Impact of Various Combustion Chamber Exhaust Temperatures on a Combined Bryton-ORC Energy Recovery System

Abstract

A combined heat and power system has been proposed and evaluated thermodynamically to generate mechanical power and hot water for various applications. The combined system consisted of a gas turbine cycle (GT) to produce the main mechanical power. An Organic Rankine cycle (ORC) is used to convert some of the GT flue gases wasted heat to additional mechanical power. The hot water is produced from two heating levels, in first level the rejected latent heat from the ORC condenser is recovered. While in second heating level the high thermal energy available in the GT working fluid after the compression process is used through a heat exchanger. A thermodynamic simulation is carried out by ASPEN plus package and the thermophysical properties of the working fluids is obtained from REFPROP. The effect of increasing the gas burner flue gases temperature from (700-1250 °C) on the main system design parameters reveals that the overall net power output has declined by 3.5% but it is greater than the standalone GT cycle by 13.4 – 17.6%. In addition, the total thermal energy recovered has declined significantly by 53.7%. Furthermore, the GT thermal efficiency has increased from 16-25% and the combined system has converted the waste heat into hot water with a temperature between 93-48.5 °C to be used in different heating applications.