Page 288 - Biosystems Engineering

Biodiesel and Ethanol in Engines 265

8.1.7 Exhaust Gas Temperature
Exhaust gas temperatures of different biodiesels at various loads are
compared with that of diesel fuel (Fig. 8.6). The exhaust gas tempera-
tures of 100 percent biodiesel and its blends are always lower than
that of diesel. The exhaust gas temperature of a blend is decreased
with increasing amount of biodiesel (Table 8.2). This is due to the less
calorific value of biodiesel than diesel. The exhaust gas temperature of
100 percent biodiesel from putranjiva is higher than that of 100 percent
biodiesel from karanja and Jatropha. From Table 8.2, we can observe
that blends of karanja result in higher exhaust gas temperature than
Jatropha and putranjiva. This is due to the variation in combustion of
blends.
It has been observed that the blends of degummed putranjiva oil
and diesel reduce emissions such as CO, NO , smoke, particulates,
x
etc. Brake thermal efficiency of blends up to 30 percent shows emis-
sions less than diesel (Fig. 8.7). For blends above 30 percent brake,
thermal efficiency and brake-specific fuel consumption shows inferior
quality. Thus, we can conclude that up to 30 percent blends of
degummed putranjiva oil with diesel can replace diesel in running a
diesel engine satisfactorily with a reduction of emissions that are very
favorable to the environment.
Transestrified oils from karanja, Jatropha, and putranjiva or that
blended with diesel fuel, have shown very satisfactory results as an

30
Diesel
Putranjiva oil
25
Karanja oil
Particulates (mg/m 3 ) 15
Jatropha oil
20

10

5

0
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Brake power (kW)

FIGURE 8.6 Particulates versus brake power of diesel fuel, 100 percent
biodiesel of Jatropha, karanja, and putranjiva at 1200 rpm, 45° angle bTDC,
and 20 compression ratios.