Performance evaluation of a low speed IDI engine fueled with diesel and Jatropha straight vegetable oil

Abstract

In context to the global objective of search for alternate energy source, the possibility of using Jatropha straight vegetable oil (JSVO) in diesel engine is studied in this work. The experimental investigations are carried out to analyze the performance and emission characteristics of neat JSVO fueled in single cylinder, low speed IDI diesel engine. The engine was initially run by the diesel to take the data as base line and then the engine was run with 100% JSVO to find out the deviations in their performance and emission characteristics in comparison with diesel fuel. To improve the performance some of the minor modifications are suggested in fuel injection system of the engine. These modifications are changing the advance angle of fuel injection, optimizing the fuel injection pressure and preheating the fuel by exhaust gases. The performance parameters evaluated include brake thermal efficiency (B T E) and brake specific fuel consumption (BSFC) where as the exhaust emission parameters include CO, CO2 , HC, NOx and smoke. It has been found that the BTE of engine with diesel fuel is 32.96% where as under similar operating conditions the BTE with JSVO was found to be 30.62%. This difference is very high as far as the efficiency of energy utilization is concerned. The deviations in performance are due to high viscosity of JSVO, high surface tension, low cetane rating and ultimately low calorific value. The emission parameters of JSVO are not favorable because the emission parameters of JSVO are much higher than the diesel fuel. Based upon the findings it can be concluded that the existing engine under present design can not run on JSVO because of low BTE, High BSFC and even bad emission characteristics. In case we want to make the engine compatible will JSVO the engine modification is to be carried out. There are many major modifications which can meet the requirement but this modification will affect the techno economic aspect of the engine. In light of these facts and data, some of the minor modification can be suggested. These modifications can improve the fuel atomization characteristics of JSVO and will improve the performance and emission characteristics of engine.