114
Alternative Fuels for Transportation
On the other hand, it seems that the methanol ratio has little effect on the
soot emission.
4.7.2.5 Carbon Dioxide (CO 2 ) Emission
CO 2 emissions are released into the atmosphere when fuel is completely
burned in an engine. As illustrated in the Figure 4.13a, when the methanol amount increased in the fuel mixture, the percentage change in CO and
UHC decreased. The percentage change in CO 2 had an opposite behavior
when compared to the CO concentrations, and this was due to improving the
combustion process as a result of the oxygen content in the methanol. The
maximum increase in the change of CO 2 was observed at 24%, 33%, and 74%
for M5, M10, and M15, respectively, compared to M0 at 20 Nm engine load
and advanced injection timing. CO 2 emissions increased with the advanced
injection timing for all fuel mixtures. As shown in Figure 4.14a through c
for M10, advanced injection timing increased the change in CO 2 by 6% and
retarded injection timing diminished in CO 2 by 8% compared to ORG and
retarded injection timing, respectively.
4.7.3 engine Combustion Studies
Combustion and heat release analysis can yield valuable information
about the effect of engine design, fuel injection system, fuel type, and
engine operating conditions on the combustion process and engine performance. Wang et al. (2008) investigated the effects of methanol mass
fraction and pilot diesel injection timing on the ignition to understand
the variation in the ignition delay and detailed combustion characteristics.
With the increase of methanol mass fraction, the maximum cylinder pressure, the maximum rate of pressure rise, and the maximum heat release
rate increased.
Huang et al. (2004b), studied combustion and heat release characteristics of a CI engine using methanol–diesel fuel blend. According to the
experimental results, increasing the methanol mass fraction in the methanol–diesel fuel blends resulted in an increase in the heat release rate
at the premixed burning phase and shortened the combustion duration
at the diffusive burning phase. Huang et al. (2004c) and Ozaktas et al.
(2000) found that there was an increase in ignition delay and increase
in premixed heat release with the combustion of methanol-blended
diesel fuel.
Ozaktas et al. (2000) studied the effect of the compression ratio on ignition delay for methanol–diesel fuel blends on an ASTM-CFR engine and
they compared the results with baseline diesel fuel. They expressed that,
with increasing compression ratio, ignition delay decreased almost linearly for all the fuel blends tested. Ignition delays of the blend fuels were
Alternative Fuels for Transportation
On the other hand, it seems that the methanol ratio has little effect on the
soot emission.
4.7.2.5 Carbon Dioxide (CO 2 ) Emission
CO 2 emissions are released into the atmosphere when fuel is completely
burned in an engine. As illustrated in the Figure 4.13a, when the methanol amount increased in the fuel mixture, the percentage change in CO and
UHC decreased. The percentage change in CO 2 had an opposite behavior
when compared to the CO concentrations, and this was due to improving the
combustion process as a result of the oxygen content in the methanol. The
maximum increase in the change of CO 2 was observed at 24%, 33%, and 74%
for M5, M10, and M15, respectively, compared to M0 at 20 Nm engine load
and advanced injection timing. CO 2 emissions increased with the advanced
injection timing for all fuel mixtures. As shown in Figure 4.14a through c
for M10, advanced injection timing increased the change in CO 2 by 6% and
retarded injection timing diminished in CO 2 by 8% compared to ORG and
retarded injection timing, respectively.
4.7.3 engine Combustion Studies
Combustion and heat release analysis can yield valuable information
about the effect of engine design, fuel injection system, fuel type, and
engine operating conditions on the combustion process and engine performance. Wang et al. (2008) investigated the effects of methanol mass
fraction and pilot diesel injection timing on the ignition to understand
the variation in the ignition delay and detailed combustion characteristics.
With the increase of methanol mass fraction, the maximum cylinder pressure, the maximum rate of pressure rise, and the maximum heat release
rate increased.
Huang et al. (2004b), studied combustion and heat release characteristics of a CI engine using methanol–diesel fuel blend. According to the
experimental results, increasing the methanol mass fraction in the methanol–diesel fuel blends resulted in an increase in the heat release rate
at the premixed burning phase and shortened the combustion duration
at the diffusive burning phase. Huang et al. (2004c) and Ozaktas et al.
(2000) found that there was an increase in ignition delay and increase
in premixed heat release with the combustion of methanol-blended
diesel fuel.
Ozaktas et al. (2000) studied the effect of the compression ratio on ignition delay for methanol–diesel fuel blends on an ASTM-CFR engine and
they compared the results with baseline diesel fuel. They expressed that,
with increasing compression ratio, ignition delay decreased almost linearly for all the fuel blends tested. Ignition delays of the blend fuels were