Article
Thermodynamics
O. Benbouaziz, A. Mameri, A. Hadef, Z. Aouachria
Summary: The study examines the effects of biogas-syngas mixture on flame structure and emissions under MILD conditions, revealing that flame structure is more sensitive to hydrogen content in the syngas. Additionally, an increase in oxygen concentration or temperature in the hot co-flow stream leads to more NO formation, while an increase in Reynolds number reduces NO emissions.
JOURNAL OF APPLIED FLUID MECHANICS
(2021)
Article
Thermodynamics
Salvatore Iavarone, Arthur Pequin, Zhi X. Chen, Nguyen Anh Khoa Doan, Nedunchezhian Swaminathan, Alessandro Parente
Summary: This study investigates the performance of the Partially Stirred Reactor (PaSR) combustion model in Moderate or Intense Low-oxygen Dilution (MILD) combustion conditions using Direct Numerical Simulations (DNS). The results show that the mixing time scale plays a dominant role in the investigated cases, and the PaSR model employing a local dynamic approach for estimating the mixing time scale achieves the best agreement with DNS data.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Thermodynamics
Maria Virginia Manna, Pino Sabia, Raffaele Ragucci, Mara de Joannon
Summary: This study experimentally identified combustion regimes for NH3/O2 mixtures diluted in N2 and found a transition from low temperature combustion to high temperature combustion at 1300K. Kinetic analyses suggest that NH2 oxidation routes play a key role in determining different combustion regimes.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
David M. Peterson
Summary: Simulations were conducted for a round supersonic combustor using a wall-modeled large eddy simulation approach to model turbulence. Combustion was modeled using a small quasi-global mechanism and a more detailed skeletal mechanism. Sensitivity to grid resolution was investigated and a function for the model constant in the partially-stirred reactor model was found. Different combinations of mechanisms and turbulent combustion models can predict the location of the pre-combustion shock train and peak mean pressure, but there are significant differences in temperature and heat release rate fields.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Chemistry, Physical
Shaocai Jin, Yaojie Tu, Hao Liu
Summary: This study reports on the experimental and kinetic modeling investigation of the co-oxidation behavior of NH3/CH4 binary fuel in a jet-stirred reactor. The experimental results reveal that NH3 tends to suppress CH4 oxidation in fuel-lean conditions, but no such effect is observed in stoichiometric and fuel-rich conditions. Kinetic modeling shows that the currently existing reaction mechanisms underestimate NO emissions in the low-intermediate temperature range, indicating the need for further optimization.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2022)
Article
Energy & Fuels
Zhenghong Zhao, Tai Zhang, Xiaoshan Li, Liqi Zhang, Zewu Zhang, Yuxiao Chen, Fan Wu, Cong Luo, Chuguang Zheng
Summary: This study investigates the effects of co-flow CO2 and H2O on the formation of NO in CH4/NH3 flames under MILD-oxy conditions, finding that CO2 dilution alters the radical pool and promotes the MILD regime, with NH3 primarily converting to NO via four routes with HNO as the major intermediate.
Article
Thermodynamics
Tong Jiang, Lingfeng Dai, Chun Zou, Wenyu Li, Haiyang Shi, Yu Yu
Summary: Ammonia has attracted attention as a carbon-free energy carrier with established infrastructure for storage and distribution. However, its low burning velocity and nitrogen content pose challenges for combustion control. Co-burning ammonia with reactive fuels like CH4 or H-2 has been developed as a strategy to overcome these issues. Syngas, produced from biomass pyrolysis, is a promising alternative fuel for transitioning to carbon-free fuels. Co-firing ammonia with syngas is a more environmentally friendly option compared to CH4, but it faces challenges of combustion instability, NOx emissions, and ammonia leakage. This study investigates NH3/syngas MILD combustion using a novel burner, analyzing the impact of temperature and O-2 mole fraction on emissions.
COMBUSTION AND FLAME
(2023)
Article
Engineering, Environmental
Jiarui Zhang, Zhixun Xia, Oliver T. Stein, Likun Ma, Fei Li, Yunchao Feng, Zihao Zhang, Andreas Kronenburg
Summary: In this study, a detailed model for simulating the combustion of aluminum particle clouds with multiple oxidizers was developed. The model was validated and found to accurately predict the distribution of condensed Al2O3. The simulation results showed differences in mass and heat transport and discrete characteristics in the temperature and condensed Al2O3 snapshots. The influence of oxidizer concentration and initial temperature on ignition distance was also analyzed.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Thermodynamics
Erica Quadarella, Arthur Pequin, Alessandro Stagni, Alessandro Parente, Tiziano Faravelli, Hong G. Im
Summary: A generalized Partially-Stirred Reactor (PaSR) model is proposed in this study, which includes multiple chemical times and provides an extension of the Eddy Dissipation Concept (EDC). The approach aims to include the whole set of chemical times involved in the reactive system and characterizes species production rates instead of fine structures. The method is validated with DNS data and shows good agreement with the filtered data, demonstrating the limitations of the old standard approach and the importance of including the whole spectrum of chemical times for a comprehensive description of turbulence-chemistry interaction.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Ziru Zhu, Yan Xiong, Xianglong Zheng, Weijie Chen, Baohe Ren, Yunhan Xiao
Summary: The study explores the impact of different fuel/air mixing modes on NOx and CO emissions in MILD combustion through experiments and numerical simulations. It was found that the temperature distribution varied under different mixing modes, with the premixing mode exhibiting a more uniform temperature distribution. Additionally, optimizing fuel distribution ratios in hybrid modes can help reduce NOx and CO emissions under different thermal intensities.
JOURNAL OF THERMAL SCIENCE
(2021)
Article
Thermodynamics
Viktor Jozsa, Milan Maly, Daniel Fuzesi, Erika Racz, Reka Anna Kardos, Jan Jedelsky
Summary: It has been discovered that distributed combustion can occur outside the MILD combustion regime without the need for flue gas recirculation. The Mixture-Temperature Controlled combustion concept has contributed to this achievement, offering both excellent flame stability and extremely low emission. The research is presently investigating the qualitative characteristics of the cold discharging mixture jet from the burner and its ignition through the use of the Schlieren technique with a high-speed camera. The results confirm the previous hypothesis that distributed combustion features a cold fuel-air mixture at the burner discharge that ignites downstream, and the flame stability is attributed to the fishbone-tiled coherent structures with significant random features.
Article
Energy & Fuels
Cuijiao Ding, Pengfei Li, Kai Wang, Guodong Shi, Feifei Wang, Zhaohui Liu
Summary: This study presents new experimental results on syngas-ammonia oxidation under both N-2 and CO2 atmospheres, investigating the effects of various parameters. It was found that high CO2 concentration delays reactant consumption and enhances CO production, while also affecting N2O formation. Additionally, NO production increases with temperature, initial CH4 concentration, and the CO/H2 ratio, but decreases with increasing equivalence ratio.
Article
Energy & Fuels
Zahraa Dbouk, Nesrine Belhadj, Maxence Lailliau, Roland Benoit, Guillaume Dayma, Philippe Dagaut
Summary: The autoxidation of n-butane was experimentally studied in different conditions. Gas phase samples were analyzed by gas chromatography (GC) and Fourier transform infrared spectroscopy, while liquid phase samples were analyzed by high resolution mass spectrometry (HRMS) and high pressure liquid chromatography (HPLC). Hydroxyl and hydroperoxyl groups were detected in the oxidation products. Kinetic modeling using a literature kinetic mechanism showed the need for improvements to describe the oxidation of n-butane under the studied conditions.
Article
Chemistry, Physical
Nikolas Schmidt, Marcel Mueller, Patrick Preuster, Lars Zigan, Peter Wasserscheid, Stefan Will
Summary: This study presents the development and optimization of a partially premixed hydrogen burner with low emissions of nitric oxides. Numerical investigation and experimental tests are conducted to improve the mixture formation and reduce NOx emissions by optimizing the geometric design of the burner and increasing the relative humidity of the combustion air.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Chemistry, Applied
Zhenghong Zhao, Xiaoshan Li, Zewu Zhang, Xiaojian Zha, Yuxiao Chen, Ge Gao, Fan Wu, Cong Luo, Liqi Zhang
Summary: This paper numerically evaluates the effects of co-flow oxygen concentration and temperature on the combustion regimes and fuel-NO mechanism of CH4/NH3 jet diffusion flames in MILD-oxy combustion. The results show that the appropriate co-flow oxygen concentration and temperature can achieve low-NOx emissions and reduce nitrogen oxide formation.
FUEL PROCESSING TECHNOLOGY
(2022)
Article
Thermodynamics
Kamila Zdybal, James C. Sutherland, Alessandro Parente
Summary: Reduced-order models (ROMs) for turbulent combustion aim to describe complex reacting flows with a small number of effective parameters. This study proposes a quantitative manifold-informed method for selecting a subset of state variables to improve the quality of low-dimensional data representations. The authors demonstrate that a mixture of major and minor species can be beneficial in reducing non-uniqueness and spatial gradients in the dependent variable space.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Mohammad Rafi Malik, Ruslan Khamedov, Francisco E. Hernandez Perez, Axel Coussement, Alessandro Parente, Hong G. Im
Summary: The development of reduced-order combustion models has been challenging in numerical combustion research. Principal Components Analysis (PCA) has shown potential in reducing the dimensionality of reactive systems. The present work applies the Manifold Generated by Local PCA (MG-L-PCA) approach in direct numerical simulation (DNS) of turbulent flames, resulting in accurate and efficient results.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
R. Amaduzzi, A. Bertolino, A. Ozden, R. Malpica Galassi, A. Parente
Summary: This work focuses on quantifying the predictive uncertainty in RANS simulation of a non-premixed lifted flame by considering the uncertainty in the model parameters of the scalar dissipation rate transport equation. Polynomial Chaos Expansions are used as surrogate models to analyze the uncertainty propagation and global sensitivity of these parameters on the quantities of interest (QoIs). The study demonstrates the effectiveness of this approach in providing predictions with estimates of uncertainty and identifies the significant role of certain parameters in affecting the flame temperature predictions.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Alberto Procacci, Ruggero Amaduzzi, Axel Coussement, Alessandro Parente
Summary: This study proposes a sparse sensing framework to create a hybrid numerical-experimental Digital Twin of a practical combustion system. The objective is to determine the optimal sensor placement for minimizing prediction error and predict the distribution of reacting scalars using limited measurements.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Energy & Fuels
Alberto Procacci, Marianna Cafiero, Saurabh Sharma, Muhammad Mustafa Kamal, Axel Coussement, Alessandro Parente
Summary: The objective of this work is to build a Digital Twin of a semi-industrial furnace using Gaussian Process Regression coupled with dimensionality reduction. The Digital Twin integrates temperature, chemiluminescence intensity, and species concentration at the outlet. Experimental measurements include flame temperature distribution, chemiluminescence measurements of OH* and CH*, and species concentration in the exhaust gases. The GPR-based Digital Twin approach is successfully applied on numerical datasets and demonstrated to work on heterogeneous datasets from experimental measurements.
Article
Computer Science, Interdisciplinary Applications
Marco Bellegoni, Leo Cotteleer, Sampath Kumar Raghunathan Srikumar, Gabriele Mosca, Alessandro Gambale, Leonardo Tognotti, Chiara Galletti, Alessandro Parente
Summary: This paper proposes a framework based on the Shear Stress Transport (SST) k-! turbulence model for simulating the Atmospheric Boundary Layer (ABL) in environmental studies. The model is implemented in the open-source OpenFOAM code and shows satisfactory performance.
ENVIRONMENTAL MODELLING & SOFTWARE
(2023)
Article
Chemistry, Physical
Saurabh Sharma, Matteo Savarese, Axel Coussement, Alessandro Parente
Summary: This article investigates the combustion characteristics of dimethyl ether and its mixtures with methane/hydrogen under flameless conditions. The results show that pure dimethyl ether combustion minimizes NO formation, with levels below 10 ppm and no CO or unburned hydrocarbons. The addition of methane reduces NO levels, reaching zero at 50% methane, but increases CO production at higher methane levels. Adding hydrogen forms a more intense reaction zone with a visible flame and higher peak temperatures, while NO emissions increase with higher hydrogen concentrations.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Mechanics
Ilya Simanovskii, Alexander Nepomnyashchy, Antonio Viviani, Patrick Queeckers, Alessandro Parente
Summary: In this study, the influence of two-dimensional spatial inhomogeneity of temperature on the dynamics and instabilities of a droplet floating on a heated liquid substrate was investigated numerically. The results showed that spatial temperature inhomogeneity led to liquid redistribution towards the region of lower temperature, accompanied by a change in droplet shape. Heating from below caused rupture of the substrate layer due to its monotonic instability, and both symmetric and asymmetric droplets were observed under the action of spatial temperature inhomogeneity.
Article
Thermodynamics
Kevin Verleysen, Diederik Coppitters, Alessandro Parente, Francesco Contino
Summary: Regions with abundant renewable energy can establish remote renewable hubs for energy transport to population-dense areas. Ammonia provides a flexible energy carrier for this purpose. A robust design optimization was performed to compare local and remote ammonia production and transport, showing the cost-effectiveness and robustness of the latter approach. However, local production provides higher efficiency and less sensitivity to uncertainties.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
Article
Thermodynamics
Kamila Zdybal, Giuseppe D'Alessio, Antonio Attili, Axel Coussement, James C. Sutherland, Alessandro Parente
Summary: In many reacting flow systems, the thermo-chemical state-space evolves close to a low-dimensional manifold (LDM), which can be obtained using dimensionality reduction methods like principal component analysis (PCA). In this paper, the authors demonstrate that local PCA can detect physically meaningful parameterization of the thermo-chemical state-space, even for complex datasets such as turbulent non-premixed flames. The results highlight the potential of enhancing data-driven techniques like local PCA by incorporating prior knowledge of the system.
APPLICATIONS IN ENERGY AND COMBUSTION SCIENCE
(2023)
Review
Engineering, Aerospace
Soledad Le Clainche, Esteban Ferrer, Sam Gibson, Elisabeth Cross, Alessandro Parente, Ricardo Vinuesa
Summary: This review focuses on the impact of new developments in machine learning on the multi-disciplinary field of aerospace engineering. It discusses the state of the art and the advantages and challenges of ML methods in various aerospace disciplines, as well as future opportunities. The article highlights the improvement of aircraft performance through ML and predicts its significant impact in the near future.
AEROSPACE SCIENCE AND TECHNOLOGY
(2023)
Article
Thermodynamics
Rodolfo S. M. Freitas, Arthur Pequin, Riccardo M. Galassi, Antonio Attili, Alessandro Parente
Summary: The accuracy of combustion predictions in Large Eddy Simulations (LES) can be affected by deficiencies in traditional/simplified closure models, especially for nonconventional fuels and combustion regimes. This study combines machine learning and sparsity-promoting techniques to improve the predictive capabilities of the Partially Stirred Reactor (PaSR) model and its associated cell reacting fraction sub-model. The obtained models are parsimonious and demonstrate the ability of machine learning approaches to improve turbulence-chemistry reactor-based combustion models.
COMBUSTION AND FLAME
(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
Mechanics
Eva Munoz, Himanshu Dave, Giuseppe D'Alessio, Gianluca Bontempi, Alessandro Parente, Soledad Le Clainche
Summary: In this study, the flow fields generated by synthetic jets were simulated and four dimensionality reduction techniques were compared. The results showed that VQPCA has advantages in developing accurate ROMs, while HODMD is useful for understanding the dynamics of synthetic jets.
Article
Computer Science, Software Engineering
Kamila Zdybal, Elizabeth Armstrong, Alessandro Parente, James C. Sutherland
Summary: We present an update to our open-source Python package, PCAfold, which assists researchers in generating, analyzing, and improving low-dimensional data manifolds. The new version, PCAfold 2.0, introduces innovative tools and algorithms for evaluating and optimizing low-dimensional manifolds. These include a method for generating a map of local feature sizes to identify problematic regions, a novel cost function for characterizing manifold topology, and two feature selection algorithms based on principal component analysis. Additionally, we propose a dimensionality reduction strategy that considers the quantity of interest (QoI) and an implementation of partition of unity networks (POUnets) for efficient reconstruction of QoIs from low-dimensional manifolds.
