Gabriele Discepoli | Università degli Studi di Perugia (original) (raw)

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Papers by Gabriele Discepoli

E3S Web of Conferences, 2021

Engine research community interest in the Radio-Frequency corona-based ignition systems is curren... more Engine research community interest in the Radio-Frequency corona-based ignition systems is currently gaining in importance mainly due to their capability to ensure robust combustion at challenging operating conditions such as very lean mixture and/or high EGR dilution. The benefits of Corona low-temperature plasma foster the early flame development thanks to combustion precursors production and to a more energetic and volumetric discharge, resulting in a larger amount of involved mixture. The corona discharge generates ionizing waves, named streamers, whose temporal and spatial variability in orientation, length and branching can affect the combustion onset and, therefore, the engine cycle-to-cycle variability. In this work, the discharge natural luminosity of a RF corona igniter, characterized by four tips electrodes, was recorded in an optically accessible engine via high-speed camera detection. A preliminary statistical analysis of the spatial and temporal streamer variability wa...

The Radio-Frequency Corona Ignition System is characterised by a wide initial combustion volume a... more The Radio-Frequency Corona Ignition System is characterised by a wide initial combustion volume and precursors production, via radical insemination by the streamers, in addition to high released thermal energy. These features lead to faster combustion, a higher tolerance for lean mixtures and EGR dilutions and, in general, more adaptability. The thermal energy released by the igniter to the surrounding medium can help to understand the performance, the behaviour and the application range. This paper proposes a systematic experimental analysis of the thermal energy released by the igniter at room temperature, via pressure-based calorimetry. This analysis, carried out at different pressures (up to 10 bar) and medium type (air or nitrogen), is extended to the whole range of the corona igniter control parameters, namely streamer duration and driving voltage. The latter is proportional to the maximum electrode voltage, as shown in the model here presented, and as confirmed by experiments...

Energy Procedia, 2015

A gasification plant was designed and built to test syngas production from biomass for electricit... more A gasification plant was designed and built to test syngas production from biomass for electricity generation on microscale. The plant is mainly composed by a downdraft reactor, a gas cleaning section with a cyclone and a wet scrubber, a blower for syngas extraction and an ICE (Internal Combustion Engine, Lombardini LGA 340), equipped with an alternator. A small quantity of producer was also eventually sent to a button cell SOFC (Solid Oxide Fuel Cell) for preliminary characterization. The plant was tested in a preliminary experimental campaign to evaluate mass and energy balances and process efficiency. Woody biomass was used and the producer gas firstly passed through impingers bottles, to condense and measure tar concentration (according to CEN/TS 15439), and then the remaining uncondensed gas was analyzed with a micro-GC (Gas Chromatograph). The paper presents and discusses the results of the preliminary tests carried out.

Vehicles

The aim of herein work is to develop an automatized algorithm for detecting, as objectively as po... more The aim of herein work is to develop an automatized algorithm for detecting, as objectively as possible, the flame front evolution of lean/ultra-lean mixtures ignited by low temperature plasma-based ignition systems. The low luminosity characterizing the latter conditions makes both kernel formation and combustion development difficult to detect accurately. Therefore, to estimate the igniter capability to efficiently ignite the mixture, ever more performing tools are required. The present work proposes a new image analysis technique, based on a dual-exposure fusion algorithm and on Convolutional Neural Networks (CNNs), to process low brightness images captured via high-speed camera on an optical engine. The performance of the proposed algorithm (PA) is compared to the one of a base reference (BR) algorithm used by the same research group for the imaging analysis. The comparison shows the capability of PA to quantify the flame radius of consecutive combustion cycles with lower disper...

International Journal of Energy Research, 2015

Solid oxide electrolyzer (SOE) can operate in co-electrolysis mode of H 2 O and CO 2 because of t... more Solid oxide electrolyzer (SOE) can operate in co-electrolysis mode of H 2 O and CO 2 because of the high operating temperature and the nickel-based fuel electrode material. In this configuration, the fuel electrode is fed with a mix of steam and carbon dioxide that is converted through electrolysis reactions into a syngas that can be further upgraded to other carbon fuels. This technology can lead to interesting scenarios in the field of energy storage and CO 2 reuse. SOE performance in terms of syngas quality and chemical equilibrium is presented in this study. An experimental test on a four-cell stack was performed to evaluate which are the effects of inlet gas composition and current density on the output syngas composition and on the thermal balance of the stack. Results were analyzed with the support of a thermodynamic model that aims to demonstrate that equilibrium condition is reached within the stack for all the involved reactions including reverse water shift. Also, we show that there is a direct relation between inlet and outlet compositions. For each composition, current density for thermoneutral condition was calculated obtaining values in the range of 377-493 mA/cm 2 depending on the composition. Such results permit to study SOE integration in a complete process for energy and CO 2 storage. Copyright

Energy Procedia, 2018

Abstract The Radio-Frequency (RF) Corona Ignition System is an innovative and promising technolog... more Abstract The Radio-Frequency (RF) Corona Ignition System is an innovative and promising technology able to produce multiple streamers to ignite the fuel throughout the combustion chamber. This system, compared to a conventional spark ignition system, involves wider initial combustion volumes and allows the engine to operate in stable conditions at leaner mixtures, higher EGR dilutions, with faster burning rates and enabling advanced combustion strategies. Due to the intrinsic operating features of the RF corona ignition system, the production of a plasma generated by a high frequency electrical field, the energy released to the surrounding medium is a fundamental parameter to understand its behaviour and impact on a given air-fuel mixture. The aim of this paper is the energetic characterization of a prototype of corona igniter, called Advanced Corona Ignition System (ACIS), by measuring the pressure increase caused by the streamers in a controlled environment, a pressure based calorimeter. The ACIS results are also compared with a multiple spark discharges (MSD) ignition system based on standard Federal Mogul spark plug technology characterized by an integrated electronics capable of managing up to 17 consecutive discharges. The energy evaluation was carried out at room temperature with air at different pressure levels, up to 10 bar.

ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology. Collocated with ASME 2011 5th International Conference on Energy Sustainability, FUELCELL 2011, 2011

ABSTRACT Nowadays, in a world characterized by the need to reduce the production of pollutants, b... more ABSTRACT Nowadays, in a world characterized by the need to reduce the production of pollutants, by global climate changes, by the progressive lack of availability of cheap fossil fuels, one of the most important goals of scientific research is to design systems that can provide energy with low environmental impact. Planar Solid Oxide Fuel Cells (SOFC) are considered to be power generators with high efficiency independent on size and low emissions. Fuel cell laboratory (FCLab) of University of Perugia has focused his studies on SOFC operating at high temperature (800–1000°C), characterized by greater flexibility in the choice of fuel. This study focuses on definition and realization of experimental test able to define the quality of a SOFC single cell and on the effect of test condition parameter. The performance of the cell is evaluated via polarization curves realized in different external conditions. Area Specific Resistance (ASR) is used as main test output. Results analysis confirm that ASR gives important information on fuel cell performance and can be used to compare an qualify SOFC single cell.

International Journal of Greenhouse Gas Control, 2012

ABSTRACT Desulfurization represents a crucial step in fuel processing for high temperature fuel c... more ABSTRACT Desulfurization represents a crucial step in fuel processing for high temperature fuel cells, because of catalysts stringent requirements. Moreover, when fuel cell stacks are used in micro-CHP applications, it is necessary to build an efficient and compact system. The use of biogas from anaerobic digestion could have a significant impact in terms of fossil fuels saving and environmental conservation. Biogas contains different impurities, among which H2S represents one of the most harmful components.

SOFC technology has reached many of the performance goals that where indicated by scientific soci... more SOFC technology has reached many of the performance goals that where indicated by scientific society and is providing several application that permits market penetration. One of the main targets is related to Micro Cogeneration Heat and Power ( -CHP) for residential application. The integration of this system with a residential house has to be deeply investigated to individuate market targets in terms of costs and efficiency. This study evaluates the Italian market condition and analyzes the integration possibility with both thermal and electrical systems. Different solutions are investigated evaluating thermal and electrical driven logic for -CHP SOFC based unit and the opportunity of integration with local electrical grid. Evaluation on heat and electricity storage was also considered as integration strategy. The study is based on electrical and thermal loads in typical residential users and the evaluation is based on Italian technical standards and guidelines. Several operating c...

Energy Conversion and Management

Energy Procedia

Abstract Charging a motorcycle engine is challenging, since requirements of lightness, system sim... more Abstract Charging a motorcycle engine is challenging, since requirements of lightness, system simplicity and engine responsiveness are key factors. This paper reports on a preliminary study on a pressure wave compressor, the “Impulse Drum Charger”. Performances of a 4-stroke motorcycle engine with and without Drum Charger were compared at the test bench and a pressure analysis in the intake manifold was carried out as well. Results show that this system is able to effectively improve engine power (up to 1.4 kW at 9500 rpm WOT) without an ECU recalibration.