# Using Canola Oil Biodiesel as an Alternative Fuel in Diesel Engines: A Review
## 5 Results and Discussion
### Combustion Characteristics  
[PERSON] et al. [57] tested different ratios of COB blended with diesel fuels in a common rail diesel engine. The experimental results are shown in Figure 11. The tested fuels were noted as BD0 (pure diesel fuel), BD10 (10% COB blended with 90% diesel fuel by vol.), BD20 (20% COB blended with 80% diesel fuel by vol.), and BD30 (30% COB blended with 70% diesel fuel by vol.). As shown in Figure 11, they found that the combustion pressure decreased with an increase in the amount of COB at low engine speed (1500 rpm). This is because the atomization effect was not good, due to the higher viscosity of COB than that of diesel fuel. However, the opposite results were observed at high engine speed (2500 rpm), because the combustion conditions (atomization effect, injection pressure, etc.) were improved at high engine speed. The rate of heat release also increased due to the presence of oxygen in the COB. In addition, [PERSON] et al. [57] also found that the combustion pressure of pure diesel decreased significantly with increasing EGR. However, the combustion pressure of COB decreased slightly with increasing EGR, and the combustion pressure of BD30 with 10% EGR was higher than that of 0% EGR at 2000 rpm. [PERSON] et al. [81] tested three ratios of COB blended with diesel fuel at different engine loads. They also showed that the combustion pressure of BD20 was a little higher than that of pure diesel at high engine load. These results showed that influence of the oxygen in the COB was greater than the influence of its high viscosity at high engine speed or load. To further prove that BD20 is a good blended fuel based on combustion characteristics at other test conditions, [PERSON] et al. [82] researched the combustion characteristics of BD20 at different pilot injection timings. The results are shown in Figure 12. They reported that the combustion pressure and heat release rate of BD20 decreased slightly as the pilot injection timing was delayed.  
Figure 11: Combustion pressures and rate of heat releases of blend fuels at (**a**) 1500 rpm and (**b**) 2500 rpm. EGR: exhaust gas recirculation.  
Figure 12: Combustion pressure (**a**) and heat release rate (**b**) of BD20 at various pilot injection timings.  
Figure 13: Combustion pressure and heat release rate (**b**) of BD20 at various pilot injection timings.  
Figure 11: Combustion pressures and rate of heat releases of blend fuels at (**a**) 1500 rpm and (**b**) 2500 rpm. EGR: exhaust gas recirculation.  
[PERSON] et al. [84] studied five kinds of COB blended diesel fuels. The compounding ratios of COB and diesel fuel were 100:0 (B100), 60:40 (B60), 40:60 (B40), 20:80 (B20), and 0:100 (D100) by volume ratio. The brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) are exhibited in Figure 13. As shown in Figure 13a, the BTE of 5 fuels increased with increasing engine load, and the value of BTE was almost constant when the engine load was more than 75%. In addition, the BTE of pure canola oil (B100) was the closest to that of pure diesel (D100), about 98.2% of that of diesel fuel. As shown in Figure 13b, the BSFC of all fuels decreased with increasing engine load, and the B100 BSFC was the highest among all fuels. These results of BTE and BSFC are all because COB has a lower heat value, which means that the COB needs to burn more fuel to get as much power as diesel fuel. These results are the same as our previous results [57; 81].