ENERGY AND EXERGETIC ANALYSIS OF A GAS CYCLE IN ASPEN PLUS

Abstract

Introduction:
Application of gas cycles operating with biogas produced from vinasses anaerobic treatment, is a way to expand the renewable energies matrix in Cuba. The study of alternatives to make this operation technology more efficient has great importance.
Objective:
To analyze energetically and exergetically a gas cycle operating with biogas.
Materials and Methods:
Process simulator Aspen Plus v10.0 was used to model gas cycle. Gas cycle energy and exergetic efficiencies at excess air different conditions (EA: 0-170%) and compression ratio (RC: 10-18) were calculated.
Results and Discussion:
For operating condition (EA: 110%, RC: 16) cycle energy and exergy efficiency were 32% and 54% respectively. Regarding exergy losses, the highest value corresponded to combustion chamber. Combustion chamber exergy efficiency increased from 69% to 73% by reheating compressed air with exhaust gases, increasing besides cycle energy and exergy efficiency to 37% and 55% respectively.
Conclusions:
An increase in excess air decreases cycle energy and exergy efficiencies because average heat input temperature decreases. An increase in compression and/or overheating ratio of compressed air decreases exergetic destruction in combustion chamber by decreasing the entropy generation and increases cycle energy and exergy efficiency.