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Bielaczyc P.,BOSMAL Automotive RandD Institute | Keskinen J.,Tampere University of Technology | Dzida J.,BOSMAL Automotive RandD Institute | Sala R.,BOSMAL Automotive RandD Institute | And 5 more authors.
SAE Technical Papers | Year: 2012

The aim of this paper is to analyse the quantitative impact of fuel sulphur content on particulate oxidation catalyst (POC) functionality, focusing on soot emission reduction and the ability to regenerate. Studies were conducted on fuels containing three different levels of sulphur, covering the range of 6 to 340 parts per million, for a light-duty application. The data presented in this paper provide further insights into the specific issues associated with usage of a POC with fuels of higher sulphur content. A 48-hour loading phase was performed for each fuel, during which filter smoke number, temperature and back-pressure were all observed to vary depending on the fuel sulphur level. The Fuel Sulphur Content (FSC) affected also soot particle size distributions (particle number and size) so that with FSC 6 ppm the soot particle concentration was lower than with FSC 65 and 340, both upstream and downstream of the POC. Conversely, FSC did not have major effects on the soot particle number reduction efficiency of the POC. Soot and other exhaust compounds accumulated within the POC during this phase, gradually built a pressure drop across the POC. The final mass of collected matter in the POC differed significantly according to the sulphur content. The efficiency of removal of gaseous pollutants by the POC was found to be markedly worse for the fuels with higher sulphur content, although this deterioration was observed to be non-linear. Following the accumulation phase, a duty cycle was applied that caused the POC to commence passive regeneration. The time taken for the POC to cleanse itself of accumulated matter and thereby eliminate the pressure drop was observed to increase with increasing fuel sulphur content. The proportion of NOx leaving the POC in the form of NO2 was also found to vary as a strong function of fuel sulphur content. Copyright © 2012 SAE International. Source

Bielaczyc P.,BOSMAL Automotive RandD Institute | Szczotka A.,BOSMAL Automotive RandD Institute | Woodburn J.,BOSMAL Automotive RandD Institute
SAE Technical Papers | Year: 2012

Cold starts are demanding events for spark-ignition (SI) internal combustion engines. When the temperatures of the engine oil, coolant and the engine block are close to the ambient temperature, start-up can be difficult to achieve without fuel enrichment, which results in significant excesses in exhaust emissions and fuel consumption. In general, the lower the ambient temperature, the more substantial these problems are. Many nations frequently experience sub-zero ambient temperatures, and the European Union (among others) has specified an emissions test at low ambient temperature (-7°C). Passenger cars typically experience one to two cold start events per day, and so both cold starts and the warm up period that follows are significant in terms of exhaust emissions. This paper examines emissions at low ambient temperatures with a special focus on cold start; emissions are also compared to start-up at a higher ambient temperature (24°C). The causes of excess emissions and fuel consumption are briefly discussed. A series of tests were performed on European passenger cars on a chassis dynamometer within an advanced climate-controlled test laboratory at BOSMAL Automotive Research and Development Institute, Poland. Emissions data obtained over the Urban Driving Cycle by testing at 24°C and at -7°C, are presented for a selection of modern Euro 5 gasoline vehicles representative of the European passenger car fleet. A full modal emissions analysis was also conducted at 24°C and at -7°C over the New European Driving Cycle. Emissions and fuel consumption were substantially higher at -7°C than at 24°C. Copyright © 2012 SAE International. Source

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