Let’s put things in perspective first. Brake thermal efficiency was ~ 35% in 1960. In 2020, Weichai announced a 50% BTE commercial engine (more details on Dieselnet). And the US Department of Energy’s SuperTruck 2 program is targeting 55% BTE next year. At least two participants announced this year that they are close to 53%.
Navistar, Book chapter in “Alternative Fuels and Advanced Vehicle Technologies for Improved Environmental Performance”, 2014 doi:10.1533/9780857097422.2.225
Here are some enabling technologies that the participants are pursuing to achieve 55% BTE and doubling of freight efficiency. Improvements include those at the engine, transmission and vehicle level. Also included are model based control of the drivetrain and emissions systems.
The table below shows some of the options being evaluated by each of the participants at the engine level. Common elements include light thermal barrier coated pistons, high compression ratios, Miller cycle, high efficiency turbochargers, waste heat recovery and close-coupled SCR.
The program enters its final year and we will see whether the participants can demonstrate achieving the targets at the DOE Annual Merit Review in 2021. See you there.