Performance optimization of a new combined power cycle based on power density analysis of the dual cycle Bahri Sahin a, * , Ugur Kesgin a , Ali Kodal b , Nurten Vardar a a Department of Naval Architecture, Yildiz Technical University, Besiktas, 80750 Istanbul, Turkey b Department of Aeronautical Engineering, Istanbul Technical University, Maslak, 80626 Istanbul, Turkey Received 30 March 2001; accepted 14 August 2001 Abstract In this paper, maximum power density (MPD) analysis of an air standard internal combustion Dual cycle has been performed. Based on the obtained results for MPD analysis of the Dual cycle, a new combined power cycle model (Dual þ Joule-Brayton) has been introduced and optimized. Optimal per- formance and design parameters are obtained analytically under the MPD conditions of the Dual cycle. Theobtainedresultsarediscussedintermsofthermalefficiency,powerandenginesizes.Itisshownthatfor thecombinedcycle,adesignbasedontheMPDconditionsismoreadvantageousfromthepointofviewof engine sizes and thermal efficiency. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Maximum power density; Performance optimization; Dual cycle; Joule-Brayton cycle; Combined cycle. 1. Introduction Duringthelastdecade,manyoptimizationstudiesforheatenginesbasedonendoreversibleand irreversiblemodelshavebeenconductedbyconsideringfinitetimeandfinitesizeconstrainsunder various heat transfer modes, mainly linear and non-linear [1,2]. In these studies, the objective functions chosen for optimization are usually power output, thermal efficiency, entropy genera- tionandecologicalbenefit.Theproperoptimizationcriteriontobechosenfortheoptimaldesign ofheatenginesmaydifferdependingontheirpurposeandworkingconditions.Forpowerplants, in which fuel consumption is the main concern, the maximum thermal efficiency criterion is very important, whereas for aerospace vehicles, for which propulsion is of great importance, the maximum power (MP) output criterion has great significance. On the other hand, for ship Energy Conversion and Management 43 (2002) 2019–2031 www.elsevier.com/locate/enconman * Corresponding author. Fax: +90-212-258-2157. E-mail address: sahinb@yildiz.edu.tr (B. Sahin). 0196-8904/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0196-8904(01)00149-2