Energy Reports (Nov 2022)
Experimental investigation of the effect of an afterburner on the light-off performance of an exhaust after-treatment system
Abstract
Future passenger cars must comply with whatever regulations will be created to mitigate greenhouse gas emissions (GHG) and pollution. Regarding the pollutants of an internal combustion (IC) engine, they are dealt with by using an exhaust after-treatment system (EATS). Yet, catalytic converters encounter light-off problems after cold start: their after-treatment efficiency is unsatisfactory until their temperature reaches a threshold, usually called the light-off temperature. Consequently, in this phase, important levels of pollutants are produced, being therefore paramount to achieve the catalyst light-off as fast as possible. Passing to EURO7, which is expected to happen in 2025 means to have the EATS ready for efficient treatment “instantaneously” after cold starting. The solutions usually used to generate more heat at the EATS level are not considered sufficient for the coming EURO7 regulation. Consequently, they must be complemented with other systems, such as the afterburner, which is an extra-combustion device. Accordingly, this paper is focused on the challenges that come with the use of such an afterburner and it presents the following: (1) a proposal for a layout and operation strategy of such a device and (2) an experimental investigation of the effect an afterburner has on the light-off performance of a usual three-way catalyst. On the latter, the cold start exhaust emissions were analyzed with and without using this extra-combustion device, thus being able to conclude on its effectiveness: full light-off of the pre-catalyst thanks to burner’s operation up to 1000 °C and, consequently, an efficient treatment of the pollutants. Equally, the paper presents the impact of the afterburner on fuel consumption and, therefore, on GHG it generates, given the fact that it burns carbon-based fuel as the engine.
