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Particulates and nitrogen oxides comprise the main emission components of the Diesel combustion and therefore are subject to exhaust emission legislation in respective applications. Yet, with ever more stringent emission standards and test-procedures, such as in passenger vehicle applications, resulting exhaust gas after-treatment systems are quite complex and costly. Hence, new technologies for emission control have to be explored. The application of non-thermal plasma (NTP) as a means to perform exhaust gas after-treatment is one such promising technology. In several publications dealing with NTP exhaust gas after-treatment the plasma state was generated via dielectric barrier discharges. Another way to generate a NTP is by a corona high-frequency discharge. Hence, in contrast to earlier publications, the experiments in this publication were conducted on an operated series-production Diesel engine with an industrial pilottype corona ignition system.

Throughout the world cost-efficient Naphtha streams are available in refineries. Owing to less processing, CO2 emissions emitted in the course of production of these fuels are significantly lower than with conventional fuels. In common CI/SI engines, however, the deployment of Naphtha is considerably restricted due to unfavourable fuel properties, e.g. low cetane/octane numbers. Former investigations illustrated high knocking tendency for SI applications and severe pressure rise for CI combustion. Moreover, the focus of past publications was on passenger vehicle applications. Hence, this paper centers on heavy-duty stationary engine applications. Consequently, measures to increase the technically feasible IMEP with regard to limitations in knocking behaviour and pressure rise were explored whilst maintaining efficient combustion and low emissions.

One promising alternative for meeting stringent NOx limits while attaining high engine efficiency in lean-burn operation are NOx storage catalysts (NSC), an established technology in passenger car aftertreatment systems. For this reason, a NSC system for a stationary single-cylinder CHP gas engine with a rated electric power of 5.5 kW comprising series automotive parts was developed. Main aim of the work presented in this paper was maximising NOx conversion performance and determining the overall potential of NSC aftertreatment with regard to min-NOx operation. The experiments showed that both NOx storage and reduction are highly sensitive to exhaust gas temperature and purge time. While NOx adsorption rate peaks at a NSC inlet temperature of around 290 °C, higher temperatures are beneficial for a fast desorption during the regeneration phase. Combining a relatively large catalyst (1.9 l) with a small exhaust gas mass flow leads to a low space velocity inside the NSC.