Investigation of processes in the WLTC test of a passenger car with a diesel engine

Abstract

The tests were carried out in accordance with the WLTP (Worldwide Light Duty Test Procedure), on a passenger car with a compression ignition engine. The analysis was conducted doe the following variables: vehicle speed, exhaust emission rate and fuel consumption volumetric rate. The subject of the research are exhaust emission components that are harmful to the health of living organisms: carbon monoxide, hydrocarbons and nitrogen oxides, as well as greenhouse gases. The research results have shown a very large range of values for carbon monoxide, organic compounds and nitrogen oxides emission rate characteristics. The average distance-specific emissions values of carbon monoxide, organic compounds and nitrogen oxides were very small and were in line with the Euro 6 requirements within a large margin. Correlation studies of the measured variables were conducted – between vehicle speed and exhaust emission rate as well as volumetric fuel consumption rates, and between exhaust emission rates and volumetric fuel consumption rates. Dimensionless statistical characteristics of the measured variables were determined, such as: extreme values, range, mean value, median, standard deviation, kurtosis, skewness and coefficient of variation. The coefficient of variation analysis made it possible to assess that the most dynamic properties could be observed in organic compounds emission rate, followed by carbon monoxide and nitrogen oxides emission rates, and finally – the vehicle speed. The vehicle speed histogram was characterized by relative uniformity apart from the dominance of the idle speed. Histograms of exhaust emission rate variables were most frequently dominated by small values.

Research on the results of the WLTP procedure for a passenger vehicle

“…The tests concerned engine exhaust emissions and the engine fuel consumption. Significant differences in the traffic conditions present for particular test phases relate to [2,3,[5][6][7][8]:…”

“…As it is known, the engine operating conditions have a strong impact on the engine performance, in particular on the engine exhaust emissions as well as its overall efficiency and, consequently, on the vehicle fuel consumption [2,3,[5][6][7][8].…”

“…Publication [2] presents the test results of a vehicles with a Diesel engine. The publication presents, among others: the results of correlation studies between the vehicle velocity, pollutant emission intensity, the particle number intensity and the volumetric fuel consumption intensity.…”

“…In another paper [2], the engine operating states were analyzed under the WLTC conditions of vehicle operation. The results of the work were used for a comparative evaluation of various shares of LPG (Liquefied Petroleum Gas) [9, 27] in a dual-fuel Diesel engine.…”