Biomedical Engineering Reference
In-Depth Information
Figure 14 shows a comparison of cetane numbers of various FAMES to diesel. While
they vary slightly for different FAMEs, they are all considerably higher than diesel's cetane
number.
70
Edible
Tallow
Inedible
Tallow
Lard
Yellow
grease
60
Canola
Diesel
Soybean
Recycle oil
50
40
30
20
10
0
Figure 14. Cetane number of FAMEs, petroleum diesel and various biodiesel fuels.
3.7. Energy Content
The energy content (also referred to as heating value) of diesel fuel is its heat of
combustion; the heat released when a known quantity of fuel is burned under specific
conditions. Biodiesel has less energy density than diesel. Biodiesel is denser than diesel as
well [4]. This relates to slightly lower fuel economy. A common blending fuel is B20, using
20% biodiesel mixed in 80% of diesel. At this mixing, the differences are only 1-2%, and
continue to decrease with lower mixes [4].
As shown in Table 12 and Figure 15, while biodiesel does have lower energy content or
heating value, regardless of the feedstock, they are very similar. This allows for better
customer assurance of standards and less need for variation of production parameters to
achieve ASTM specifications.
