LAUSR

Abstract By connecting the finite time thermodynamics and the finite speed thermodynamics, an irreversible reciprocating Diesel cycle model is established with considering the irreversibilities caused by finite piston speed, heat transfer, friction, and internal irreversible loss. Through numerical calculations, the relationships among net power output ( P ), thermal efficiency ( η ), ecological function ( E ), ecological coefficient of performance ( E C O P ) and compression ratio ( γ ), piston speed and piston speed ratio are analyzed. As it is shown in the results, the relation curves of P − γ , η − γ , E − γ , E C O P − γ characteristics of the cycle are parabolic ones, and those of P − η and E − η characteristics of the cycle are loop-shaped ones. When piston speed ratio is a constant, the maximum net power output increases, the maximum ecological function first increases and then decreases, the maximum thermal efficiency and the maximum ecological coefficient of performance both decrease with the increase of piston speed. When piston speed is a constant, the maximum net power output and the maximum ecological function both first increase and then decrease, and the maximum thermal efficiency and maximum ecological coefficient of performance both decrease with the increase of piston speed ratio.