EXPERIMENTAL INVESTIGATIONS ON A 4-S C. I. ENGINE USING ALTERNATE FUELS

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INTRODUCTION

Dr. Diesel used peanut oil as fuel in his engine. A lot of research on vegetable oils as fuels was carried out 60 years ago, but interest lagged because of cheap and plentiful supplies of petroleum at that time.

Rapid depletion of petroleum fuel and environmental pollution problem led man to search for alternate fuels again. At present the world is highly dependent on petroleum fuels and this re4sults in major drain of our foreign exchange resources. Diesel engines are most efficiently used for commercial transportation, agricultural and industrial power plants. The consumption of diesel is several times higher than petrol. More over the exhaust gases of these engines will cause considerable environmental pollution too. The recent down turn in petroleum-based energy costs has shifted research in he area of alternative fuels.

Experimental evidence from several investigations has proved that vegetable oils are suitable for diesel engines and can be directly used with out any modifications.

AVAILABILITY OF OILS

India with just 2.4% of the global area supports more than 16% of the world’s human population and 17% of the cattle population. According to economic survey (2000-2001), of the cultivable land area, about 175 million hectares are classified as waste and degraded or marginal land. If the non-forest waste lands could be used to cultivate plants which survive on soil and which can produce oil seeds, these could be effectively used to combat fuels storage in the country and at the same time bring such degrade lands back to its productive capacity. Pongamia is suitable candidate for this purpose. Pongamia is synonymous with Karanji oil. The theoretical potential of this oil is estimated to be135, 000 tones but the actual collection has been stagnant around 4000 to 6500 tones in the past 8 years. The Pongamia oil has got its own importance, as this oil is mainly used for soaps and after sulphonating and sulphation in the leather tanning industry. The oil has been known for its curative effect of skin problems. Pongamia oil is extracted from the seeds of tree, which belongs to the species Pongamia Glabra vent. The yield of kernels per tree is reported to vary between 8 kg to 24 kg. The kernels contain 29-39% of oil.

Sunflower and Soya bean need relatively wet lands. Both are edible oils and used in soap and pharmaceutical industry.

PROBLEMS ENCOUNTERED WHILE USING AND REMEDIES

The major draw back of vegetable oils is in general for direct use in diesel engine is its high viscosity about 10-12 times that of diesel fuel and poor volatility.

These problems may be overcome by
1. Blending vegetable oils with diesel.
2. Esterification.
3. Increasing the injection pressure.
4. Pre heating the oil.

The term Esterification means conversion of one ester into the other (glycerol is replaced with methyl alcohol, the fatty acids remaining same). The chemical conversion reduces viscosity four fold. As it is evident glycerol is the byproduct of the reaction and a valuable commercial commodity. Esterification reduces the viscosity of Pongamia oil (at 250 C) from 125 cp to 50 cp and density from 0.9 to 0.885 kg/m3 and Cietane number increases from 48 to 55.

Preheating the vegetable oils is done through the external heater or using the exhaust gas re-circulation to match viscosity of the oils to diesel.