Studies on Closed Irreversible Cycles Analysis Based on Finite Physical Dimensions Thermodynamics

Abstract

The paper develops generalizing entropic approaches of irreversible closed cycles. The mathematical models might be applied to four possible operating irreversible trigeneration cycles. The models involve the reference entropy, the number of internal irreversibility, the thermal conductance inventory, the proper temperatures of external heat reservoirs, the mean log temperature differences, and four possible designing operational constraints. The reference entropy is always the entropy variation rate of the working fluid during the reversible heat input. The number of internal irreversibility allows the evaluation of the reversible heat output via the ratio of overall internal irreversible entropy generation and the reference entropy. The designing operational constraints allow the replacement of the reference entropy function of the convenient finite physical dimensions parameters. The paper presents initially the number of internal irreversibility and the energy efficiency equations for engine and refrigeration cycles. The second part develops, as an example, the influences between the imposed operational constraint and the maximum temperature on the cycle as a finite physical dimensions parameter for the basic Joule – Brayton irreversible cycle. The third part is applying the mathematical models to four possible standalone trigeneration cycles. It was assumed that there are the required consumers of the all useful heat delivered by the trigeneration system. The design of trigeneration system must know the ratios of refrigeration rate to power and of the useful heat rate to power.