Durability Studies on Gas Engine Oil along with Performance and Emission Characteristics of Heavy Duty Turbocharged Natural Gas Powered Engine 2018-01-0638

Natural gas has been considered and implemented as alternative fuel to gasoline and diesel powered vehicles worldwide. Although natural gas belongs to petroleum fuel family, it has considerable recourses worldwide to ensure long energy security and comparatively lower carbon to hydrogen ratio that make it more environment friendly. This paper presents the effect of long duration endurance test on gas engine oil along with performance and emission characteristics of 5.8 L turbocharged heavy duty natural gas engine. The six cylinder engine was chosen due to its importance for urban bus transportation. The engine was subjected to long duration endurance test of 800 hrs with closed loop monitoring and controlled conditions as per 6 mode engine load cycle. During the complete endurance test of 800 hours, performance and emission characteristics of the engine were analyzed after completion of every 100 hours as per Full Throttle Performance Test and European Transient Cycle (ETC). Also, engine oil sampling and analysis along with oil consumption were undertaken after completion of every 100 hrs. The durability studies were performed on state of the art transient engine dynamometer having sophisticated emission measurement facilities. Subsequently, the engine oil performance was evaluated in field trials.

The performance parameters of the engine lubricant such as kinematic viscosity @ 100 deg C, kinematic viscosity @ 40 deg C, viscosity index, Total Base Number (TBN), Oxidation and Nitration over the complete endurance test of 800 hrs were within the permissible limits. Wear elements like Pb, Sn, Fe, Si and Cr were within limits over the period of endurance test of 800 hrs. However, there was increase observed in Al and Cu. During the endurance test of 800 hrs, it is observed that regulated emissions carbon monooxide (CO), total hydro carbon (THC), methane (CH4) and particle number (PN) increases marginally while no significant change is observed in nitrogen oxide (NOx). Test results indicates that over the period of endurance test of 800 hrs, all the major exhaust emissions species such as CO, THC, CH4 & NOx emissions were lower than the Euro IV emission norms for the heavy duty engines and there were no significant changes in the carbon dioxide (CO2) values. The actual field data shows the improvement in the engine oil drain period interval.