(123b) A New Method for Exhaust Aftertreatment Design - Integrated Engine and Aftertreatment Analysis

Currently, the engine and aftertreatment (catalytical converter) design are separate process. This might lead to several empirical interactions to finalize the engine calibration and aftertreatment layout for a specific project (tailpipe emission target together with engine performance target).

            This report describes a ‘back of the envelope” methodology to quickly assess the tailpipe emission of a given engine and aftertreatment system.  This allows to do combination system (engine and aftertreatment) selection at the early stage of development to reduce time and cost.

            There are three main benefits from this methodology:

• It can define the optimal operating range for a given powertrain, with the consideration of engine out emission, fuel economy targets and aftertreatment conversion efficiency.
• It can estimate the catalyst light-off time with provided engine out emission data, or vice versa.
• For a given engine out exhaust gas temperature, species concentration and tailpipe emission target, this methodology can provide the maximum allowable aftertreatment system thermal inertia with defined catalyst light-off time, or vice versa, to meet a specific tail-pipe emission target.