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The numerical reconstruction of the liquid jet generated by a multi-hole injector, operating in flash-boiling conditions, has been developed by means of a Eulerian- Lagrangian CFD code and validated thanks to experimental data collected with schlieren and Mie scattering imaging techniques. The model has been tested with different injection parameters in order to recreate various possible engine thermodynamic conditions. The work carried out is framed in the growing interest present around the gasoline direct-injection systems (GDI). Such technology has been recognized as an effective way to achieve better engine performance and reduced pollutant emissions. High-pressure injectors operating in flashing conditions are demonstrating many advantages in the applications for GDI engines providing a better fuel atomization, a better mixing with the air, a consequent more efficient combustion and, finally, reduced tailpipe emissions.

Technological and commercial development of vehicles specifically conceived for urban use would certainly be a crucial aspect in making mobility sustainable in urban contexts thanks to their limited in size and low fuel consumption and emissions. Hybrid drive trains are particularly suited to this purpose: if properly designed, very small-sized thermal engines can give all the energy and power required for the application, also making pure electric driving possible when required. The authors are involved since a decade in proposing new low-cost solutions to address this market sector. Market itself explored these possibilities and nowadays offers some BEV solutions in this market share, but it is still lacking in proposing solutions for a parallel full hybrid drive. The main reason must be searched in the complexity of normally applied parallel-hybrid propulsion systems which is not compatible with the limited costs of the application.

Internal combustion engines are actually one of the most important source of pollutants and greenhouse gases emissions. In particular, on-the-road transportation sector has taken the environmental challenge of reducing greenhouse gases emissions and worldwide governments set up regulations in order to limit them and fuel consumption from vehicles. Among the several technologies under development, an ORC unit bottomed exhaust gas seems to be very promising, but it still has several complications when it is applied on board of a vehicle (weight, encumbrances, backpressure effect on the engine, safety, reliability). In this paper, a comprehensive mathematical model of an ORC unit bottomed a heavy duty engine, used for commercial vehicle, has been developed.

Alternative vehicle powertrains (hybrid, hydrogen, electric) are among the most interesting solutions for environmental problems afflicting urban areas. Electric and hybrid vehicles are now slowly taking place in the automotive sector, but on a Tank To Wheels (TTW) basis, the most effective alternative powertrain is surely represented by Fuel Cell Electric Vehicles (FCEV): those fuelled by hydrogen seem to be the ones closest to market. The design of a FCEV however, is not straightforward and involves several issues (fuel cell sizing, hydrogen storage, components efficiency, sizes and weights). Basing on these considerations, the Authors present a software procedure for the optimal design of the components of a passenger FCHEV (Fuel Cell Hybrid Electric Vehicle).

This paper reports the results of experimental tests performed at ENEA (Italian National Agency for New Technologies, Environment and Sustainable Development) in its “Casaccia” Energy Research Center to evaluate the energetic and environmental performances of a Heavy-Duty Compressed Natural Gas (HD CNG) engine fuelled with a hydrogen-methane blend of 15% in volume. A lean burn Mercedes 906 LAG engine has been optimized properly calibrating ECU engine maps regarding both ignition advance and air to fuel ratio (AFR). It was therefore possible to correct ignition advance to take into account the faster combustion speed given by the hydrogen content of the fuel mixture. Equivalence ratio (Lambda) has instead been modified in order to minimize the NOx emissions. All the tests were performed on a steady engine test-bed focusing the attention on the most important parts of the engine maps.

Hybrid electric vehicles (HEVs) are worldwide recognized as one of the best and most immediate opportunities to solve the problems of fuel consumption, pollutant emissions and fossil fuels depletion, thanks to the high reliability of engines and the high efficiencies of motors. Moreover, as transport policy is becoming day by day stricter all over the world, moving people or goods efficiently and cheaply is the goal that all the main automobile manufacturers are trying to reach. In this context, the municipalities are performing their own action plans for public transport and the efforts in realizing high efficiency hybrid electric buses, could be supported by the local policies. For these reasons, the authors intend to propose an efficient control strategy for a hybrid electric bus, with a series architecture for the power-train.

The most used technology able to inhibit NOx formation in combustion chamber is the Exhaust Gas Recirculation (EGR). Smoke limits, however, can be easily reached when EGR grow up to fulfill the emission limits. Further percentage increase, necessary to observe the oncoming more severe regulations, can be performed only if a control strategy is implemented on A/F ratio lower limit, based on turbo-charging level. In this paper the authors present an analysis performed on a medium size light duty turbocharged direct injection Diesel engine aimed to the definition of the current engine layout limit in terms of smoke emission and turbocharger functionality, in case of increased EGR rates, both in short route and in long route configuration. The theoretical activity based on a mathematical model of the engine has been supported by a focused experimental campaign on test bench, with engine in original configuration and equipped with a long route EGR pipe.

Cooling system design has a crucial role in defining engine performance and operational limits. Many further improvements can be obtained both in the precision in controlling temperatures of the various engine parts (especially during transient operation), and in the energy consumption of the system. Moreover, the warm-up transient can be relevantly reduced producing benefic effects on vehicle emissions and interior conditioning and comfort. Taking the lead by these considerations, the authors developed an integrated model of an engine cooling system, which is characterized by a complete modularity and permits the simulation of any possible design configuration. The model acts as a “virtual engine cooling system”: its coupling with simple ECU models permits an off-line evaluation of the efficiency of new control strategies, model-based too. In this work a novel model for the engine thermal behavior is proposed to be included in the described modeling architecture.

Literature showed quite clearly that the efficiency of Air to Fuel Ratio (AFR) control for Spark Ignition (SI) Internal Combustion Engines (ICE) strongly depends on its capacity to deal with the fuel-flow phenomena inside intake manifolds. Moreover, engine performances (such as power output, specific fuel consumption, and exhaust gas emissions) are directly related to the efficiency of the combustion process, which, on its turn, can be affected substantially by the air/fuel ratio variations related to the fuel-film dynamics. In this work a comprehensive model-based air/fuel ratio control technique is proposed: this is based on a dynamical model of the air dynamics inside inlet manifolds and on the online identification of the fuel-film parameters. Here the identification procedure is illustrated in detail and validated basing on experimental data regarding a single-cylinder engine.

One of the most promising near-future alternatives to traditional gasoline and Diesel Internal Combustion Engines is the utilization of alternative fuels. Among these, Liquefied Petroleum Gases (LPG) play a key role for its wide availability and high energetic density. The adoption of liquid phase injection systems would permit the highest achievable performances from both a traditional (power output, acceleration, …) and an environmental (pollutants and greenhouse emissions) point of view. Those systems, however, still present many unsolved problems, substantially limiting their use. The authors here report the results of an intense research activity aimed to the realization of a model-based A/F controller to be used on-board for liquid-phase LPG injected engines. All the main dynamical phenomena involved were modeled: it was so possible to analyze in detail the efficiency of the system in terms of A/F control (strictly related to pollutant emissions) and power output of the engine.

Fuel cells are widely accepted to be the alternative powertrain with the highest potential to compete with the internal combustion engine for a mean-long future sustainable prospective for passenger mobility: Proton Exchange Membrane Fuel Cells (PEMFC) seem to be the most promising technology. Anyway, the final goal is still far to be reached, since often the great potential advantages connected with fuel cells are not completely obtained, due to the difficulties encountered in component design and optimization. Moreover, H2 availability still appears to be one of the most important limitations. Taking the lead by these considerations the authors derived a physically consistent integrated mathematical model of a PEM propulsion system: the model is fully modular and is aimed both to gain a deeper insight of the complex chemical and thermo-fluid-dynamical processes involved, and to the development of control strategies for the propulsion system and all its auxiliaries.

In reciprocating IC engines, very precise predictions of the mass of air inducted are required in order to improve both manifold design and fuel injection control. To achieve this goal, a deeper knowledge of the boundary conditions on intake and exhaust manifolds must be obtained, and a set of very accurate experimental data is needed to perform model validation. In this paper an experimental activity is reported, which has been performed on a pipe test-rig which guarantees high reproducibility of the fluid-dynamic transients. Based on the obtained data, the authors validated a modified non-isentropic version of the method of characteristics, specifically conceived for the simulation of varying area engine manifolds.

In reciprocating IC engines, very precise predictions of the mass of air inducted are required in order to improve engine design. To achieve this goal, a deeper knowledge of the boundary conditions on intake and exhaust manifolds must be obtained. A set of very accurate experimental data is also needed to perform model validation. In this paper an experimental activity was performed on a pipe test-rig which guarantees high reproducibility of the fluid-dynamic transients. Based on the obtained data, the authors introduced two parameters, which are able to improve the precision of the dynamic models of the flow past valves and through sudden enlargements.

Many advantages are related to the use of LPG as fuel in SI injected ICE. Most of them regard the lower environmental impact with respect to gasoline. The liquid-phase injection is one of the most important aspects of these engines, being able to guarantee the maintenance (and even an increase) of the more traditional engine performances (power, acceleration, driveability, etc) and to match the 3-way catalytic converter A/F specifications. In this paper the transient phenomena occurring in an LPG injection system have been studied, focusing the attention on the problems related to A/F and liquid-phase control.