Exhaust Gas Recirculation, Late Intake Valve Closure and High Compression Ratio for Fuel Economy Improvement in a MPI Gasoline Engine

2014 ◽  
Author(s):  
Yunlong Li ◽  
Yiqiang Pei ◽  
Jing Qin ◽  
Shaozhe Zhang ◽  
Yu Shang ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Fuel Economy ◽  
Gasoline Engine ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Valve Closure ◽  
Intake Valve ◽  
High Compression Ratio ◽  
Fuel Economy Improvement ◽  
Gas Recirculation

Strategies for using valvetrain flexibility instead of exhaust manifold pressure modulation for diesel engine gas exchange and thermal management control

2019 ◽  
pp. 146808741988063 ◽  
Author(s):  
Kalen R Vos ◽  
Gregory M Shaver ◽  
Mrunal C Joshi ◽  
Aswin K Ramesh ◽  
James McCarthy
Keyword(s):  
Thermal Management ◽  
Pressure Control ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Valve Closure ◽  
Exhaust Manifold ◽  
Intake Valve ◽  
Cylinder Deactivation ◽  
Valve Opening ◽  
Gas Recirculation

At low-to-moderate loads, modern diesel engines manipulate exhaust manifold pressure to drive exhaust gas recirculation and thermally manage the aftertreatment. In these engines, exhaust manifold pressure control is typically achieved via either a valve after the turbine, a variable geometry turbine, or wastegating. The study described here demonstrates how valvetrain flexibility enables engine operation without requiring exhaust manifold pressure control. Specifically, intake valve closure modulation and cylinder deactivation at elevated engine speeds, along with exhaust valve opening modulation at low engine speeds, can match, or improve, efficiency and thermal management compared to a stock thermal calibration that requires exhaust manifold pressure control. During low-speed, low-load operation, the stock engine uses elevated exhaust manifold pressures to increase the required fueling (for thermal management) and to drive exhaust gas recirculation. Exhaust valve opening modulation can instead be implemented to enable similar aftertreatment warm-up, while cylinder deactivation allows aftertreatment temperature maintenance with a 40% reduction in fuel consumption. During high-speed, low-to-moderate loads, the stock engine implements thermal management operation by decreasing exhaust manifold pressure. Intake valve closure modulation together with cylinder deactivation can instead be implemented to enable fuel-efficient thermal management improvements via charge flow control.

Development of a Miller cycle engine with single-stage boosting and cooled external exhaust gas recirculation

2016 ◽  
Vol 231 (6) ◽  
pp. 766-780 ◽  
Author(s):  
Yongsheng He ◽  
Jim Liu ◽  
Bin Zhu ◽  
David Sun
Keyword(s):  
Fuel Consumption ◽  
Compression Ratio ◽  
Fuel Economy ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Single Stage ◽  
Exhaust Gas ◽  
Brake Specific Fuel Consumption ◽  
Miller Cycle ◽  
Gas Recirculation

In this paper, the development of a Miller cycle gasoline engine which has a high compression ratio from 11.5:1 to 12.5:1, single-stage turbocharging and external cooled exhaust gas recirculation is described. The improvement in the fuel economy by adding external cooled exhaust gas recirculation to the Miller cycle engine at different geometric compression ratios were experimentally evaluated in part-load operating conditions. The potential of adding external cooled exhaust gas recirculation in full-load conditions to mitigate pre-ignition in order to allow higher geometric compression ratios to be utilized was also assessed. An average of 3.2% additional improvement in the fuel economy was achieved by adding external cooled exhaust gas recirculation to the Miller cycle engine at a geometric compression ratio of 11.5:1. It was also demonstrated that the fuel consumption of the engine with external cooled exhaust gas recirculation was reduced by 3–7% in a wide range of part-load operating conditions and that the engine output of the Miller cycle engine at a geometric compression ratio of 12.5:1 increased at 2000 r/min in the full-load condition. The Miller cycle engine with external cooled exhaust gas recirculation at a geometric compression ratio of 12.5:1 achieved a broad brake specific fuel consumption range of 220 g/kW h or lower, with the lowest brake specific fuel consumption of 215 g/kW h. While there are still challenges in implementing external cooled exhaust gas recirculation, the Miller cycle engine with single-stage turbocharging and external cooled exhaust gas recirculation showed its potential for substantial improvement in the fuel economy as one of the technical pathways to meet future requirements in reducing carbon dioxide emissions.

Improving diesel engine efficiency at high speeds and loads through improved breathing via delayed intake valve closure timing

2017 ◽  
Vol 20 (2) ◽  
pp. 194-202 ◽  
Author(s):  
Kalen R Vos ◽  
Gregory M Shaver ◽  
Xueting Lu ◽  
Cody M Allen ◽  
James McCarthy ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Exhaust Gas ◽  
Valve Closure ◽  
Effective Pressure ◽  
Intake Valve ◽  
Brake Mean Effective Pressure ◽  
Gas Recirculation

Valve train flexibility enables optimization of the cylinder-manifold gas exchange process across an engine’s torque/speed operating space. This study focuses on the diesel engine fuel economy improvements possible through delayed intake valve closure timing as a means to improve volumetric efficiency at elevated engine speeds via dynamic charging. It is experimentally and analytically demonstrated that intake valve modulation can be employed at high-speed (2200 r/min) and medium-to-high load conditions (12.7 and 7.6 bar brake mean effective pressure) to increase volumetric efficiency. The resulting increase in inducted charge enables higher exhaust gas recirculation fractions without penalizing the air-to-fuel ratio. Higher exhaust gas recirculation fractions allow efficiency improving injection advances without sacrificing NOx. Fuel savings of 1.2% and 1.9% are experimentally demonstrated at 2200 r/min for 12.7 and 7.6 bar brake mean effective pressure operating conditions via this combined strategy of delayed intake valve closure, higher exhaust gas recirculation fractions, and earlier injections.

scholarly journals Exploring alternative combustion control strategies for low-load exhaust gas temperature management of a heavy-duty diesel engine

2018 ◽  
Vol 20 (4) ◽  
pp. 381-392 ◽  
Author(s):  
Wei Guan ◽  
Hua Zhao ◽  
Zhibo Ban ◽  
Tiejian Lin
Keyword(s):  
Fuel Consumption ◽  
Control Strategies ◽  
Fuel Efficiency ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Valve Closure ◽  
Intake Valve ◽  
Gas Temperature ◽  
Exhaust Gas Temperature ◽  
Gas Recirculation

The employment of aftertreatment systems in modern diesel engines has become indispensable to meet the stringent emissions regulations. However, a minimum exhaust gas temperature of approximately 200 °C must be reached to initiate the emissions control operations. Low-load engine operations usually result in relatively low exhaust gas temperature, which lead to reduced or no exhaust emissions conversion. In this context, this study investigated the use of different combustion control strategies to explore the trade-off between exhaust gas temperature, fuel efficiency, and exhaust emissions. The experiments were performed on a single-cylinder heavy-duty diesel engine at a light load of 2.2 bar indicated mean effective pressure. Strategies including the late intake valve closing timing, intake throttling, late injection timing (Tinj), lower injection pressure (Pinj), and internal exhaust gas recirculation and external exhaust gas recirculation were investigated. The results showed that the use of external exhaust gas recirculation and lower Pinj was not effective in increasing exhaust gas temperature. Although the use of late Tinj could result in higher exhaust gas temperature, the delayed combustion phase led to the highest fuel efficiency penalty. Intake throttling and internal exhaust gas recirculation allowed for an increase in exhaust gas temperature at the expense of higher fuel consumption. In comparison, late intake valve closure strategy achieved the best trade-off between exhaust gas temperature and net indicated specific fuel consumption, increasing the exhaust gas temperature by 52 °C and the fuel consumption penalty by 5.3% while reducing nitrogen oxide and soot emissions simultaneously. When the intake valve closing timing was delayed to after −107 crank angle degree after top dead centre, however, the combustion efficiency deteriorated and the HC and CO emissions were significantly increased. This could be overcome by combining internal exhaust gas recirculation with late intake valve closure to increase the in-cylinder combustion temperature for a more complete combustion. The results demonstrated that the ‘late intake valve closure + internal exhaust gas recirculation’ strategy can be the most effective means, increasing the exhaust gas temperature by 62 °C with 4.6% fuel consumption penalty. Meanwhile, maintaining high combustion efficiency as well as low HC and CO emissions of diesel engines.

Effect of addition of hydrogen and exhaust gas recirculation on characteristics of hydrogen gasoline engine

2017 ◽  
Vol 42 (12) ◽  
pp. 8288-8298 ◽  
Author(s):  
Yaodong Du ◽  
Xiumin Yu ◽  
Lin Liu ◽  
Runzeng Li ◽  
Xiongyinan Zuo ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Gas Recirculation

Effect of addition of hydrogen and TiO2 in gasoline engine in various exhaust gas recirculation ratio

2019 ◽  
Vol 44 (21) ◽  
pp. 11205-11218 ◽  
Author(s):  
S. Manigandan ◽  
P. Gunasekar ◽  
S. Poorchilamban ◽  
S. Nithya ◽  
J. Devipriya ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Gas Recirculation
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