Abstract:  Based on the finite time thermodynamic theory and the endoreversible Dual cycle model established in previous literature, this paper further considers the specific heat model of non-ideal gas working fluid, studies the cycle performance, deduces the basic optimization relationship between the cycle power and efficiency, analyzes the effects of heat transfer loss coefficient (B), cut-off ratio (ρ), freedom degree (d) of monatomic gas and the maximum temperature ratio (τ) on the cycle characteristics by numerical calculations, and compares the cycle performance differences under different specific heat models. The results show that, with the increases of τ and d, the maximum power (Pmax), the maximum efficiency (ηmax), the corresponding efficiency (ηPmax) under the maximum power condition, the corresponding compression ratios (γP,γη) under the maximum power and the maximum efficiency conditions will all increase; with the increase of B, ηmax and ηPmax will both decrease, γη will remain unchanged; with the increase of ρ, Pmax, ηmax, γP and γη will first increase and then decrease, the specific heat models have no qualitative influence but only quantitative influence on the cycle performance, the values of Pmax, ηmax, ηPmax, γP and γη under the specific heat model of the non-ideal gas condition are the minimum. The conclusions obtained in this paper have certain reference significance for the design of practical heat engines.

Key words:  Dual cycle, Non-ideal gas, finite time thermodynamics, power, efficiency