Modeling and Measuring Exhaust Backpressure Resulting from Flow Restriction Through an Aftertreatment System

This paper describes the pressure loss characteristics of a variety of substrates (with and without washcoat) that have different cell densities, lengths, and diameters. Both experimental and analytical approaches were used to determine pressure loss characteristics. Engine dynamometer testing was conducted as an experimental approach to measure pressure losses at several different speed and load points. A simple, but comprehensive, analytical model was also developed to estimate pressure loss and equivalent power loss in an exhaust system. The model provides for losses due to the substrate resistance and the inlet/outlet headers. The experimental approach demonstrated that the model was an effective tool to provide assistance during the screening of exhaust system design alternatives.