OPTIMIZING THE DESIGN OF A HYDROGEN ENGINE WITH PILOT DIESEL FUEL IGNITION

A diesel engine was, converted to dual-fuel hydrogen operation, igniti on being started by a 'pilot' quantity of diesel fuel but with 65 to 9 0% of the energy being supplied as hydrogen. With later injection timi ng, use of delayed port admission of the gas, and a modified combustio n chamber, thermal efficiencies were achieved nearly 15% greater than those for diesel as the sole fuel. A 'solid' water injection technique was used to curb knock under full load conditions when the power outp ut equalled or exceeded that of a similar diesel engine. The indicator diagrams under these conditions closely approach those of the Otto cy cle. The development was assisted by computer simulation using a novel self-ignition and flame propagation model. The very fast burning rate s obtained with stoichiometric hydrogen-air mixtures show combustion t o occur within 5 degrees of crank rotation yet Otto cycle thermal effi ciency was not achieved. However, greenhouse gases are shown to be red uced by more than 80%, nitrogen oxides by up to 70%, and exhaust smoke by nearly 80%.