Increasing the Theoretical Efficiency of The Spark-Ignition Engine Cycle by Adding Inert Gas at Part-Load

Abstract

Abstract The article presents calculations of the theoretical efficiency of the spark ignition engine cycle. Calculations of the efficiency of the Otto cycle were carried out with the use of throttling to a certain value of manifold vacuum in relation to atmospheric pressure, which is to simulate the operation of a real engine in the partial load range. The determined efficiency is the benchmark for determining the efficiency of the same cycle with a decreasing of throttling by adding an inert gas in the form of argon. This approach, apart from limiting the pumping work in the comparative cycle, increases the isentropic exponent in the compression and expansion processes, and thus translates into an increase in the efficiency of the considered cycle. The calculations were performed for various ranges of throttling pressure with the use of air and air with argon addition. The results are compiled in the form of a 3D diagram, taking into account the limiting ranges of throttling pressures and maintaining the ratio of argon mass to air mass at a certain level not exceeding 20% of the air mass involved in the process. Up to about 5.4% increase in the cycle efficiency was observed with an argon addition of 20% by weight. The obtained results are the basis for conducting research on a real object.