The brake thermal efficiency of engine using neat RSO is 26.5%
at the rated output which is lower than efficiency of engine
using diesel fuel about 29.9%. Injection of DEE with RSO
increases the brake thermal efficiency of engine. The maximum
brake thermal efficiency of engine is 28.5% with 200 g/h of DEE.
There is a large reduction in smoke emission of engine with
RSO–DEE operation from 6.1 BSU with neat RSO to 4 BSU with
DEE at the optimum quantity of 200 g/h at rated power. The
reduction in smoke emission is due to the better combustion
of injected fuel in the hotter combustion chamber by the early
combustion of DEE. The smoke emission of base diesel engine
is 3.4 BSU at rated output.
DEE injection reduces hydrocarbon and carbon monoxide emissions.
The decrease in HC and CO level with DEE operation is
due to combustion enhancement by the DEE.
NOx levels are higher with DEE compared with neat RSO due to
higher premixed heat release rate. NOx emission is 9.3 g/kWh
with RSO–DEE at the optimum DEE quantity of 200 g/h, where
as for diesel and RSO it is 10.7 g/kWh and 6.9 g/kWh,
respectively.
The premixed combustion phase with DEE is higher than RSO
due to the early burning of DEE.
RSO results in higher combustion duration than neat Diesel. The
addition of DEE with RSO results in reduced combustion duration.
The combustion duration reduces from 47CA to 44CA
with DEE injection. This is mainly due to fast diffusion combustion
rate as compared to neat RSO.
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