Antonio Paolo Carlucci

Multiwalled Carbon Nanotubes (MWCNTs) as Ignition Agents for Air/Methane Mixtures

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.

Improvements in Dual-Fuel Biodiesel-Producer Gas Combustion at Low Loads through Pilot Injection Splitting

AbstractIn dual-fuel engines, a combustible mixture of air and generally a gaseous fuel is ignited, thanks to the injection and autoignition of a small amount of liquid fuel. It is well-known that dual-fuel engines suffer from poor combustion when operated at low loads. This behavior, due mainly to the presence of an overlean mixture into the combustion chamber, leads to unacceptably high levels of carbon monoxide and unburned hydrocarbons emitted at the exhaust. In order to solve this problem a possible solution could be to split the pilot injection of liquid fuel into two split injections, the second having the function of boosting the combustion of gaseous fuel also during the late combustion phase. In this paper this solution has been implemented on a diesel common rail single cylinder research engine converted to operate in dual-fuel mode. The composition of the gaseous fuel, indirectly injected, simulated a typical producer gas. The liquid fuel used during the experiments was biodiesel, injected by ...

Potentialities of a Common Rail Injection System for the Control of Dual Fuel Biodiesel-Producer Gas Combustion and Emissions

AbstractThis 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 amoun...

Photo-Induced Ignition of Different Gaseous Fuels Using Carbon Nanotubes Mixed with Metal Nanoparticles as Ignitor Agents

ABSTRACT This article 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 a function of mixture weight ratio, observing that a higher MWCNT amount with 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.

Application of a gas sensors array to the detection of fuel as contamination defect in engine oil

In this work we proposed a system based on metal oxide gas micro-sensors to estimate diesel or gasoline contamination in different engine oil samples. The gas-sensing layers (undoped, Pt, Pd, Rh-doped SnO2, In2O3 and mixed In2O3-SnO2) have been synthetized by the sol-gel method and deposited by spin-coating onto 2 mm times 2 mm silicon substrates equipped by Pt heater on the back and Pt interdigitated electrodes on the front. The sensor array has been exposed to no-used and used commercial engine oil samples contaminated with different amounts of unburned fuel. The results of data analysis (DWT-based feature extraction, PCA and Gaussian mixture model classifier (GMM)) showed that different fuel contaminated used engine oils can be discriminated and successfully classified by the sensor array.

Combustion Development and Exhaust Emissions of a Dual-Fuel DI Diesel Engine With Variable In-Cylinder Bulk Flow and Methane Supply Strategies

An extensive experimental campaign was performed on a diesel common rail research engine, converted to operate in dual-fuel mode, in order to investigate the effects of in-cylinder bulk flow and methane supply strategies on combustion and emissions. Three different bulk flow structures of the charge were induced inside the cylinder by activating/deactivating the two different inlet valves of the engine (i.e. swirl and tumble). Methane was injected into the inlet manifold at different pressure levels, varying the injector position. In order to obtain a stratified-like air-methane mixture, the injector was mounted very close to the inlet valve, while, to obtain a homogeneous-like one, methane was injected more upstream. By combining the two different positions of the injector and the three bulk flow structures, seven different engine inlet setups were tested, at different values of engine speed and load. Moreover, the effects of various pilot injection parameters, such as injection advance, diesel fuel quantity and rail pressure, were investigated. From in-cylinder pressure and heat release curves some output parameters, representative for combustion development, were calculated while emissions concentrations in the exhaust gases were measured. Main and interaction effects on dual-fuel combustion and exhaust emissions of all the operating parameters described above were studied by means of DOE technique, in order to perform a synthetic and complete analysis of the combustion behavior. The obtained results showed that the charge bulk motion produced by the swirl inlet valve is able to induce a more rapid and complete combustion of the air-methane mixture inside the cylinder. At low engine loads, this results in a contemporary reduction of unburned hydrocarbons and nitrogen oxides content at the exhaust, especially injecting the methane at high pressure and in stratified-like configuration. Furthermore, the analysis of the exhaust pollutant concentrations revealed that complex interactions effects between some unexpected operating parameters exist, such as between pilot injection pressure and engine inlet configuration. Generally, it was demonstrated that the stratified-like configuration of methane injection is an effective method to reduce unburned hydrocarbon emissions at the engine exhaust.Copyright

Improved Photo-Ignition of Carbon Nanotubes/Ferrocene Using a Lipophilic Porphyrin under White Power LED Irradiation

The aim of this work is to investigate and characterize the photo-ignition process of dry multi-walled carbon nanotubes (MWCNTs) mixed with ferrocene (FeCp2) powder, using an LED (light-emitting diode) as the light source, a combination that has never been used, to the best of our knowledge. The ignition process was improved by adding a lipophilic porphyrin (H2Pp) in powder to the MWCNTs/FeCp2 mixtures—thus, a lower ignition threshold was obtained. The ignition tests were carried out by employing a continuous emission and a pulsed white LED in two test campaigns. In the first, two MWCNT typologies, high purity (HP) and industrial grade (IG), were used without porphyrin, obtaining, for both, similar ignition thresholds. Furthermore, comparing ignition thresholds obtained with the LED source with those previously obtained with a Xenon (Xe) lamp, a significant reduction was observed. In the second test campaign, ignition tests were carried out by means of a properly driven and controlled pulsed XHP70 LED source. The minimum ignition energy (MIE) of IG-MWCNTs/FeCp2 samples was determined by varying the duration of the light pulse. Experimental results show that ignition is obtained with a pulse duration of 110 ms and a MIE density of 266 mJ/cm2. The significant reduction of the MIE value (10–40%), observed when H2Pp in powder form was added to the MWCNTs/FeCp2 mixtures, was ascribed to the improved photoexcitation and charge transfer properties of the lipophilic porphyrin molecules.

Photo-induced combustion of gaseous fuels using carbon nanotubes as ignitor agents: Driving and measuring systems, characterizations

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 sources 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 nanoparticles 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.

Benefits of Enabling Technologies for the ICE and Sharing Strategies in a CHP System for Residential Applications

AbstractIn this paper, a detailed survey has been carried out in order to evaluate the performance of a micro combined heat and power (CHP) system, based on an internal combustion engine (ICE) fed ...

Application of the Mean-Variance Theory and Resampling Technique for the Italian Energy Portfolio Settlement

The energy planning based on Mean - Variance theory, guides the investors in investment decisions, trying to maximize the return and minimize the risk of investment. However, this theory is based on strong hypotheses and, in addition, input data are often affected by estimation errors. Moreover, this theory determines poor diversification increasing return and risk of the portfolio, and strong variability of the outputs when inputs are varied.In the first part of the paper, the Mean - Variance theory was applied to the energy generation in Italy; in particular, the analysis was on the actual energy mix, but also assuming the use of nuclear technology and taking into account verisimilar improvement, of technologies in the future.On the other hand, in the second part of the paper, a methodology has been applied in order to limit the problems of Mean-Variance theory applied to the energy mix settlement. In particular, the input variables have been calculated using Monte Carlo simulation, in order to reduce the estimation error, and the Resampled Efficiency TM technique has been applied in order to calculate the resulting new “average” efficient frontier. This methodology has been applied either not limiting or limiting the minimum and maximum percentage for every energy generation technology, in order to simulate constraints due, for example, to the technological characteristics of the plant, the availability of the sources and eventually to norms, to the territorial characteristics and to the socio-political choices. The application of Mean - Variance theory allowed to obtain energy portfolio, alternative to the actual, characterized by higher values of expected returns an lower values of risk.It was also shown that the application of the Resampled Efficiency TM technique with data originated with the Monte Carlo simulation effectively tackles the problems of Mean - Variance theory; in this way, the decision maker is helped in making decisions in the energy system policy and development.Thanks to this approach, applied in particular to the Italian energy contest, it was also possible to evaluate the effectiveness of the introduced modifications to the Italian actual energy mix to achieve the 2020 European Energy Directive targets in particular concerning the reduction of CO2 levels.