Biodeisel

Definition

Bio-diesel is a vegetable oil processed to resemble Diesel Fuel. The first use of peanut oil was made in 1895 by Dr. Rudolf Diesel himself (1858-1913), who predicted- "The use of vegetable oils engine fuels may seem insignificant today. But such oils may become in course of time as important as petroleum and the coal tar products of the present time." Bio-diesel is the ethyl or methyl ester of fatty acid. Bio-diesel is made from virgin or used vegetable oils (both edible and non-edible) and animal fats through trans-esterification. Just like diesel, bio-diesel operates in compression ignition engines, which essentially require very little or no engine modifications up to require very little or no engine modifications up to 20% blends, and minor modifications for higher percentage blends because bio-diesel is similar to diesel but is very eco-friendly.

The Recent depletion and fluctuation in prices due to uncertain supplies for fossil fuel, make us to search renewable, safe and non-polluting sources of energy. India is not self sufficient in petroleum and has to import about two third of its requirements. Presently Indian Government spend Rupees 90,000 crores for petroleum fuel and annual consumption is around 40 millions tons. One of the solutions to the current oil crisis and toward off any future energy and economic crunch is to explore the feasibility of substitution of diesel with an alternative fuel which can be produced in our country on a massive scale to commercial utilization.

Indian Government, research institution and automobile industries are taking interest on bio-diesel from various non-edible oil bearing trees like Jatropha, Karanji, Mahua & Neem. As India is short of edible oils even for human consumption and since the cost of edible oil is also very high, it is preferable to use non-edible oils. Jatropha curcas is one of the prospective bio-diesel yielding crops. This paper highlights our work on alternate fuels and the importance of choosing jatropha. It reduces pollution drastically in terms of sulphates and carbon mono-oxide. To start with, we reduced the viscosity problem faced to a large extent by carrying out the transesterification process in our chemistry laboratory. we also studied the cost factor involved in the usage of jatropha. Performance test was conducted on an electrical loaded diesel engine and a study on the emissions was made using Exhaust Gas Analyser in our thermal laboratory. The pollution levels came down drastically and performance was better with various blends of jatropha and diesel.

Process Explanation

If methanol is used in the above reaction, it is termed methanolysis and fatty acid methyl esters are generated, which are called biodiesel. Three consecutive and reversible reactions are believed to occur in the transesterification which are given below:

Triglyceride + ROH Catalyst Diglyceride + R' COOR

Diglyceride + ROH Catalyst Monoglyceride + R" COOR

Monoglyceride +ROH Catalyst Glycerol + R"' COOR

The first step is the conversion of triglycerides to diglycerides, followed by the conversion of diglycerides to monoglycerides, and finally monoglycerides to glycerol, yielding one methyl ester molecule from each glyceride at each step. When methanol is used in the esterification A catalyst and excess alcohol are used to increase rate of reaction and to shift the equilibrium to the product side, respectively .

Performance Test On IC Engine

The engine used for the present investigation is a single cylinder "comet" vertical Diesel Engine (1500rpm, 3.5kW, water cooled). Engine is coupled with an eddy current dynamometer. In the present work, the experiments were carried out at constant speed and for varying load conditions i.e., no load, 25%, 50%, 75% and 100% of the rated load. The injection parameters were kept constant for the existing engine for entire test program. The static fuel injection timing and the fuel injection pressure for the given engine the 27 o before TDC and 220 bars respectively as specified by the manufacturer. The engine was started and warm-up with diesel fuel and then the diesel fuel line was cut off and simultaneously the fuel line, which connects the fuel under investigation, was opened. No additives were added to the system before conducting the test. Esterified vegetable oil was injected directly to the combustion chamber as conventional fuel injection. The test was done separately for the four fuels, which are taken for the investigation. In each case the observations were recorded after steady state was reached.