Considering the importance of alternative fuels in IC engines for environment safety, compressed natural gas has been extensively employed in SI engines. However, scarce efforts have been made to investigate the effect of compressed natural gas on engine lubricant oil for a long duration. In this regard, a comprehensive analysis has been made on the engine performance, emissions, and lubricant oil conditions using gasoline ( G)92 and compressed natural gas at different operating conditions using reliable sampling methods. The key parameters of the engine performance like brake power and brake-specific energy consumption were investigated at 80% throttle opening within 1500–4500 range of r/min. For the sake of emission tests, speed was varied uniformly by varying the load at a constant throttle. Furthermore, the engine was run at high and low loads for lubricant oil comparison. Although compressed natural gas showed a decrease in brake-specific energy consumption (7.94%) and emissions content, ( G)92 performed relatively better in the case of brake power (39.93% increase). Moreover, a significant improvement was observed for wear debris, lubricant oil physiochemical characteristics, and additives depletion in the case of compressed natural gas than those of ( G)92. The contents of metallic particles were decreased by 23.58%, 36.25%, 42.42%, and 66.67% for iron, aluminum, copper, and lead, respectively, for compressed natural gas.

Lube oils are the viscous petroleum products used in automobiles to reduce the friction. The eventual fate of lube oil is either incineration or dumping off into ground, but these resources cannot be disposed off easily due to their libellous effects on environment. This article aims to study the regeneration of deteriorated oil and impact of regenerated oil on engine performance and engine emissions. The effectuality of regeneration is studied by comparing the results of the key parameters (specific gravity, viscosity, total acid number, flash point and ash contents) of regenerated oil with that of non-deteriorated and deteriorated oil. Engine performance and emissions for regenerated oil were compared with non-deteriorated and deteriorated oil. The brake power and torque increased by 4.1% and 4.6%, respectively, following the regeneration process. After re-refining of lube oil, specific gravity, flash point, kinematic viscosity, ash content and total acid number improved by 6.75%, 2.66%, 15.6%, 1.7% and 10.64%, respectively. In case of deteriorated oil, HC, NOx and CO increased by 23.6%, 42.2% and 11.8%, respectively. But after regeneration of oil, these emissions decreased as compared with deteriorated oil. It can be reasoned out that regeneration mends oil properties and has positive impact over engine performance and emissions.

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