Current Issue : July-September Volume : 2026 Issue Number : 3 Articles : 5 Articles
The production of high-performance glass fibers relies critically on achieving a homogeneous melt with a specific thermal history, which is directly determined by the precise control and optimization of the melting equipment. To enhance the melting efficiency and material quality, this study investigates the optimization of the electric assistance system in a 200 t/d oxygen-enriched glass fiber melting furnace. By integrating CFD (Computational Fluid Dynamics) simulation techniques, a furnace model encompassing both the combustion zone and molten glass phase is developed. The study focuses on the impact of an oxy-fuel combustion + electric assistance system on the glass melting process. The influence of different input voltages on the furnace is analyzed through temperature, velocity, and flow fields. Glass melting efficiency and quality are evaluated using residence time, melting factor, and homogenization factor, considering both the residence time of molten glass and quality factors. The results indicate that a voltage scheme with the highest input voltage at the furnace inlet, combined with a relatively high voltage at the furnace outlet, is optimal, leading to the superior glass melting quality and the longest furnace service lifespan....
In this study, thermogravimetric analysis was employed to investigate the non-isothermal combustion behavior and kinetic characteristics of poplar biomass under air and oxy-fuel (O2/CO2) atmospheres. The effects of heating rate and oxygen concentration on combustion performance, gaseous emissions, and kinetic parameters were systematically analyzed. Results show that poplar biomass combustion consists of four distinct stages: moisture evaporation, devolatilization with volatile oxidation, char and fixed carbon oxidation, and final burnout. Increasing the heating rate intensifies the combustion process, shifting characteristic temperatures to higher values and significantly enhancing the comprehensive combustion index. Compared with air combustion, oxy-fuel conditions reduce ignition temperature and the temperature corresponding to the maximum combustion rate, leading to an earlier ignition and a more concentrated reaction interval. Higher oxygen concentrations further improve overall combustion performance and promote more complete carbon conversion. Gas emission analysis indicates that oxy-fuel combustion effectively suppresses NO2 and SO2 formation, demonstrating notable emission-reduction potential. Kinetic analysis using the Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa isoconversional methods shows that the activation energy varies with conversion degree and is generally higher under oxy-fuel atmospheres than in air. Overall, oxy-fuel combustion enhances biomass reactivity while achieving coordinated emission control through increased oxygen partial pressure and improved heat and mass transfer, supporting its practical application in biomass energy systems....
This study aims to investigate the combustion characteristics, thermal distribution, and nitrogen oxide (NOx) formation of two radiant tube designs—conventional and staged combustion—under air–fuel ratios of 1:10 and 1:11. A three-dimensional numerical model was developed in ANSYS Fluent 2023 R1 to compare flame temperature, wall temperature gradients, and pollutant emissions. The results reveal that flame temperature is the dominant factor in NOx formation. The conventional tube, with flame temperatures around 1800 ◦C, shows decreasing NOx emissions as the air–fuel ratio increases (corresponding to lower flame temperatures). In contrast, the staged combustion tube exhibits flame temperatures exceeding 1900 ◦C, where the thermal mechanism dominates, leading to a sharp increase in NOx emissions far above the conventional design. These findings highlight that in staged combustion systems, inadequate consideration of flame temperature and mixing characteristics may cause NOx control to fail or even reverse....
This study investigates the emission characteristics and flame behavior of an air-staged swirl burner operating on LPG. The burner is equipped with a 45◦ vane swirler and an adjustable secondary-air section. Experiments were conducted at air velocities ranging from 20 to 43 m/s using a Testo 350 gas analyzer, while temperature measurements were obtained with thermocouples positioned 90 mm downstream of the burner exit. The results show that increasing the secondary-air opening leads to a monotonic decrease in the mean exit temperature and NOx formation over the entire velocity range. In contrast, CO concentrations increase at higher air velocities and larger secondary-air fractions due to reduced residence time and partial quenching of the reaction zone. The fully staged configuration (100%) achieved the lowest NOx levels (≤3 ppm) at 20 m/s, whereas the non-staged case resulted in the highest temperatures and NO emissions. Overall, the experimental results demonstrate that a moderate secondary-air opening provides the best compromise between low NOx emissions and acceptable CO levels for compact LPG-fired swirl combustors....
Spontaneous combustion of coal piles threatens the production and transportation safety of coal mining, which is attracting more and more attention. To understand the underlying physics, conducting pore-scale research on the spontaneous combustion of coal piles is critical. To enable pore-scale research, a pore-scale model of the spontaneous combustion of a coal pile is described, and governing equations are introduced. To understand the competition between airflow, heat–mass transfer, and oxidation reaction, the lattice Boltzmann method (LBM) is utilized, which offers distinct advantages in handling complex pore geometries, multi-physics coupling, and reactive transport at the pore scale. The present model integrates, for the first time in a pore-scale LB framework, airflow driven by thermal buoyancy, convective heat and mass transfer, and Arrhenius-type oxidation kinetics within a realistic coal pile geometry. After the numerical method is validated, the effects of inflowing air velocity, inflowing air temperature, oxygen concentration, and coal particle size are discussed. With an increase in inflowing air velocity, convective heat transfer is enhanced, and the coal pile maximum temperature decreases monotonically. According to the Arrhenius equation, with an increase in the inflowing air temperature and oxygen concentration, the oxidation reaction is accelerated, and the coal pile maximum temperature increases. When the size of the coal particle increases, the oxidation reactive area decreases, and the coal pile maximum temperature decreases, while the steady temperature is not affected....
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