Quality assurance of exhaust emissions test data

Abstract

Tight requirements posed by the increasingly stringent legislation complicate the design procedure for exhaust aftertreatment devices and systems. Since design optimization relies heavily on experiments and tests, emissions test data acquisition should comply with strict quality standards. Time-varying exhaust emission measurements incorporate a wealth of information stemming from the engine type, its fuel injection and ignition management and valve timing and the exhaust gas treatment devices present. The objective of this paper is to present the preliminary development process of a test data quality assurance methodology that may be coded in the form of computer software. This paper is a first attempt in this direction and is based on 15 years of experimental and computational experience of the authors' laboratory in exhaust gas treatment testing and modelling. The methodology comprises three steps. The first step involves modal analysis of the driving cycles. This allows comparison between different types of engine and test procedure regarding engine management philosophy and exhaust aftertreatment characteristics. The second step involves a systematic data synchronization and preprocessing procedure, which significantly improves data quality. The third and most important part of the methodology involves systematic checking by means of molecular and elemental balance calculations.