power density obtained without optimization. We further utilized the XAI model to comprehensively examine the impacts of operating parameters, providing valuable decision aids for the researchers, technicians, and engineers in manufacturing optimal power MMFCs at a significantly lower cost and faster rate.

Configurations and Operation Methods of Diesel-Based Solid Oxide Fuel Cell System

Solid oxide fuel cell (SOFC) can use a wide variety of carbon-based fuels. Diesel can act as a high-quantity fuel because of its high heat value and ease of transport. In this study, three different system configurations were proposed by a model in ASPEN PLUS V12 and fitted by data measured in the large size cell. The effects of key operation parameters, including reforming temperature, steam-to-carbon ratio (S/C) and recycling rate of the anode off-gas, were studied, which were characterized by the system efficiency and output power. As a result, the highest system efficiency was gotten with a water condenser and an anode off-gas recycling module in the system. The best operation method occurs when the thermal load of the diesel reformer is compensated by the heat released by anode off-gas combustion. This research will lay a theoretical foundation for the upcoming design of a physical diesel-based SOFC system.

Application of Lightweight Deflectometer to Assess Structural Competency of Nontraditional Airfield Pavements During Contingency Aircraft Operations

This paper discusses the use of the heavy and light weight deflectometer devices, hereafter referred to as HWD and LWD, respectively, to monitor the structural condition of airfield pavements during aircraft operations at contingency environments. Four airfield pavements like those encountered at contingency environments, referred to as nontraditional airfield pavements, were selected to conduct accelerated pavement traffic testing with simulated C-17 and C-130 aircraft. Pavement rut development was monitored, and both HWD and LWD tests were also conducted at selected traffic intervals. Both HWD and LWD were capable of tracking the pavement deterioration under accelerated traffic testing, which indicates that the LWD could be considered a potential rapid and practical pavement evaluation tool for nontraditional pavements during contingency aircraft operations. Based on current rutting failure threshold, a termination criterion in relation to a reduction in the stiffness parameter from the LWD test could be preliminarily used to aid in expediently determining acceptable aircraft operations on nontraditional airfield pavements. The influence of key operational parameters such as base plate dimension, the depth of influence from the impact force, and pavement rut formation must be further investigated to improve the effectiveness and applicability of the LWD test for nontraditional airfield pavements. The results from this study could be of interest to other low-volume road applications such as in agriculture, oilfield, large construction sites, and mining where pavement evaluation and management practices could be improved with the use of practical tools such as the LWD during the operations of heavy equipment or machinery.

All-optical logic gates using E-shaped silicon waveguides at 1.55 μm

Owing to the advanced fabrication technology of silicon, silicon waveguides are particularly attractive for implementing all-optical signal processing devices and switches. Therefore, in this paper, a silicon-on-silica waveguide that consists of four slots arranged in the shape of letter E is proposed to be employed as the building block for simulating fundamental all-optical logic gates (AOLGs), including XOR, AND, OR, NOT, NOR, NAND, and XNOR, at 1.55 μm telecommunications wavelength. The operation concept of these logic gates relies on the constructive and destructive interference that results from the phase difference induced by optical beams that are incident on the E-shaped waveguide. The performance of the target logic gates is assessed against the contrast ratio (CR) metric. Moreover, the dependence of the spectral transmission on the device's key operating parameters is investigated and assessed. Compared to other reported designs, the results obtained by conducting simulations using the finite-difference-time-domain in lumerical commercial software show that the proposed waveguide can operate at a higher speed of 80 Gb/s and attain higher CRs of 36, 39, 35.5, 28.8, 30, 38, and 36.7 dB for logic XOR, AND, OR, NOT, NOR, NAND, and XNOR, respectively. This suggests that by using the proposed scheme, AOLGs could be realized more feasibly with greater performance and faster operation toward satisfying the present and future needs of light wave circuits and systems.

Capacitance Variations and Gate Voltage Hysteresis Effects on the Turn-ON Switching Transients Modeling of High-Voltage SiC MOSFETs

This paper presents a discrete and real-time capable dynamic behavioural model of the turn-on switching transition of high-voltage and high-current Silicon Carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) half-bridge power modules. The dynamic switching model utilizes the Shichman and Hodges equations using voltage-dependent non-linear device capacitances and module electrical parameters to obtain an accurate dynamic model of the device switching transients. The key device states gate-source voltage, drain current and drain-source voltage are modelled. The paper investigates the impact of correct device capacitance modelling with low off-state gate-source voltage values, impacting the device capacitances and causes gate-voltage hysteresis effects. It has been shown that the presented discrete-time dynamic switching model accurately describes the turn-on transient and the results highlight the importance of correct capacitance and threshold voltage characterization data. The modelling results are compared to experimental measurements conducted in a 3.3 kV/750 A SiC MOSFET power module. The model exhibits an average accuracy of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim 4\%$</tex-math></inline-formula> for turn-on energy and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim 1.3\%$</tex-math></inline-formula> for the turn-on time compared to measurements. These models are valuable for rapid and cost effective design and validation of advanced gate-driver circuits and for determining key design and operating parameters such as deadtime, switching frequency and switching losses.

Investigation of Process Parameters of a Novel Magnetorheological Finishing Process for External Cylindrical Surfaces

The recent rise in the demand for high precision, close tolerances, and super surface finish quality of components and part assembly modules in the competitive manufacturing industrial environment for the enhanced working life and functional requirements of machines globally. Three revolving curved tip tools based magnetorheological process is designed and developed to fine finish the external cylindrical surfaces of soft and hard materials. The effect of the key operational machining parameters on the surface roughness of a newly developed magnetorheological process was carried out using a one factor at a time method. The magnetizing current, the revolving speed of the tools, the rotational speed of the workpiece, workpiece traverse speed are the parameters that have been considered for this purpose. The experimentation has been performed on the aluminium workpiece because of its broad applicability, such as manufacturing shafts, rods, pistons, and other circular components. The primary purpose of this study was to determine the range of essential control parameters for the newly developed finishing process. The percentage reduction in Ra, Rq, and Rz values are 69.64%, 58.21%, and 54.48%, respectively, after 60 minutes of finishing at magnetizing current 2A, the revolving speed of the tools 30 RPM, the rotation speed of the workpiece 600 RPM and feed 10 cm/min.

Insights of biomass gasification combined with CO2 absorption enhanced reforming in an 8 MWth dual fluidized bed

Biomass gasification combined with CO2 absorption enhanced reforming (AER) emerges as a clean and efficient technology for H2 enrichment and CO2 removal, yet an in-depth understanding of in-furnace phenomena and fundamental physics is still lacking. In this work, the AER gasification in an industrial-scale DFB reactor is numerically studied by integrating the multi-phase particle-in-cell (MP-PIC) framework with complex reaction kinetics regarding gasification, carbonation, and calcination. After model validations, the effects of several key operating parameters on the AER gasification performance are studied. As compared with conventional gasification, AER gasification promotes H2 concentration by 15.3% but reduces CO2 concentration by 55.8%, leading to syngas quality improvement. Moreover, AER gasification performance in the DFB reactor can be improved by: (i) increasing gasification temperature; (ii) increasing steam-to-biomass ratio; (iii) adjusting bed material and (iv) decreasing particle size. The present work provides a cost-effective tool to study the physical-thermal-chemical behaviors of AER gasification in industrial-scale DFB reactors.

Integrated ozonation and mineralization of alkyl xanthate: Influence of operation parameters and structure-activity relationship

Xanthate is widely used in the flotation process of sulfide ores, and large amount of flotation wastewater with xanthate is produced and caused serious wastewater pollution due to its excessive usage. This study intensively studied ozonation and various ozone based advanced oxidation processes (AOPs) for alkyl xanthates (AXs) degradation and mineralization, including catalytic ozonation, peroxone and photocatalytic ozonation. The key operation parameters, such as ozone dosage, ratio of different oxidants and solution were studied. All integrated ozonation processes improved the mineralization efficiency of AXs, among which TiO2 photocatalytic ozonation is the most efficient, and the chemical oxygen demand (COD) removal rate can reach 84.9% in 60 min. A quantitative structure-activity relationship (QSAR) model was also established for ozonation of xanthates for the first time, based on quantum chemical calculation of series of xanthate structures and their degradation rate constants in ozonation. It reveals that the main factor affecting the ozonation rate constant is the molecular volume, which is negatively linearly correlated with the length of carbon chain of alkyl substituent group. The degradation intermediates of potassium amyl xanthate were measured by ultraviolet-visible spectroscopy (UV-Vis) and gas chromatography-mass spectroscopy (GC-MS), based on which a degradation path of xanthate was proposed. This work provides deeper understanding of advanced oxidation and mineralization of AXs, and may guide the development of treating technology for flotation wastewater.

Effects of electric potential and organic loading on the removal of hydrogen sulfide emitted from wastewater sediments using a submerged electrochemical oxidation system

Hydrogen sulfide (H2S), commonly generated by the anaerobic decay of organic substances in wastewater sediments, is a main odorous compound in domestic sewer networks. In this study, a submerged electrochemical oxidation system (SEOS), in which electrodes were applied directly to wastewater sediments, was tested to reduce H2S. To evaluate the SEOS performance, a series of experiments were conducted using a laboratory-scale closed batch reactor and a full-scale manhole under various electric potentials applied to the SEOS and organic concentrations in terms of COD. In the batch test, the concentration of H2S in the headspace dropped to its detection limit within 30 min when an electric potential greater than 10 V was applied. In addition to the H2S reduction, the COD concentration in the liquid phase was gradually reduced due to the electrochemical oxidation of organic contents, and the oxidation-reduction potential rapidly increased to higher than −100 mV. In the full-scale test with a continuous stream of wastewater with high COD concentrations, the concentration of H2S in the headspace decreased to less than 1 ppmv at an applied electric potential of 10 V and a specific power input (SPI) of 1.0 kW/kg-COD. Both the electric potential and SPI were found to be key operating parameters, and these parameters must be carefully selected to achieve both effective H2S removal and high energy efficiency simultaneously. The SEOS may be a feasible alternative for solving odor-related problems in domestic sewer networks.

Efficient Photocatalytic Degradation of Methylene Blue Dye from Aqueous Solution with Cerium Oxide Nanoparticles and Graphene Oxide-Doped Polyacrylamide.

A cerium oxide nanoparticles (CeO2-NPs)/graphene oxide (GO)/polyacrylamide (PAM) ternary composite was synthesized through free-radical polymerization of acrylamide in the presence of CeO2 nanoparticles and GO in an aqueous system. The synthesized composite material was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy techniques and applied for the photocatalytic degradation of methylene blue (MB) dye from an aqueous solution. Tauc's model for direct transition was used to model for the optical band gap. The key operating parameters such as the amounts of CeO2-NPs and GO, pH, initial MB concentration, type of light irradiation, and contact time have been optimized to achieve the highest MB degradation percentage. The photocatalysis process was pH-dependent, and the optimum pH value was found to be 12.0. Under UV-A light, 90% dye degradation occurred in 90 min. The degradation of MB was also specified in terms of total organic carbon (TOC) and chemical oxygen demand (COD). Free-radical capture experiments were also performed to determine the role of radical species during the photocatalytic oxidation process. The photocatalytic process showed that the equilibrium data is in good agreement with the Langmuir-Hinshelwood kinetic model. A rate constant of 0.0259 min-1 was obtained. The hydrogel was also tested to assess its reusability, which is an important key factor in practical wastewater treatment. The photocatalytic activity only decreased to 75% after nine uses.

Coal-fueled chemical looping gasification: A CFD-DEM study

Chemical looping gasification (CLG) is an emerging technology for reducing greenhouse gas emissions, yet the complex physical-thermal-chemical behaviour in the CLG unit has not been well understood. This work developed a high-fidelity computational fluid dynamics-discrete element method (CFD-DEM) reactive model considering four heat transfer modes (e.g., conduction, convection, radiation, and reaction heat) and complex heterogeneous and homogeneous reactions. The hydrodynamics and thermochemical characteristics in a CLG unit operating under several key operating parameters are numerically studied. The contribution from each heat transfer mode is quantified and the relationship between particle-scale behaviour and mesoscale bubble structures is quantitatively illuminated. The results show that the solids vertical dispersion coefficient is one order of magnitude larger than the horizontal one. At a low solid holdup, the interphase drag force plays a dominant role and particles in the bubble phase have higher vertical slip velocities. The ratio of particle-averaged heating rates for char particles through conduction, convection, radiation, and reaction take 5.41%, 14.91%, 14.39%, and 65.29%, and that for oxygen carriers take 7.77%, 23.46%, 20.33%, and 48.44%, respectively. For char particle and oxygen carriers, the reaction heat dominates the heat transfer process. Increasing gas inlet velocity promotes particle mixing, alleviates dead zone, and finally increases gas products while increasing the char to oxygen carrier mass ratio decreases gas products. The present work provides a cost-effective tool for the in-depth understanding of heat and mass transfer mechanisms in the CLG process.