Experimental Study and Comparison of a Few Lean (gasoline-natural gas) Dual ‎F‎uels Based on Safe Optimum Spark Advance

Strong dependence of the human’s daily life on the engine-powered vehicles, increasing environmental pollutions, especially in urban areas, and reduction of the world oil resources have challenged the energy researchers to make appropriate decisions at regional scale for selecting alternative fuels to improve the engine efficiency and fuel economy. In the current work, the lean-burn idea jointed to dual (gasoline-NG) fuel has been considered to develop the SI engines. To investigate the performance and exhaust gas emissions, experimental tests were performed using a single-cylinder research engine with gasoline-NG dual fuels, including four mass-based blends of the two fuels (G100, G87.5, G75, and G62.5 containing gasoline at 100‎‎%, 87.5%, 75%, and 62.5%, respectively, with the remaining part being composed of NG), at 1800 rpm ES and 0.9 ER under at least seven different SAs. The result showed that increasing the NG fraction in the fuel blend, both the σ and COV of imep decreased. It was implicitly observed that, for blended fuels, non-uniform distribution of each fuel can serve as a new source for cyclic variations. Under the considered lean burning condition at optimal safe SA, the imep and output torque for the gas-contained fuel blends were comparable to those obtained by the pure gasoline. Also, it was detected that an increase in the CR reduced the emitted amounts of HC and CO ‎pollutants.‎