Exergetic performance analyses of three different cogeneration plants

Abstract

Energy cost and consumption are increasing, so that efficiency becomes more important, from the production to the end users. Energy reserves are limited; increasing demand and environmental concerns make efficiency important. To provide cost-effective and clean power generation, gas turbines and cogeneration are becoming the key technology that must be researched and developed. Three different cogeneration cycles are analyzed by using first and second laws of thermodynamics and exergy analysis method. The three cycles are basic, air heated, and fuel air heated cycles. The performance analysis of the devices such as turbine, recuperator, combustion chamber, compressor, and heat exchanger for the whole cycle is obtained and discussed. For different excess air rates, compression ratios (r), and ambient (inlet air) temperatures, the Z factor (ratio of lost exergy to useful exergy), specific fuel consumption, and specific work and other performance parameters of the devices were obtained and discussed. It is found that excess air rates have the most effect on the performance of the three cycles.

Keywords

• cogeneration
• power
• air-fuel heating
• exergy