SAE seminar showcases engine with 42% thermal efficiency

    Recently, the 2014 SAE High-Efficiency Internal Combustion Engine Symposium was successfully concluded in Detroit, the United States, on April 6-7, 2014. At the SAE High-Efficiency Internal Combustion Engine Symposium, the EGR Car designed by the Southwest Research Institute (SwRI) attracted the most attention. The Southwest Research Institute used the 2012 Buick Regal GS as its EGR car for display. As shown in the picture, the 2012 Buick Regal GS is covered with colorful decals, and its appearance is very eye-catching. Its internal power configuration is even more powerful. It uses an advanced combustion system, which greatly improves its fuel efficiency and greatly reduces exhaust emissions. Among them, the advanced combustion system was designed by the Southwest Research Institute, and it has been purchased by a large European automobile manufacturer and is planned to be put into production.

    This time, the advanced combustion system designed by the Southwest Research Institute uses a 2.0-liter D-EGR engine, which is a four-cylinder engine in which only a single cylinder is used in the exhaust gas recirculation process to improve the exhaust gas recirculation process and the recycling process of the hydrogen and carbon monoxide mixture. According to Dr. Terry Alger, deputy director of the Southwest Research Institute, the D-EGR engine has a brake thermal efficiency of 42% in zero-load to full-load tests.

    Dr. Terry Alger, associate director of the Southwest Research Institute, and Chris Chadwell, manager of SI engine research at the Southwest Research Institute, presented their respective research groups’ progress in natural gas engines and advanced engine technologies at the 4th SAE Annual Meeting, held at the Westin Book Cadillac Hotel in Detroit. Terry Alger, Chris Chadwell and their colleagues at the Southwest Research Institute, Jacob Zuehl and Raphael Gukelberger, jointly published a technical paper titled “A Demonstration of Dedicated EGR on a 2.0L GDI Engine.”

PSA Group plans to mass produce the D-EGR engine in 2018

    According to engineers at the Southwest Research Institute, the D-EGR engine is only a four-cylinder engine, so it only uses a single cylinder to participate in the exhaust gas recirculation process. As the total number of engine cylinders increases, the number of cylinders participating in the exhaust gas recirculation process can also increase accordingly. In the above D-EGR engine, the operation mode of the single cylinder participating in the exhaust gas recirculation process adopts a complex control strategy, which helps to improve the engine exhaust gas recirculation tolerance and reduce a series of power losses caused by the external reformer.

    In the D-EGR engine, a hydrogen and carbon monoxide rich mixture enters the recirculation system together with other exhaust gases. The hydrogen and carbon monoxide rich mixture helps to offset the many disadvantages of exhaust gas recirculation system cooling. The hydrogen and carbon monoxide rich mixture can increase the engine combustion rate and thus improve the tolerance of the engine exhaust gas recirculation system, thereby also improving the engine combustion stability. In addition, the hydrogen and carbon monoxide rich mixture also has a lower minimum ignition energy, which helps to improve fuel combustion and reduce the content of hydrocarbons in the exhaust gas, thereby improving the combustion efficiency of the engine.

    Engineers at the Southwest Research Institute of the United States said that the D-EGR engine uses naturally aspirated operation and has an ultra-high compression ratio of 14: 1. Compared with ordinary engines with a compression ratio of only 11.7: 1, experimental results show that high-compression ratio engines using D-EGR cycle perform better in exhaust emissions than low-compression ratio engines.

    Engineers from the Southwest Research Institute of the United States also said that the knock phenomenon of the D-EGR engine when using ordinary gasoline (US standard 87 AKI, AKI is the anti-knock index) has reached the same high level as that of premium gasoline (US standard 93 AKI). The D-EGR engine also uses a two-stage turbocharging system. When the engine speed is between 1500-5500 rpm, the D-EGR engine can not only ensure the minimum brake mean effective pressure (BMEP) of 17 bar through the two-stage supercharging system, but also ensure the torque output target and gear shifting smoothness.

    The D-EGR engine system is equipped with a dedicated circuit design, a two-stage supercharging system, a high-energy ignition system and fuel injectors that can deliver additional fuel to the mixture.

Effective fuel consumption rate benefits

    Terry Alger said that the US FTP (Federal Test Program) test showed that the D-EGR engine had a 13% improvement in transient driving cycle indicators compared to ordinary engines; at the same time, in the US Environmental Protection Agency Highway Fuel Economy Test (HwFET), its test indicators increased by 10%. At an engine speed of 2000 rpm, the effective fuel consumption rate of the D-EGR engine increased from 385 g/kWh of ordinary engines to 330 g/kWh, and its minimum effective fuel consumption rate also increased from 236 g/kWh to 212 g/kWh. The experimental results conducted by the Southwest Research Institute of the United States showed that under specific working conditions, the fuel efficiency of the D-EGR engine can be improved by 30%.

    This time, the D-EGR project of the Southwest Research Institute is a continuation of its High Efficiency Dilute Gasoline Engine (HEDGE) project. The purpose of the High Efficiency Dilute Gasoline Engine project is to improve the fuel efficiency of gasoline engines by equipping them with a cooled exhaust gas recirculation system, which can eventually make the fuel efficiency of gasoline engines reach the same level as that of diesel engines or even exceed that of diesel engines. The D-EGR project will be led by Chadwell and continue to enter the latest stage - HEDGE III.

    The D-EGR R&D project plans to achieve the goal of D-EGR engine emissions meeting the stringent LEV3 emission standards in 2018.