Improving Brake Thermal Efficiency Using High-Efficiency Turbo and EGR Pump While Meeting 2027 Emissions
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Cited by 3 publications
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Impact of off-road engine electrification through EGR pumping on CO2, soot, and NOx emissions reductions during steady-state operating conditions
Off-road vehicles are emphasizing brake thermal efficiency improvements to meet upcoming diesel emission standards set by the California Air Resources Board (CARB), aiming for enhanced engine and vehicle component efficiency. CARB is implementing regulations demanding a 90% reduction in oxides of nitrogen (NOx) emissions compared to current EPA Tier 4 standards, extending to off-highway vehicles by 2031. The experimental study described in this paper investigated how high-efficiency turbocharging (HET) and electric 48 V EGR pumping (EGRP) enable improved fuel efficiency in a 13.6 L off-road Diesel engine during steady-state operation. The integration of a 48 V EGR Pump enables the complete use of the high-efficiency turbo, encompassing both fuel reduction and NOx mitigation, at reduced engine delta pressure (exhaust—intake manifold pressure). Fuel consumption reductions in excess of 8% at low-speed/high-loads, nearly 5% on the torque curve at 1200 rpm, and 1.6%–3.1% in high-speed/high-load scenarios were demonstrated. NOx levels were generally similar to or lower than the baseline. Soot emissions remained comparable to or lower than the baseline. Open cycle efficiency (OCE) was improved across all points studied. Closed cycle efficiency improved under specific conditions, particularly at low-speed/high-load scenarios for which advanced injection timing could be used as a result of improved EGR flow control with the EGR pump. The OCE improvements were driven by reduced pumping work, with primary attribution to the high-efficiency turbocharger. The EGR pump played a pivotal role in maintaining engine-out NOx levels, especially under conditions where the conventional high-pressure EGR system would have been limited due to reduced pressure differentials between the intake and exhaust manifold (as a result of the high-efficiency turbocharging).
Impact of off-road engine electrification through EGR pumping on CO2, soot, and NOx emissions reductions during steady-state operating conditions
Off-road vehicles are emphasizing brake thermal efficiency improvements to meet upcoming diesel emission standards set by the California Air Resources Board (CARB), aiming for enhanced engine and vehicle component efficiency. CARB is implementing regulations demanding a 90% reduction in oxides of nitrogen (NOx) emissions compared to current EPA Tier 4 standards, extending to off-highway vehicles by 2031. The experimental study described in this paper investigated how high-efficiency turbocharging (HET) and electric 48 V EGR pumping (EGRP) enable improved fuel efficiency in a 13.6 L off-road Diesel engine during steady-state operation. The integration of a 48 V EGR Pump enables the complete use of the high-efficiency turbo, encompassing both fuel reduction and NOx mitigation, at reduced engine delta pressure (exhaust—intake manifold pressure). Fuel consumption reductions in excess of 8% at low-speed/high-loads, nearly 5% on the torque curve at 1200 rpm, and 1.6%–3.1% in high-speed/high-load scenarios were demonstrated. NOx levels were generally similar to or lower than the baseline. Soot emissions remained comparable to or lower than the baseline. Open cycle efficiency (OCE) was improved across all points studied. Closed cycle efficiency improved under specific conditions, particularly at low-speed/high-load scenarios for which advanced injection timing could be used as a result of improved EGR flow control with the EGR pump. The OCE improvements were driven by reduced pumping work, with primary attribution to the high-efficiency turbocharger. The EGR pump played a pivotal role in maintaining engine-out NOx levels, especially under conditions where the conventional high-pressure EGR system would have been limited due to reduced pressure differentials between the intake and exhaust manifold (as a result of the high-efficiency turbocharging).
Fuel Efficiency Evaluation of an Off-Road Diesel Engine with an EGR Pump and High-Efficiency Turbocharger across Various Drive Cycles
<div>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 NO<sub>x</sub> and CO<sub>2</sub> emissions while improving fuel efficiency when paired with a high-efficiency turbocharger.</div> <div>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 NO<sub>x</sub> 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.</div> <div>Experiments were conducted at selected operating points to achieve optimal brake thermal efficiency while keeping BSNO<sub>x</sub> within 25% of baseline values. These results helped develop a calibration map for both transient and steady-state testing.</div> <div>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.</div> <div>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</div> <div>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. BSNO<sub>x</sub> 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.</div>
<div class="section abstract"><div class="htmlview paragraph">This review covers advances in regulations and technologies in the past year in the field of vehicular emissions. We cover major developments towards reducing criteria pollutants and greenhouse gas emissions from both light- and heavy-duty vehicles and off-road machinery. To suggest that the transportation is transforming rapidly is an understatement, and many changes have happened already since our review last year [<span class="xref">1</span>]. Notably, the US and Europe revised the CO<sub>2</sub> standards for light-duty vehicles and electrification mandates were introduced in various regions of the world. These have accelerated plans to introduce electrified powertrains, which include hybrids and pure electric vehicles. However, a full transformation to electric vehicles and the required grid decarbonization will take time, and policy makers are accordingly also tightening criteria pollutant standards for internal combustion engines. California has published the Advanced Clean Cars II standards and Europe has held various workshops outlining the core elements of future Euro 7 regulations. These will likely be the last major regulations for criteria pollutants, and compliant vehicles will likely be zero-impact emitting, that is with tailpipe emissions at or lower than the ambient concentrations. Meeting these regulations will require adoption of several advanced engine and emission control technologies which we discuss here. Emphasis will be on reducing cold start emissions, likely requiring active thermal management strategies. The challenge will be to lower criteria pollutants while also reducing fuel consumption, and we review some approaches being considered. The story is similar for heavy-duty vehicles, where meeting California’s Low NOx regulations and Euro VII scenarios require significantly improved engine controls and after-treatment systems. New system solutions and hardware additions show a pathway to meeting the regulations, although we caution that much more work is needed ahead to achieve the reductions over extended durability limits and with healthy engineering margins. We also review the impact of alternative fuels on reducing well-to-wheels (WTW) greenhouse gas emissions, along with recommendations to continue improving market fuel quality to reduce negative impact on criteria pollutants. Finally, while this paper does not intend to provide a detailed review of battery electric or fuel cell vehicle technology, we touch upon a few studies which discuss the outlook of powertrain diversification from a total cost of ownership and greenhouse gas reduction perspective.</div></div>
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