Page 284 - Biosystems Engineering

262 Cha pte r Ei g h t

heat is released during burning. NO emission is increased with
x
increasing temperature of combustion chamber. Biodiesel has lower
calorific value than neat diesel, and therefore the rate of increase of
NO is low with load than with diesel. 27
x
Walker observed that NO started at 6.2 g/mile for diesel and
28
x
decreased to around 5.6 g/mile with 100 percent ester (biodiesel),
with a slightly more reduction with rapeseed ethyl ester rather than
rapeseed methyl ester.
It is observed that with increasing of load NO emission of three
x
transesterified oils (karanja, Jatropha, and putranjiva) is increased
(Fig. 8.3).With increasing the percentage of biodiesel in blends
(Table 8.2) NO emission is decreased due to a decrease of the calorific
x
value of the blend and thus a lower exhaust gas temperature. Jatropha
blend shows the lowest NO emission than the others. Hydrocarbon
x
emission of biodiesel (Fig. 8.4) is lower than diesel due to better com-
bustion of biodiesel. A higher percentage of biodiesel in blend gives
fewer hydrocarbon emissions. Smoke, CO, and particulates (Fig. 8.5)
of the three oils are lower than diesel, indicating a good impact on the
environment and living beings. Higher concentrations of biodiesel in
blend (Table 8.2) results in lower CO emission because of higher igni-
tion temperatures and better combustion of biodiesel than diesel, and
fewer exhaust emissions.

120

Diesel
100 Putranjiva oil
Karanja oil
Jatropha oil
NOx (ppm) 60
80

40

20

0.0 0.5 1.0 1.5 2.0 2.5 3.0
Brake power (kW)
FIGURE 8.3 Nitrogen oxide versus brake power of diesel fuel, 100 percent
biodiesel of Jatropha, karanja, and putranjiva at 1200 rpm, 45° angle bTDC,
and 20 compression ratios.