Article
Chemistry, Physical
Fanli Shan, Dingrui Zhang, Lingyun Hou, Hong Fang, He Zhang, Jun Zhang
Summary: The improved FPV model successfully avoids the scalar over-mixing effect of the traditional model, leading to a moderate growth of the mixing and reacting zone in near-wall combustion simulations. This improvement enhances the accuracy of predicting species concentrations.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Thermodynamics
Xu Wen, Hendrik Nicolai, Henrik Schneider, Liming Cai, Johannes Janicka, Heinz Pitsch, Christian Hasse
Summary: A large-eddy simulation was conducted on a swirl-stabilized multi-stream laboratory-scale pulverized coal burner designed for oxy-fuel investigation, showing that the oxy-coal flame is narrower than the air-coal flame and particle clustering phenomenon can be observed in the oxy-fuel atmosphere. The distributions of thermo-chemical quantities are significantly different under different conditions.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Michael Pfitzner, Markus Klein
Summary: A new chemical reaction rate source term is proposed and its implications for premixed flame modeling are discussed. Analytic flame profiles, 1D laminar flame pdfs, and the evaluation of laminar flame Eigenvalues are derived and compared to classical results. A method to evaluate progress variable pdf from DNS data is introduced, which factorizes into flat flame pdf, geometrical wrinkling factor, and correction factor.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Xudong Jiang, Junjun Guo, Zhengyun Wei, Erica Quadarella, Hong G. Im, Zhaohui Liu
Summary: A flamelet/progress variable model accounting for differential diffusion effects is proposed and applied to LES of turbulent oxy-fuel flames. The model incorporates the influences of combustion progress, mixture fraction, and turbulence on variable Lewis numbers. The model is evaluated on a laminar coflow flame and implemented in a fully coupled LES of oxy-fuel jet flames, showing accurate capture of the effects of differential diffusion and good predictions on temperature and species distribution.
COMBUSTION AND FLAME
(2023)
Article
Energy & Fuels
Dominik Meller, Linus Engelmann, Oliver T. Stein, Andreas M. Kempf
Summary: Highly-resolved Large Eddy Simulations (LES) were conducted to investigate combustion characteristics and NOx formation in swirl-induced recirculation zones of the Brigham Young University (BYU) Burner Flow Reactor (BFR). The simulations utilized the in-house LES tool PsiPhi, employing a flamelet/progress variable (FPV) approach to model the reactive multiphase flow. A reduced CRECK mechanism with 120 species and 1551 reactions, including all NOx formation mechanisms, was used. Comparisons with experimental data showed good agreement in radial profiles of major gas species. Two variants of determining NO species were explored: direct extraction from the flamelet table and solving an additional transport equation for NO. The latter approach showed superior performance in predicting NO reactions within the furnace.
Article
Energy & Fuels
Dominik Meller, Timo Lipkowicz, Martin Rieth, Oliver T. Stein, Andreas Kronenburg, Christian Hasse, Andreas M. Kempf
Summary: A coaxial burner with a hydrogen-supported pulverized coal flame, operated by CRIEPI in Japan, is investigated using large eddy simulation. A new flamelet model is introduced to predict the laboratory flame properties, with consideration of probe effects. The study also tests the impact of suction probe on experimental measurements, showing improved agreement between experiment and simulation when probe effects are considered.
Article
Thermodynamics
Yicun Wang, Changxiao Shao, Kun Luo, Ruipeng Cai, Tai Jin, Jianren Fan
Summary: In this paper, the authors focus on the development and validation of the TSFPV model for simulating turbulent spray flames. The improved SEST model is used to generate the spray flamelet library, and the TSFPV model is verified on different flame configurations. The results show good agreement with experimental measurements, indicating the potential of the TSFPV model for spray combustion modeling.
Article
Energy & Fuels
Masayuki Taniguchi
Summary: A model was developed to evaluate flame propagation velocity for co-combustion, finding that the maximum velocity increased with smaller particle diameter and higher volatile content for coal combustion. However, coal's velocity was usually lower than that of gas fuels due to delays in pyrolysis reactions and residual solid particles. The model is useful for designing burners for solid-gas co-combustion.
Article
Thermodynamics
Xu Wen, Ali Shamooni, Oliver T. Stein, Liming Cai, Andreas Kronenburg, Heinz Pitsch, Andreas M. Kempf, Christian Hasse
Summary: A carrier-phase direct numerical simulation (CP-DNS) was conducted to investigate pulverized coal combustion and NOx formation mechanisms in a mixing layer, focusing on the early devolatilization phase. The study found that different reaction pathways and chemical timescales can affect the production rates and consumption rates of NOx species.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Amir H. Mahdipour, M. Mahdi Salehi
Summary: The study investigates the performance of using LFD model in premixed combustion, finding that it can correctly predict filtered reaction rates and scalar fields as long as turbulent and laminar mixing are accurately predicted. Deviations from DNS results are attributed to shortcomings in the strained flamelet library and non-flamelet effects. Comparisons with another sub-filter scale model using the same strained flamelet library are made, discussing the relative performances of the two models.
FLOW TURBULENCE AND COMBUSTION
(2022)
Article
Thermodynamics
Xu Wen, Hendrik Nicolai, Paulo Debiagi, Diego Zabrodiec, Anna Massmeyer, Reinhold Kneer, Christian Hasse
Summary: Large-eddy simulations are conducted for a 40 kWth self-sustained pulverized torrefied biomass furnace in air and oxy-fuel atmospheres. The results show that the flame in the oxy-fuel atmosphere is longer and broader due to different flow dynamics. The different atmospheres also significantly affect the combustion characteristics and NOx emissions.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Energy & Fuels
Filip Juric, Marko Ban, Peter Priesching, Carsten Schmalhorst, Neven Duic, Milan Vujanovic
Summary: The research focuses on reducing the impact of the transport sector on climate change and carbon dioxide emissions by utilizing biofuels and e-fuels, with the development and validation of combustion models to generate lookup databases for autoignition and laminar flame speeds under different conditions.
Article
Energy & Fuels
Yuhua Liu, Jingzhang Liu, Qinggang Lyu, Jianguo Zhu, Fei Pan
Summary: In this study, the microstructure changes of fuel during preheating process were analyzed to reveal the impact on particle change behavior during combustion. It was found that during preheating, the main forms of N, C, and O elements in coal were pyrrole, hydrocarbon, and carbon-oxygen single bond respectively.
Article
Thermodynamics
Xu Wen, Ali Shamooni, Hendrik Nicolai, Oliver T. Stein, Andreas Kronenburg, Andreas M. Kempf, Christian Hasse
Summary: In this study, a carrier-phase direct numerical simulation (CP-DNS) is conducted to analyze a pulverized coal flame with flue gas recirculation (FGR). The study considers detailed gas phase kinetics and includes heavy hydrocarbon molecules. Two flamelet models are used to analyze the structure of the flame and evaluate their performance in predicting thermo-chemical quantities.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Ali Cemal Benim, Cansu Deniz Canal, Yakup Erhan Boke
Summary: Computational investigation of swirling pulverized coal and biomass flames for oxy-combustion reveals that the Reynolds Stress Model (RSM) captures unsteady dynamics better than the k-epsilon model. Predicted velocities show better agreement with measurements using RSM. However, both models underestimate the measurements, with discrepancies quantified in peak values of axial velocity. Biomass flame is predicted to be nearly twice as long as coal flame.
Article
Thermodynamics
Hualin Xiao, Kun Luo, Tai Jin, Jiangkuan Xing, Min Chai, Jianren Fan
Summary: This study investigates the influence of combustion on scaled kinetic energy transport in a swirling partially premixed flame under gas turbine conditions.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Xu Wen, Hendrik Nicolai, Paulo Debiagi, Diego Zabrodiec, Anna Massmeyer, Reinhold Kneer, Christian Hasse
Summary: Large-eddy simulations are conducted for a 40 kWth self-sustained pulverized torrefied biomass furnace in air and oxy-fuel atmospheres. The results show that the flame in the oxy-fuel atmosphere is longer and broader due to different flow dynamics. The different atmospheres also significantly affect the combustion characteristics and NOx emissions.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Hannes Boettler, Haris Lulic, Matthias Steinhausen, Xu Wen, Christian Hasse, Arne Scholtissek
Summary: In order to reduce CO2 emissions, hydrogen combustion has become increasingly popular for technical applications. Lean hydrogen-air flames show promising features but also tend to exhibit thermo-diffusive instabilities, leading to cellular structures and increased flame surface area. It is important to develop reduced-order models to efficiently predict these flame characteristics in computational simulations.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Tien Duc Luu, Ali Shamooni, Oliver T. Stein, Andreas Kronenburg, Sebastian Popp, Hendrik Nicolai, Henrik Schneider, Xu Wen, Christian Hasse
Summary: A multiphase flamelet/progress variable (FPV) model is developed for the large eddy simulation (LES) of gas-assisted pulverised coal combustion (PCC). The model is validated against experimental evidence and shows good agreement in terms of predicted mean and RMS velocities, as well as mean gas temperature. The contributions of different fuel streams to the coal flame are analyzed, revealing dominance of pilot or volatile combustion in different regions of the furnace.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Jiangkuan Xing, Kun Luo, Ryoichi Kurose, Jianren Fan
Summary: Coal/biomass co-firing is a sustainable alternative to reduce emissions from fossil fuel utilization. An extended FPV model was developed to study the combustion characteristics of the co-firing flame, and it was found that the model could well reproduce the flame behaviors in different combustion stages.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Xu Wen, Federica Ferraro, Hendrik Nicolai, Nozomu Hashimoto, Jun Hayashi, Noriaki Nakatsuka, Kazuki Tainaka, Christian Hasse
Summary: Large-eddy simulation (LES) with a detailed model was used to study a turbulent pulverized coal flame and characterize the soot evolution. A flamelet model was employed to describe the gas phase kinetics, and a quadrature-based moment method (QBMM) was used to describe the soot statistics considering various physicochemical processes. The simulation results were compared to experimental data, and good agreement was observed for various measurements such as PAHs-LIF, soot-LII, and SEM images. The contributions of different physicochemical processes to soot growth were quantified, with chemical surface growth being identified as the most important.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Xu Wen, Ali Shamooni, Hendrik Nicolai, Oliver T. Stein, Andreas Kronenburg, Andreas M. Kempf, Christian Hasse
Summary: In this study, a carrier-phase direct numerical simulation (CP-DNS) is conducted to analyze a pulverized coal flame with flue gas recirculation (FGR). The study considers detailed gas phase kinetics and includes heavy hydrocarbon molecules. Two flamelet models are used to analyze the structure of the flame and evaluate their performance in predicting thermo-chemical quantities.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Engineering, Chemical
Dali Kong, Shuai Wang, Kun Luo, Jianren Fan
Summary: Biomass gasification combined with CO2 absorption-enhanced reforming was numerically studied in a BFB reactor using the MP-PIC method. The effects of operating parameters on particle behaviors, bubble dynamics, and reactor performance were analyzed. A lower operating pressure improved gas-solid contact efficiency and performance, while higher temperature and S/B ratio promoted H2 generation but deteriorated gasification performance. Mixed bed material significantly improved gasification performance by enhancing H2 generation and CO2 removal.
Article
Engineering, Environmental
Dali Kong, Shuai Wang, Kun Luo, Qilong Xu, Jianren Fan
Summary: Biomass gasification combined with CO2 absorption enhanced reforming (AER) is a clean and efficient technology for H2 enrichment and CO2 removal. This study numerically investigates AER gasification in an industrial-scale DFB reactor using the multi-phase particle-in-cell (MP-PIC) framework. The effects of key operating parameters on AER gasification performance are studied, and it is found that AER gasification improves H2 concentration by 15.3% and reduces CO2 concentration by 55.8%. The study also provides recommendations for improving AER gasification performance in the DFB reactor.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Thermodynamics
Xu Wen, Lukas Berger, Florian vom Lehn, Alessandro Parente, Heinz Pitsch
Summary: This study investigates the NOx formation characteristics of a thermodiffusively unstable premixed hydrogen flame. The results show that curvature directly affects NOx formation, especially the dominant NNH and N2O reaction pathways. The contribution of the thermal-NO pathway is negligible. The flamelet model gives good predictions in positively-curved flame segments, but discrepancies exist in negatively-curved flame regions.
COMBUSTION AND FLAME
(2023)
Article
Energy & Fuels
Qingqing Xue, Jiangkuan Xing, Xinzhou Tang, Kun Luo, Haiou Wang, Jianren Fan
Summary: This study aims to identify accurate and general heat release rate markers for ammonia-methane cofiring flames. Through calculations and database construction, the study successfully determined the chemical formulas that can accurately approximate the heat release rate.
Article
Energy & Fuels
Runhui Zhang, Xiaoke Ku, Jianzhong Lin, Kun Luo
Summary: This work presents the development of an efficient three-dimensional pyrolysis model for large biomass particles with arbitrary shapes. The model utilizes the composed-sphere concept and the Voronoi tessellation to account for the shrinkage of the parent particle and resolve heat transfer and porosity inside the particle. The model is validated using six different particles and pyrolysis processes, showing good agreement with experimental data, and sensitivity analyses of three different parameters are conducted. The developed model not only characterizes different-shaped particles effectively but also provides more intra-particle details during the pyrolysis of large biomass particles.
Article
Engineering, Chemical
Jiahui Yu, Shuai Wang, Kun Luo, Jianren Fan
Summary: This study develops a coupled framework by combining computational fluid dynamics (CFD) with discrete element method (DEM), and further introduces the volume-of-fluid (VOF) method for studying multiphase flow systems. A smoothing method is implemented to ensure accurate calculation of interphase and interfacial interactions. An advanced VOF-based surface-capturing method, Iso-Advector, is introduced to effectively describe interface evolution and interfacial interactions. The integrated model is verified through three benchmark cases, with good agreement between numerical results and experimental measurements, demonstrating the reliability of the model in simulating multiphase flow systems.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Engineering, Multidisciplinary
Yonghui Qiao, Jianren Fan, Kun Luo
Summary: The mechanism of energy loss in healthy aortic blood flow is explored using clinical measurements and computational modeling techniques. The primary causes of energy loss are viscous friction and aortic wall deformation. These findings can inform the development of new hemodynamic markers and clinical assessment tools for vascular wall health.
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
(2023)
Article
Thermodynamics
Xin Liu, Qiang Wang, Kun Luo, Yanfei Mu, Haiou Wang, Jianren Fan
Summary: The study finds that using a liquid-cooled plate and metallic phase change material can improve battery thermal management. Gallium filling significantly reduces cell temperature and improves temperature dispersion uniformity, but a higher coolant mass flow rate has less impact on cell temperature and increases system energy consumption.
APPLIED THERMAL ENGINEERING
(2024)