Multi-Level Modeling of Real Syngas Combustion in a Spark Ignition Engine and Experimental Validation

Caputo, C.; Cirillo, D.; Costa, Michela; Blasio, Gabriele Di; Palma, Maria Di; Piazzullo, Daniele; Vujanović, Milan

doi:10.4271/2019-24-0012

Cited by 9 publications

(9 citation statements)

References 47 publications

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“…From the numerical point of view, a proper "digital twin" of the CMD ECO20X system was built and a multi-objective and multi-disciplinary optimization problem was solved through a software platform allowing the integration of different simulation tools. As a first step, a proper simulation model of the CMD ECO20X system was developed through both the Thermoflex TM and the GT-Suite ® one-dimensional simulation tools: the section of production, cooling, and cleaning of the syngas was schematized within a proper Thermoflex TM model [30], while the ICE was modeled in the GT-Suite ® environment [31]. The choice of using two different sub-models was mandatory, as explained in reference [30], to obtain a predictive model of the system performance as the gasifier and engine operating conditions were varied (i.e., the equivalence ratio of the gasifier, the biomass composition, the ICE spark advance, and other governing parameters) [32].…”

Section: Numerical Analysismentioning

confidence: 99%

The “INNOVARE” Project: Innovative Plants for Distributed Poly-Generation by Residual Biomass

et al. 2020

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The valorization of residual biomass plays today a decisive role in the concept of “circular economy”, according to which each waste material must be reused to its maximum extent. The collection and energy valorization at the local level of biomass from forest management practices and wildfire prevention cutting can be settled in protected areas to contribute to local decarbonization, by removing power generation from fossil fuels. Despite the evident advantages of bioenergy systems, several problems still hinder their diffusion, such as the need to assure their reliability by extending the operating range with materials of different origin. The Italian project “INNOVARE—Innovative plants for distributed poly-generation by residual biomass”, funded by the Italian Ministry of Economic Development (MISE), has the main scope of improving micro-cogeneration technologies fueled by biomass. A micro-combined heat and power (mCHP) unit was chosen as a case study to discuss pros and cons of biomass-powered cogeneration within a national park, especially due to its flexibility of use. The availability of local biomasses (woodchips, olive milling residuals) was established by studying the agro-industrial production and by identifying forest areas to be properly managed through an approach using a satellite location system based on the microwave technology. A detailed synergic numerical and experimental characterization of the selected cogeneration system was performed in order to identify its main inefficiencies. Improvements of its operation were optimized by acting on the engine control strategy and by also adding a post-treatment system on the engine exhaust gas line. Overall, the electrical output was increased by up to 6% using the correct spark timing, and pollutant emissions were reduced well below the limits allowed by legislation by working with a lean mixture and by adopting an oxidizing catalyst. Finally, the global efficiency of the system increased from 45.8% to 63.2%. The right blending of different biomasses led to an important improvement of the reliability of the entire plant despite using an agrifood residual, such as olive pomace. It was demonstrated that the use of this biomass is feasible if its maximum mass percentage in a wood matrix mixture does not exceed 25%. The project was concluded with a real operation demonstration within a national park in Southern Italy by replacing a diesel genset with the analyzed and improved biomass-powered plant and by proving a decisive improvement of air quality in the real environment during exercise.

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Section: Numerical Analysismentioning

confidence: 99%

The “INNOVARE” Project: Innovative Plants for Distributed Poly-Generation by Residual Biomass

et al. 2020

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“…More details about the conducted measurement campaign can be found in ref. [20]. The mass fractions of the species composing the different producer gases and their chemical characteristics (stoichiometric air-to-fuel ratio α ST and LHV) are reported in Table 3 as deriving from measurements taken on the real system.…”

Section: Technical Characteristics Of the Mchp Layoutmentioning

confidence: 99%

“…Indeed, inert species composing the syngas lower the lower calorific value, hence the amount of primary energy exploitable through combustion at a given mass of fuel, that leads to a power de-rating of the conversion system [20,21]. However, the insulating effects of inert species as N 2 (this last present in the mixture with a mass fraction of even above the 50%) at the cylinder walls, although well-known from literature, are positive in reducing heat losses but have not yet been quantified into detail especially in syngas powered systems.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Syngas Composition on Engine Thermal Balance in a Biomass Powered CHP Unit: A 3D CFD Study

Costa,

Piazzullo

2024

Energies

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Syngas from biomass gasification represents an interesting alternative to traditional fuels in spark-ignition (SI) internal combustion engines (ICEs). The presence of inert species in the syngas (H2O, CO2, N2) reduces the amount of primary energy that can be exploited through combustion, but it can also have an insulating effect on the cylinder walls, increasing the average combustion temperature and reducing heat losses. A predictive numerical approach is here proposed to derive hints related to the possible optimization of the syngas-engine coupling and to balance at the best the opposite effects taking place during the energy conversion process. A three-dimensional (3D) computational fluid dynamics (CFD) model is developed, based on a detailed kinetic mechanism of combustion, to reproduce the combustion cycle of a cogenerative engine fueled by syngas deriving from the gasification of different feedstocks. Numerical results are validated with respect to experimental measurements made under real operation. Main findings reveal how heat transfer mainly occurs through the chamber and piston walls up to 50° after top dead center (ATDC), with the presence of inert gases (mostly N2) which decrease the syngas lower calorific value but have a beneficial insulating effect along the liner walls. However, the overall conversion efficiency of the biomass-to-ICE chain is mostly favored by high-quality syngas from biomasses with low-ashes content.

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“…The combustion phase is modeled through the predictive model named "EngCylCombSITurb" (Hernandez et al, 2005). This approach is preferred to the classical Wiebe function (Heywood, 1988), where the fuel burned mass fraction is defined through a sigmoid-like function, as this last is validated for traditional fuels but it fails for nontraditional ones as for hydrogen-NG blends, whose chemical characteristics and combustion behavior depend upon the volumetric fractions of the components (Caputo et al, 2018;Caputo et al, 2019). The adopted model calculates the laminar speed through the following expression:…”

Section: Engine Model Development and Validation Under Ng Fuelingmentioning

confidence: 99%

“…Therefore, these parameters are here calculated for each mixture within the Chemkin ™ environment by relying on the detailed kinetic mechanism Gri-Mech 3.0 (Smith et al, 1999), so as to build a more customized combustion model as the hydrogen fraction varies in the fuel mixture. The validation of this approach was previously performed by Caputo et al, 2019, with reference to a ternary mixture of H 2 -CH 4 -CO with respect to experimental measurements under reference conditions. Figure 2 reports the calculated laminar flame speed as a function of the equivalence ratio for NG, hydrogen, and three blends of hydrogen-NG (hydrogen volume fraction at 10, 20, and 30%) at standard pressure and temperature and by varying the fuel-air equivalence ratio.…”

Section: Engine Model Development and Validation Under Ng Fuelingmentioning

confidence: 99%

Hydrogen Addition to Natural Gas in Cogeneration Engines: Optimization of Performances Through Numerical Modeling

Costa¹,

Piazzullo²,

Dolce³

2021

Front. Mech. Eng.

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A numerical study of the energy conversion process occurring in a lean-charge cogenerative engine, designed to be powered by natural gas, is here conducted to analyze its performances when fueled with mixtures of natural gas and several percentages of hydrogen. The suitability of these blends to ensure engine operations is proven through a zero–one-dimensional engine schematization, where an original combustion model is employed to account for the different laminar propagation speeds deriving from the hydrogen addition. Guidelines for engine recalibration are traced thanks to the achieved numerical results. Increasing hydrogen fractions in the blend speeds up the combustion propagation, achieving the highest brake power when a 20% of hydrogen fraction is considered. Further increase of this last would reduce the volumetric efficiency by virtue of the lower mixture density. The formation of the NOx pollutants also grows exponentially with the hydrogen fraction. Oppositely, the efficiency related to the exploitation of the exhaust gases’ enthalpy reduces with the hydrogen fraction as shorter combustion durations lead to lower temperatures at the exhaust. If the operative conditions are shifted towards leaner air-to-fuel ratios, the in-cylinder flame propagation speed decreases because of the lower amount of fuel trapped in the mixture, reducing the conversion efficiencies and the emitted nitrogen oxides at the exhaust. The link between brake power and spark timing is also highlighted: a maximum is reached at an ignition timing of 21° before top dead center for hydrogen fractions between 10 and 20%. However, the exhaust gases’ temperature also diminishes for retarded spark timings. Lastly, an optimization algorithm is implemented to individuate the optimal condition in which the engine is characterized by the highest power production with the minimum fuel consumption and related environmental impact. As a main result, hydrogen addition up to 15% in volume to natural gas in real cogeneration systems is proven as a viable route only if engine operations are shifted towards leaner air-to-fuel ratios, to avoid rapid pressure rise and excessive production of pollutant emissions.

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Multi-Level Modeling of Real Syngas Combustion in a Spark Ignition Engine and Experimental Validation

Cited by 9 publications

References 47 publications

The “INNOVARE” Project: Innovative Plants for Distributed Poly-Generation by Residual Biomass

The “INNOVARE” Project: Innovative Plants for Distributed Poly-Generation by Residual Biomass

The Effects of Syngas Composition on Engine Thermal Balance in a Biomass Powered CHP Unit: A 3D CFD Study

Hydrogen Addition to Natural Gas in Cogeneration Engines: Optimization of Performances Through Numerical Modeling

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