46 research outputs found

    Effects of Waste Cooking Oil Biodiesel Use on Engine Fuel Consumption and Emissions: a Study on the Impact on Oxidation Catalyst and Particulate Filter

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    Abstract The wide use of biodiesel has been driven by its reduction potential on greenhouse emissions from diesel engines without significant technological modifications. In this study a diesel engine for non-road applications has been fuelled with Waste Cooking Oil biodiesel blended with commercial fossil fuel at 6% and 30% v/v. In line with literature trends, experimental results indicate a significant reduction of PM emissions and only a slight increase in NOx emissions. This study has been focused on diesel emissions and in particular on the analysis of PM/NO2 ratio in presence of the Diesel Oxidation Catalyst (DOC). In fact, although the NO2/NOx ratio on raw exhaust is almost unaffected, the use of biodiesel shows a slight reduction of the NO-NO2 light-off temperature. This reduction can ensure more favorable operating conditions for the Diesel Particulate Filter (DPF), and has a positive effect on fuel consumption reduction. In order to deeply analyze these issues, a numerical model of an Aftertreatment system (AS) representing the a DOC and a DPF has been developed and validated with experimental data

    pyrolysis in screw reactors a 1 d numerical tool

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    Abstract This paper is focused on the numerical analysis of a screw pyrolyzer with special attention on kinetics, heat and mass transfer phenomena by means of a computational 1D tool. A steady-state model has been developed to generate temperature profiles and conversion patterns over the reactor axis. Residence time distribution capabilities have been considered to take into account the axial dispersion. The framework, including heat transport processes, is based on a 4 parallel Distributed Activation Energy Model. Its structure includes the three major biomass pseudo-component occurring in the biomass thermal degradation. The results of a generic biomass are then analyzed in terms of products distribution and heat transfer characteristics

    anaerobic digestion of liquid fraction coffee grounds at laboratory scale evaluation of the biogas yield

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    Abstract Coffee is one of the most popular beverage in the world. The International Coffee Organization (ICO) in the last 4 years registered an average world consumption higher than 8x10 6 tons. Over 50% of this mass is discarded after use, becoming a significant waste source known as spent coffee grounds (SCG). SCG usage as a raw material for biogas production emerges with great potential. It is a biomass that does not need pre-treatment, rich in lipids and can be easily separated in bars and restaurants. Lipid concentrations in SCG can reach more than 25% of its dry weight and have a good biogas production behavior, producing over 1 liter of CH 4 /g-VS. In this paper, the analysis of biogas yield potential of SCG recovery is presented using a laboratory scale batch anaerobic reactor, fed with the liquid fraction obtained by spent coffee filtration. Airtight glass reactors have been realized to guarantee the anaerobic digestion conditions. The reactors, divided into two groups A and B, fed with SGC and cow manure respectively, have been monitored for 22 days at a temperature of 37 °C. The accumulated methane production for a total of 1444 ml of biogas for group A and 1047 ml of methane for Group B was observed. Group A had an output of 296 ml.CH 4 /g-VS and group B 312 ml.CH 4 /g-VS. Group A presented fractions of 53.7% of CH 4 and 37.80% of CO 2 . The B group showed 36.7% of CH 4 and 27.9% of CO 2 . In the Group A, the methane production from SGC, reached concentration higher than 50%. This result shows the SCG liquid fraction energy recovery potential using an anaerobic digestion process

    Control Strategy Influence on the Efficiency of a Hybrid Photovoltaic-Battery-Fuel Cell System Distributed Generation System for Domestic Applications☆

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    AbstractThe full exploitation of locally available renewable resources together with the reduction of system installation and management costs are key issues of diffused Distributed Generation (DG). In the given context, hybrid systems are already at an advanced stage of development which typically integrate several sub-systems. In such hybrid systems, Renewable Energy Sources generation systems (e.g. photovoltaic panels) are coupled to energy storage devices (electric batteries) and with programmable generators (a diesel generator or, more recently, with a sub-system based on fuel cells) allowing stable operations under a wide range of conditions. In this paper a solution which uses hydrogen and fuel cells as a programmable source is presented and is studied by means of a mixed experimental and numerical: a Hardware-In-Loop test bench designed and realized at the Department lab, able to reproduce the behavior of a hybrid system for domestic applications. The system is controlled by means of a rule-based control strategy acting on the common DC-bus whose optimization has a significant influence both on system design and on its overall system energy performances. Results show that Rule-Based strategy have a great potential towards cost reduction and components lifetime increase, while energy efficiency mainly depends on correct system sizing

    Dual-fuel injection fundamentals: experimental – numerical analysis into a constant-volume vessel

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    Abstract Dual-fuel combustion mode in compression ignition engines has been tested thoroughly, showing high potential for the reduction of emissions (especially nitric oxides and particulate matter) while keeping unchanged the fuel conversion efficiency compared with conventional Diesel engines. Controlling the reactivity of the secondary fuel is crucial for this kind of application. To this aim, a combined experimental/numerical approach is proposed in this study to provide, on one side, experimental data in controlled conditions for the calibration of the numerical models; on the other side, a numerical framework for the accurate simulation of the dual-fuel injection in engine-like operating conditions. More in detail, a constant-volume combustion vessel has been used to simulate and analyze the injection process varying the characteristic control parameters. Detailed high-resolution images of the injection and combustion processes were acquired for the validation of the numerical framework. Numerical simulations, carried out by means of the CONVERGE CFD code using a Reynolds Average Navier Stokes (RANS) approach allow for understanding the key differences between the nominal and off-design settings. Results have been compared with the experimental data in terms of liquid spray penetration. A comparison with high resolution images has also been done to prove the accuracy of the model to describe the spray evolution in terms of spray characteristics. In the provided picture, this contribution aims at demonstrating the robustness of the experimental/numerical framework that is essential for further development of such engine solution

    Preparation and reactivity of diazoalkane complexes of ruthenium stabilised by an indenyl ligand

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    Diazoalkane complexes [Ru(η5-C9H7)(N2CAr1Ar2)(PPh3)L]BPh4 (1-3) [L = PPh3, P(OMe)3, P(OEt)3; Ar1 = Ar2 = Ph; Ar1 = Ph, Ar2 = p-tolyl; Ar1Ar2 = C12H8 fluorenyl] were prepared by allowing chloro-complexes [RuCl(η5-C9H7)(PPh3)L] to react with an excess of diazoalkane in ethanol. Complexes 1-3 reacted with ethylene CH2=CH2 (1 atm) and maleic anhydride [ma, CH=CHCO(O)CO] to afford η2-alkene complexes [Ru(η5-C9H7)(η2-CH2=CH2)(PPh3)L]BPh4 (4, 5) and [Ru(η5-C9H7){η2-CH=CHCO(O)CO}(PPh3)L]BPh4 (7). Further, complexes 1-3 underwent cycloaddition with acrylonitrile CH2=C(H)CN, giving 1H-pyrazoline derivatives [Ru(η5-C9H7){η1-N=C(CN)CH2C(Ar1Ar2)NH}(PPh3)L]BPh4 (6). Treatment of diazoalkane complexes 1-3 with acetylene CH≡CH under mild conditions (1 atm, room temperature) led to dipolar cycloaddition, affording 3H-pyrazole complexes [Ru(η5-C9H7)-{η1-N=NC(Ar1Ar2)CH=CH}(PPh3)L]BPh4 (8), whereas reaction with terminal alkynes RC≡CH (R = Ph, p-tolyl, But) gave vinylidene derivatives [Ru(η5-C9H7){=C=C(H)R}(PPh3)L]BPh4 (9). The latter reacted with nucleophiles such as amines and alcohols to give amino- and alkoxy-carbene derivatives [Ru(η5-C9H7){=C(NHPrn)(CH2Ph)}(PPh3)L]BPh4 (11) and [Ru(η5-C9H7){=C(CH3)(OEt)}(PPh3)L]BPh4 (10), respectively. In addition, complexes 9 reacted with phenylhydrazine to afford nitrile derivatives [Ru(η5-C9H7)(NC≡CH2R)(PPh3)L]BPh4 (12) and phenylamine, whereas the reaction with water led to hydrolysis of the alkyne and formation of carbonyl complexes [Ru(η5-C9H7)(CO)(PPh3)L]BPh4 (13). Lastly, treatment of vinylidene complexes 9 with the phosphines PPh3 and P(OMe)3 afforded alkenylphosphonium derivatives [Ru(η5-C9H7){C(H)=C(R)PPh3}(PPh3)L]BPh4 (14) and [Ru(η5-C9H7){C(R)=C(H)P(OMe)3}(PPh3)L]BPh4 (15), respectively. Compound [Ru(η5-C9H7){C(H)=C(H)PPh3}(PPh3)L]BPh4 (16) was also prepared. The complexes were characterised by spectroscopy (IR and NMR) and X-ray crystal structure determinations of [Ru(η5-C9H7){N2C(C12H8)}(PPh3){P(OEt)3}]BPh4 (3c), [Ru(η5-C9H7){=C=C(H)Ph}(PPh3){P(OEt)3}]BPh4 (9d) and [Ru(η5-C9H7){C(H)=C(Ph)PPh3}(PPh3){P(OEt)3}]BPh4 (14d).Diazoalkane complexes [Ru(eta(5)-C9H7)(N(2)CAr1Ar2)(PPh3)L]BPh4 (1-3) [L = PPh3, P(OMe)(3), P(OEt)(3); Ar1 = Ar2 = Ph; Ar1 = Ph, Ar2 = p-tolyl; Ar1Ar2 = C12H8 fluorenyl] were prepared by allowing chloro-complexes [RuCl(eta(5)-C9H7)(PPh3)L] to react with an excess of diazoalkane in ethanol. Complexes 1-3 reacted with ethylene CH2-CH2 (1 atm) and maleic anhydride [ma, CH-CHCO(O)CO] to afford eta(2)-alkene complexes [Ru(eta(5)-C9H7)(eta(2)-CH2=CH2)(PPh3)L]BPh4 (4, 5) and [Ru(eta(5)-C9H7){eta(2)-CH=CHCO(O)CO}(PPh3)L] BPh4 (7). Further, complexes 1-3 underwent cycloaddition with acrylonitrile CH2=C(H)CN, giving 1H-pyrazoline derivatives [Ru(eta(5)-C9H7){eta(1)-N=C(CN)CH2C(Ar1Ar2)NH}(PPh3)L]BPh4 (6). Treatment of diazoalkane complexes 1-3 with acetylene CH equivalent to CH under mild conditions (1 atm, room temperature) led to dipolar cycloaddition, affording 3H-pyrazole complexes [Ru(eta(5)-C9H7)-{eta(1)-N=NC(Ar1Ar2) CH=CH}(PPh3)L]BPh4 (8), whereas reaction with terminal alkynes RC equivalent to CH (R = Ph, p-tolyl, Bu-t) gave vinylidene derivatives [Ru(eta(5)-C9H7){=C=C(H) R}(PPh3)L]BPh4 (9). The latter reacted with nucleophiles such as amines and alcohols to give amino- and alkoxy-carbene derivatives [Ru(eta(5)-C9H7){=C(NHPrn)(CH2Ph)}(PPh3)L]BPh4 (11) and [Ru(eta(5)-C9H7){=C(CH3)(OEt)}(PPh3)L] BPh4 (10), respectively. In addition, complexes 9 reacted with phenylhydrazine to afford nitrile derivatives [Ru(eta(5)-C9H7)(N equivalent to CCH2R)(PPh3)L]BPh4 (12) and phenylamine, whereas the reaction with water led to hydrolysis of the alkyne and formation of carbonyl complexes [Ru(eta(5)-C9H7)(CO)(PPh3)L]BPh4 (13). Lastly, treatment of vinylidene complexes 9 with the phosphines PPh3 and P(OMe)(3) afforded alkenylphosphonium derivatives [Ru(eta(5)-C9H7){C(H) =C(R)PPh3}(PPh3)L]BPh4 (14) and [Ru(eta(5)-C9H7){C(R)=C(H) P(OMe)(3)}(PPh3)L]BPh4 (15), respectively. Compound [Ru(eta(5)-C9H7){C(H)=C(H)PPh3}(PPh3)L]BPh4 (16) was also prepared. The complexes were characterised by spectroscopy (IR and NMR) and X-ray crystal structure determinations of [Ru(eta(5)-C9H7){N2C(C12H8)}(PPh3){P(OEt)(3)}]BPh4 (3c), [Ru(eta(5)-C9H7){=C=C(H) Ph}(PPh3){P(OEt)(3)}] BPh4 (9d) and [Ru(eta(5)-C9H7){C(H)=C(Ph) PPh3}(PPh3){P(OEt)(3)}]BPh4 (14d)

    Design of a multi-energy system under different hydrogen deployment scenarios

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    Multi Energy Systems (MES) are effective means to increase Renewable Energy Sources (RES) penetration in the energy system and therefore to move toward a decentralized low-carbon system. Several energy vectors can be integrated together to exploit synergies in a MES framework, such as electricity, heat and hydrogen. The latter is one of the most promising energy carriers to promote widespread use of MES. Predictive management and well-defined sizing methodology are mandatory to achieve maximum performance out of MES. In this study a grid-connected MES consisting of a photovoltaic (PV) plant, a Battery Energy Storage System (BESS) and a Proton Exchange Membrane Fuel Cell (PEMFC) as a programmable Combined Cooling Heat and Power (CCHP) source, is modelled. Natural gas is considered as an alternative fuel to pure hydrogen. Mixed Integer Linear Programming and Genetic Algorithm are used respectively to solve operation and sizing problems. A single-objective optimization approach, including emission factors as optimization constraints, is carried out to find the optimal configuration of the MES. Several future scenarios are studied, considering different percentages of hydrogen in the gas mixture and comparing the techno-economic performance of the system with respect to a pure hydrogen fueling scenario. Results showed that the environmental objective within the design optimization, promote the use of hydrogen, especially in scenarios with high share of green hydrogen
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