
Alessandro StagniPolitecnico di Milano | Polimi · Department of Chemistry, Materials and Chemical Engineering "Giulio Natta"
Alessandro Stagni
PhD in Industrial Chemistry and Chemical Engineering
About
76
Publications
19,711
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,966
Citations
Introduction
My research activity deals with the kinetic modeling of pollutants formation in combustion processes, and the chemical-kinetic analysis of reacting systems of hydrocarbons. This is ultimately targeted at accommodating the information included in detailed kinetic mechanisms into large-scale computations. For this reason, my research interest is devoted, to a major extent, to the reduction of chemical kinetic mechanisms to a skeletal level.
Additional affiliations
January 2021 - present
November 2019 - February 2020
June 2017 - January 2021
Publications
Publications (76)
The ongoing global energy transition towards renewable zero-carbon energy carriers demands a disruptive evolution of the combustion process inside internal combustion engines (ICEs). In many ways, ammonia (NH 3) is an ideal candidate as future energy carrier due to the absence of carbon content, a well-established renewable production process, and...
The practical use of hydrogen as a fuel for Internal Combustion Engines (ICEs) poses unresolved challenges. However, many issues concerning combustion control and emissions do not originate from the fuel itself but rather from the inevitable interference of lubricant oil in the combustion process. This study investigates the catalytic action of lub...
This research introduces an innovative approach to predict benzene Lower and Upper Flammability Limits (LFL and UFL). The focus of this study is on predicting the flammable range of benzene/air/steam mixtures utilizing a freely-propagating flame method, incorporating an optically-thin approximation to model soot radiation. The investigation delves...
Co-firing ammonia with coal is a promising and feasible technology for reducing coal-related carbon emissions. Pyrolysis and ignition of ammonia-coal blended fuels are the key steps for flame stability and boiler operation safety throughout the conversion process but remain unclear. In this work, an extended Euler-Lagrange framework coupled to deta...
In the near future, biomass is expected to be a key resource for fulfilling clean energy requirements. The pre-dictive modeling of biomass conversion in industrial systems is still challenging due to the multi-scale nature of the processes involved, including complex chemical reactions. To provide a detailed description and analysis of these reacti...
The kinetic mechanisms describing the combustion of longer-chain fuels often have limited applicability due to the high number of species involved in their oxidation and decomposition paths. This work proposes a combined methodology for developing compact but accurate kinetic mechanisms of these fuels and applies it to dimethoxymethane (DMM), or ox...
div class="section abstract"> In the rapidly changing scenario of the energy transition, data-driven tools for kinetic mechanism development and testing can greatly support the evaluation of the combustion properties of new potential e-fuels. Despite the effectiveness of kinetic mechanism generation and optimization procedures and the increased ava...
Understanding the chemistry behind the oxidation of ammonia/hydrogen mixtures is crucial for ensuring the flexible use of such mixtures in several applications, related to propulsion systems and power generation. In this work, the oxidation of ammonia/hydrogen blends was investigated through an experimental and kinetic-modeling study, where the low...
The urgent need to reduce the dependence on fossil fuels has re-ignited the interest toward Hydrogen Internal Combustion Engines (HICEs). Nevertheless, there are still criticalities that need to be assessed for accelerating the development of this technology. The undesired but unavoidable participation of lubricant oil to the combustion process can...
Dimethyl ether (DME) is a widely recognized alternative fuel which can be sustainably produced from different feedstock. Its oxidation mechanism belongs to the most deeply understood within oxygenated fuels. The oxidation of DME in the presence of NO has gained renewed attention in recent experimental and modeling efforts because of a rather comple...
Validation is an essential procedure in the development of a predictive model in several engineering fields. In addition, recent data analysis techniques and the increasing availability of data have the potential to provide a deeper understanding of experimental data and simulation models. This work proposes a systematic, objective, and automatic m...
Unraveling the low-temperature chemistry of ammonia is still an open challenge in combustion kinetics, yet of primary importance because of the novel combustion concepts operating in these conditions, as well as of the rising interest on ammonia as an energy carrier. In this work, a fundamental investigation of the H-abstraction reactions from H2NO...
A generalized Partially-Stirred Reactor (PaSR) model is presented in this work based on the inclusion of multiple chemical times. The PaSR model has shown promising results at modelling turbulence-chemistry interaction in Large-Eddy Simulations (LES) and Reynolds-Averaged Navier-Stokes (RANS), providing an extension of the well-known Eddy Dissipati...
Dimethyl ether (DME), a widely studied alternative fuel, is known to exhibit complex low- and high-temperature oxidation chemistry. It is also the smallest molecule in the families of symmetric ethers and oxymethylene ethers that receive attention as renewable fuels. Thanks to several studies performed in facilities such as shock tubes, jet-stirred...
Ammonia/hydrogen mixtures are among the most promising solutions to decarbonize the transportation and energy sector. The implementation of these alternative energy carriers in practical systems requires developing suitable numerical tools, able to estimate their burning velocities as a function of both thermodynamic conditions and mixture quality....
Hydrogen sulfide chemistry has recently undergone a renewed interest due to the current energy transition, requiring a proper treatment of such impurities in the sources like shale gas or biogas. Moreover, the lower-temperature, diluted conditions considered nowadays for reducing pollutant emissions require a wider-range development and validation...
One of the major drivers beyond the development of flameless technology is its potential to cut the emissions of nitrogen oxides (NOx) far below the harmful levels for both human health and the environment. Yet, although decades of research have consolidated the knowledge on the processes of NOx formation at high temperature, a complete understandi...
Fundamental studies on Flame-Wall Interaction (FWI) are of the utmost importance to unravel the intricate coupling between chemistry and transport in the near-wall region, and to characterize the quenching dynamics. For this purpose, an accurate description of reaction kinetics is especially needed. In this work, the role of chemistry during the wa...
The development of scientific predictive models has been of great interest over the decades. A scientific model is capable of forecasting domain outcomes without the necessity of performing expensive experiments. In particular, in combustion kinetics, the model can help improving the combustion facilities and the fuel efficiency reducing the pollut...
In this work, we propose a novel data-driven approach for detailed kinetic mechanisms optimization. The approach is founded on a curve matching-based objective function and includes a methodology for the optimisation of pressure-dependent reactions via logarithmic interpolation (PLOG format). In order to highlight the advantages of the new formulat...
Coke oven gas (COG) is a valuable by-product of coke-making process, due to its high H2 content and calorific value. The potential exploitation of COG as an energy carrier requires a proper characterization of its kinetic behavior. Moreover, the residual presence of aromatic compounds in COG can potentially affect both its combustion efficiency and...
Carrier-phase direct numerical simulation of detailed NOx formation in pulverized coal flames (PCC) with fuel-bound nitrogen is conducted in a 3D temporally evolving mixing layer setup where Lagrangian particles (Colombian bituminous coal) in an air stream (upper half of the domain) mix with the products of lean volatile/air combustion in the lower...
Fast biomass pyrolysis is an effective and promising process for high bio-oil yields, and represents one of the front-end technologies to provide alternative, sustainable fuels as a replacement of conventional, fossil-based ones. In this work, the effect of droplet initial diameter on the evaporation and ignition of droplets of crude fast pyrolysis...
Fast-pyrolysis bio-oils (FPBOs) obtained from lignocellulosic biomass are gaining attention as sustainable fuels for various applications, including the transport sector and power production. A significant fraction of bio-oils is constituted by nitrogen-containing compounds (N fuels) that should be considered when developing surrogate models for FP...
The numerical investigation of quenching distances in laminar flows is mainly concerned
with two setups: head-on quenching (HOQ) and side-wall quenching (SWQ). While most
of the numerical work has been conducted for HOQ with good agreement between simulation and experiment, far less analysis has been done for SWQ. Most of the SWQ simulations used s...
Coke oven gas (COG) is a valuable by-product of coke-making process, due to its high H2 content and calorific value. The potential exploitation of COG as an energy carrier requires a proper characterization of its kinetic behavior. Moreover, the residual presence of aromatic compounds in COG can potentially affect both its combustion efficiency and...
The numerical investigation of quenching distances in laminar flows is mainly concerned with two setups: head-on quenching (HOQ) and side-wall quenching (SWQ). While most of the numerical work has been conducted for HOQ with good agreement between simulation and experiment, far less analysis has been done for SWQ. Most of the SWQ simulations used s...
The influence of the addition of ammonia on the oxidation of methane was investigated both experimentally and numerically. Experiments were carried out at atmospheric pressure, using a fused silica jet-stirred reactor, and a recrystallized alumina tubular reactor designed on purpose to reach temperatures as high as ∼2000 K. A temperature range of 6...
The large number of species included in the detailed kinetic mechanisms represents a seriouschallenge for numerical simulations of reactive flows, as it can lead to large CPU times, even forrelatively simple systems. One possible solution to mitigate the computational cost of detailed numericalsimulations, without sacrificing their accuracy, is to...
A complete understanding of the mechanism of ammonia pyrolysis and oxidation in the full range of operating conditions displayed by industrial applications is one of the challenges of modern combustion kinetics. In this work, a wide-range investigation of the oxidation mechanism of ammonia was performed. Experimental campaigns were carried out in a...
The stable operation of low-temperature combustion processes is an open challenge, due to the presence of undesired deviations from steady-state conditions: among them, oscillatory behaviors have been raising significant interest. In this work, the establishment of limit cycles during the combustion of hydrocarbons in a well- stirred reactor was an...
Benzaldehyde is an aromatic aldehyde commonly considered in bio-oil surrogate formulation, and an important intermediate in the oxidation of other aromatic reference fuels such as toluene. However, its oxidation has never been previously investigated experimentally and no product formation profiles were reported in the very limited pyrolysis studie...
Numerical simulations of multi-dimensional laminar flames with complex kinetic mechanisms are computationally very demanding, because of the large number of species and the strong non-linearity and stiffness of governing equations. In this work, we present and apply a novel adaptive chemistry methodology for mitigating the computational cost of suc...
The application of porous media in compression ignition engines has significant effects on its combustion behavior. In this work, a Computational Fluid Dynamics (CFD) analysis of combustion in diesel engine is performed for 100% load, and the effects of porous media addition in the combustion chamber are quantified. With a porosity of 66.7%, silico...
In this work, the flammable range of several hydrocarbons was predicted using a freely-propagating flame method for pure hydrocarbons and their mixtures, investigating the effects of operating conditions, in terms of temperature, pressure, fuel/oxidizer composition. The model showed accurate agreement with a wide set of experimental data. The avera...
The sharing of scientific and scholarly data has been increasingly promoted over the last decade, leading to open repositories in many different scientific domains. However, data sharing and open data are not final goals in themselves, the real benefit is in data reuse, which allows leveraging investments in research and enables large-scale data-dr...
Fully-resolved simulations of the heating, ignition, volatile flame combustion and char conversion of single coal particles in convective gas environments are conducted and compared to experimental data (Molina and Shaddix, 2007). This work extends a previous computational study (Tufano et al., 2016) by adding a significant level of model fidelity...
The oxidation of neat methane (CH4) and CH4 doped with NO2 or NO in argon has been investigated in a jet-stirred reactor at 107 kPa, temperatures between 650 and 1200 K, with a fixed residence time of 1.5 s, and for different equivalence ratios (Φ), ranging from fuel-lean to fuel-rich conditions. Four different diagnostics have been used: gas chrom...
The influence of the main process parameters on the oscillatory behavior of methane oxidation was analyzed in conditions relevant for Low Temperature Combustion (LTC) processes. The investigation was performed by means of direct comparisons between experimental measurements realized in two Jet Stirred Flow Reactors used at atmospheric pressure. Cou...
Biogas (mainly methane and carbon dioxide) produced from biomass anaerobic digestion is considered as a potential renewable gas-phase fuel. That is why the study of the mutual effects of CH4/NOx have attracted considerable attention in the past decade. In this work, the oxidation of methane with and without NOx addition has been investigated in a j...
Repositories for scientific and scholarly data are valuable resources to share, search, and reuse data by the community. Such repositories are essential in data-driven research based on experimental data. In this paper we focus on the case of combustion kinetic modeling, where the goal is to design models typically validated by means of comparisons...
The use of isolated droplets as idealized systems is an established practice to get an insight on the physics of combustion, and an optimal test field to verify physical submodels. In this context, this work examines the dynamics of soot formation from the combustion of hydrocarbon liquid fuels in such conditions. A detailed, heterogeneous kinetic...
The continuous research towards novel combustion technologies, operating at high temperatures and pressures, has recently raised the question of the influence of low temperature chemistry in such conditions. As a first step in identifying the potentially critical conditions where low temperature oxidation might play a major role, this theoretical s...
The Catalytic Partial Oxidation (CPO) of two octane isomers, 2,2,4-trimethyl pentane (iso-octane) and n-octane, chosen as representative of gasoline is investigated by means of adiabatic tests and mathematical modeling. CPO experiments were carried out in a lab scale auto-thermal reformer with honeycomb monolith catalysts (2% Rh/α-Al2O3), equipped...
Nowadays, detailed kinetics is necessary for a proper estimation of both flame structure and pollutant formation in compression ignition engines. However, large mechanisms and the need to include turbulence/chemistry interaction introduce significant computational overheads. For this reason, tabulated kinetics is employed as a possible solution to...
Moderate or intense low oxygen dilution (MILD) combustion has been the subject of numerous studies in recent years. An issue remains, however, in the definition of the boundaries of the MILD combustion regime with respect to non-premixed configurations without predefined reference temperatures. A flamelet definition is applied to non-premixed confi...
Experimental and computational investigation is carried out to elucidate the fundamental mechanism of autoignition of n-heptane, n-decane, and n-dodecane in non-premixed flows at elevated pressures up to 6 bar. The counterflow configuration is employed. In this configuration, an axisymmetric flow of a gaseous oxidizer stream is directed over the su...
In this work, a skeletal kinetic mechanism is obtained for the Integrated Development on Engine Action (IDEA) surrogate, i.e. a mixture of n-decane (ND) and α-methylnaphthalene (MN), and comprehensively validated. The lumped POLIMI_TOT_1407 pyrolysis and oxidation mechanism of hydrocarbon and oxygenated fuels, containing 451 species and 17,747 reac...
Because the numerical simulation of soot production in turbulent flames is quite challenging, it is useful to consider simpler aerodynamic configurations retaining unsteady strain rate and curvature effects. The present article reports detailed numerical simulations of a planar vortex interacting with a sooting laminar diffusion flame formed by a p...
The increasing number of experimental data, accurate thermodynamic and reaction rate parameters drive the extension, revision, and update of large size kinetic mechanisms. Despite these detailed mechanisms (i.e. the models) generally allow good predictive capabilities, their management and update are critical. The usual validation procedure of a ki...
This work examines the importance of preferential evaporation and liquid species diffusion on the ignition of multicomponent surrogate fuels in homogeneous mixtures. To this end, a model is developed that considers the evaporation of a monodisperse droplet cloud in a homogeneous and isobaric gas-phase environment. The mathematical model accounts fo...
In the continual effort to reduce emissions and improve efficiency, moderate or intense low-oxygen dilution combustion has been suggested for aeroengine applications. This new application of moderate or intense low-oxygen dilution combustion requires further insight in applying the knowledge from conventional analyses of well-mixed systems to non-p...
Moderate or intense low oxygen dilution (MILD) combustion has been the subject of numerous studies in recent years. The boundaries of the MILD regime have, however, only been defined with respect to premixed configurations. These previous definitions have been based on the initial and final states of a perfectly-stirred reactor relative to the fuel...
The use of simplifying techniques to obtain skeletal kinetic mechanisms with the required accuracy is often a necessary step when computationally demanding simulations are concerned. In this work, a novel approach for an automatic mechanism reduction, aimed at retaining accuracy on specific target species, is proposed. Starting from the consolidate...
Detailed chemistry represents a fundamental prerequisite for a realistic simulation of combustion process in diesel engines. In this work, the authors developed a reduced mechanism for n-dodecane starting from the comprehensive POLIMI_TOT_1407 kinetic mechanism, already well validated and tested in a wide range of operating conditions. This reduced...
Combustion in next-generation aero-engines may occur in conditions in, or approaching, moderate or intense low oxygen dilution (MILD) combustion. Under these conditions, fresh fuel is injected into a hot, low oxygen environment. Autoignition delays for ethylene, with detailed chemical kinetics, in three different oxidants are systematically analyse...
The low and the high temperature oxidation mechanism of n-heptane has been extensively studied in recent and past literature due to its importance as a primary reference fuel. Recent advanced analytical methods allowed to identify several intermediate oxygenated species, at very low temperature conditions in jet stirred reactors. On these bases, ne...
The kinetic modeling of the pyrolysis and combustion of liquid transportation fuels is a very complex task for two different reasons: the challenging characterization of the complex mixture of several hydrocarbon isomers and the complexity of the oxidation mechanisms of large hydrocarbon and oxygenated molecules. While surrogate mixtures of referen...
When it comes to handling large hydrocarbon molecules and describing the pyrolysis and combustion behavior of complex mixtures, the potential and limitations of detailed ch