Page 202 - Energy from Toxic Organic Waste for Heat and Power Generation

180 Energy from Toxic Organic Waste for Heat and Power Generation

fuel breakup and evaporation and reduced droplet size. In turn, this may
lower combustion duration at a faster rate of heat release. However, due to
addition of fuel oil by more than 20% in HOME, producer gas fueled dual
fuel operation resulted in lower brake thermal efficiency due to reduced
ignition centers caused by the decreased high-cetane number fuel in the
total fuel combination (HOME, fuel oil, and producer gas) used.
Use of RCC in producer gas fueled engine prevents the flame from
spreading over to the squish region, resulting in better mixture formation
of blend along with air-PG combination. Enhanced BTE could also be due
to uniform mixture formation caused by the increased swirl and changes
in the flow field at all engine loads [13]. However, in case of HOME-PG
dual fuel operation with HCC, combustion may be started with decreased
air motion inside the engine cylinder, leading to lower performance of dual
fuel engine. Therefore, it is noticed that use of RCC in a HOME+FO-PG
fueled engine increases the combustion during the expansion stroke, and
thus, improves the premixed combustion of fuel blend, preventing the
combustion of fuel blend during diffusion phase. The BTE obtained for
HOME-producer gas (HCC) and HOME-producer gas (RCC) opera-
tion with 10%, 20%, and 30% fuel oil were found to be 17.01%, 17.60%,
18.49%, and 17.86%, respectively, compared to 20.65% for diesel-PG oper-
ation (HCC).
The variations in exhaust gas temperature (EGT) for different fuel com-
binations are shown in Fig. 11.21. Results showed that HOME-PG oper-
ation resulted in higher EGT compared to diesel-PG operation. It could
be attributed to more burning of HOME during diffusion combustion
phase caused by its higher viscosity, leading to incomplete combustion. It is
noticed that dual fuel operations with RCC decrease EGT when fuel oil
is added in HOME. It could be due to enhanced combustion caused by
the improved swirl and fuel properties. Increased EGT in dual fuel mode
of operation is mainly due to the excess energy supply to the engine. But,
addition of fuel oil in HOME enhances the flame propagation, and more-
over, RCC may further facilitate the flame to travel over entire combustion
chamber. In addition, better mixture formation of HOME+FO blend along
with air-PG combination is also responsible for these results. However, dual
fuel engine with HOME-PG combination with HCC resulted in increased
exhaust gas temperature due to reduced premixed combustion, i.e., un-
burnt hydrocarbon burns during the diffusion combustion phase rather
than at the premixed combustion phase. Therefore, this results in increased
EGT. However, the addition of fuel oil in HOME decreases EGT due to a