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International Journal of Energy for a Clean Environment
SJR: 0.195 SNIP: 0.435 CiteScore™: 0.74

ISSN Imprimir: 2150-3621
ISSN En Línea: 2150-363X

International Journal of Energy for a Clean Environment

Formerly Known as Clean Air: International Journal on Energy for a Clean Environment

DOI: 10.1615/InterJEnerCleanEnv.2016006692
pages 123-138

EXERGY ANALYSIS OF A THERMAL STATION IN A DISTRICT HEATING SYSTEM

George Adrian Untea
Politehnica University of Bucharest, Faculty of Mechanics and Mechatronics, Splaiul Independentei nr. 313, sector 6, 060042, Bucharest
Alexandru Dobrovicescu
Politehnica University of Bucharest, Faculty of Mechanics and Mechatronics, Splaiul Independentei nr. 313, sector 6, 060042, Bucharest, Romania
Tudor Prisecaru
University Politehnica of Bucharest, Bd. Libertatii nr. 3, bloc A2, sc. A, ap. 17, Bucharest 040127, Romania
Emilia-Cerna Mladin
University Politehnica of Bucharest, Bd. Libertatii nr. 3, bloc A2, sc. A, ap. 17, Bucharest 040127, Romania
Malina Prisecaru
Politehnica University of Bucharest, Faculty of Mechanics and Mechatronics, Splaiul Independentei nr. 313, sector 6, 060042, Bucharest, Romania

SINOPSIS

This study is concerrned with an energy and exergy analysis of a district heating system that supplies heat in a neighborhood of Bucharest. The system is analyzed for the cold season period, from October to April. The chain of transformation from the fuel energy to the end-use energy is considered, together with associated losses. For this purpose, the system is divided into three main components: production of heat and electricity, district heating network and consumer (buildings). The heat source is a cogeneration plant made up of four internal combustion engines each of which can provide 14.1 MW of electricity and 13.7 MW of heat. A supplementary 12.5 MW of heat is produced in a separate boiler. The energy and exergy analysis was performed for the fuel and the plant main components. The results indicated a mean exergy efficiency of 44% for the engines and 16% for the boiler. The plant overall exergy efficiency of the plant is 37.1%, while its energy efficiency is 87.52%. When the final transformation to the end-use energy (final energy) is considered, the exergy balance of the whole system comes to 32.1%. The importance of cogeneration in incresing the rational use of resources is highlighted, as well as the negative effect on the overall efficiency of decreasing the working fluid temperature.