Improving the accuracy of the gravimetric method for control particulate matter in diesel exhaust

Abstract

The work is devoted to solving the actual scientific-practical problem of improving the accuracy of the gravimetric method of control of the normalized ecological index of diesel engines – average operating mass emissions of particulate matter (PM) with exhaust gases – indicator PT. Based on the analysis of requirements of regulatory documents – interna-tional standard ISO 8178, UNECE Regulations R-83, R-49, R-96 and oth-ers regarding the conditions of gravimetric measurements of this indicator, as well as the world and own experience of such measurements, the authors identified the factors that influence the accuracy of the gravimetric method of PM control and made recommendations for improving the accuracy of this method. To evaluate the effectiveness of the recommendations created a scientific – practical base for studies of the accuracy of gravimetric mea-surements of PM, consisting of: mathematical models for determination of temperature conditions of sampling in systems of mass emission control of PM – tunnels and the resulting error in PT measurements; experimental setup and research methodology for determining methodological error of PT measurements, which depends on the temperature conditions of sam-pling in the tunnel; method of estimating the significance of instrumental – δРТin and methodical – δРТtf components of the resulting measurement er-ror of the indicator РТ – δРТ. On the basis of this scientific-practical base, experimental and computational studies of the accuracy of the gravimetric PM control method, which meets the requirements of the international stan-dard ISO 8178, were carried out, and installed instrumental, methodolog-ical and resultant measurement errors of average operating emissions PM emission using this method: δРТin= ±3.3...±4.5 %; δРТtf= – 4.5...6.3%; δРТ = -9.0...10.8 %. The effectiveness of the recommendations made by the authors is confirmed and it is established that their implementation al-lows to increase the accuracy of the gravimetric method of PM control in 3 times by eliminating the error δРТtf and reducing the value of δPT to the minimum level of instrumental error δРТin = ±3.3 %.