Experimental assessment of pre-turbo aftertreatment configurations in a single stage turbocharged diesel engine. Part 1: Steady-state operation

Abstract

Elsevier Luján, JM.; Bermúdez, V.; Piqueras, P.; Garcia Afonso, O. (2015). Experimental assessment of pre-turbo aftertreatment configurations in a single stage turbocharged diesel engine. AbstractDiesel oxidation catalysts and diesel particulate filters are standard aftertreatment systems in Diesel engines which are traditionally placed downstream of the turbine. However, pre-turbo aftertreatment configurations are being approached as a way to improve the aftertreatment performance in terms of light-off and passive regeneration. This exhaust line architecture can also benefit fuel economy. The objective of this work is to analyse experimentally how the pre-turbo aftertreatment placement impacts on the performance of a single stage turbocharged Diesel engine.The work has been divided into two parts focused on steady-state and transient engine operation separately. The first part comprises the analysis of the experimental results corresponding to steady-state operating conditions. The range of operation covers different engine loads and speeds. The engine response with pre-turbo aftertreatment placement is mainly affected by the change in the pumping work caused by the aftertreatment pressure drop reduction and its new location, which avoids the multiplicative effect of the turbine expansion ratio when setting the engine back-pressure. These effects become more significant as the engine load increases benefiting fuel consumption from low to high loads. Concerning aftertreatment performance, the results evidence noticeable benefits in DPF passive regeneration and CO/HC emissions reduction at low engine load.

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

“…It is not very damaging in terms of fuel consumption in most of the EUDC since pre-turbo aftertreatment placement benefits from the aftertreatment pressure drop location [19]. However, the last acceleration is requiring not only further VGT closing but also higher pedal demand, which is plotted in Figure 4(c), and hence higher fuel consumption during this phase.…”

“…After 5 s at motoring conditions, the pedal was again pushed up to 80% in engine load in 0.2 s. This phase is referred as hot wall operation since wall temperature remains high during the load step due to thermal inertia. [19]. Under steady-state operating conditions at low engine load and speed, the reduction in aftertreatment pressure drop and the fact that it is not multiplied by the pressure ratio to set the engine back-pressure are not completely able to compensate the pulse amplitude reduction across the aftertreatment system in pre-turbo placement.…”

“…The soot mass is calculated from the measurement of the soot opacity [26]. As indicated in the Part 1 of this work [19] the procedure is considered suitable for comparison proposals since although the application of empirical correlations non-based on mass evaluation can be a source of uncertainty the tests are the same in all the aftertreatment configurations.…”

“…Nevertheless, since it is not a direct measurement but a calculation, it was calibrated under steady-state operation with the measurements performed by the gravimetric balance according to the methodology proposed by Serrano et al [13]. For the sake of brevity the reader is referred to Part 1 of the work [19] where further details on the main characteristics of the instrumentation are provided.…”

“…The study under transient operation has been performed with the same engine and test cell facility that in Part 1 of the work, which is devoted to steady-state operating conditions [19]. Table 1 Figure 2.…”