Fuel Efficiency Evaluation of an Off-Road Diesel Engine with an EGR Pump and High-Efficiency Turbocharger across Various Drive Cycles

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.