The experimental results demonstrate that the hydrogen addition in the intake air has an
influence on improvement of engine power, and energy consumption (Fig. 5, 7,
. NO
emissions are very complicated (Fig. 9). Higher smoke of exhaust gases is observed (Fig. 10).
The higher engine power with hydrogen addition (Fig. 5, 7) is due to the additional heat
released from hydrogen combustion and to the reduced combustion duration (1). The
combustion of hydrogen addition provides additional heat energy, which is one of the reasons
for а higher engine output. The shorter combustion duration causes lower heat transfer rate
thought the combustion chamber walls and higher diesel fuel heat utilization. As a result of
the calculations that were done, the increase of the whole heat added to the engine cycle due
to hydrogen combustion is 2,44% averaged over the entire investigated engine speed region.
But the averaged power improvement obtained as a result of the experimental investigation is
15% (Fig. 7). The middle indicated pressure improvement at 1500 rpm is 14.8% (Fig. 5).
These facts show that the power improvement comes not only from the energy added as a
result of hydrogen addition. The greater part of power increase is due to combustion process
improvement by the means of combustion duration reduction because of superior combustion
and flame propagation properties of hydrogen. The proofs of this statement are the curves of
net heat release and net heat release rate shown respectively on (Fig. 4) and (Fig. 3).
Whether or not the energy used to make the hydrogen is less than the improved combustion energy is for another study.
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