Abstract
The results of the development and research of a promising full-flow dynamic method of variable volume sampling to determine in laboratory conditions the values of mass emissions of pollutants from the exhaust gases of automobile engines are presented. Emissions are determined by the test procedures for complete vehicles in driving cycles, or separately of their engines in motor test cycles.Current mass emissions of pollutants are calculated from time-synchronized instantaneous concentrations and instantaneous flow rates of the mixture of exhaust gases and air. In the mixing chamber, which serves the exhaust gases and air, also serves calibration gas mixture with a flow rate that is changed in accordance with the periodic function. This is used to determine the transfer functions of the inverse calculation of the instantaneous flow rate of the mixture of exhaust gases and air, and the current values of the concentrations of pollutants at the time of sampling. Mass emissions of gaseous pollutants are calculated as the difference between the total mass emissions of pollutants and the mass emissions of pollutants that are added with the flow of the calibration gas mixture.The performance of the dynamic full-flow variable-volume sampling method is proved by comparing the calculated (carbon balance method) and directly measured fuel consumption by cars in driving cycles. The difference between the directly measured and calculated (for certain mass emissions of pollutants) fuel consumption does not exceed±3.5 %. This is a satisfactory result, taking into account, in particular, the measurement uncertainty in the dynamics of rapidly changing concentrations of pollutants, diluted exhaust gas flow rate, fuel consumption, and the determination of carbon content in the fuel.Fundamentally new possibilities have been obtained for measuring the mass specific emissions of pollutants by forced-ignition engines and modern diesel engines (Euro-6 environmental class) and promising low-emission vehicles.
Highlights
Road transport is the dominant source of pollution by toxic substances of atmospheric air in places of mass concentration of the population
This leads to the introduction by countries of the world of stricter standards for the standards of emissions of pollutants by vehicles, in particular, the «Euro-6», «LEV-3», and «Tier-3» standards
Among the standardized components of exhaust emissions (EG) of internal combustion engines in the EU, special attention is paid, in particular, to particles (PM) – one of the most harmful components in the composition of exhaust gases, nitrogen oxides (NOx), total hydrocarbons (T.HC) and their non-methane parts (NMHC), carbon monoxide (CO), and other toxic substances that cause multibillion-dollar macroeconomic losses to society
Summary
Road transport is the dominant source of pollution by toxic substances of atmospheric air in places of mass concentration of the population This leads to the introduction by countries of the world of stricter standards for the standards of emissions of pollutants by vehicles, in particular, the «Euro-6», «LEV-3», and «Tier-3» standards. A fundamentally insurmountable drawback of the standard method of sampling a constant volume is the generally high values of the EG dilution factor, which are obtained at most engine operating modes in test, in particular, driving cycles. The concentrations of individual pollutants (primarily carbohydrates) in diluted exhaust gases can be comparable with their concentrations in ambient air This significantly complicates, and in some cases, in principle, makes it impossible to measure emissions of environmentally friendly cars that meet «Euro-6», «LEV-3», and «Tier-3» standards. The urgent task is to find an alternative to the standard method of sampling a constant volume, which imposes fundamental restrictions on the determination of low emissions
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