Technical gazette, Vol. 23 No. 3, 2016.
Original scientific paper
https://doi.org/10.17559/TV-20160208112755
Exergy analysis of a Brayton cycle with variable physical properties and variable composition of working substance
Marija Živić
orcid.org/0000-0003-2072-376X
; Josip Juraj Strossmayer University of Osijek, Mechanical Engineering Faculty in Slavonski Brod, Trg Ivane Brlić Mažuranić 2, 35000 Slavonski Brod, Croatia
Antun Galović
; University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Ivana Lučića 5, 10000 Zagreb, Croatia
Jurij Avsec
; University of Maribor, Faculty of Energy Technology, Hočevarjev trg 1, 8270 Krško, Slovenia
Mario Holik
orcid.org/0000-0002-4755-7522
; Josip Juraj Strossmayer University of Osijek, Mechanical Engineering Faculty in Slavonski Brod, Trg Ivane Brlić Mažuranić 2, 35000 Slavonski Brod, Croatia
Abstract
The exergy analysis of a Brayton cycle is performed in the paper. The four input variables: the ratio of the compressor exit and inlet pressures, the ratio of inlet temperature of gases in turbine and inlet temperature of air in compressor and the isentropic efficiencies of the compressor and turbine are analysed. The temperature ratio is varied in a way that the compressor inlet temperature of air is maintained constant, while the turbine inlet temperature of flue gases is varied from 900 to 1200 °C. In the combustion chamber methane is completely combusted with excess air ratio which is determined by the temperature of flue gases at the turbine inlet. The analysis further includes variability of the molar heat capacities of air and flue gases with temperature and variability of their heat capacity ratios. The exergy destruction in turbine, compressor and combustion chamber and also total exergy efficiency of the cycle are considered in the analysis.
Keywords
Brayton cycle; variable physical properties; variable composition of working substance; maximum work output; maximum thermal efficiency
Hrčak ID:
160140
URI
Publication date:
19.6.2016.
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