b d
dP/d(θ), ar/ egree
16
12
8
4
0
IT = 30°BTDC
N = 1200 rpm
Diesel
Dual
4
8
12
16
20
24
Load, Nm
216
Alternative Fuels for Transportation
Figure 7.8
Effect of engine load on pressure rise rate for diesel and dual fuel engine. (From Selim,
M. Y. E., Renewable Energy, 22(4), 473–89, 2000. Reprinted with permission from Elsevier
Publications.)
the overall equivalence ratio (Saleh and Selim 2010). Figure 7.8 shows the
increase in dual fuel combustion noise as compared to base diesel engine
(Selim 2000). This combustion noise is well related to the overall engine noise
and roughness. A concentrated ignition source is needed for the combustion
of the inducted fuel at low loads.
Choice of pilot fuel can help to reduce the engine roughness as illustrated in Figure 7.9 (Selim, Saleh, and Radwan 2008). A pilot fuel that is
easy to self-ignite, derived from the Jojoba plant, with reduced ignition
delay period, may reduce the maximum pressure rise rate and hence engine
noise. Further, injection timing of the pilot fuel, injector opening pressure,
and pilot fuel quantity and intake temperature are some of the important
variables controlling the performance of dual fuel engines at light loads.
Poor combustion of the gaseous fuel at low loads because of dilute fuel–
air mixtures results in high carbon monoxide and unburned hydrocarbons
emissions. Any measure that lowers the effective lean flammability limit of
the charge and promotes flame propagation will improve part load performance. Preheating of the intake charge and increase in pilot diesel quantity
resulted in higher thermal efficiency. However, at high loads and high intake
temperatures, increased admission of the gaseous fuel can result in uncontrolled reaction rates near the pilot fuel spray and lead to knock. Resorting
dP/d(θ), ar/ egree
16
12
8
4
0
IT = 30°BTDC
N = 1200 rpm
Diesel
Dual
4
8
12
16
20
24
Load, Nm
216
Alternative Fuels for Transportation
Figure 7.8
Effect of engine load on pressure rise rate for diesel and dual fuel engine. (From Selim,
M. Y. E., Renewable Energy, 22(4), 473–89, 2000. Reprinted with permission from Elsevier
Publications.)
the overall equivalence ratio (Saleh and Selim 2010). Figure 7.8 shows the
increase in dual fuel combustion noise as compared to base diesel engine
(Selim 2000). This combustion noise is well related to the overall engine noise
and roughness. A concentrated ignition source is needed for the combustion
of the inducted fuel at low loads.
Choice of pilot fuel can help to reduce the engine roughness as illustrated in Figure 7.9 (Selim, Saleh, and Radwan 2008). A pilot fuel that is
easy to self-ignite, derived from the Jojoba plant, with reduced ignition
delay period, may reduce the maximum pressure rise rate and hence engine
noise. Further, injection timing of the pilot fuel, injector opening pressure,
and pilot fuel quantity and intake temperature are some of the important
variables controlling the performance of dual fuel engines at light loads.
Poor combustion of the gaseous fuel at low loads because of dilute fuel–
air mixtures results in high carbon monoxide and unburned hydrocarbons
emissions. Any measure that lowers the effective lean flammability limit of
the charge and promotes flame propagation will improve part load performance. Preheating of the intake charge and increase in pilot diesel quantity
resulted in higher thermal efficiency. However, at high loads and high intake
temperatures, increased admission of the gaseous fuel can result in uncontrolled reaction rates near the pilot fuel spray and lead to knock. Resorting