50 % brake thermal efficiency – the realization of a vision

GHG and CO2 legislations in US, Europe and China demand a reduction of emissions in the range of 25 to 30% for heavy commercial vehicles in the current decade. To meet these challenging targets, a further increase of the efficiency of the internal combustion engine is one of various optimization parameters. AVL develops engine concepts to increase the brake thermal efficiency (BTE) to 50%, focusing on base-engine improvements. This requires a spec. fuel consumption below 170 g/kwh. This article shows AVL’s research results, which are based on the testing results of a single cylinder research engine and on 1D-thermodynamic simulations. From these results, challenges for design and friction requirements are derived. Finally, the strengths and weaknesses of diesel engine concepts with the potential for 50% BTE are discussed.