Abstract: This article discusses the Otto cycle using Van der Waals gas as a working medium and replacing the adiabatic process with the polytropic process. It presents the output work and efficiency of this cycle, and analyzes the effects of the polytropic exponent n and compression ratio r on the cycle parameters. Through numerical calculations, it is concluded that both the polytropic exponent and compression ratio have impacts on the cycle parameters, and when the numerical value of the polytropic exponent is equal to the adiabatic exponent, the cycle’s output work and efficiency are maximized.

Key words: Van der Waals gas, polytropic process, Otto cycle