Experimental Evaluation of Advanced Turbocharger Performance on a Light Duty Diesel Engine

Abstract

Engine manufacturers are continually faced with the challenges of meeting more stringent emission regulations while maintaining the customer requirements for fuel economy improvement. This challenge has required future turbochargers to have good efficiency at low flow area and sufficient surge margin, while customer demand and market competition drive for high power or high power density characteristics. This combination of competing requirements translates into turbocharger designs that have high efficiency over wide operation range on both the turbine and compressor. Instead of having two or three turbochargers arranged in series, or parallel and operated sequentially, as some auto manufacturers have successfully demonstrated in production vehicles [1,2], this project focused on a singlestage turbocharger solution for high-efficiency operation over wide operation range. A single-stage solution provides benefits from constraints on packaging, cost, durability, and potential heat dissipation concerns in the boost system. ABSTRACTFor diesel engines to meet current and future emissions levels, the amount of EGR required to reach these levels has increased dramatically. This increased EGR has posed big challenges for conventional turbocharger technology to meet the higher emissions requirements while maintaining or improving other vehicle attributes, to the extent that some OEMs resort to multiple turbocharger configurations. These configurations can include parallel, series sequential, or parallelseries turbocharger systems, which would inevitably run into other issues, such as cost, packaging, and thermal loss, etc.This study, as part of a U.S. Department of Energy (USDoE) sponsored research program, is focused on the experimental evaluation of the emission and performance of a modern diesel engine with an advanced single stage turbocharger.A production IHI (Ishikawajima Harima Heavy Industries) turbocharger was selected as the base architecture for the turbocharger design with optimizations focused on compressor impeller and turbine wheel designs.An advanced impeller design was used on the compressor side to improve the efficiency and surge margin at low mass flow areas of the compressor map, allowing greater EGR flow while extending the flow capacity by using an active casing treatment on the compressor cover.Mixed flow turbine technology was used on the turbine side, due to its performance characteristics; particularly high efficiency at low speed ratios relative to the base conventional radial flow turbine. This characteristic is relevant to increased EGR operation required for future diesel applications.Both steady state and transient engine dynamometer testing of FTP transient cycles at Tier II Bin 5 emission levels show that the advanced turbocharger technology enables around 3% fuel economy improvement on the engine while meeting the same emissions level.

Control-oriented turbine power model for a variable-geometry turbocharger

“…This is verified using the experimental data from steady-state tests performed on a heavy-duty turbocharged diesel engine. 26,27 The entire engine operational range is mapped via 195 steady-state speed and load points. The vane position is based on the turbocharger control signal u vgt and varies from the fully closed position to the fully open position.…”

Experimental Investigation of the Loading Strategy of an Automotive Diesel Engine under Transient Operation Conditions

“…However, for the "fast-slow" loading strategies with 50% and even bigger 50% CPL (e.g., Strategies 4,5,7,8,10,and 11), the average ratio of fuel consumption, soot and CO in transient process increased to different degrees, and the biggest increase of strategy 11 is 9%, 92.2% and 65.3%, respectively. This is because of the above loading strategies (strategy 4,5,7,8,10,11). Due to the rapid oil supply rate in the early period and the long duration of high speed injection, the AFR in the early transient process decreases rapidly and causes the larger anoxic environment in the cylinder.…”

“…The emission performance under the non-linear loading strategy is better than that under the linear loading strategy, if the κ is a negative, and vice versa. However, the smoke and CO emissions deteriorated under the "fast-slow" loading strategies with overlarge CPLs (e.g., Strategies 4,5,7,8,10,and 11), and the emissions increase as the ELR and CPL increase. For example, the peak values of smoke and CO emissions are 40.1% and 926 ppm and the increasing rates are 449.3% and 122.5% in Strategy 11, respectively, which demonstrates that the emissions performance seriously deteriorates.…”

“…Their share in the highly competitive auto market keeps increasing, however, their transient operation is particularly important in daily operation conditions, especially in urban roads, where engine loads and speeds vary frequently and suddenly. In order to meet the increasingly stringent emission regulations and improve the popularity rate of diesel engines in the highly competitive automobile market, it is necessary to study their fuel economy and emission performance [1][2][3][4][5][6][7][8].…”

Regenerative Hydraulic Assisted Turbocharger

“…Both VGT and EGR valve controllers are map based with gain scheduled Proportional-Integral-Derivative (PID) controllers. Detailed engine and turbocharger model validation results can be found in [24].The performance of the vehicle system simulator is shown through the tracking of the desired vehicle velocity trajectory in Figure 7.…”