Page 187 - Biofuels Refining and Performance

170 Chapter Six

optimum results. Compared to transesterification, the process of degum-
ming is simple, very easy, and less costly, and the reduction in viscosity
of vegetable oil is very small.
Nag et al. [25] degummed karanja, putranjiva, and jatropha oils by
phosphoric acid treatment. Before degumming the oils, the fuel properties
of three oils have been measured and compared with diesel (Table 6.1).
Acid concentrations of 1%, 2%, 3%, 4%, and 5% were used at 40 C with
vigorous stirring. The stirring was continued for 10 min after adding the
acid. After stirring, the mixtures were held for 1 week to complete the
reactions and to settle the gum materials. Then the mixtures were filtered
through a packed bed filled with charred sawdust. Viscosities of the fil-
trate were then measured.
Performance and emission measurement. After studying the properties of
the jatropha, karanja, and putranjiva oils, they were degummed. In this
context, the Ricardo variable-compression engine (Ricardo & Co. Engineers
Ltd., England, single cylinder, 3-in bore, 35/8 in stroke) was run with
10%, 20%, 30%, and 40% blends of degummed karanja, jatropha, and
putranjiva oils with diesel at different loads (0–2.7 kW) and different
timings (45 , 40 , 35 , and 30 bTDC [before top dead center]). To meas-
ure emissions, an automotive exhaust monitor (model PEA205) and smoke
meter (model OMS103, Indus Scientific Pvt. Ltd., India) were used.
Degumming by acid treatment lowers the viscosity. Viscosities of
karanja, jatropha, and putranjiva oils degummed at 40 C and at various
acid concentrations are shown in Fig. 6.1. Karanja oil with 4% acid
treatment had the lowest viscosity, whereas jatropha and putranjiva oils
both had the lowest viscosities with 1% acid treatment.

Effect of timing. By observing the performance data at various timings
(45 , 40 , and 35 bTDC) in Fig. 6.2, it was concluded that at 45 bTDC
timing, the nonedible karanja, jatropha, and putranjiva oils gave the
highest yields, whereas at 40 bTDC timing, diesel gave the highest
yield. That may have been due to the different ignition temperatures of
the nonedible oils from diesel.

TABLE 6.1 Fuel Properties of Three Nonedible Oils and Diesel
Properties Karanja Jatropha Putranjiva Diesel
Viscosity in cSt (at 40 C) 43.67 35.38 37.62 5.032
Cetane number 29.9 33.7 31.3 46.3
Calorific value (kJ/kg) 36,258 38,833 39,582 42,707
Pour point ( C) 5 2 3 12
Specific gravity at 25 C 0.932 0.916 0.918 0.834
Flash point ( C) 215 280 48 78
Fire point ( C) 235 291 53 85
Carbon residue (%) 1.4 0.2 0.9 0.1