Sudhir Kumar Tyagi¹, Subhash Chandra Kaushik^2,* and Vivek Tiwari³

^1,2,3 Centre for Energy Studies, Indian Institute of Technology, Delhi, New Delhi-110016, India.
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^* Author to whom correspondence should be addressed

Received: 16 December 2002 / Accepted: 18 June 2003 / Published: 31 December 2003

Abstract: An ecological optimization along with a detailed parametric study of an irreversible regenerative Brayton heat engine with isothermal heat addition have been carried out with external as well as internal irreversibilities. The ecological function is defined as the power output minus the power loss (irreversibility) which is ambient temperature times the entropy generation rate. The external irreversibility is due to finite temperature difference between the heat engine and the external reservoirs while the internal irreversibilities are due to nonisentropic compression and expansion processes in the compressor and the turbine respectively and the regenerative heat loss. The ecological function is found to be an increasing function of the isothermal-, sink- and regenerative-side effectiveness, isothermal-side inlet temperature, component efficiencies and sink-side temperature while it is found to be a decreasing function of the isobaric-side temperature and effectiveness and the working fluid heat capacitance rate. The effects of the isobaric-side effectiveness are found to be more than those of the other parameters and the effects of turbine efficiency are found to be more than those of the compressor efficiency on all the performance parameters of the cycle.

Keywords: irreversible modified Brayton cycle; isothermal heat addition; regular combustion chamber; converging combustion chamber.