Thermodynamic Optimization for an Endoreversible Dual-Miller Cycle (DMC) with Finite Speed of Piston

Power output ([Formula: see text]), thermal efficiency ([Formula: see text]) and ecological function ([Formula: see text]) characteristics of an endoreversible Dual-Miller cycle (DMC) with finite speed of the piston and finite rate of heat transfer are investigated by applying finite time thermodynamic (FTT) theory. The parameter expressions of the non-dimensional power output ([Formula: see text]), [Formula: see text] and non-dimensional ecological function ([Formula: see text]) are derived. The relationships between [Formula: see text] and cut-off ratio ([Formula: see text]), between [Formula: see text] and [Formula: see text] , as well as between [Formula: see text] and [Formula: see text] are demonstrated. The influences of [Formula: see text] and piston speeds in different processes on [Formula: see text] , [Formula: see text] and [Formula: see text] are investigated. The results show that [Formula: see text] and [Formula: see text] first increase and then start to decrease with increasing [Formula: see text]. The optimal cut-off ratio [Formula: see text] will increase if piston speeds increase in heat addition processes and heat rejection processes. As piston speeds in different processes increase, the maximum values of [Formula: see text] and [Formula: see text] increase. The results include the performance characteristics of various simplified cycles of DMC, such as Otto cycle, Diesel cycle, Dual cycle, Otto-Atkinson cycle, Diesel-Atkinson cycle, Dual-Atkinson cycle, Otto-Miller cycle and Diesel-Miller cycle. Comparing performance characteristics of the DMC with different optimization objectives, when choosing [Formula: see text] as optimization objective, [Formula: see text] improves 26.4% compared to choosing [Formula: see text] as optimization objective, while [Formula: see text] improves 74.3% compared to choosing [Formula: see text] as optimization objective. Thus, optimizing [Formula: see text] is the best compromise between optimizing [Formula: see text] and optimizing [Formula: see text]. The results obtained can provide theoretical guidance to design practical DMC engines.