NOISE, EMISSIONS AND FUEL ECONOMY STUDY ON A SMALL DI DIESEL ENGINE USING JATROPHA BIO-DIESE,

Abstract

In the present investigation, the effect of jatropha methyl-ester (JME) as a fuel on the engine noise, emissions and fuel economy of a small air-cooled DI diesel engine was studied. In the first study, speed, load and fuel injection timing were varied according to (3x3x3) full factorial design and radiated engine noise, cylinder pressure, fuel consumption, smoke and emissions of HC and NOx were measured. In order to evaluate the nature of cylinder pressure rise and combustion characteristics of jatropha methyl-ester (JME) and diesel, cylinder pressures were recorded for all the speeds, loads and injection timings combinations. The cylinder pressure data were recorded for 50 consecutive cycles and then averaged in order to eliminate cycle to cycle variations. Comparative study of engine radiated noise, emissions and fuel economy was carried between jatropha methyl-ester (JME) and diesel. Ricardo's method was applied to estimate the combustion noise from radiated engine noise using 1/3rd octave cylinder pressure level and sound pressure level spectra. The spectra were obtained for advanced and retarded injection timings. The structural attenuation of the test engine was obtained and it shows good agreement with those available in the literature. The response surface quadratic models were generated for the five output parameters viz. engine noise, smoke, bsfc, unburned hydrocarbons and NOx in terms of three input parameters: speed, load and injection timing. The response surface equations were then solved as multi-objective nonlinear constrained optimization problem using the Design-Expert 7.0.0 software, which makes use of the desirability functions. Further, based on the results; identification of optimized zone for speed, load and injection timing, which gives the engine noise, fuel economy and exhaust emissions within their mean limits of the test results were carried out. The second study was carried out to determine the effect of injection system parameters and exhaust gas recirculation on engine radiated noise, exhaust emissions and bsfc. In this investigation, injection system parameters viz. number of spray holes (4&5), hole diameter (0.18mm & 0.23 mm), nozzle opening pressure (240, 250 &260 bar) and exhaust gas recirculation (0 %, 10% & 20%) were varied and their effects on engine noise, iii smoke, unburned hydrocarbon and NOx emissions were studied. Experiments were conducted at selected speed-load combinations such as 1800 and 3200 rpm for 40 % and 100 % loads. Prediction of five engine responses viz. engine noise, bsfc, smoke level, NOx and 1-IC emissions were made using six engine input parameters (Engine speed, Load, Injection timing, Nozzle type, EGR, Nozzle Opening Pressure) by means of artificial neural network for diesel as well as for JME. The training algorithm used in the present study was Levenberg-Marquardt. The activation function selected for the hidden layer was logistic sigmoid whereas for the output neuron, it was linear activation function. The analysis achieved reasonably good approximations. iv