Experimental investigation of the effect of combined hydrogen and diesel combustion on the particulate size distribution from a high speed direct injection diesel engine

The effects of hydrogen addition and exhaust gas recirculation (EGR) levels on the exhaust particulate matter size distribution in a diesel engine have been investigated. The experiments were performed on a 2.0 litre, 4-cylinder, direct injection engine equipped with a modern high-pressure common rail. A nano-Micro-Orifice Uniform Deposit Impactor (nano-MOUDI) was used in this work to study the particulate matter size distribution. All tests were conducted at the set operating point of 1,500 rpm. The experimental work showed that the particulate matter size distribution was not dramatically altered by the addition of EGR, but the main peak was shifted towards the nucleation mode with the addition of hydrogen. The addition of hydrogen increases the emissions of nitrogen oxides (NOx), but reduces the emissions of unburnt hydrocarbons (THC). Conversely, the addition of EGR reduces NOx, but can increase THC. Hydrogen addition increases the peak cylinder pressure and the maximum rate of pressure rise.