Second Law Analysis of Alternative Regenerative Gas Turbine

Abstract

The second law of thermodynamics has proved to be a very powerful tool in optimization of complex thermodynamic systems. This paper involves an exergy analysis of three configurations of gas turbine units, simple unit with no regenerator, conventional regenerative gas turbine unit and alternative regenerative gas turbine unit. Obviously, in conventional regenerative gas turbine cycle, the position of regenerator is placed immediately after the low pressure turbine. In the current study the position of regenerator is suggested to be immediately after the high pressure turbine. This may result in preheating the compressed air to a high temperature before admitting to the combustion chamber and also lowers the low pressure turbine exit temperature.Results show that the second law efficiency of alternative regenerative gas turbine has been increased throughout the pressure ratio range (6-20) for fixed turbine inlet temperature (1400K) as well as throughout the turbine inlet temperature range (1100 -1750 K) for optimum pressure ratio nearly by (52% , 12%) and (23% , 11.6%) as compared to simple and conventional regenerative cycle respectively. The exergy loss due to irreversibility in combustion chamber, regenerative and exhaust gases was found to be decreased nearly by 60% and 39.4 respectively as compared to simple cycle as well as by32.5%, 22.5% and 13.9% respectively as compared to conventional regenerative cycle