Current Issue : January-March Volume : 2026 Issue Number : 1 Articles : 5 Articles
Reducing the anthropogenic impact on the environment is an increasingly urgent challenge, particularly in the energy and heat generation sectors. This study presents the results of an experimental investigation into the combustion characteristics of four nozzle types in a burner system. The experiments focused on emissions of NOx and CO under varying equivalence ratios. This study presents an experimental investigation of combustion with one swirl-stabilized nozzle and two multihole plates under varying equivalence ratios (ϕ). The swirl-stabilized configuration produced the highest NOx, reaching 54.4 ppm at ϕ = 0.9, which we attribute to higher flame temperatures and longer effective residence. In contrast, the multihole plates—122 holes of 1.0 mm and 36 holes of 4.0 mm in a 100 mm insert—exhibited lower NOx and lower temperatures owing to more effective fuel–air mixing. CO showed a strong dependence on both geometry and ϕ; the lowest levels occurred near ϕ ≈ 0.9, consistent with optimal combustion. The findings underscore the importance of nozzle geometry and air–fuel ratio in optimizing combustion efficiency and minimizing harmful emissions, providing valuable insights for the development of low-emission combustion systems in modern energy applications....
Biomass combustion for the production of electricity and heat remains one of the most widespread renewable energy technologies. Biomass is commonly utilized in fluidized bed combustion systems. Over the years, numerous issues related to the preparation and combustion of biomass in fluidized beds have been identified, including fouling and slagging, which involve the formation of deposits. These phenomena can be mitigated through various methods, including design modifications to boilers, the application of additives, and the careful selection and classification of fuel. Several fuel indices have been proposed to predict the behavior of fuels in terms of their tendency to cause fouling and slagging. Most of these indices were developed for fossil fuels, and the discrepancies between them suggest that although these indices are widely applied, their applicability to agricultural residues, such as straw, remains uncertain. Researchers working in this field emphasize the need for further research, particularly focusing on the comparison of developed indices with the results of biomass combustion at both laboratory and industrial scales. In this study, ten assortments of straw sourced from Poland were selected, and chemical composition analyses were conducted to determine selected fuel indices. The analyzed straw samples were then combusted in a 100 kWth laboratory-scale circulating fluidized bed unit. Using a specialized austenitic steel probe, the growth rate of the deposit was measured. The collected deposit masses for each straw type were then compared with the calculated fuel indices. The best correlation between the interpretation of the index values and the deposit mass on the probe was observed for the Rs index. However, due to the low sulfur content of straw, Rs numerical interpretation was not adequate. Overall, the indices indicating both good correlation coefficients and an appropriate numerical interpretation for fouling tendency were B/A, Fu, and Cl....
At present, the characteristics of supercritical hydrothermal combustion for heavy oils remain unclear, which severely limits the application of this process. In this work, the effect of key parameters on the characteristics of supercritical hydrothermal combustion of heavy oil are studied. The heat value at a heavy oil concentration of 30 wt.% is 12.21 MJ·kg−1, significantly higher than that of an alcohol–water mixture with an equivalent mass fraction. Thus, the minimum ignition temperature of heavy oil can reach the subcritical temperature of 300 ◦C. Appropriately increasing pressure and the oxidation coefficient can enhance burnout efficiency, but an excessively high oxidation coefficient will produce adverse effects. The optimized parameters for heavy oil supercritical hydrothermal combustion are a preheating temperature of 350 ◦C, a fuel concentration of 30 wt.%, an oxidation coefficient of 1.5, and a reaction pressure of 25 MPa, resulting in a burnout rate of 99.15%....
Under electrical overload conditions, the molten dripping of thermoplastic wire insulation materials—particularly crosslinked polyethylene (XLPE)—poses a severe fire hazard and significantly complicates fire prevention and control. This study systematically investigated the formation mechanism, periodic characteristics, and flame interaction behavior of molten dripping in XLPE-insulated wires subjected to varying overload currents (0–80 A). Experiments were conducted using a custom-designed test platform equipped with precise current regulation and high-resolution video imaging systems. Key dripping parameters—including the initial dripping time, dripping frequency, and period—were extracted and analyzed. The results indicate that increased current intensifies Joule heating within the conductor, accelerating the softening and pyrolysis of the insulation, thus resulting in earlier and more frequent dripping. A thermodynamic prediction model was developed to reveal the nonlinear coupling relationships between the dripping frequency, period, and current, which showed strong agreement with the experimental data, especially at high current levels. Further flame morphology analysis showed that molten dripping induced pronounced vertical flame disturbances, while the lateral flame spread remained relatively unchanged. This phenomenon promotes vertical flame propagation and can trigger multiple ignition points, thereby increasing the fire complexity and hazard. The study enhances our understanding of the coupling mechanisms between electrical loading and molten dripping behavior and provides theoretical and experimental foundations for fire-safe wire design and early-stage risk assessment....
The escalating global demand for primary energy—still predominantly met by conventional carbon-based fuels—has led to increased atmospheric pollution. This underscores the urgent need for alternative energy strategies capable of reducing carbon emissions while meeting global energy requirements. Hydrogen, as a clean combustible fuel, offers a promising alternative to hydrocarbons, producing neither soot, CO2, nor unburned hydrocarbons. Although nitrogen oxides (NOx) are the primary combustion by-products, their formation can be mitigated by controlling flame temperature. This study investigates the viability of hydrogen as a clean energy vector by simulating an unsteady, turbulent, non-premixed hydrogen jet flame interacting with an air co-flow. The numerical simulations employ the Unsteady Reynolds-Averaged Navier–Stokes (URANS) framework for efficient and accurate prediction of transient flow behavior. Turbulence is modeled using the Shear Stress Transport (SST k-ω) model, which enhances accuracy in high Reynolds number reactive flows. The combustion process is described using a presumed Probability Density Function (PDF) model, allowing for a statistical representation of turbulent mixing and chemical reaction. The simulation results are validated by comparison with experimental temperature and mixture fraction data, demonstrating the reliability and predictive capability of the proposed numerical approach....
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