Abstract
Employing finite-time thermodynamics, the effects of irreversibility factors, i.e., friction, heat transfer of cylinder wall, compression and expansion efficiencies and variable specific heats (temperature-dependent specific heats of the working fluid) on the air-standard Atkinson and Dual-Atkinson cycles are analyzed. In addition, a numerical comparison between the Atkinson and Dual-Atkinson cycles is made. Moreover, numerical examples show the relations between the thermal efficiency and compression ratio and between power and compression ratio. As mentioned, compression ratio, r sub(c), initial temperature, T sub(1), specific heat defined by a sub(p), b sub(v) and k sub(1), friction defined by b and heat transfer defined by \({\alpha}\) and \({\beta}\) are some of the key parameters of the internal combustion engines. The effects of these on the performances of the Atkinson and Dual-Atkinson cycles are presented in this article. According to the findings, the thermal efficiency and the output power of the Dual-Atkinson are higher than those of the Atkinson cycle at the same condition. Also, these irreversibility factors must be considered to design and analyze the Atkinson and Dual-Atkinson cycles. The obtained results also will provide guidance for the design of internal combustion engines.