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Measurement of car engines exhaust pollutants emissions is very important because of their harmful effects on the environment. This article presents the assessment of repeatability of the passenger car engine exhaust pollutants emission research results obtained in the conditions of a chassis dynamometer. The research was conducted in a climate chamber, enabling the temperature conditions to be determined from − 20 to + 30 °C. The emission of CO, CH4, CO2, NOX, THC, and NMHC was subjected to the analysis. The aim of the research is to draw attention to the accuracy of the pollutant emission research results in driving cycles, and the comparison of pollutant emission results and their repeatability obtained in successive NEDC cycles under cold and hot start conditions. The results of the analysis show that, in the case of a small number of measurements, the results repeatability analysis is necessary for a proper interpretation of the pollutant emission results on the basis of the mean value. According to the authors’ judgment, it is beneficial to determine the coefficient of variation for a more complete assessment of exhaust emission result repeatability obtained from a small number of measurements. This parameter is rarely presented by the authors of papers on exhaust components emission research.

Road transport contributes to almost a quarter of carbon dioxide emissions in the EU. To analyze the exhaust emissions generated by vehicle flows, it is necessary to use specialized emission models, because it is infeasible to equip all vehicles on the road in the tested road sections with the Portable Emission Measurement System (PEMS). However, the currently used emission models may be inadequate to the investigated vehicle structure or may not be accurate due to the used macroscale. This state of affairs is especially related to full hybrid vehicles, since there are none of the microscale emission models that give estimated emissions values exclusively for this kind of drive system. Several automakers over the past decade have invested in hybrid vehicles with great opportunities to reduce costs through better design, learning, and economies of scale. In this work, the authors propose a methodology for creating a CO2 emission model, which takes relatively little computational time, and the models created give viable results for full hybrid vehicles. The creation of an emission model is based on the review of the accuracy results of methods, such as linear, robust regression, fine, medium, coarse tree, linear, cubic support vector machine (SVM), bagged trees, Gaussian process regression (GPR), and neural network (NNET). Particularly in the work, the best fit for the road input data for the CO2 emission model creation was the GPR method. PEMS data was used, as well as model training data and model validation. The model resulting from this methodology can be used for the analysis of emissions from simulation tests, or they can be used for input parameters for speed, acceleration, and road gradient.

Reciprocating piston engines are the major propulsion devices for light aircrafts, helicopters, and essentially all automotive vehicles. They are expected to fulfil both present-day and future demands for engine performance, durability, fuel economy, and exhaust emissions legislation. One of the key factors related to these demands is the need to the limit thermomechanical internal losses, wear, and lubricating oil consumption, which are in turn conditioned by the tribological behavior of the piston-cylinder assembly. Consequently, this latter system requires a multi-directional approach in terms of manufacturing. Apart from various modifying techniques (e.g. laser texturing), a conventional plateau-honing operation is still the standard technology for shaping cylinder liner surface microstructure. This paper describes the distinctions between variations in the performance of the engines in relation to cylinder liner roughness parameters due to different honing settings. Five air-cooled reciprocating aircraft engines (FRANKLIN 4A-235-B31) served as the objects of research. The engines passed durability tests on the dynamometer bed, including operation under artificially intensified wear conditions. The results show a significant impact of the brand-new honed cylinder liner surface microstructure on the engine output parameters. Detailed study proves that some of the cylinder liner roughness parameters, specifically, the slope of the root mean square line (RMS) for valley roughness Rvq and the linear triangle area for valleys A2, are strongly correlated with the engine operational properties. Higher values of Rvq and A2 are associated with an improvement in engine performance but result in a deterioration in the exhaust harmful emission.Keywords Gasoline internal combustion engine Á Engine performance Á Plateau honing Á Piston-cylinder assembly Á Cylinder liner Á Surface roughness Á Abrasive wear Á Tribological behavior Abbreviations A2Roughness profile parameter-linear triangle area for valleys (lm) CO Concentration of carbon monoxide in exhaust (%) HC Concentration of hydrocarbons in exhaust (ppm) ge Brake-specific fuel consumption (BSFC; g/kW h) Ne Engine output power (kW) Mo Engine output torque (N m) go Engine total efficiency (%) P-C Piston-cylinder Rq Roughness profile parameter-root mean square of heights (lm) Rvq Roughness profile parameter-slope of a linear regression of valley region (lm)

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