Thermodynamic Analysis of a Combined Heat and Power System

In the present analysis combustion products coming out from the gas turbine (GT) are studied on the basis of their concentration. A computer program is made in EES and different parameters are studied for the analysis. From the result it is observed that if regenerator is used in the gas turbine cycle then the concentration of N 2 and O 2 is 0.91% and 1.41% higher respectively in flue gases than that of GT cycle without regenerator. The concentration of CO 2 and H 2O is 2.17% and 17.64% lesser respectively in flue gases for GT cycle with and without regenerator. As the fuel is the combination of the carbon and hydrogen, after burning with oxygen it generates heat energy, CO 2 and H 2O. That is why concentration of H 2O and CO 2 in combustion product increases and that of oxygen decrease. Results show that enthalpy of combustion products at a temperature of 155°C is -28077 kJ/kmol for GT cycle with regenerator and for without regenerator enthalpy is -28027 kJ/kmol at a temperature of 389°C. From the results it may be concluded that regeneration not only increases the efficiency of GT cycle but generates a concentration of N 2, O 2, CO 2 and H 2O in such a manner that enthalpy of combustion gas is increased. Regenerator lowers the exergy destruction in the cycle and increased the fuel utilization efficiency for the cycle. Exergy destruction in most of the thermal systems is due to combustion/chemical reaction, heat transfer and friction including unrestrained expansions of gases and liquids. The inefficiency of combustion may be reduced by preheating the combustion air and reducing the air fuel ratio.