Article
Thermodynamics
Pascale Domingo, Luc Vervisch
Summary: The Bray-Moss-Libby (BML) bi-modal asymptotic limit is applied to establish a relation between the variation rate of mean turbulent flame brush thickness, flame surface wrinkling, and turbulent burning velocity in a premixed turbulent flame. It is found that the amplification of flame surface by turbulence and the increase in turbulent burning velocity may require modulation by a corrective term proportional to the rate of variation of turbulent flame brush thickness.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Arun Ravi Varma, Umair Ahmed, Markus Klein, Nilanjan Chakraborty
Summary: The relationship between turbulent burning velocity, bending effect, and flame surface area is discussed, along with the effects of tangential strain rate, normal strain rate, displacement speed, and curvature.
COMBUSTION AND FLAME
(2021)
Article
Chemistry, Physical
Guo-Peng Zhang, Guo-Xiu Li, Hong-Meng Li, Jia-Cheng Lv
Summary: The study examines the effects of different diluents on the propagation characteristics of H2/CO/air mixture turbulent premixed flames. Increasing hydrogen fraction, turbulence intensity, or equivalence ratio leads to higher ST and ut. CO2 dilution shows a stronger inhibitory effect on ST compared to N2 dilution.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Thermodynamics
Sina Kheirkhah, Omer L. Gulder
Summary: The article reviews the validity of the flamelet assumption in turbulent premixed flames and discusses the discrepancies between the assumption and actual flame behavior. It suggests that relaxing the flamelet assumption can better explain the combustion speed and behavior of turbulent premixed flames.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Tejas Kulkarni, Fabrizio Bisetti
Summary: The thickness of the turbulent flame brush is crucial for modeling premixed turbulent combustion. Contrary to turbulent diffusion theory, the evolution of the flame brush differs due to flame propagation, density changes across the front, and hydrodynamic instabilities. An alternate Eulerian framework based on surface density formalism is proposed to analyze mechanisms of turbulent flame brush growth.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
D. A. Knyazkov, T. A. Bolshova, V. M. Shvartsberg, A. A. Chernov, O. P. Korobeinichev
Summary: This paper investigates the laminar burning velocity and structure of methyl methacrylate flames with and without trimethylphosphate additives. The study aims to develop a predictive gas-phase chemical kinetic model for flame inhibition of polymethyl methacrylate by phosphorus-containing fire retardants. The experimental and numerical results validate the combustion mechanism and discuss the performance of the kinetic model in predicting the flame inhibition.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Qingshuang Fan, Xin Liu, Leilei Xu, Arman Ahamed Subash, Christian Brackmann, Marcus Alden, Xue-Song Bai, Zhongshan Li
Summary: This paper presents experimental studies on the structures and burning velocities of premixed ammonia/air jet flames at high Karlovitz number conditions. NH and OH radicals were measured using PLIF imaging and LDA measurements. The results show that the NH layer remains thin and continuous, the NH and OH layers overlap in a thin region, and the turbulent burning velocity is linearly related to the turbulent intensity.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Zhen Lu, Yue Yang
Summary: This study investigates the pressure effects on turbulent burning velocity and flame surface area, particularly the impact of enhanced stretch factor at high pressures. By combining sub models for stretch factor and flame surface area, a predictive model for turbulent burning velocity is developed, showing good agreement with DNS results.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Sanjeev Kr. Ghai, Umair Ahmed, Markus Klein, Nilanjan Chakraborty
Summary: An integral form of the energy conservation equation has been derived for statistically steady premixed flame-wall interaction within turbulent boundary layers. The equation is validated based on Direct Numerical Simulation data and shows the significance of wall heat flux and chemical heat release in the energy integral equation. The Nusselt number is found to be intrinsically related to the turbulent burning velocity in flame-wall interactions. The study also highlights the limitations of reaction rate closures in estimating the mean Nusselt number in turbulent boundary layers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Xinlu Han, Marco Lubrano Lavadera, Christian Brackmann, Zhihua Wang, Yong He, Alexander A. Konnov
Summary: The formation of nitric oxide (NO) in methane (CH4) flames has been extensively studied, but discrepancies between simulations using different kinetic mechanisms and experimental results persist. Experimental data was collected for NO formation in post-flame zones of CH4+O2+N2 flames with varying oxygen ratios. Analysis showed that thermal-NO production plays a key role in the increase of NO mole fraction in stoichiometric and fuel-lean flames as oxygen ratio increases.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Martin Rieth, Andrea Gruber, Forman A. Williams, Jacqueline H. Chen
Summary: In this study, direct numerical simulations were used to investigate the local effects of molecular diffusion on the overall burning rates of fuel-lean turbulent premixed hydrogen-enriched flames. The analysis revealed that diffusion of hydrogen species can remain the rate-controlling processes even at high turbulence intensity.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Hazim Shehab, Hiroaki Watanabe, Yuki Minamoto, Ryoichi Kurose, Toshiaki Kitagawa
Summary: Three-dimensional direct numerical simulations were used to investigate the influence of turbulence-flame interactions on flame structure and morphology. The most significant fuel consumption and heat release rates were found at negatively-curved flamelets. The shape of intense reaction zones was quantified and compared to planar flames, showing complex shapes like tubes and pancakes. As turbulence level increased, the number of intense reaction zones also increased, expanding to cover more parts of the flame front.
COMBUSTION AND FLAME
(2022)
Article
Engineering, Multidisciplinary
Siva P. R. Muppala
Summary: In this study, an algebraic premixed turbulent model is validated for molecular transport effects in hydrogen-blended fuel. Three variants of the model are presented, incorporating the influence of turbulent flame speed and Lewis number on flame diffusion. Experimental data is compared with theoretical predictions, confirming the accuracy of the model.
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Thermodynamics
Arnaud Mura, Vincent Robin, Kim Q. N. Kha, Michel Champion
Summary: This study investigates the effects of thermal expansion on turbulent flames and diffusion phenomena. A joint probability-density function (PDF) for the progress variable and velocity is introduced to analyze the evolution of scalar fluxes in a planar premixed turbulent flame brush. The analysis reveals the presence of counter-gradient diffusion (CGD) and gradient diffusion (GD) regions within the flame brush. The results also demonstrate the relationship between the normalized turbulent scalar flux and classical nondimensional numbers, providing a basis for closure models for the turbulent flux of the progress variable.
COMBUSTION SCIENCE AND TECHNOLOGY
(2023)
Article
Energy & Fuels
Guoqiang Xiong, Gesheng Li, Weilin Zeng, Junjie Liang
Summary: The steady flamelet method was used in the large eddy simulation (LES) of turbulent cool flames to investigate its capability. The results showed that it accurately captured the mean and variance trends for temperature, mixture fraction, and formaldehyde, as well as described the flame morphology of the two-stream flamelet form.
Article
Energy & Fuels
Yingna Du, Chen Huang, Wei Jiang, Qiangwei Yan, Yongfei Li, Gang Chen
Summary: In this study, anionic surfactants modified hydrotalcite was used as a flow improver for crude oil under low-temperature conditions. The modified hydrotalcite showed a significant viscosity reduction effect on crude oil. The mechanism of the modified hydrotalcite on viscosity and pour point of crude oil was explored through characterization and analysis of the modified hydrotalcite and oil samples.
Article
Energy & Fuels
Mohammad Saeid Rostami, Mohammad Mehdi Khodaei
Summary: In this study, a hybrid structure, MIL-53(Al)@MWCNT, was synthesized by combining MIL-53(Al) particles and -COOH functionalized multi-walled carbon nanotube (MWCNT). The hybrid structure was then embedded in a polyethersulfone (PES) polymer matrix to prepare a mixed matrix membrane (MMM) for CO2/CH4 and CO2/N2 separation. The addition of MWCNTs prevented MIL-53(Al) aggregation, improved membrane mechanical properties, and enhanced gas separation efficiency.
Article
Energy & Fuels
Yunlong Li, Desheng Huang, Xiaomeng Dong, Daoyong Yang
Summary: This study develops theoretical and experimental techniques to determine the phase behavior and physical properties of DME/flue gas/water/heavy oil systems. Eight constant composition expansion (CCE) tests are conducted to obtain new experimental data. A thermodynamic model is used to accurately predict saturation pressure and swelling factors, as well as the phase boundaries of N2/heavy oil systems and DME/CO2/heavy oil systems, with high accuracy.
Article
Energy & Fuels
Morteza Afkhamipour, Ebad Seifi, Arash Esmaeili, Mohammad Shamsi, Tohid N. Borhani
Summary: Non-conventional amines are being researched worldwide to overcome the limitations of traditional amines like MEA and MDEA. Adequate process and thermodynamic models are crucial for understanding the applicability and performance of these amines in CO2 absorption, but studies on process modeling for these amines are limited. This study used rate-based modeling and Deshmukh-Mather method to model CO2 absorption by DETA solution in a packed column, validated the model with experimental data, and conducted a sensitivity analysis of mass transfer correlations. The study also compared the CO2 absorption efficiency of DETA solution with an ionic solvent [bmim]-[PF6] and highlighted the importance of finding optimum operational parameters for maximum absorption efficiency.
Article
Energy & Fuels
Arastoo Abdi, Mohamad Awarke, M. Reza Malayeri, Masoud Riazi
Summary: The utilization of smart water in EOR operations has gained attention, but more research is needed to understand the complex mechanisms involved. This study investigated the interfacial tension between smart water and crude oil, considering factors such as salt, pH, asphaltene type, and aged smart water. The results revealed that the hydration of ions in smart water plays a key role in its efficacy, with acidic and basic asphaltene acting as intrinsic surfactants. The pH also influenced the interfacial tension, and the aged smart water's interaction with crude oil depended on asphaltene type, salt, and salinity.
Article
Energy & Fuels
Dongao Zhu, Kun Zhu, Lixian Xu, Haiyan Huang, Jing He, Wenshuai Zhu, Huaming Li, Wei Jiang
Summary: In this study, cobalt-based metal-organic frameworks (Co-based MOFs) were used as supports and co-catalysts to confine the NHPI catalyst, solving the leaching issue. The NHPI@Co-MOF with carboxyl groups exhibited stronger acidity and facilitated the generation of active oxygen radicals O2•, resulting in enhanced catalytic activity. This research provides valuable insights into the selection of suitable organic linkers and broadens the research horizon of MOF hybrids in efficient oxidative desulfurization (ODS) applications.
Article
Energy & Fuels
Edwin G. Hoyos, Gloria Amo-Duodu, U. Gulsum Kiral, Laura Vargas-Estrada, Raquel Lebrero, Rail Munoz
Summary: This study investigated the impact of carbon-coated zero-valent nanoparticle concentration on photosynthetic biogas upgrading. The addition of nanoparticles significantly increased microalgae productivity and enhanced nitrogen and phosphorus assimilation. The presence of nanoparticles also improved the quality of biomethane produced.
Article
Energy & Fuels
Yao Xiao, Asma Leghari, Linfeng Liu, Fangchao Yu, Ming Gao, Lu Ding, Yu Yang, Xueli Chen, Xiaoyu Yan, Fuchen Wang
Summary: Iron is added as a flocculant in wastewater treatment and the hydrothermal carbonization (HTC) of sludge produces wastewater containing Fe. This study investigates the effect of aqueous phase (AP) recycling on hydrochar properties, iron evolution and environmental assessment during HTC of sludge. The results show that AP recycling process improves the dewatering performance of hydrochar and facilitates the recovery of Fe from the liquid phase.
Article
Energy & Fuels
He Liang, Tao Wang, Zhenmin Luo, Jianliang Yu, Weizhai Yi, Fangming Cheng, Jingyu Zhao, Xingqing Yan, Jun Deng, Jihao Shi
Summary: This study investigated the influence of inhibitors (carbon dioxide, nitrogen, and heptafluoropropane) on the lower flammability limit of hydrogen and determined the critical inhibitory concentration needed for complete suppression. The impact of inhibitors on explosive characteristics was evaluated, and the inhibitory mechanism was analyzed with chemical kinetics. The results showed that with the increase of inhibitor quantity, the lower flammability limit of hydrogen also increased. The research findings can contribute to the safe utilization of hydrogen energy.
Article
Energy & Fuels
Zonghui Liu, Zhongze Zhang, Yali Zhou, Ziling Wang, Mingyang Du, Zhe Wen, Bing Yan, Qingxiang Ma, Na Liu, Bing Xue
Summary: In this study, high-performance solid catalysts based on phosphotungstic acid (HPW) supported on Zr-SBA-15 were synthesized and evaluated for the one-pot conversion of furfural (FUR) to γ-valerolactone (GVL). The catalysts were characterized using various techniques, and the ratio of HPW and Zr was found to significantly affect the selectivity of GVL. The HPW/Zr-SBA-15 (2-4-15) catalyst exhibited the highest GVL yield (83%) under optimized reaction conditions, and it was determined that a balance between Bronsted acid sites (BAS) and Lewis acid sites (LAS) was crucial for achieving higher catalytic performance. The reaction parameters and catalyst stability were also investigated.
Article
Energy & Fuels
Michael Stoehr, Stephan Ruoff, Bastian Rauch, Wolfgang Meier, Patrick Le Clercq
Summary: As part of the global energy transition, an experimental study was conducted to understand the effects of different fuel properties on droplet vaporization for various conventional and alternative fuels. The study utilized a flow channel to measure the evolution of droplet diameters over time and distance. The results revealed the temperature-dependent effects of physical properties, such as boiling point, liquid density, and enthalpy of vaporization, and showed the complex interactions of preferential vaporization and temperature-dependent influences of physical properties for multi-component fuels.
Article
Energy & Fuels
Yuan Zhuang, Ruikang Wu, Xinyan Wang, Rui Zhai, Changyong Gao
Summary: Through experimental validation and optimization of the chemical kinetic model, it was found that methanol can accelerate the oxidation reaction of ammonia, and methanol can be rapidly oxidized at high concentration. HO2 was found to generate a significant amount of OH radicals, facilitating the oxidation of methanol and ammonia. Rating: 7.5/10.
Article
Energy & Fuels
Radwan M. EL-Zohairy, Ahmed S. Attia, A. S. Huzayyin, Ahmed I. EL-Seesy
Summary: This paper presents a lab-scale experimental study on the impact of diethyl ether (DEE) as an additive to waste cooking oil biodiesel with Jet A-1 on combustion and emission features of a swirl-stabilized premixed flame. The addition of DEE to biodiesel significantly affects the flame temperature distribution and emissions. The W20D20 blend of DEE, biodiesel, and Jet A-1 shows similar flame temperature distribution to Jet A-1 and significantly reduces UHC, CO, and NOx emissions compared to Jet A-1.
Article
Energy & Fuels
Jiang Bian, Ziyuan Zhao, Yang Liu, Ran Cheng, Xuerui Zang, Xuewen Cao
Summary: This study presents a novel method for ammonia separation using supersonic flow and develops a mathematical model to investigate the condensation phenomenon. The results demonstrate that the L-P nucleation model accurately characterizes the nucleation process of ammonia at low temperatures. Numerical simulations also show that increasing pressure and concentration can enhance ammonia condensation efficiency.
Article
Energy & Fuels
Shiyuan Pan, Xiaodan Shi, Beibei Dong, Jan Skvaril, Haoran Zhang, Yongtu Liang, Hailong Li
Summary: Integrating CO2 capture with biomass-fired combined heat and power (bio-CHP) plants is a promising method for achieving negative emissions. This study develops a reliable data-driven model based on the Transformer architecture to predict the flowrate and CO2 concentration of flue gas in real time. The model validation shows high prediction accuracy, and the potential impact of meteorological parameters on model accuracy is assessed. The results demonstrate that the Transformer model outperforms other models and using near-infrared spectral data as input features improves the prediction accuracy.