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A combination of fuel cells with internal combustion engines (FC/ICE hybrids) for light duty vehicle propulsion has the potential to offer significant benefits over conventional battery electric hybrid architectures. Specifically, compared to conventional battery / ICE hybrids the FC/ICE hybrid concept may offer improvements in vehicle utility, performance, and emissions. Furthermore, the FC/ICE hybrid can be implemented at a substantially lower cost than that associated with full fuel cell vehicles (FCVs). Numerous studies have indicated significant emission and energy efficiency benefits from FCVs, especially those based on proton exchange membrane fuel cells (PEMFCs). However, recent more detailed studies indicate that achieving competitiveness with IC engine-based powertrains, especially with respect to cost, would require significant additional improvements in fundamental PEMFC technology.

The task of matching engine, control system and catalytic converter has become very complex as the automotive industry strives to meet stringent demands for pollution abatement. To address the need for a robust, accurate modeling tool we have created a microkinetics-based simulation program that describes the reactions taking place on the surface of a catalytic converter. This chemically detailed approach permits the construction of faithful simulations of both steady state and transient performance of the catalyst using a combination of experimental measurements, literature data and quantum chemical calculations. The model can be coupled to existing simulations of the engine and control elements, notably those based on GT-Power.

Although alternative NOx control schemes, such as catalysis, are promising means of reducing emissions from Diesel engines, many such methods have yet to be developed into reliable and cost-effective solutions. Consequently, NOx reduction through in-cylinder techniques remains the most widely used approach in meeting current and future emissions standards. One such common technique is the use of an inert diluent, such as water/steam or exhaust gas recirculation (EGR), introduced into the combustion chamber to reduce the peak flame temperatures associated with NO formation. Here the role of water/steam in reducing NOx emissions is analyzed in depth. In particular, two methods of water injection are studied: stratified fuel-water-fuel injection and intake manifold fumigation. In each case, the NOx emissions are modeled using a two-zone characteristic time model (CTM) based on the dominant physical and chemical subprocesses occurring in the cylinder.

Most computational schemes and kinetic models for engine-out NOx emissions from Diesels are based on the Zeldovich or extended Zeldovich mechanism. However, at pressures typical of both the premixed and diffusion portions of the combustion process, the third-body reaction leading to the formation of N2O (O + N2 + M) becomes faster than the leading reaction in the Zeldovich mechanism (O + N2). As in gas turbines, particularly those involving lean-premixed combustor designs, NO formation in Diesels through the N2O mechanism can thus proceed more efficiently than through the traditional route. Decomposition of NO in the combustion products during the power stroke can also occur by both the reverse Zeldovich reactions and the second order step that produces N2O (2NO ® N2O + O). Based on these observations, a skeletal mechanism consisting of seven elementary reactions is used to develop a two-zone model for NOx emissions from direct injection (DI) Diesel engines.