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The use of Compressed Natural Gas as an alternative fuel in urban transportation is nearly established and represents an efficient short and medium term solution to face with urban air pollution. However, in order to completely exploit its potential, the engine needs to be specifically designed to operate with this fuel. In the latest years, the authors have investigated the performances of a Heavy Duty Turbocharged CNG fuelled engine both experimentally and by using some analytical tools specifically developed by them which have been used for the engine optimisation. In the present paper the simulation approach has been enlarged by means of a co-operative use of a CFD code and experimental analysis on the actual engine. The numerical simulation of combustion process has, in fact, been used, to interpret series of pressure cycles, aiming to analyse how cyclic fluctuations influence engine behaviour in terms of combustion efficiency and temperature and pollutant distribution.

In 2011-2013, regulations will be tightened for non-road vehicles, via the application of Stage III-B standards in Europe. With state-of-the-art technology (high pressure common rail, cooled EGR), non-road diesel engines will require DPFs to control PM, as 90% reduction is requested with respect to STAGE III-A standards. Additional challenges may also foresee the obtainment of STAGE III-B standards with STAGE III-A engine technology, by means of retrofit systems for PM control. In that case, retrofit systems must furthermore guarantee simple control systems, and must be robust especially in terms of limited back pressure increase during normal operation. Moreover, retrofit systems must offer flexibility from the design point of view, in order to be correctly operated with several engines of same class, possibly characterized by totally different PM flow rates, temperature, NOx and O₂ availability.

The use of biodiesel has been widely accepted as an effective solution to reduce greenhouse emissions. The high potential of biodiesel in terms of PM emission reduction may represent an additional motivation for its wide use. This potential is related to the oxygenated nature of biodiesel, as well as its lower PAH and S, which leads, in general, to lower PM emissions as well as equal or slightly higher NOx emissions. According to these observations a different behavior of the Aftertreatment System (AS), especially as far as control issues of the Diesel Particulate Filter are concerned is also expected. The competition with the food sector is currently under debate, thus, besides second generation biofuels (e.g. from algae), the transesterification of Waste Cooking Oil (WCO) is another option, however needing further insight.

According to European Union strategies, hydrogen technologies have a significant potential for the decarbonization of the automotive sector. Fuel Cells are considered a highly sustainable alternative to internal combustion engines for hybrid powertrain solutions. Since experimental tests on real prototypes are extremely costly in terms of time and resources, they represent a limit to the development rapidity of such complex vehicles. Consequently, simulation models are gaining further importance for their intrinsic time- and cost-saving characteristics, while their predictive capability is crucial. Accordingly, the development of the so-called “digital twins” able to accurately represent the real-time digital counterpart of a physical system has become an important research issue.

The international community is making significant efforts to face climate changes related to substantial greenhouse gas (GHG) emissions. Among all the sectors, transport is responsible for almost a quarter of global GHG emissions, 72% of which is imputable to road vehicles. It’s also expected that, without significant measures, these emissions may grow at a faster rate than other sectors. Furthermore, rising fuel costs and availability concerns have made the electrification of road transportation an attractive option to reduce oil dependency. However, this solution produces an electricity demand increase, causing significant overload conditions that could affect the reliability of the distribution sector.