Abiding by the “Transient Cycle Tests” method required as pollutant emission standard for diesel engines by EPA of Executive Yuan, the five types of fuel are all tested at the facilities built by CPC Refinery Research Institute.
In the transient cycle tests for 1200 seconds, the integrated power is 9.90075 kw-hr for the premium diesel and 8.98792, 8.98792, 9.12836, and 9.05813 kw-hr for the four types of biodiesel as shown in Table 6-3-5. The power loss for using biodiesel is 7.8-9.2% which is close to the aforementioned static power loss. For the weight BSFC (g/bhp-hr), it is higher for using biodiesel than premium diesel by 3.7-20.4% in average. The fuel consumption is increased with the increase of biodiesel addition ratio.
To evaluate the pollutant emission conditions for biodiesel and premium diesel, when Cummins B5.9 diesel engine is used, the pollutant emission index for premium diesel is 0.435g/bhp-hr for total hydrocarbon(THC), 2.055g/bhp-hr for carbon oxide(CO), 6.304 g/bhp-hr for nitrogen oxide(NOx), and 0.1324g/bhp-hr for particulate matter(PM) (Table 6-3-4). After biodiesel BD9505 is used, the THC, CO, NOx, and PM emission is 0.309, 1.530, 5.743, and 0.0993 g/bhp-hr respectively. When using the other types of biodiesel of BD8020, BD5050, and B100, the pollutant emission index is reduced more than premium diesel as shown in Table 6-3-4.
The THC and CO emission index is lower by 18.4-37.0% and 11.3-25.5% for biodiesel than premium diesel. For NOx emission, there is not negative effect expect biodiesel B-100. For PM emission, biodiesel is less by 21.8-35.3% than premium diesel as shown in Figure 6-2-5. It indicates that when biodiesel is used, it can effectively reduce the emission of THC, CO, and PM pollutants.
Pollutant of pollution emission is measured by the opacity smoke meter made by Nipponkiki company of Japan in the study. The pollution emission inspection of engines is referred to national standard of Republic of China CNS-11645 for pollution emission test method of full loading at fixed speed. When adding biodiesel during Cummins B5-9 engines operating, the maximum power output at speed of 100% and 60% test conditions, the pollution emission is close to zero with insignificant difference. Therefore the tests are measured at 40% speed of maximum power output in full loading. The results show that the pollution emission is 53.8, 43.3, 38.3, 34.8, and 33.6% for the five types of fuel premium diesel, BD9505, BD8020, BD5050, and B100, respectively. The pollution emission for using biodiesel is reduced by 19.5-37.5% in average more than for using premium diesel.
The pollution emission tests were carried out for one vehicle each at stage 1, 2, and 3 without moving and loading in spontaneous speed, according to CNS-11644 methods. The results are shown in Table 6-4-2-1.
- For the tests on stage-1 car without loading and with speeding smoke, the pollutant results is 58%, 47.9%, 47.2%, 31.8%, and 58% when using BD9505, BD8020, B20, B100, and premium diesel. The pollution emission is improved by 45.1% for B100 as the most efficient over the premium diesel. For using BD9505, BD8020, and B20, there is no significant performance on pollution emission.
- For the tests on stage-2 car, the pollution emission of 85.5% for B100 is the most significant. For BD9505 and BD8020, the smoke reduction is 42.5% and 55.1%. But only 18.7% for B20.
- For the tests on stage-3 car, the smoke improvement of 89.4% for B100 is most significant while that of BD9505 and BD8020 is 7.07% and 62.6%. For B20, the improvement is merely 7.3%.
- It can be concluded that there is no significant improvements of pollution emission when using B20 and best performance when using B100 for cars of all stages. For BD9505 and BD8020, no improvements for stage-1, but good performance for stage-2 and stage-3 cars.
If the inspection requirement is based on the premium diesel of commercial grade, all the biodiesel types have met so can be used. However there is improvement to make as follows:
pour point
For -3oC as the maximum requirement for premium diesel at present, it cannot be met for the four types of biodiesel. The reason is that biodiesel contains nature vegetable oil which the flow point is essentially higher and cannot be improved. But the problem is solved by adding 500-1,000ppm of flow improvement agents thus it is not an issue in the future. As referring to what the advanced countries have made, the standards for biodiesel is not built upon that for premium fossil diesel of commercial grade. The required criteria for biodiesel or mixed fuel are setup independently and they all meet those for premium diesel except the flow point.