Page 209 - Energy from Toxic Organic Waste for Heat and Power Generation

Power Generation From Renewable Energy Sources 187

However, intermittent supply of producer gas and lower mixing rates may
significantly affect the delay period. For single fuel operation, the ignition
delay can be specified with one component of total combustion stage that
contains liquid fuel ignition alone. As the present work has three different
fuels, the changes in delay period are quite complex issue. Diesel fuel with
same combustion chamber (HCC) resulted in lowered ID during producer
gas combustion as diesel has higher cetane number and the break up has
been favored with existing nozzle due to better injection. Therefore, im-
proved air-fuel mixing will lower ignition delay for diesel-PG operation.
However, HOME-PG operation with existing HCC leads to increased de-
lay period as biodiesel results in larger fuel particles and its mixing with
air along with producer gas becomes difficult. But ignition delay with ad-
dition of fuel oil in HOME and producer gas combinations with RCC is
found to be marginally lower when compared to HOME-producer gas
operation (HCC). Reduced viscosity of HOME due to addition of fuel
oil improves fuel spray characteristics, further enhancing the in-cylinder
temperature inside engine cylinder. This improves air utilization caused by
the development of swirl and squish due to use of RCC. Further, it leads
to better burning of the charge with flow of high-velocity flames caused
by the use of RCC and increased combustion temperature throughout the
combustion chamber. Use of more fuel oil fraction (20% by vol) in HOME
during dual fuel operation resulted in slightly increased delay period due
to increased physical mixing of fuels with air. Therefore, study showed that
HOME+FO20-PG(RCC) resulted in better mixing of air and fuel leading
to shorter ignition delay due to better volatility and reduced density of
HOME. The ignition delay values for HOME-PG(HCC) and HOME-
PG(RCC) operation with 10%, 20%, and 30% fuel oil were found to be
19.01, 17.1, 15.5 degree CA and 16.12 degree C, respectively, compared to
13.2 degree C for diesel-producer gas operation (HCC).
The combustion duration for the dual fuel combinations used shown
in Fig. 11.28 was calculated based on the duration between the start of
combustion and 90% cumulative heat release. From the figure, it follows
that combustion duration increases with increase in the power output and
is due to increase in quantity of fuel injected. For the HOME-producer gas
dual fuel combination with RCC, reduced combustion duration was ob-
served due to proper mixing of air-fuel with enhanced improved premixed
combustion. Dual fuel operation with basic combustion chamber (HCC),
the second peak in the diffusion-burning phase, was found to be higher
for HOME-producer gas when compared to diesel-producer gas dual fuel