Assessment of the Internal Catalyst Efficiency in a Diesel Engine of a Vehicle under the Conditions Simulating Real Driving

Abstract

The application of a catalyst on a surface inside a combustion chamber is known as a supplementary method of exhaust gas aftertreatment. The efficiency of this method in the reduction in exhaust emissions as well as its influence on other engine properties has been analyzed in multiple scientific works. Most often, these works present the results of investigations carried out on dynamometers under engine stationary conditions. There are no results of the catalyst investigations performed under dynamic states, particularly on-going real time analyses during engine operation. Therefore, the authors set out to explore the efficiency of the in-cylinder catalyst of a diesel engine under dynamic conditions simulating actual vehicle operation. A unique methodology was applied. The investigations were carried out in road conditions in a test simulating the New European Driving Cycle (NEDC) homologation test in compliance with the similarity criteria of the zero-dimensional characteristics of vehicle speed during the investigations and in the homologation test. For the research, the authors used portable exhaust emissions measurement equipment. A unique method of test results analysis was also applied (a continuous method in the time domain). As a result of the tests being repeated several times, it was observed that the application of an internal catalyst under different operating engine conditions repeatedly results in: an approx. 2% reduction in the emissions of carbon monoxide, hydrocarbons, and carbon dioxide; a similar increase in the emission of nitrogen oxides; and a significant (over 10%) reduction in the particle number. The obtained results substantiate the purpose of actions aiming at improving the efficiency of the internal catalyst.