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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.

Computer software, which simulates the thermodynamic and gas dynamic of internal combustion engines, are used extensively during design and development process. This paper analyzes the 1D boundary multi-pipe junctions calculations using the Method of Characteristics (MOC). Sonic flows can be encountered in the exhaust manifolds of internal combustion engines (especially racing engines) and in the model a check if the flow is sonic or not have been made. Flows with more than one manifold have flow toward the junction, need an equivalent “Datum” manifold, with an airflow as the sum of all flows, an averaged area and stagnation enthalpy has been defined in order to calculate the pressure loss when crossing the junction. The pressure loss terms have been calculated as function of the flow-ratio of the gas flowing to the manifold to the total incoming flow and the pipe angle.

The actual type approval procedure of vehicles, based on a fixed driving cycle for all the vehicles (NEDC), is not representative of their real on-road usage: the driving style and its influence on consumption and emissions cannot be neglected. The on-road impact of vehicles on their real use is not known and it is difficult to measure (the PEMS are expensive, have big volume and mass and need continuous maintenance); the objective of this work is to develop a methodology to calculate in real time the energy and environmental impact of spark ignition vehicles, using the onboard sensors of the vehicle and emissions models to calculate them. An onboard instrumentation able to communicate with the electronic system of the vehicle (OBD/CAN) was developed to collect all the sensor data installed on a vehicle: those values are used as input values to the emissions models of CO₂, CO, HC and NOx developed in the present work.

Hydrogen-enriched combustion has been studied by several institutions and companies over the last three decades. The purpose of adding hydrogen to conventional fuels is to extend the lean limit of combustion because hydrogen improves flame stability and allows a lower temperature combustion. Even with stoichiometric mixture, HCNG advantages had been demonstrated, since blends determine a reduction of noxious emissions. In the framework of an EU project called BONG-HY, bench tests with HCNG on a natural gas vehicle had been carried on at ENEA. Results of lab tests showed a fair improvement of the efficiency and CO2 emissions as well as an overall improvement regarding local pollutants.

Passenger vehicles are one of the most significant source of pollution in the cities. The emissions production of a vehicle is strictly dependent on how the vehicle is used. This paper has the objective to characterize a Euro IV vehicle so to understand in depth the behavior in its real usage on road in terms of fuel consumption and emissions. An Honda Civic 2.0 Euro4 vehicle has been tested and the experimental results are reported. The experiments have been carried out by means of two tools: a OBD2 interface to connect a laptop PC to the vehicle for collecting engine parameters (Alessandrini et al. 2006) and the HORIBA OBS1300 equipment to measure CO, NOx, HC emissions and the exhaust gas flow, pressure and temperature. Three types of experimental tests have been made: a set of them on a dynamometer chassis and a part on road.