Performance and Emission Investigation of Jatropha and Karanja Biodiesels on Single Cylinder Compression-Ignition Engine with Optical Imaging

In last three decades, extensive data on global climate has confirmed that the emissions of greenhouse gases such as carbon dioxide, nitrous oxide, water vapor, methane and ozone gas along with solid particulates and effluents from burning petroleum products rank among the highest pollutants. Dwindling supply of fossil fuels has provided major impetus for developing renewable and environment friendly sources of energy. Therefore, there is a huge demand for utilization of fuels derived from biological sources. In this research, methyl esters based biodiesels derived from two non-edible plants Jatropha and Karanja are investigated. The objective is to investigate the performance and emission characteristics of pure Jatropha and Karanja biodiesels and their blends at 30% v/v with the certified diesel. Each fuel was characterized for its chemical and physical properties before testing for engine performance. Experiments were conducted on a 3401 single cylinder direct injection compression-ignition engine. Fuel was injected at a constant oil rail pressure of 240Pa with volume of 100mm3 per injection cycle at a constant speed of 1500 rpm. Each fuel and their blends were evaluated for three injection timings of -5° ATDC, -1° ATDC, and 3° ATDC. The fuels were analyzed in terms of combustion characteristics, brake thermal efficiency (BTE), brake power (BP), brake specific fuel consumption (BSFC), gaseous emissions (CO, unburned hydrocarbons, and NOx). Furthermore, optical imaging was utilized to examine the temperature and soot distribution in the combustion chamber. Results indicate that ignition delays were shorter and consequently the cylinder pressure and amount of premixed burn were higher for biodiesels and their blends compared to those for diesel. Engine performance data for neat Jatropha and Karanja methyl esters (J100, K100) and their blends (J30, K30) showed an increase in BTE (10.9%, 7.6% for neat and blend, respectively), BSFC (13.1% and 5.6%), and NOx emission (9.8% and 12.9%), and a reduction in BSHC (8.64% and 12.9%), and BSCO (15.56% and 4.0%). The soot analysis from optical images qualitatively showed that biodiesels and their blends emit less soot compared to diesel. The temperature profiles obtained from optical imaging further supported higher NOx in biodiesels and their blends compared to diesel. Additionally, the optical data indicated that retarding the injection timing leads to lower flame temperatures and NOx levels along with higher soot formation for all test fuels. The physicochemical properties such as fatty acid profile, cetane number, and oxygen content in biodiesels supported the observed combustion and emission characteristics of the fuels tested in this study.