Luciano Strafella

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 ...

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.

Photo-ignition process of multiwall carbon nanotubes and ferrocene by continuous wave Xe lamp illumination

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.

Programmable driving boards of Xenon flash lamps for photo-ignition process of carbon nanotubes added to air/methane fuel mixture

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 sources 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.

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 ...