This study investigates geometric parameters of commercially available or recently published models of catalyst substrates for passenger vehicles and provides a numerical evaluation of their influence on heat-up behavior. Parameters considered to have a significant impact on the thermal economy of a monolith are: internal surface area, heat transfer coefficient, and mass of the converter, as well as its heat capacity. During simulation experiments, it could be determined that the primary role is played by the mass of the monolith and its internal surface area, while the heat transfer coefficient only has a secondary role. Furthermore, an optimization loop was implemented, whereby the internal surface area of a commonly used substrate was chosen as a reference. The lengths of the thin wall and high cell density monoliths investigated were adapted consecutively to obtain the reference internal surface area. The results obtained by this optimization process contribute to improving the heat-up performance while simultaneously reducing the valuable installation space required.

Diesel engines, in combination with modern turbocharging and common rail injection systems, feature comparably high efficiencies coupled with favorable torque characteristics. Therefore, besides the utilization in commercial vehicles, diesel engines gained large market shares within the passenger car sector. The European Union regulates the deployment of biofuels and has issued several targets throughout the years; focusing on the urge to reduce carbon dioxide emissions, as well as on the growing demand for independence of fossil energy sources. This contribution presents investigations on fuel blends containing different shares of biomass to liquid, hydrotreated vegetable oils, and fatty acid methyl ester applied in a state of the art light-duty diesel engine. In general, the reviewed fuel blends exhibit good applicability for the utilization in the test engine with default settings of injection timing and exhaust gas recirculation; adjustments on the just mentioned parameters unveil further potential in terms of emissions and efficiency. Particularly the potential of biomass to liquid blends to partly mitigate the tradeoff between particulate matter and nitrogen oxides deserves distinct attention.

This paper presents a newly developed method using rapid prototyping (RP) to develop gas engine cylinder heads with optimized charge motion characteristics to adapt to lean-burn and Miller combustion process requirements. The geometry in close vicinity to the inlet valve seats was designed to increase swirl and flow performance of the cylinder heads. A three-dimensional (3D) printer was used to realize a rapid prototyping concept for the testing of multiple designs; the effects of the different designs were measured using a static flow test bench and a laser-optical method to visualize the flow patterns. The results of the static flow bench tests showed potentially higher flow and swirl performance, with one high-swirl version proving beneficial specifically for lean-combustion and one high-flow version matching the Miller combustion requirements. The two cylinder head versions were then manufactured and the lean-combustion version was tested for on-engine performance on a 150 kW sewage-gas driven lean-combustion engine. It has been shown that the cylinder head generates higher swirl on the test bench but achieves only a slight increase in combustion speed on the test engine. The potential to increase engine efficiency by intensifying swirl is, therefore, considered exploitable. Research has further shown the coefficient of variance (CoV) was reduced by 0.3–1.2%. Charge exchange losses have also been demonstrated to decrease at all tested engine settings. It has further been found that higher swirl intensity has a positive impact on engine emission levels, as the engine out carbon monoxide (CO) emission can be reduced by approximately 70 mg·m−3.

In the field of emission control, the thermal behavior of catalytic converters plays a dominant role and is a determining factor for achieving current and future emission limits. This abstract reflects upon the potential of electrically heated catalytic converters exemplified by an exhaust gas after-treatment system for passenger vehicles. The demanding technical framework