Ecological performance analysis of an endoreversible regenerative Brayton heat-engine Yasin Ust, Aykut Safa, Bahri Sahin * Department of Naval Architecture, Yildiz Technical University, 34349 Besiktas, Istanbul, Turkey Accepted 17 April 2004 Available online 24 June 2004 Abstract A performance analysis based on an ecological performance criterion has been performed for an endoreversible regenerative Brayton heat-engine. In the model, the heat-transfer ir- reversibilities were considered and other irreversibilities were neglected. The ecologic objec- tive-function, defined as the power output minus the loss rate of availability is taken as the optimization criterion. The optimum performance parameters that maximize the ecological objective function are investigated. The effect of the regenerator effectiveness on the global and optimal performance have been discussed. The results obtained are compared with those of the maximum-power criterion. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Brayton heat engine; Ecological optimization; Regenerator effectiveness 1. Introduction In recent years, many optimization studies for heat engines based on the endo- reversible and irreversible models have been carried out by considering finite-time and finite-size constraints under various heat-transfer modes, especially linear and nonlinear ones. The reader interested in these optimization studies could refer to literature surveys written by Bejan [1], Chen et al. [2] and Durmayaz et al. [3]. Usually in these studies, the power and the thermal efficiency were chosen according * Corresponding author. Tel.: +90-212-259-7070; fax: +90-212-258-2157. E-mail address: sahinb@yildiz.edu.tr (B. Sahin). 0306-2619/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.apenergy.2004.04.009 www.elsevier.com/locate/apenergy Applied Energy 80 (2005) 247–260 APPLIED ENERGY