Abstract
In this study, the exergy and exergoeconomic analyses of simple typical thermal power plants are carried out. The general methodology for defining and calculating exergetic efficiencies, exergy destruction, exergoeconomic factors, total cost, improvement potential and exergy related costs in thermal systems are presented. The procedure is based on the Specific Exergy Costing approach and sensitivity cost analysis. Thermodynamic working fluid properties are obtained by employing both THERMAX and MATLAB software packages. For the considered normal operating and economic conditions; the percentage ratio of the exergy destruction to the total exergy destruction and Potential Improvement was found to be maximum in the boiler, with 88.4% and 92.8%, respectively. The exergoeconomic factor is calculated for the boiler, turbine, condenser and pump, with values of 0.23, 0.35, 0.42, and 0.39, respectively. The total costs of exergy loss are 5153, 1737, 619, and 43 $/hr, for the boiler, turbine, condenser, and pump, respectively. Sensitivity and parametric analyses confirm that the exergoeconomic factor, total annual plant cost, and unit cost of the work and steam, increase with the rise in the interest rate, while they decrease with increasing the annual number of working hours. With the increase of the working boiler temperature, the unit cost of work and steam drop, while the exergoeconomic factor and the total cost rise. The total cost, unit cost of work and steam, increase with the increase in the reference environmental temperature, however, the exergoeconomic factor decreases. For the proposed conditions, the total cost of the plant is 14,000 $/hr for a considered fuel cost of 0.0255 $/kWh, including 10,000 $/hr for the cost of the steam production at 650°C with a unit steam cost of 0.029 $/kWh. It’s a valuable achievement to have determined values and clear parametric influences that could be of great assistance to the site engineers and operators to effectively establish their unique jobs, while playing with the conflicts of the use of energy, exergy, and cost.