Influence of reference temperature on exergy and exergoeconomic performance of a natural gas fired thermal power plant

The influence of reference temperature on exergy and exergoeconomic performance parameters of a thermal plant was investigated. The plant was simulated using HYSYS (2003) process simulator software and the exergy and exergoeconomic analyses were done using Microsoft EXCEL spreadsheet. As reference temperature increased from 15 degrees C to 35 degrees C, exergy efficiency decreased from 11.7% to 11.5% and irreversibility increased from 1790 MW to 1812 MW. Also, overall exergy cost decreased from 6650.78 MW to 6055.40 MW and monetary cost from $75,343.84/h to $68,430.19/h. The optimum (base case) reference temperature, where the exergy and the monetary exergy loss costs were at minimum, was found to be 30 degrees C. At this temperature both the condenser and boiler units made significant contributions to the process exergy and monetary exergy loss costs. The study concluded that the performance of the thermal plant depends on reference temperature, efficiencies of condenser and boiler units.