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Publications (204)
This study introduces a comprehensive numerical model capable of simulating the evaporation of suspended droplets under different gravity conditions. Unlike previous studies, this work provides a detailed description of the multicomponent evaporation process by integrating: (i) interface-resolved evaporation; (ii) suspension by the action of the su...
Carbon nanoparticle (CNP) formation from hydrocarbons combustion is of high interest not only for the study of pollutant (soot) emissions, but, above all, in the area of advanced materials. CNP optical and electronical properties, relevant for practical applications, significantly change with their size, morphology, and nano-
structure. This work e...
This work proposes an innovative model for multicomponent phase change in interface-resolved simulations. The two-phase system is described by a geometric Volume-Of-Fluid (VOF) approach, and considers multiple components in non-isothermal environments, relaxing the hypothesis of pure liquid droplets usually studied in the literature. The model incl...
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...
Blending petroleum fuels with oxygenates is a common approach to stem the depletion of crude oil while also mitigating the impact of their combustion on the environment. It has recently been considered that n-butyl acetate (BA, C6H12O2 , boiling point of 399K) could be a viable oxygenate additive to diesel fuel. In this application it is important...
Thermal pyrolysis of hydrocarbons is a promising solution for the industrial production of hydrogen and valuable carbon materials. Pyrolysis reactor design and scale up strongly benefit from predictive chemical kinetic models capable to comprehensively describe the reactivity in the gas phase, including the undesirable formation of amorphous carbon...
Managing a major event in a road tunnel requires more resources than an open-air event. In the case of fire, the confined environment of road tunnels can represent a critical situation for both users and rescuers. The safety level of a tunnel can be estimated by using dedicated risk models that consider, on the one hand, the traffic (type, quantity...
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...
An experimental and numerical study of combustion of a gasoline certification fuel (‘indolene’), and four (S4) and five (S5) component surrogates for it, is reported for the configurations of an isolated droplet burning with near spherical symmetry in the standard atmosphere, and a single cylinder engine designed for advanced compression ignition o...
α-Methylnaphthalene (AMN) is the primary reference bicyclic aromatic compound of diesel, and it is commonly used as a component of diesel, kerosene and jet-fuel surrogates formulated to describe real fuel combustion kinetics. However, few experimental data on neat AMN combustion are available in the literature. This work provides the first measurem...
In this work, we present a methodology on automatic generation of predictive lumped sub-mechanisms for normal and branched alkanes. This methodology aims at obtaining lumped reaction mechanisms that preserve the chemical behavior of each reaction class in the detailed model. To achieve this goal, detailed sub-mechanisms for combustion of alkanes ar...
Experimental and computational investigation is carried out to elucidate the influence of iso-butanol on critical conditions of autoignition of n-decane and n-heptane. The counterflow configuration is employed. In this configuration an axisymmetric stream of air is directed over the surface of an evaporating pool of a liquid fuel. A stagnation plan...
This paper presents an experimental and numerical study of the combustion of isolated n‑butyl acetate droplets in the standard atmosphere. Numerical simulations are reported using a model that incorporates unsteady gas and liquid transport, variable properties, and radiation. Three skeletal mechanisms of n‑butyl acetate, derived from a large detail...
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...
As the space sector now tends to develop reusable rockets to decrease the cost of access to space, methane is envisioned by several actors around the world as a key fuel for this application. However, the knowledge of methane oxycombustion in rocket engines conditions is very limited due to the high pressure and temperature encountered. This is a m...
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...
In Italy, mainly due to its complex orography, there are more than 50% of road tunnels longer than 500 m belonging to the Trans European Road Network. Moreover, many road tunnels, were designed and built several years ago, where both traffic flows and vehicle sizes were different. Generally speaking, it is possible to state that if on one hand road...
The aim of this research is to analyze the fire events occurred inside the Gran Sasso unidirectional highway tunnel in Italy. The Gran Sasso tunnel consists of two parallel one-way tubes with a length of about 10100 m. The tunnel, managed by Strada dei Parchi S.p.A., is one of the 14 tunnels belonging to the A24 and A25 motorways subject to the app...
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...
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...
As detailed chemical mechanisms are becoming viable for large scale simulations, knowledge and control of the uncertainty correlated to the kinetic parameters are becoming crucial to ensure accurate numerical predictions. A flexible toolbox for the optimization of chemical kinetics has therefore been developed in this work. The toolbox is able to u...
Chemical recycling of solid plastic waste (SPW) is a paramount opportunity to reduce marine and land pollution and to enable the incorporation of the circular economy principle in today's society. In addition to more conscious behaviors and wiser product design (“design for recycling”), a key challenge is the identification of the leading recycling...
Combustion of a seven-component surrogate for a research grade 87 octane gasoline mixed with 10% ethanol is investigated experimentally and numerically from the perspective of an isolated droplet burning under conditions that promote one-dimensional gas transport. The numerical analysis included a kinetic mechanism comprised of 398 species and 24,8...
This work presents a comprehensive kinetic modeling study of the pyrolysis and oxidation of chloromethane. Theoretical calculations were performed for the decomposition reaction CH3Cl + M = CH3 + Cl + M and for a set of relevant H‐abstraction reactions (CH3Cl + R, R = Cl, Ḣ, ȮH, HȮ2, O2, Ö, ĊH3, Ċ2H3, Ċ2H5; CH4 + Cl, C2H6 + Cl, C2H4 + Cl, C2H2 + Cl...
An interface-resolved simulation of the combustion of a fuel droplet suspended in normal gravity is presented in this work, followed by an extensive analysis on the physical aspects involved. The modeling is based on DropletSMOKE++, a multiphase solver developed for the modeling of droplet vaporization and combustion in convective conditions. A wid...
The European Directive 2004/54/EC-concerning minimum safety requirements for tunnels on the trans-European road network-requires a quantitative risk analysis for tunnels belonging to the trans-European road network and longer than 500 m, based on accident data. Strada dei Parchi S.p.A. is a company that manages a large number of road tunnels belong...
This paper illustrates the accidents data observed in 14 road tunnels of the Italian motorway A24 and A25, with particular emphasis on two top events such as fires and release of dangerous goods. Consistent data regarding this kind of events are essential to improve the reliability of quantitative risk analysis models for road tunnels. According to...
In a context of growing level of environmental awareness, emission from aviation are the subject of increasing scrutiny. This situation poses important challenges because, due to safety, practical and economic factors, aero-transportation technologies are not likely to undergo rapid paradigm shifts. An area where important innovations are being int...
Experimental data and detailed numerical modelling are presented on the burning characteristics of a model gasoline/biofuel mixture consisting of n-heptane and iso-butanol. A droplet burning in an environment that minimises the influence of buoyant and forced convective flows in the standard atmosphere is used to promote one-dimensional gas transpo...
This paper aims at presenting the DropletSMOKE++ solver, a comprehensive multidimensional computational framework for the evaporation of fuel droplets, under the influence of a gravity field and an external fluid flow. The Volume Of Fluid (VOF) methodology is adopted to dynamically track the interface, coupled with the solution of energy and specie...
The development of processes with near-zero emissions such as MILD, flameless, and OXY-fuel combustion are of great interest in various energy scenarios. The assessment and design of new burners to meet energy demands and pollution reduction strongly depends on an accurate description of the chemistry involved in the combustion process. The main ou...
Polycyclic aromatic hydrocarbons (PAHs) are known as soot precursors, but their formation/consumption is not fully understood. A recent comprehensive experimental study of premixed laminar ethylene flame [23] investigated the transition from gas-phase to soot particles. The complex fluid dynamics of this system is taken into account to compare mode...
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...
Despite the recent interest in large carboxylic acid oxidation due to their presence in pyrolysis bio-oils, their kinetics of pyrolysis and oxidation has not been experimentally addressed. For the first time, this paper reports a new set of experimental data for the oxidation in a jet-stirred reactor of two high molecular weight carboxylic acids: b...
This chapter illustrates the state of the art of the risk analysis methods and models for road tunnels with particular reference to the users’ egress models.
This chapter describes the interdependence and estimate the reliability of the tunnel infrastructure measures, equipment and management procedures considered in the proposed model.
This chapter describes the approach used to determine the evolution of the consequences for each of the accidental scenarios considered in the risk analysis procedure. The consequence analysis allows to estimate which are the negative effects of the accidents that can affect both the egress and tenability of tunnel users.
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...
Fast biomass pyrolysis is an effective and promising process to obtain high yields of bio-oils, whose upgrading provides valuable fuels for energy application or chemicals for industry. The growing interest in the use of bio-oils in combustion devices to produce energy motivates this study, in which we present the first comprehensive kinetic model...
This paper aims at presenting the DropletSMOKE++ solver, a comprehensive multidimensional computational framework for the evaporation of fuel droplets, under the influence of a gravity field and an external fluid flow. The Volume Of Fluid (VOF) methodology is adopted to dynamically track the interface,coupled with the solution of energy and species...
This chapter describes the egress model of the users who are present in the tunnel. Starting from the user position, the available emergency exits and the dynamics of the accidental scenario, it is possible to verify the required safe egress time of the exposed users with the tenability thresholds.
This chapter describes model calibration in order to verify its consistency. The sensitivity analysis carried out on the parameters and measures considered in the proposed model is described, with the aim of analysing their effect of the shape and position of the F-N curve. In addition, the result of a comparison made using QRAM software and carrie...
This chapter describes in detail the vehicle queue formation model for each lane inside the tunnel following an accident.
The risk analysis process for road tunnels with particular reference to the concept of risk and safety is described in this chapter. In particular, the specific characteristics of the risk models and the techniques of risk representation and acceptance are presented.
This chapter describes the implementation process of the F-N curve, which makes possible to represent the societal risk and subsequently verify its acceptance with respect to the ALARP criterion. The F-N curve is evaluated starting from the frequencies of occurrence of the accidental events and the number of fatalities determined by each accidental...
This chapter describes the logical structure of the proposed tunnel risk analysis model. In particular, the event tree technique for estimating the frequencies of the accidental scenarios and the procedure for defining the location of the accidental scenarios along the tunnel are illustrated.
This chapter describes the distribution model of users in vehicles that are stopped in a queue in each lane of the tunnel. The model allows to estimate the number of users present along the queue of each lane according to the traffic and the type of vehicles.
This book illustrates a new quantitative risk analysis model for road tunnels that is capable of evaluating the role of infrastructure measures, equipment and management procedures as prescribed by EU Directive 2004/54/EC. The risk assessment draws on the typical F-N curves of societal risk, evaluated with the help of event tree analysis, vehicle q...
A detailed kinetic mechanism of soot formation and oxidation is revised and extended to include temperature-dependent collision efficiencies. The collision efficiency for various particle size is studied and compared with experimental data and molecular dynamics simulations for the PAH dimerization where the experimental data are not available. Thi...
Combustion-generated nanoparticles cause detrimental effects to not only health and environment but also combustion efficiency. A detailed kinetic mechanism employing a discrete sectional model is validated using experimental data obtained in laminar counterflow diffusion flames of ethylene/oxygen/nitrogen. Two configurations, named Soot formation...
Experimental and computational investigations are carried out to elucidate the fundamental mechanisms of autoignition of surrogates of jet-fuels at elevated pressures up to 6 bar. The jet-fuels tested are JP-8, Jet-A, and JP-5, and the surrogates tested are the Aachen Surrogate made up of 80 % n-decane and 20 % 1,3,5-trimethylbenzene by mass, Surro...
This paper illustrates and describes the results of a modelling work on the effect of fire dynamics, queue vehicle formation, tunnel geometry on the evacuation modelling in road tunnels. The modelling approach is based on a CFD simulation of the fire development and interaction with tunnel geometry, the effect of vehicular blockage on smoke movemen...