Emission Characteristics of a Diesel Engine fueled with Diesel-biodiesel-JP-4 Blends

The main objective of this research is to study the effects of JP-4-biodiesel-diesel fuel blends and operating parameters on the emission characteristics of a CI engine. The experimental tests were performed on a four-cylinder DI diesel engine. The Mixture-RSM method was used to develop mathematical models based on experimental data. The results showed that with the increase of the biodiesel proportion in the fuel blend, the emission of hydrocarbon and carbon monoxide in the exhaust decreases due to oxygen contents in the molecular structure of biodiesel that leads to effective combustion. According to the results, HC and CO emissions boosted up significantly with the use of jet fuel JP-4 in fuel mixture due to the lower cetane index of jet fuel in comparison with diesel and biodiesel. Results also indicated that the NOx formation is highly related to biodiesel proportion in fuel mixture due to less compressibility and its higher cetane number. On the other hand, the results indicated that NOx emissions reduced by using JP-4 as a result of retarded combustion of jet fuel that reduces combustion temperature. According to the results, CO and HC emission decreased at higher engine loads due to a more complete combustion condition. However, the NOx emission continuously intensifies at the higher levels of engine load due to the arising temperature of combustion gas. Generally, the results indicated that the use of JP4 fuel can improve NOx emissions of the engine but it does not have a desirable effect on other emission characteristics of the engine.