Study on Hydrogen-Assist Diesel Combustion : 1st Report, Effects of Hydrogen in Intake Mixture on Combustion and Exhaust Emission Characteristics of a Diesel Engine(Thermal Engineering)

Abstract

The present study experimentally investigated the performance and emission characteristics of a diesel engine with hydrogen added to the intake air at late diesel-fuel injection timings. The diesel-fuel injection timing and the hydrogen fraction in the intake mixture were varied while the available heat produced by diesel fuel and hydrogen was kept constant at a certain value. As the hydrogen fraction was increased, NO first deceased, attained minimum, and then increased. The maximum rate of incylinder pressure rise also showed minimum at 10vol% hydrogen fraction. The indicated thermal efficiency was almost constant or slightly increased with small amount of hydrogen. A combination of hydrogen addition and late diesel-fuel injection timing contributed to low temperature combustion, in which NO decreased without the increase in unburned fuel.