30
Alternative Fuels for Transportation
column for purification and recycled. The transesterification works well
when the feedstock oil is of high quality. However, quite often low quality oils are used as raw materials for biodiesel preparation. In cases where
the free fatty acid content of the oil is above 1%, difficulties arise due to the
formation of soap, which promotes emulsification during the water washing
stage and at a FFA content above 2%, the process becomes unworkable. The
most important variables that influence transesterification reaction time and
conversion are
1. Oil temperature
2. Reaction temperature
3. Ratio of alcohol to oil
4. Type of catalyst and concentration
5. Intensity of mixing
6. Purity of reactants
2.4 Engine Tests
2.4.1 Performance and emissions Studies
Suitability of vegetable oils for fuel purposes has been investigated by many
researchers all over the world during the past few decades. A typical engine
test conducted by Ramadhas et al. (2005a) is described as follows. Rubber
seed oil, typical nonedible type oil was considered for evaluating engine
short-term performance and emission characteristics. Engine tests have been
conducted on diesel engines using various blends of rubber seed oil diesel.
The variation of brake thermal efficiency of the engine with various blends is
depicted in Figure 2.2. The experimental results reveal that with increasing
brake power, the brake thermal efficiency of the blends is increased. There
was considerable increase in efficiency of the engine with blends as compared to the neat of rubber seed oil. The brake thermal efficiency of 80:20
(rubber seed oil:diesel) blend, closely matches with that of diesel oil. The
higher percentage of rubber seed oil in the blends had given lower thermal
efficiency as compared to diesel. The reason for the drop in thermal efficiency was attributed to higher viscosity and poor combustion characteristics of rubber seed oil.
Nwafor, Rice, and Ogbonna (2000) conducted tests using rapeseed oil on
single cylinder diesel engine and reported that rapeseed oil with standard
timing produced the highest mechanical efficiency (Figure 2.3). Vegetable oils
with longer ignition delay and longer combustion duration do not require
any advanced injection at low engine speed. They reported that diesel fuel
Alternative Fuels for Transportation
column for purification and recycled. The transesterification works well
when the feedstock oil is of high quality. However, quite often low quality oils are used as raw materials for biodiesel preparation. In cases where
the free fatty acid content of the oil is above 1%, difficulties arise due to the
formation of soap, which promotes emulsification during the water washing
stage and at a FFA content above 2%, the process becomes unworkable. The
most important variables that influence transesterification reaction time and
conversion are
1. Oil temperature
2. Reaction temperature
3. Ratio of alcohol to oil
4. Type of catalyst and concentration
5. Intensity of mixing
6. Purity of reactants
2.4 Engine Tests
2.4.1 Performance and emissions Studies
Suitability of vegetable oils for fuel purposes has been investigated by many
researchers all over the world during the past few decades. A typical engine
test conducted by Ramadhas et al. (2005a) is described as follows. Rubber
seed oil, typical nonedible type oil was considered for evaluating engine
short-term performance and emission characteristics. Engine tests have been
conducted on diesel engines using various blends of rubber seed oil diesel.
The variation of brake thermal efficiency of the engine with various blends is
depicted in Figure 2.2. The experimental results reveal that with increasing
brake power, the brake thermal efficiency of the blends is increased. There
was considerable increase in efficiency of the engine with blends as compared to the neat of rubber seed oil. The brake thermal efficiency of 80:20
(rubber seed oil:diesel) blend, closely matches with that of diesel oil. The
higher percentage of rubber seed oil in the blends had given lower thermal
efficiency as compared to diesel. The reason for the drop in thermal efficiency was attributed to higher viscosity and poor combustion characteristics of rubber seed oil.
Nwafor, Rice, and Ogbonna (2000) conducted tests using rapeseed oil on
single cylinder diesel engine and reported that rapeseed oil with standard
timing produced the highest mechanical efficiency (Figure 2.3). Vegetable oils
with longer ignition delay and longer combustion duration do not require
any advanced injection at low engine speed. They reported that diesel fuel