Monovalent Natural Gas Combustion and Downsizing for Lowest CO₂ Emissions

Authors

Dr. sc. techn. M. Warth, Dipl.-Ing. S. Streng, Dr.-Ing. P. Wieske, Dr.-Ing. U. Mohr, MAHLE International GmbH, Stuttgart; B.Eng. J. Hall, MAHLE Powertrain Ltd., Northampton

Year

2016

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 799

Summary

Due to inherent compromises in a bivalent engine design, the positive fuel properties of natural gas can be only partially utilized. This article presents the potential for a consistently monovalent design of a 1.2 L three-cylinder natural gas engine. In comparison, the potential of a bivalent engine variant and that of a gasoline engine with the same power and torque ratings is also described. Peak cylinder pressures of 180 bar and specific output levels of up to 110 kW/L pose considerable challenges to the mechanical and thermal load capacity of the engine. Cylinder components specific to natural gas can yield significant fuel consumption advantages and high specific power output at the same time. Variable turbine geometry exhaust gas turbocharging in combination with natural gas port fuel injection increases torque at low engine speeds, improves transient boost pressure build-up, and allows for stoichiometric operation across the operating map. For a vehicle of the compact van class, up to 31 % in CO₂ savings can be realized compared with the gasoline mass-production engine.