Page 202 - Biofuels Refining and Performance

Processing of Vegetable Oils as Biodiesel and Engine Performance 185

3. Secondary injection.
4. Carbon buildup in the intake port and exhaust-valve stems.
5. Carbon filling of the compression ring grooves.
6. Abnormal lacquer and varnish buildup.

Tahir [56] has determined the fuel properties of sunflower oil and its
ME. The properties were favorable for diesel engine operation, but the
problem of high viscosity (14 times higher than diesel at 37 C) of sunflower
oil might cause blockage of fuel filters, higher valve-opening pressure, and
poor atomization in the combustion chamber. Transesterification of sun-
flower oil to its ME has been suggested to reduce viscosity of the fuel. The
viscosity of ME at 0 C was closer to that of No. 2 diesel fuel, but below
0 C, it was not possible because of the pour point of 4 C.
Pryor et al. [57] have conducted a short-term performance test on a
small, test diesel engine using crude soybean oil, crude degummed soy-
bean oil, and soybean ethyl ester. The engine developed about 3% more
power output with crude legume soybean oil, but the development was
insignificant with soybean ethyl ester. The fuel flow of soybean oil was
13–30% higher and for the ethyl ester it was 11–15% higher, depending
upon the load on the engine. The exhaust temperature throughout the
test was 2–5% higher for soybean oil and 2–3% lower for ethyl ester than
the diesel fuel.
Clark et al. [58] have tested methyl and ethyl esters of soybean oil as
a fuel in CI engine. Esters of soybean oil with commercial diesel fuel
additives revealed fuel properties comparable to diesel fuel, with the
exception of gum formation which manifested itself in problems with
the plugging of fuel filters. Engine performance with esters differed
little from the diesel fuel performance. Emissions of nitrous oxides for
the esters were similar, or slightly higher than diesel fuel. Measurement
of engine wear and the fuel injection test showed no abnormal charac-
teristics for any of the fuels after 200 h of testing.
Laforgia et al. [59] has prepared biodiesel from degummed vegetable
oil with 99.5% methanol and an alkaline catalyst (KOH). On engine
performance, pure biodiesel and blends of biodiesel combined with 10%
methanol had a remarkable reduction in smoke emissions. When the
injection timing was advanced, better results were obtained.
Pischinger et al. [60] have conducted engine and vehicle tests with ME
of soybean oil (MESO) 75–25% gas oil—MESO blend and 68–23–9%
gas oil—MESO—ethanol blend. The fuel properties of the blend indi-
cated a 6% lower volumetric calorific value of the ester, a drastic reduc-
tion in kinematics viscosity, and a greater ethane number than that of
gas oil. The engine results indicated about 7% higher BSFC with a mar-
ginal difference in power and torque in comparison with gas oil. The
smoke emission was much lower with ME.