Resumo

AGUDELO, John; AGUDELO, Andrés  e  PEREZ, Juan. Energy and Exergy analysis of a light duty diesel engine operating at different altitudes. Rev.fac.ing.univ. Antioquia [online]. 2009, n.48, pp. 45-54. ISSN 0120-6230.

Altitude above sea level produces a reduction in air density affecting the combustion process, pollutant emissions, and engine performance. In this work the combustion diagnosis of an automotive turbocharged diesel engine was carried out from in-cylinder pressure signal. Tests were performed at three altitudes above sea level, under steady state operating conditions, using conventional diesel fuel. As altitude above sea level increased, the fuel/air mixture became richer. The brake specific fuel consumption, combustion duration, premixed combustion phase, maximum temperature, heat rejected to the gases and exergy destruction were also increased; at the same time, brake thermal efficiency, maximum in-cylinder pressure and in-cylinder exergy decreased. Mechanical efficiency and injection timing remained approximately invariable. Exergy destruction differences were caused by the combustion process, without significant effects during compression and expansion. The greater irreversibility resulting from altitude increase was linked with the lower energy quality of the exhaust gases.

Palavras-chave : Tasa de calor liberado; altitud; motores diesel; análisis exergético.