Combustion, Cryogenic Combustion and Sprays

To request a copy of a publication send an email to antonio.ficarella02@gmail.com.

2017

“Photo-Induced combustion of Gaseous Fuels using Carbon Nanotubes as Ignitor Agents: driving and measuring systems, Characterizations”, P. Visconti, P. Primiceri, L. Strafella, A. Lay-Ekuakille and A.P. Carlucci, 2017 I2MTC, May 22-27, Torino (Italy).

Aim of this work is to describe the electronic driving system and the entire experimental setup realized in order to photo-ignite a gaseous fuel/air mixture enriched with Multi-wall carbon nanotubes (MWCNTs) with added metal impurities, makers of photo-ignition process. The realized electronic boards present different features such as variable flash brightness, pulse duration and high flash rate, allowing to fully characterize the combustion process under investigation. Varying the Xenon light source's parameters, the needed light energy/power to ignite MWCNT/Fe mixtures with different weight ratio was found. Experimental results show that lower energy thresholds are required with increasing MWCNTs amount respect to ferrocene. Then, the photo-induced ignition of CNTs mixed with nano-particles was used in a properly realized experimental setup for triggering the combustion of different CNT-enriched air/fuel mixtures (CH4, Liquid Propane and H2). The combustion tests triggered by MWCNTs/ferrocene photo-ignition show better performances (shorter ignition delays, higher peak pressure values and a higher fuel burning rate), for all used gaseous fuels and all tested air / fuel ratios, compared with those obtained by using a traditional spark plug.

“Photo-Ignition process analysis of Multi-Wall carbon nanotubes and ferrocene by CW Xenon lamp as function of mixture ratio and wavelength range”, P. Visconti, P. Primiceri, D. Longo, L. Strafella, M. Lomascolo, G. Mele, P. Carlucci,  Beilstein Journal of Nanotechnology 8 (2017) 134-144 (DOI:10.3762/bjnano.8.14) ISSN: 2190-4286.

This work aims to investigate and characterize the photo-ignition phenomenon of MWCNT/ferrocene mixtures by using a continuous wave (CW) xenon (Xe) light source, in order to find the power ignition threshold by employing a different type of light source as was used in previous research (i.e., pulsed Xe lamp). The experimental photo-ignition tests were carried out by varying the weight ratio of the used mixtures, luminous power, and wavelength range of the incident Xe light by using selective optical filters. For a better explanation of the photo-induced ignition process, the absorption spectra of MWCNT/ferrocene mixtures and ferrocene only were obtained. The experimental results show that the luminous power (related to the entire spectrum of the Xe lamp) needed to trigger the ignition of MWCNT/ferrocene mixtures decreases with increasing metal nanoparticles content according to previously published results when using a different type of light source (i.e., pulsed vs CW Xe light source). Furthermore, less light power is required to trigger photo-ignition when moving towards the ultraviolet (UV) region. This is in agreement with the measured absorption spectra, which present higher absorption values in the UV–vis region for both MWCNT/ferrocene mixtures and ferrocene only diluted in toluene. Finally, a chemo-physical interpretation of the ignition phenomenon is proposed whereby ferrocene photo-excitation, due to photon absorption, produces ferrocene itself in its excited form and is thus capable of promoting electron transfer to MWCNTs. In this way, the resulting radical species, FeCp2 + • and MWCNT − , easily react with oxygen giving rise to the ignition of MWCNT/ferrocene samples. 

“Photo-Induced Ignition of different Gaseous Fuels using Carbon Nanotubes mixed with metal nanoparticles as Ignitor Agents”, P. Carlucci, P. Visconti, P. Primiceri, L. Strafella, A. Ficarella, D. Laforgia, Combustion Science and Technology 189 (2017) Issue 6 937-953 (DOI:10.1080/00102202.2016.1256880).

This paper describes the photo-induced ignition process of Multi Walled Carbon Nano-Tubes (MWCNTs) /ferrocene mixtures by pulsed Xe lamps using programmable driving boards with adjustable parameters such as variable flash rate and pulse’s energy/intensity. Varying the energy of incident light pulse, minimum ignition energy values were found as function of mixture weight ratio, observing that higher MWCNT amount respect to metal nano-particles leads to lower ignition energy. The photo-induced ignition of CNTs mixed with nano-particles was then used in a properly realized experimental setup for triggering the combustion of CNT-enriched fuel mixtures. Different types of gaseous fuels mixed with air (CH4, Liquid Propane and H2) were tested: the combustion process triggered by MWCNTs/ferrocene photo-ignition shows better performances, for all used gaseous fuels and for all tested air/fuel ratios, compared with those obtained by using a traditional spark plug. In particular, CNT-based photo-induced combustion evolves more rapidly with shorter ignition delays, higher peak pressure values and a higher fuel burning rate as observed by reported experimental tests.

“Programmable driving boards of Xenon flash lamps for photo-Ignition process of Carbon Nanotubes added to Air/Methane fuel mixture”, P. Visconti, P. Primiceri, R. Tramis, D. Longo, L. Strafella and A.P. Carlucci, Proceedings of 2016 IEEE 16th International Conference on Environment and Electrical Engineering (EEEIC), June 7-10, 2016 – Florence (Italy). 

This paper describes the design and testing of programmable driving boards for turning on Xenon flash lamps, with the aim to photo-ignite a gaseous fuel/air mixture enriched with Multi-walled carbon nanotubes with added metal impurities, makers of photo-ignition process. The key factor of realized electronic boards is the availability to adjust the triggering parameters of pulsed Xe lamps, allowing to fully characterize the combustion process under investigation. By using the designed PC-configurable boards in the realized experimental setups, the effects of Xenon light source’s parameters such as pulse luminous intensity, flash-rate and time duration have been investigated in order to find the needed light energy/power to ignite MWCNT/Fe mixtures with different weight ratio (from 1:4 to 4:1). Experimental results show that lower energy thresholds are required with increasing MWCNTs amount respect to ferrocene.

2016

“Design and testing of user-configurable driving boards of pulsed Xenon lamps with adjustable flash duration and brightness for Carbon-Nanotubes photo-induced ignition”, P. Visconti, P. Primiceri, D. Longo, R. Tramis, A.P. Carlucci, Journal of Engineering and Applied Sciences 11 (2016) 12336-12342.

This paper describes the design and testing of programmable driving boards for turning on Xenon flash lamps, with the aim to photo-ignite Multi-wall carbon nanotubes (MWCNT) with added metal impurities (ferrocene), makers of photo-ignition process. The realized ac powered electronic boards present different features such as variable flash brightness, pulse duration and high flash rate as function of user-adjustable potentiometers or by PC provided command signals. By using the designed PC-configurable boards in the realized experimental setup, the lighting parameters (i.e. pulse energy/power and energy density) for different Xe lamps have been measured and optimized. Varying temporal/luminous parameters of used light sources by means of realized driving boards, different pulse energy and power values were obtained, in order to fully exploit and analyze MWCNTs/ferrocene photo-induced ignition. Finally, employing these boards, the ignition of MWCNT/Ferrocene mixtures has been triggered and investigated. 

“Multi-Walled Carbon Nanotubes (MWCNTs) as ignition agents for air/methane mixtures”, A.P. Carlucci, G. Ciccarella, L. Strafella,  IEEE Transactions on Nanotechnology Volume 15, Issue 5, September 2016, Article number 7347419, Pages 699-704 (DOI: 10.1109/TNANO.2015.2505907) ISSN: 1536-125X.

The possibility to ignite the single wall carbon nanotubes (SWCNTs) once exposed to the radiation of a flash camera, was observed for the first time in 2002. Subsequently, it was proposed to exploit this property in order to use nanostructured materials as ignition agents for fuel mixtures. Lastly, in 2011, it was shown that SWCNTs can be effectively used as ignition source for an air/ethylene mixture filling a constant volume combustion chamber; the observed combustion presented the characteristics of a homogeneous-like combustion. In the presented experimental activity, the potentiality of igniting an air/methane mixture by flashing multiwall carbon nanotubes (MWCNTs) has been exploited, and the results compared with those obtained igniting the mixture with a traditional spark plug. In detail, two types of tests have been carried out: the first, aiming at comparing the combustion process flashing a variable amount of nanoparticles introduced into the combustion chamber at fixed air/methane ratio; the second, at comparing the combustion process with the one obtained using a traditional engine spark plug, varying the air/methane ratio and at fixed amount of MWCNTs. During tests, the combustion process has been characterized measuring the pressure into the combustion chamber as well as acquiring images with a high-speed camera. The results confirm that the ignition triggered with MWCNTs leads to a faster combustion, without observing a well-defined flame front propagation, observed, as expected, with the spark assisted ignition. Moreover, dynamic pressure measurements show that the MWCNTs photo-ignition determines a more rapid pressure gradient and a higher heat release rate compared to spark assisted ignition.

2015

“Air-Methane mixture ignition with Multi-Walled Carbon NanoTubes (MWCNTs) and comparison with spark plug”, A.P. Carlucci, L. Strafella, Proceedings di ATI 2015 - 70th Conference of the ATI Engineering Association, Roma, 9-11 settembre 2015; Energy Procedia 82 (2015) 915-920 (DOI:10.1016/j.egypro.2015.11.839) ISSN: 1876-6102.

This paper presents the potentialities of a new ignition system based on exposition of multi-walled carbon nanotubes containing 75% in weight of ferrocene to a low-consumption flash camera. The experiments were performed in a constant-volume chamber equipped with an optical access, to allow the acquisition of high-speed camera images, and with a piezoresistive pressure sensor. The chamber was filled with an air-methane gaseous mixture and its combustion was triggered by flashing the nanotubes. The resulting combustion process was compared with the one obtained triggering the mixture ignition with a traditional spark plug. The combustion process was characterized for different air-methane ratios.

2014

"Application and Comparison of Different Combustion Models of High Pressure LOX/CH4 Jet Flames", A. Sciolti, M.G. De Giorgi, A. Ficarella, Energies, 7, 477-497. ISSN 1996-1073,  2014

The present work focuses on the numerical modeling of combustion in liquid-propellant rocket engines. Pressure and temperature are well above thermodynamic critical points of both the propellants and then the reactants show liquid-like characteristics of density and gas-like characteristics for diffusivity. The aim of the work is an efficient numerical description of the phenomena and RANS simulations were performed for this purpose. Hence, in the present work different kinetics, combustion models and thermodynamic approaches were used for combustion modeling first in a trans-critical environment, then in the sub-critical state. For phases treatment the pure Eulerian single phase approach was compared with the Lagrangian/Eulerian description. For modeling combustion, the Probability Density Function (PDF) equilibrium and flamelet approaches and the Eddy Dissipation approach, with two different chemical kinetic mechanisms (the Jones-Lindstedt and the Skeletal model), were used. Real Gas (Soave-Redlich-Kwong and Peng-Robinson) equations were applied. To estimate the suitability of different strategies in phenomenon description, a comparison with experimental data from the literature was performed, using the results for different operative conditions of the Mascotte test bench: trans-critical and subcritical condition for oxygen injection. The main result of this study is the individuation of the DPM approach of the most versatile methods to reproduce cryogenic combustion adapted for different operating conditions and producing good results.

"Potentialities of a common rail injection system for the control of dual fuel biodiesel-producer gas combustion and emissions", A.P. Carlucci, A. Ficarella, D. Laforgia, Journal of Energy Engineering Volume 140, Number 3 A4014011-1 — A4014011-8 (DOI: 10.1061/(ASCE)EY.1943-7897.0000150), 2014.

This paper conducts an extensive experimental campaign for dual fuel biodiesel-producer gas combustion development and the related pollutant emissions and reports the results with the aim of highlighting the effect of biodiesel pilot injection parameters. For this purpose, a common rail diesel research engine was converted to operate in dual fuel mode; the gaseous fuel was introduced into the engine through an indirect injector housed well upstream of the engine intake duct; and the composition of the gaseous fuel simulating the producer gas was obtained using a mixing system able to generate a gaseous mixture of carbon monoxide (CO), hydrogen (H2), and nitrogen (N2) with the desired amount for each of them. The biodiesel pilot injection required to ignite the gaseous fuel was instead sprayed into the cylinder using a common rail high-pressure injection system. During tests, the biodiesel injection amount, pressure, and advance were varied on several levels, together with the composition and amount of gaseous fuel. The cylinder pressure was sampled and, from it, heat release rate and indicated mean effective pressure were estimated. Moreover, gaseous pollutant emissions at the exhaust were measured. The results demonstrate that biodiesel pilot injection parameters are crucial to control the development of combustion and emission levels when the engine is operated in dual fuel biodiesel-producer gas mode. Therefore, the potentialities of the common-rail high-pressure injection system may be developed to optimize as much as possible the operation of such engines in terms of power output, increase in combustion efficiency, and reduction of environmental impact.

2012

"Chemical Kinetics and Injection Modeling for HP LOX/CH4 Jet Flames", Maria Grazia De Giorgi, Aldebara Sciolti, Antonio Ficarella, 67° Congresso Annuale ATI, Trieste (Italy), Sept. 11-14, 2012.

The aim of the present work is to compare different approaches for modeling combustion in cryogenic LOx/CH4 rockets. The oxidizer is liquid oxygen, delivered to combustion chambers as a spray of droplets; the fuel is gaseous methane. Pressure and temperature are well above thermodynamic critical points of both the propellants and so the reactants show liquid-like characteristics for density and gas-like characteristics for diffusivity. A so complex behavior leads to some difficulties in choosing the most appropriate modeling approach for phenomenon description. In literature it is possible to find a large number of experimental works concerning cryogenic combustion of liquid oxygen and gaseous hydrogen under sub-critical and trans-critical conditions but also for methane as fuel. In the present work LOx-methane combustion for G1 and G2 cases of RCM3-VO4 test plane of ONERA have been investigated to compare different approaches in numerical modeling of cryogenic flame. The most important aspects taken into account are combustion models, kinetics descriptions and thermodynamic properties. The Eddy Dissipation combustion model and the Probability density function PDF model were compared; the Jones- Lindstedt and the Skeletal mechanisms were used for kinetics description for the Eddy Dissipation model; for thermodynamic approach, in the current work gas was modeled using both ideal gas and real gas equation of state (Peng-Robinson and SRK) and liquid oxygen was treated with a Lagrangian approach in a hybrid Eulerian- Lagrangian approach for mixture. Numerical predictions were compared with experimental data from literature.

"SPRAY AND COMBUSTION MODELING IN HIGH PRESSURE CRYOGENIC JET FLAMES", Maria Grazia De Giorgi, Aldebara Sciolti, Antonio Ficarella, GT2012-69544, Proceedings of ASME Turbo Expo 2012 - GT2012, June 11-15, Copenhagen, Denmark, Europe, 2012.

The aim of the present work is the investigation of the combustion phenomenon in liquid-propellant rocket engines. The combustion of liquid oxygen and gaseous methane in a shear coaxial injector under supercritical pressure was analyzed. To realize an efficient numerical description of the phenomena, it is important to treat the LOx jet in a manner which takes into account its real behavior. In the present work different kinetics, combustion models and thermodynamics approaches were used in association with the description of the jet as a discrete phase. For all the approaches used, a comparison with experimental data from literature was performed.

2011

Different Combustion Models Applied to High Pressure LOX/CH4 Jet Flames, M. G. De Giorgi, A. Sciolti, A. Ficarella, 4th European Conference for Aerospace Sciences , July 4, 2011 – July 8, 2011, Saint Petersburg, Russia.

The combustion phenomena in liquid-propellant rocket engines are highly complex. The combustion occurs at operating conditions well above of the thermodynamic critical points of the fluid where reactants properties

show liquid-like densities, gas-like diffusivities, and pressure-dependent solubility. Actually, there is a great interest in the development of reusable liquid rocket engines that operates with methane and liquid oxygen as propellants. In the numerical study of LOX/CH4 jet flames there are some critical aspects to be taken into account.

The choice of the combustion model is a critical point: it should be accurate in the phenomena description but it should also characterized by a low computational cost. In the present study different combustion models were used as the Eddy-dissipation finite-rate approach based on Arrhenius chemical kinetics, the equilibrium mixture fraction model (PDF) and the Steady State Flamelet approaches.

In the case of reacting models based on chemical kinetics, both simplified and more complex kinetics models can be used to numerically describe the flames but the critical point in the choice is the individuation of the

best compromise between computational cost and accuracy. In this work different chemical kinetics schemes were used, as the Skeletal mechanism and the Jones- Lindstedt mechanism, that permit to limit the number of reactions and species but taking into account also the intermediate species in the flame.

Finally a purpose of this work is also to develop a pure Eulerian (i.e., single-phase) methodology by using both ideal gas and real gas equation of state and to compare with the discrete phase approach that uses an

Eulerian description of the gas phase and Lagrangian equations for the dilute spray. For all the models used, a comparison with experimental data from literature was performed.

"Comparisons between different combustion models for High pressure LOX/ CH4 jet flames", M. G. De Giorgi, A. Sciolti, A. Ficarella, 41st AIAA Fluid Dynamics Conference and Exhibit, 27-30 June 2011, Honolulu, Hawaii, USA.

This paper presents an investigation of LOX/CH4 Liquid Rocket Engines injector flames to investigate the impact of real gas effects and the combustion models on the predictions. In liquid-propellant rocket engines the combustion occurs at operating conditions well above of the thermodynamic critical points of the fluid where reactants properties show liquid-like densities, gas-like diffusivities, and pressure-dependent solubility. So using real gas properties as accurately as possible is a key issue in the preliminary design of LRE injectors and combustion chambers. In the numerical study of LOX/CH4 jet flames a critical aspect is the choice of the combustion model, that should be accurate and a well compromise between phenomena description and computational costs. Complex, simplified and reduced kinetics scheme could be implemented in the CFD modeling of cryogenic spray and to make a well choice of the modeling approach it is necessary to estimate the mixing and kinetic time scales in the case of study. In the rockets it’s generally possible to assume that the chemistry is infinitely fast and that burnt gas conditions can be approximated like similar to the chemical equilibrium condition. Under these conditions a simple finite rate combustion model is less

realistic; otherwise an Eddy Dissipation Approach or Flamelet model could more realistically model phenomena. In this work LOX/CH4 jet flames at high pressure have been simulated by implementing different kinetic mechanisms usually presented in literature for the methane/air flame, starting from the simple one step mechanism up to the detailed Skeletal model derived from the Grimech 3.0. Then results obtained using some simplified mechanisms, as the Modified Jones-Lindstedt kinetics model, more accurate for combustion in presence of pure oxygen have been compared with the previous ones. EDC and Non- Premixed Combustion Model, including flamelet approaches are implemented in the CFD Fluent v.13.0 code, like in the present work, it is not possible to take into account real gas effetcs with the non-premixed model. Real gas effects have been also considered in the case of EDC combustion model. In a liquid rocket engine at high pressures real gas effect needs to be modelled by using a Real Gas Equation of State (RG EOS). In the current work the real

gas effects have been modelled by the Soave-Redlich-Kwong (SRK) real gas model.

2010 and before

“Numerical modelling of high-pressure cryogenic sprays”, MG. De Giorgi, L. Tarantino, A. Ficarella, D. Laforgia. AIAA 40th Fluid Dynamics Conference and Exhibit, Chicago, USA, June 28 – July 1, 2010.

Super-critical mixing and combustion phenomena involves a large spectrum of interconnected physical processes which determine complexity in the problem formulation. Near critical or trans-critical condition the reacting mixture exhibits large variation in thermodynamic and transport properties, which affect drastically the mixing and combustion processes.

The aim of this investigation is the implementation by user defined routines of thermodynamically consistent real gas mixing equation of state into the commercially available CFD-code ANSYS Fluent and the validation using experimental data. CFD simulations have been also performed by using different approaches: the Soave Redlich-Kwong real gas model and Peng Robinson have been implemented to model the physical properties of the species.

This work is divided in two parts: in the first part a numerical analysis has been conducted to study the nitrogen high pressure flow in liquid rocket near the critical point , in the second the numerical study of the LOX/H2 and LOX/CH4 injection, mixing and combustion in liquid rocket engines with shear coaxial injectors, at supercritical conditions by using one-step reaction mechanism and detailed chemical kinetic reaction mechanism.

“Real Fluid Modelling of Supercritical Reacting Flows in Liquid Rocket Engine”, M.G. De Giorgi, A. Ficarella, EUCASS 2009, Versaille (France), Yuly 2009.

A current problem is to understand the injection, mixing and combustion in typical liquid rocket engines and combustion chambers conditions. Until now, only H2/LOx injection and combustion has been investigated deeply, while there is a lack in experimental data and numerical studies in literature on LOX/CH4 combustion, and it is not possible to transfer concepts design from LOX/H2 injector to LOX/CH4 injector. At typical injection conditions H2 is far in the supercritical region and shows in a good approximation ideal gas behavior. Methane however is near critical and real gas effects are to be taking into account in the mixing process. The prediction of all thermodynamic properties depend on the equation of state chosen. In the present work CFD simulations have been performed for the simulation of supercritical LOx- CH4 spray using the Soave-Redlick-Kwong and the Peng Robinson equations of state.

“Study Of Supercritical Cryogenic Spray”, MG. De Giorgi, A. Ficarella, A. Leuzzi, Festival dell’innovazione- Giornata Sulla Ricerca Nel Settore Aerospaziale In Puglia, Bari (Italy), Dec. 4th, 2008. 

“Combustion Conditions Discrimination Properties of Pt-doped TiO2 Thin Film Oxygen Sensor”, L. Francioso, D.S. Presicce, P. Siciliano, A. Ficarella, Sensors and Actuators B: Chemical, Volume 123, Issue 1, 10 April 2007, Pages 516-521. 

Present work focuses on evaluation of microfabricated Pt-doped titanium oxide thin film sensors capability to discriminate different combustion conditions of a real gasoline engine; actually, zirconia-based lambda probes are a well-established technology in the field of combustion control for fuel injection engines, but these devices suffer high production cost. A cheap mass fabrication method to produce thin film platinum-doped titania sensors is presented, together with an experimental validation of performances under real working conditions. A dedicated experimental bench enabled simultaneous data acquisition of a Bosch lambda probe Mod. LSF 4.2 and the Pt-doped TiO2 thin film sensor fabricated onto ceramic alumina substrates.

Three different operative temperatures were investigated concerning response times and successful classification rate; a simple threshold-based ON/OFF data analysis allows satisfactory results about discrimination between rich and lean combustion conditions.

"Optimization Of An Industrial Coal Pulvirezed Swirled Burner By Cfd Modelling", M.G. De Giorgi, A. Ficarella, D. Laforgia, Atti del 61° Congresso Nazionale ATI, Perugia, 12-15 Settembre 2006. 

In this study an industrial pulverized coal swirl burner has been modelled by a CFD commercial code , Fluent 6.2.16.

The current study focuses on the modelling of coal combustion, taking into account: coal devolatilisation, volatile combustion and char combustion.

Previous to simulate the real industrial burner, three-dimensional numerical simulations of a pulverized coal furnace (IFRF) were used to assess the influence of the coal combustion model on predicted results, by comparison with experimental data. In particular, two different combustion models have been used for the volatile combustion: the equilibrium mixture fraction model (PDF), and the Finite Rate model where the turbulence-chemistry interaction has been modelled with the Eddy Dissipation. After these investigations the PDF combustion model has been chosen to study a real industrial burner and to estimate the NOx. A 3-D numerical model of the burner was studied under different operating conditions. The computations were performed to show the effect of the primary and secondary mass flow rate on the burner performance, with particular attention to the NO emissions.

Temperature and doping effects on performance of titania thin film lambda probe, D.S. Presicce, L. Francioso, M. Epifani, P. Siciliano, A. Ficarella, Sensors and Actuators B: Chemical, Volumes 111-112, 11 November 2005, Pages 52-57.

The aim of this work is to carry out a performance comparison between a commercial Bosch Lambda probe and a sol–gel TiO2 thin film deposited on alumina substrates. Actually, zirconia-based lambda probes are a well-established technology in the field of combustion control in fuel injection engines. An experimental bench was realized in order to perform the contemporary data acquisition of a Bosch lambda probe Mod. LSF 4.2 and TiO2 thin film sensors. The signals of both the sensors are acquired with an electrometer with a scanner card on real gasoline engine. Fast response time is observed from TiO2 sol–gel sensor, while best results were obtained from first experimental data on Pt-doped devices, that outline that the response time was comparable with the commercial probe.

"Cheap silicon technology integrated sol-gel combustion sensor", Francioso, L., Presicce, D.S., Epifani, M., Siciliano, P., Ficarella, A., Proceedings of SPIE - The International Society for Optical Engineering, Volume 5836, 2005, Article number 27, Pages 255-262, Smart Sensors, Actuators, and MEMS II; Seville; Code 66130. ISSN: 0277786X DOI: 10.1117/12.608565; 9 May 2005 through 11 May 2005.

The aim of this work is the fabrication of a cheap sol-gel Pt-doped TiO2 thin film sensor on silicon substrate, evaluate electrical performances of electrical interconnections and responses of sensitive film in severe environment like exhaust of combustion process. The sensor will be implemented as microsensors for NOx or oxygen detection, while a preliminary investigation on real operative conditions shows that the transducers perform a response time (t90) in real condition smaller than 1 second at 600 °C. Application field of this type of transducer will be evaluated in a real spark ignition engine, to monitor air/fuel ratio and also monitoring the combustion quality in other industrial combustion processes like domestic heating systems. The production process of this devices, and particularly thin film deposition, can be carried out on a 3" silicon wafer and obtaining with a single batch process more than 300 sensors for wafer, 2x2 mm2. The sensors are provided with an integrated heater and a thermometer to perform temperature compensation. Actually this work try to develop an affordable process to integrate cheap sol-gel deposition process with silicon technology; a particular study is devoted to a complete photolithographic patterning of titania sensitive film, that is very difficult to etch after complete annealing, in order to have sensitive film only onto well defined areas of wafer. Same process, with little modification, can be applied to different kind of sensitive film, pure and doped ones. Different strategies on protective coating were evaluated to reduce electrical contacts degradation at high temperatures, obtaining long time stability of overall microsensor.

“Response evaluation of TiO2 sensor to flue gas on spark ignition engine and in controlled environment”, L. Francioso, D. S. Presicce, M. Epifani, P. Siciliano, A. Ficarella, Sensor and Actuators, B, 107 (2), 563-571, 2005.

Increasingly strict emissions regulations and heightened environmental awareness on the part of users around the world have led to energetic research into emissions reduction by various automobile manufacturers and research institutes. In this paper we tested sol–gel TiO2 sensor in order to evaluate the reliability and combustion sensor properties in controlled environment and on spark ignition engine. Experiments were carried out for understanding influence of single gas component of flue gas on the response of TiO2 sensor and evaluate transducer behaviour on real spark ignition engine. Higher responses were obtained for oxygen and nitrogen oxide, rather than CO2 and CH4. So TiO2 sensor was more sensitive towards the first components of mixture, and good response times were observed on engine bench.

“Performance Comparisons between Commercial and TiO2 Thin Film Lambda Probes”, L. Francioso, D. S. Presicce, M. Epifani, R. Rella, P. Siciliano, D. Laforgia, A. Ficarella, Eurosensor XVIII, Roma, 12-15 September 2004.

The aim of this work is to evaluate performance comparison between a commercial Bosch Lambda probe and a sol-gel TiO2 thin film deposited an alumina substrates. Actually, zirconia based lambda probes are a well-established tecnology in the field of combustion control in fuel injection engines.The signals of both sensors is acquired with fast scanner electrometer on real gasoline engine. Fast response time of about 1 second from rich to lean mixture is observed from TiO2 sol-gel sensor.

“Automotive Application of Sol-gel TiO2 Thin Film-based Sensor for Lambda Measurement”, L. Francioso, D. S. Presicce, A. M. Taurino, R. Rella, P. Siciliano, A. Ficarella, Sensors & Actuators B: Chemical, n. 95, pp. 66-72, Oct. 2003.

“A TiO2 Sensor Probe for Monitoring the Exhaust Gas for Automotive Application”, al E-MRS Spring Meeting, Strasbourg (France), June 10-13, 2003.” Presentato anche con il titolo "Microsensore allo stato solido per il controllo della combustione di un motore", in coll. con D. S. Presicce, L. Francioso, A. Ficarella, D. Laforgia, R. Rella, P. Siciliano, Atti del 58° Congresso Nazionale ATI, Padova-San Martino di Castrozza, 9-12 settembre 2003.

"Sol-gel TiO2 Thin Film sensors for combustion control in automotive applications", D. S. Presicce, A. Ficarella, D. Laforgia, L. Francioso, R. Rella, P. Siciliano, Proceedings of the 6th International Conference on Engines for Automobile ICE03, Capri, Sept. 14-19, 2003. SAE Paper SAE-NA 2003-01-83.

“Sol-gel TiO2 thin film sensor for lambda measurement”, D. S. Presicce, A. Ficarella, D. Laforgia, L. Francioso, R. Rella, P. Siciliano, congresso AISEM, Trento, febbraio. Presentato anche al 2003 EUROSENSOR XVI, The 16th European Conference on Solid-State Transducers, Prague (Czech Republic), 15-18 settembre 2002.

“Numerical Simulation of Flow-Field and Dioxines Chemistry for Incineration Plants and Experimental Investigation”, A. Ficarella, D. Laforgia, Atti del Dipartimento di Ingegneria dell’Innovazione, Università di Lecce, 1999. Waste Management, n. 20, pp. 27-49, Feb. 2000.

"Isothermal and Reactive Modeling of a Dry Low NOx Combustor: Computational Study", in collaborazione con D. Laforgia e P. Lonero, Proceedings of Flowers 97, Firenze (Italia), 30 luglio - 1 agosto 1997.

"Residence Time Behaviour and Decomposition of Dioxines in Biomedical and Hazardous Waste Incineration Plant", in collaborazione con D. Laforgia, 49° Congresso Nazionale ATI, Perugia, 26-30 settembre 1994.

"Theoretical Study of Post Combustion Chamber for Hospital and Hazardous Waste", in collaborazione con D. Laforgia, presentato al CROCUS (Combustion related Organization Common and Unified Symposium), Salsomaggiore Terme, 20-23 settembre, 1994.

“Theoretical and Experimental Study of Post-Combustion Chamber”, in collaborazione con F. Amodio, L. Lacquaniti, G. Blasi, D. Laforgia, Journees Internationales su les Flamme, Biarritz (Francia), 16-18 marzo, 1994.

"3-D Thermal-Fluid Dynamic Study of Hazardous Hospital Waste Incinerator", in collaborazione con G. Blasi, D. Laforgia e N. Stasolla, Journees Internationales su les Flamme, Biarritz (Francia), 16-18 marzo, 1994.

"Hospital and Special Waste Incineration: Laboratory and Pilot Plant Experimentations", in collaborazione con F. Amodio, G. Blasi, D. Laforgia, G. Morabito, D. Ricci, Journees Internationales su les Flamme, Biarritz (Francia), 16-18 marzo 1994.