As regulations become more stringent, engine manufacturers are adopting
innovative technologies to reduce emissions while maintaining durability and
reliability. One approach involves optimizing air handling systems. Eaton
developed a 48 V electric exhaust gas recirculation pump (EGRP) to reduce
NOx and CO2 emissions while improving fuel efficiency
when paired with a high-efficiency turbocharger.
This study integrates an electric EGRP and a high-efficiency turbocharger onto a
13.6L John Deere off-road diesel engine to evaluate the impact on fuel
efficiency and NOx emissions across various drive cycles including
the nonroad transient cycle (NRTC), the low load application cycle (LLAC), the
constant speed–load acceptance (CSLA) test, and the ramped modal cycle (RMC).
The study highlights the benefits and limitations of the prototype EGRP on an
off-road engine. Since the setup did not include aftertreatment systems,
engine-out emissions were analyzed.
Experiments were conducted at selected operating points to achieve optimal brake
thermal efficiency while keeping BSNOx within 25% of baseline values.
These results helped develop a calibration map for both transient and
steady-state testing.
For the CSLA tests, the time response to achieve 90% load was slower with the
EGRP-equipped engine compared to the stock engine. Additionally, the NRTC, a
regulatory cycle for the United States and the European Union, and the LLAC did
not achieve the desired torque set points with the EGRP and high-efficiency
turbocharger. The EGRP’s slower-than-desired response when it decelerates led to
excess EGR flow, which affected the engine’s ability to produce torque. This was
a key finding of the study.
The measured engine speed and engine load with the EGRP engine configuration were
utilized to develop a modified version of the NRTC and LLAC, referred to in this
article as the modified NRTC and the modified LLAC. The modified NRTC and
modified LLAC were run on the stock engine to accurately compare the performance
of the stock hardware with the EGRP and high-efficiency turbocharger hardware
for the same transient cycles, albeit cycles that are no longer specifically the
regulatory NRTC and LLAC cycles. The intent of the modified LLAC and the
modified NRTC is to show what the possible benefits of EGRP and high-efficiency
turbocharging may likely be if the transient response shortcoming of the EGRP is
addressed
BSFC improved with the EGRP and high-efficiency turbocharger hardware for the
modified NRTC, modified LLAC, and RMC. The modified NRTC showed a 1.3%
improvement, the modified LLAC exhibited a 2.5% improvement, and the RMC
demonstrated a 1.3% improvement. BSNOx increased by 12.9% for the
modified NRTC, decreased by 11.1% for the modified LLAC, and increased by 2.8%
for the RMC with the EGRP configuration. The BSPM increased by 34.2% for
modified LLAC and improved by 33.1% for the modified NRTC.
