Results repeatability evaluation of exhaust emission data obtained in laboratory WLTC test conditions using stationary and PEMS analysers

The article presents an assessment of the exhaust emission results repeatability in the WLTC test using two types of measurement systems: stationary laboratory analysers and a PEMS. The tests were conducted in laboratory conditions at BOSMAL Institute of Automotive Research and Development on a passenger car with a gasoline engine on a chassis dynamometer. The assessment included CO₂, CO, NOₓ, THC emissions and the particle number (PN) in each phase of the WLTC test (LOW, MIDDLE, HIGH, EX-HIGH) and in the entire test. The coefficient of variation (CV) was used to assess the repeatability. The results showed greater repeatability of measurements in the case of laboratory analysers, especially for CO₂ and CO. The PEMS system showed greater variability, especially in the dynamic test phases. Despite this, the results validation confirmed the compliance of the PEMS system with regulatory requirements. The article emphasizes the importance of the precision of exhaust emission tests in the context of measurement technologies development and the implementation of more restrictive emission standards, and it indicates CO₂ as the most stable parameter for both systems