Dual fuel H2-diesel heavy duty truck engines with optimum speed power turbine

Abstract

The turbocharged direct injection lean burn Diesel engine is the most efficient engine now in production for transport applications with full load brake engine thermal efficiencies up to 40-45 % and reduced penalties in brake engine thermal efficiencies reducing the load by the quantity of fuel injected. The secrets of this engine's performances are the high compression ratio and the lean bulk combustion mostly diffusion controlled in addition to the partial recovery of the exhaust energy to boost the charging efficiency. The major downfalls of this engine are the carbon dioxide emissions and the depletion of fossil fuels using fossil Diesel, the energy security issues of using foreign fossil fuels in general, and finally the difficulty to meet future emission standards for soot, smoke, nitrogen oxides, carbon oxide and unburned hydrocarbons for the intrinsically "dirty" combustion of the fuel injected in liquid state and the lack of maturity the lean after treatment system. Renewable hydrogen is a possible replacement for the future of the Diesel that is free of carbon dioxide and other major emissions, with the only exception of nitric dioxides. In this paper, a Diesel engine is modelled and converted to run hydrogen retaining the same of Diesel full and part load efficiencies. The conversion is obtained by introducing a second direct fuel injector for the hydrogen. The dual fuel engine has slightly better than Diesel fuel efficiencies all over the load range and it may also permit better full load power and torque outputs running closer to stoichiometry. The development of novel injectors permitting multiple injections shaping as in modern Diesel despite the extremely low density of the hydrogen fuel is indicated as the key area of development of these engines. © 2013 Springer-Verlag.