The effects on engine performance and fuel consumption of Cummins B5.9 engines, were studied by using premium diesel of commercial grade, BD9505, BD8020, BD5050, and B100. Take the premium diesel of commercial grade as an example. It is added in Cummins for engine tests. The power mapping was measured using 8-10rmp as one increment. The idle to maximum speed of the engine was measured for the corresponding performance and fuel consumption. The maximum power output is 113.0Kw and the maximum torque force is 517Nm when the premium diesel of commercial grade was used on engines. When biodiesel BD9505, BD8020, BD5050 and B100 were used, the maximum power output was 104.2Kw, 104.7Kw, 104.9Kw, and 102.7Kw while the torque was 481Nm, 482Nm, 487Nm, and 482Nm. The test results showed that, when the four types of biodiesel were used, the maximum power was decreased by 7.8%, 7.3%, 7.2%, and 9.1% by comparing with that of premium diesel of commercial grade. The torque was reduced by 5.8-7.0% as shown in Table 6-3-3. For the average power and torque in the tests of speed range, the average horsepower of using biodiesel is reduced by 7.3-8.4% while the average torque is reduced by 7.2-8.0% than using premium diesel of commercial grade.
Comparing the horsepower and torque of five types of fuel oil as shown in Figure 6-3-1 and 6-3-2, the difference of 6-8% is close in the speed range of 600-2600rpm. However, when comparing the engine power characteristics shown in Figure 6-3-3, the difference of engine output power is more significant when the engine speed is increased in the 800-2600rpm speed range for the four types of biodiesel and the premium diesel of commercial grade. It indicates that the vehicle engines have more obvious power reduction at high speed and high loading turning conditions when using biodiesel.
To evaluate the fuel consumption performance objectively on the five types of fuel oil, “Brake Specific Fuel Consumption (BSFC)” shown in Table 6-3-3 and Figure 6-3-2 is used, rather than fuel consumption of engines throughout the study. The average BSFC of premium diesel is 212.7h/bhp-hr while that of the four types of biodiesel is 212.8, 219.0, 225.9, and 244.5h/bhp-hr respectively. It indicates that the vehicle consumes maximum 15.0% more fuel when using biodiesel than premium diesel. If it is based on volumetric BSFC, the fuel consumption is 255.2 l/hr-hp when using premium diesel and is 269.2, 272.6, 269.1, and 279.5 l/hr-hp when using the four types of biodiesel. It indicates that using biodiesel consumes 5.5-9.5% more fuel than using premium diesel.