To address the challenges of combustion stability and pollutant control during biomass co-combustion in coal-fired boilers under deep peak regulation, a numerical simulation study was conducted on a 660 MW front-and-rear wall opposed-fired pulverized coal boiler using computational fluid dynamics (CFD) technology. First, the reliability of the numerical model was validated under the Boiler Maximum Continuous Rating (BMCR) condition by comparing the simulated results of furnace outlet temperature and NO concentration with on-site operational data, with relative errors of 1.2% and 1.9%, respectively, both within the acceptable range of 5%. Subsequently, the effects of different biomass co-combustion ratios (0%, 5%, 10%, 15%, 20%) and injection positions (primary air nozzles of lower, middle, and upper burners) on the in-furnace velocity field, temperature field, component distribution (O₂, CO, CO₂), and NO emissions were systematically analyzed. The results indicate that increasing the biomass co-combustion ratio does not alter the overall variation trend of flue gas components but significantly affects their concentrations: the O₂ content at the furnace outlet decreases gradually, while the CO₂ content increases, and the NO emission concentration decreases continuously. A 20% co-combustion ratio is identified as the optimal choice, balancing combustion efficiency and NO reduction. Regarding injection positions, biomass injected at the middle burner’s primary air nozzle achieves the best NO control effect, reducing NO emissions by 22% compared to pure coal combustion. This is attributed to the formation of a stable reducing atmosphere in the main combustion zone, which facilitates NO_x reduction. The research findings provide valuable theoretical references and technical support for the parameter optimization and safe, low-emission operation of biomass co-combustion in large-scale coal-fired boilers.

Microporous metal materials have promising applications in the high-temperature industry for their high heat exchange efficiency. However, due to their complex internal structure, analyzing the heat transfer mechanisms presents a great challenge. This I confirm work introduces a mathematical model to accurately calculate the radiative thermal conductivity of microporous open-cell metal materials. The finite element and lattice Boltzmann methods were employed to calculate the thermal conduction and thermal radiation conductivities separately and validated for aluminum foams, with the relative errors all less than 9.3%. The results show that the thermal conductivity of microporous metal materials mainly increased with an increase in temperature and volume-specific surface area but decreased with an increase in porosity. Analysis of the spectral radiation characteristics shows that the surface plasmon polariton resonance and the magnetic polariton resonance appearing at the gas–solid interface of the metal foam significantly increase the dissipation effect of the gas–solid interface, further reducing the metal foam’s heat transfer efficiency. This indicates the potential of this work for use in the design of specific microporous metal materials like energy management devices or heat transfer exchangers in the aerospace industry.

Accurate thermal characterization of closed mesoporous metal gels is vital for high-temperature uses, yet microscale effects often ignored in macroscopic models significantly impact heat transfer. This study introduces a new predictive method based on an equivalent Voronoi model, accounting for the Knudsen effect and microscale electromagnetic interactions. Predicted thermal conductivity closely matched experimental results, with an average error of 5.35%. The results demonstrate that thermal conductivity decreases with porosity, increases with temperature, and varies with pore size, with a minimum of 17.47 W/(m·K) observed at ~1 μm. Variations in refractive index, extinction coefficient, and specific surface area exert negligible influence. Conductive heat transfer is suppressed under Knudsen-dominated conditions at small pore sizes. Electromagnetic analysis around the pore size corresponding to minimum conductivity reveals localized surface plasmon resonances and magnetic coupling at the gas–solid interface, which enhance radiative dissipation and further reduce thermal conductivity. Radiation dissipation efficiency increases with decreasing porosity and pore size. This model thus serves as a predictive tool for designing high-performance thermal insulation systems for elevated-temperature applications.

The closed mesoporous polymer gels have garnered significant attention as advanced thermal insulation materials due to their superior lightweight characteristics and excellent thermal management capabilities. To accurately predict their thermal performance, this study develops a novel mathematical model that integrates fractal geometry theory, Kirchhoff’s thermal conduction principles, comprehensive Rosseland diffusion approximation, and Mie scattering theory. The conductive thermal conductivity component was formulated based on a diagonal cross fractal structure, while the radiative component was derived considering microscale radiative effects. Model predictions exhibit strong agreement with experimental results from various mesoporous polymer gels, achieving a prediction error of less than 11.2%. Furthermore, a detailed parametric analysis was conducted, elucidating the influences of porosity, cell size, temperature, refractive index, and extinction coefficient. The findings identify a critical cell size range (1–100 µm) and porosity range (0.74–0.97) where minimum thermal conductivity occurs. This proposed modeling approach offers a robust and efficient theoretical tool for designing and optimizing the thermal insulation characteristics of closed mesoporous polymer gels, thereby advancing their application in diverse energy conversion and management systems.

Based on the acid-sensitive characteristics of SBA-15 during synthesis, this study varied the acid types, pH values, and mixed acid ratios during SBA-15 preparation to enhance the performance of CaO/Cr-SBA-15 dual-functional materials (DFMs) in integrated CO₂ capture and utilization for oxidative dehydrogenation of ethane (ICCU-ODHE). It was found that the SBA-15 support synthesized in an H₂SO₄ environment exhibited a high specific surface area and abundant surface silanol groups, which facilitated the dispersion of Cr and increased the proportion of Cr⁶⁺ active sites, thereby achieving the highest ethane conversion. In contrast, the moderate surface acidity of the HCl-prepared support facilitated the selective dehydrogenation of ethane over Cr active sites, effectively inhibiting side reactions and maximizing ethylene selectivity. Further investigations into the effects of pH and mixed acids revealed that pH 1 is optimal for SBA-15 preparation. At this value, the support reached its maximum mesoporous ordering and specific surface area, allowing for optimal Cr dispersion. Consequently, the ethane conversion, ethylene selectivity, and DFM yield all reached their peak values. Any deviation from this pH led to degradation of the support structure and reduced Cr dispersion, resulting in a significant decline in catalytic performance. Among the tested materials, the CaO/Cr-SBA-15-Cl-S DFM synthesized with an HCl-H₂SO₄ mixed acid demonstrated the superior reactivity, achieving an ethylene yield of 33.95%. Long-term cycling tests indicated that the material possesses good stability, with its performance attenuation primarily attributed to coking and adsorbent sintering.

Biomass co-firing is an effective approach for improving the low-carbon and flexible operation of coal-fired boilers under deep peak-shaving conditions. In this study, a 3D CFD model was established for a subcritical four-corner tangentially fired boiler to investigate the effects of biomass blending percentage, injection position, and boiler load on combustion characteristics and NO formation. The results show that increasing the biomass blending percentage improves the uniformity of the flow and temperature fields, promotes more complete pulverized coal combustion, and enhances boiler combustion efficiency. Among the investigated load conditions, the 70% load shows a relatively more favorable combustion state in terms of flow field distribution, temperature level, and species distribution. Compared with B-layer primary air injection, BC-layer secondary air injection shows a stronger tendency to reduce NO formation under the simulated conditions. These results indicate that proper biomass blending and optimization of the injection position can effectively improve combustion uniformity and suppress NO formation.