Comparison of Turbocharging and Pressure Wave Supercharging of a Natural Gas Engine for Light Commercial Trucks and Vans

• Published in: Energies (Basel) 2021-09, Vol.14 (17), p.5306
• Main Authors: Zsiga, Norbert, Skopil, Mario A., Wang, Moyu, Klein, Daniel, Soltic, Patrik
• Format: Article
• Language: English
• Subjects: Automobiles; Automotive parts; boosting; Catalysts; Catalytic converters; Cold; Diesel engines; Elastic waves; Emission control equipment; Engines; exhaust aftertreatment; Exhaust gases; Exhaust systems; Friction reduction; Gas flow; Gas temperature; Gases; low-end torque; Miller valve timing; Natural gas; pressure wave supercharging; Redesign; Thrust bearings; Torque; Transient response; Trucks; turbocharging; Vans; Water injection
• ISSN: 1996-1073; 1996-1073
• DOI: 10.3390/en14175306

To increase the efficiency of a natural gas engine, the use of a Miller camshaft was analysed. To avoid a decline in the low-end torque and also in the transient response, a pressure wave supercharger (Comprex™) was compared to the conventional single-stage turbocharger. The analyses for this conceptual comparison were performed experimentally, and the data were then used to run simulations of driving cycles for light commercial vehicles. A torque increase of 49% resulted at 1250 rpm when the Comprex™ was used in combination with a Miller camshaft. Despite the Miller camshaft, the Comprex™ transient response was still faster than the turbocharged engine. Using the same camshaft, the turbocharged engine took 2.5-times as long to reach the same torque. Water injection was used to increase the peak power output while respecting the temperature limitations. As the Comprex™ enables engine braking by design, we show that the use of friction brakes was reduced by two-thirds. Finally, a six-times faster catalyst warmup and an up to 90 °C higher exhaust gas temperature at the three-way catalytic converter added to the benefits of using the Comprex™ supercharger. The known drawbacks of the Comprex™ superchargers were solved due to a complete redesign of the machine, which is described in detail.