Particulate matter emissions of automobiles : development of a low-cost measurement system

Details

Supervisors

Jeanmart, Hervé ; Contino, Francesco

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil mécanicien

Abstract

Particulate matter emissions of vehicles have become a matter of great concern due to their adverse health effects and to the inability to measure them correctly. Actual vehicle inspection tests are indeed unable to detect the presence of a particulate filter on modern diesel cars although this after-treatment device allows to reduce the particulate matter emissions with 90 %. Particulate matter is moreover laborious to quantify since it is characterized by a number and mass concentration that depend on the size of the measured particles. The "Dieselgate" has also questioned the reliability of the current vehicle emission tests. There is consequently a need for reliable and representative measurements of particulate matter emissions of vehicles that are affordable for automobile inspection tests. The objective of the present Master's thesis is to develop a low-cost PM measurement system that is able to detect the presence of a diesel particulate filter and to assess its efficiency. In addition, a general idea of the amount of particulate matter present in the exhaust gases of an on-road vehicle is also pursued. In order to have an order of magnitude of particulate matter concentrations in exhaust gases, the present Master's thesis develops a conversion model based on the Euro norms. The conversion model is applied to two cars of the same model but complying with the Euro 3 and Euro 6b norm. As expected, the mass concentrations computed for the most recent car are more severe and within the order of magnitude of 1 mg/m³, as opposed to 5-20 mg/m³ for the car complying with Euro 3. In this paper, two low-cost measurement systems that quantify a particulate mass concentration of PM2.5 based on the optical backscatter principle are compared to three state-of-the-art measurement systems made available by GOCA. These sensors are compared during tests at low load on two diesel cars dating from 2001 and 2016 and characterized respectively by the absence and presence of a particulate filter. The tests at low load include a low and high idle speed test. A packaging for the low-cost sensors is developed for the experiments and it includes a dilution, a measurement chamber and two pumps. The improved setup of the sensor allows to minimize the clogging, condensation and to tackle the temperature limits imposed by the low-cost sensor. The present Master's thesis addressed the feasibility of using low-cost optical sensors for measuring particulate matter emissions of diesel cars. Further experiments with low-cost sensors on a recent car with and without DPF should indicate whether the distinction obtained during the experiments is indeed due to the absence of a particulate filter.