Experimental assessment of a pre-turbo aftertreatment configuration in a single stage turbocharged diesel engine. Part 2: Transient operation

• Experimental evaluation of Diesel engine with pre-turbo aftertreatment configuration.
• Analysis of engine performance and emissions under transient operation.
• Driving cycles reveal potential for consumption reduction based on control optimisation.
• Pre-turbo DPF and DOC placement benefits aftermtreatment warm-up.
• Two-stage boosting systems to overcome driveability drawbacks under cold operation.

This paper corresponds to the second part of a work devoted to analyse the impact of the pre-turbo aftertreatment configuration on the performance of a single stage turbocharged Diesel engine. This second part focuses on the analysis of the engine response under transient operating conditions. To address the causes and effects of the change in engine response several types of transient processes consisting of driving cycles and load transient tests have been evaluated as starting point of the analysis.These tests make possible to account for the influence of the aftertreatment thermal inertia and how it affects the engine and aftertreatment performance obtained during driving cycles and under highly demanding transient operation. The pre-turbo aftertreatment placement also provides advantages in terms of faster aftertreatment warm-up. Therefore, the benefits on DPF (diesel particulate filter) passive regeneration as well as DOC (diesel oxidation catalyst) light-off leading to lower gas emissions have been assessed. The results have been compared against baseline emissions measured during experiments with post-turbo aftertreatment placement. Finally the influence of the thermal inertia on driveability in sudden accelerations as a function of the wall temperature along the exhaust line and boosting architecture is assessed combining the analysis of experimental and modelled data.