Page 445 - Advances in Eco-Fuels for a Sustainable Environment

398 Advances in Eco-Fuels for a Sustainable Environment

0.7
0.6

0.5 Diesel
BSFC(kg/kW-hr) 0.4 A20

A40
0.3
A60
0.2
A80
0.1 A100

0
0 1 2 3 4 5 6
BP(kW)

Fig. 14.3 Variation of BSFC with BP for diesel and different proportions of AME diesel blends.

Fig. 14.3 shows the variation of BSFC with brake power for different proportions of
AME diesel blends and diesel. It is observed that the BSFC decreases with increasing
BP for all AME-diesel blends at all loads. Among the different AME-diesel blends,
A20 has lower BSFC than that of other blends. The BSFC for A20 is 0.2778kg/kW-h
and for diesel is 0.2808kg/kW-h at maximum load. The BSFC for biodiesel is higher
than that of diesel fuel because of higher density and viscosity and lower heating value
[30]. The biodiesel is fed into the engine on a volumetric basis for every cycle of
operation which leads to increasing fuel supply and to get the equal output, thereby
increasing fuel consumption. Further, the increase in BSFC for AME-diesel blends
may change the injection and combustion timing due to the higher cetane number
of biodiesel. On comparing the different biodiesel blends, the A20 has less BSFC
due to the following reasons.
l The A20 combination has 80% diesel and 20% AME, but in the case of diesel fuel, there is no
oxygen content.
l The A20 blend has lower density and viscosity because of a higher percentage of diesel
availability.
l The A20 blend has a higher heating value than the other blends because of a higher percent-
age of diesel fuel.

14.3.4 Exhaust gas temperature

The burning efficiency of the engine is found through the temperature of exhaust
gases. The EGT is an indicator of the heat of the fuels tested at the combustion period.
Basically, there are four stages involved in the combustion such as ignition lag, period
of uncontrolled combustion, period of controlled combustion, and after burning. If the
engine has more misfires, improper injection timing, or the after burning stage, then
there will be the possibility of low EGT.