Effect of hydrogen-diesel fuel co-combustion on exhaust emissions with verification using an in–cylinder gas sampling technique

An overview of the effects of fuel molecular structure on the combustion and emissions characteristics of compression ignition engines

“…At higher engine loads (and thus higher levels of hydrogen addition and a subsequently richer hydrogen-air (H 2 -air) stoichiometry) it was suggested that the reduction in ignition delay arises from a higher in-cylinder temperature which offsets the reduced oxygen level. 65 Figure 8 shows similar trends in ignition delay when burning methane-hydrogen (CH 4 -H 2 ) mixtures, pilot ignited by diesel fuel, in a compression ignition engine 67 as seen in the case of hydrogen only intake aspirated mixtures ( Figure 7). Furthermore, Figure 8 shows that, for the same engine load, the ignition delay period is considerably longer for all CH 4 -H 2 mixtures relative to only diesel fuelling.…”

“…[71][72][73] However, when operating at specific engine load conditions and for advanced diesel fuel injection timings, considerable reductions in exhaust NO x emissions with H 2 -diesel fuel co-combustion have been observed in other studies. [74][75][76] Figure 10 shows the concentration of exhaust NO x emissions for H 2 -diesel fuel co-combustion experiments conducted by Talibi et al, 65 utilising a fixed flow rate of the pilot diesel fuel and with the engine load increased by increasing the hydrogen level. In Figure 10, for a diesel injection duration of 250 ms, levels of NO x emitted remain at approximately 20 ppm until the increase in hydrogen results in an engine load (IMEP) of 4 bar, beyond which the further addition of hydrogen results in a rapid increase in NO x emissions.…”

“…72,74,76,77,113 Figure 13 shows the percentage reduction in the total particulate mass plotted against the percentage reduction in fuel carbon supplied to the engine at constant engine loads for H 2 -diesel fuel co-combustion tests. 65 The proportions of diesel fuel and hydrogen were adjusted to achieve constant loads, and the percentage reductions in both particulates and fuel carbon were calculated against the values obtained with the engine operating on only diesel fuel (no hydrogen addition). It can be seen in Figure 13 that, for an engine IMEP below 4 bar, the reduction in PM emissions lies in the top half of the graph, which implies a reduction in the PM emissions beyond that obtained by simple fuel carbon displacement.…”

A Taguchi-fuzzy based multi-objective optimization study on the soot-NOx-BTHE characteristics of an existing CI engine under dual fuel operation with hydrogen

“…The brake thermal efficiency increased from approximately 23%e28% with 30% hydrogen enrichment. In another study [10], carried out on a naturally aspirated, direct injection diesel engine with hydrogen as the dual fuel, combustion showed an increase in NOx and CO 2 emissions with decrease in the particulates, CO and THC emissions. An investigation was carried out in [22] on a four-stroke diesel engine with a single cylinder.…”

Comprehensive investigation on hydrogen and fuel cell technology in the aviation and aerospace sectors

“…However, the amounts of NOx emissions released from burning hydrogen are extremely low compared to those released when burning kerosene [25]. Generally, the overall reduction of NOx when using hydrogen fuel is due to the fact that the water vapour generated from burning hydrogen absorb most of the energy released from the combustion process and thus reduce peak combustion temperatures preventing the formation of NOx [26]. The water vapour contributes to the formation of contrails which also has global warming effects.…”