Abstract: It is pointed out that the main purpose of introducing the ecological figure of merit of a thermodynamic cycle is to make the best compromise between the rate of function and its dissipation of the cycle. Thus, the ecological figure of merit of a thermodynamic cycle should be based on the general ecological criterion function, while that based on the objective function of exergy analysis is not applicable in many cases. The significance and application of the ecological figure of merit are also discussed.

Key words: finite-time thermodynamics, thermodynamic cycle, ecological figure of merit