Hat Cycle Exergetic Analysis and Thermoeconomic Evaluation of Fuel Costs

Abstract

The need of advanced and high performance power cycles is becoming an ever increasing social demand, to reduce environmental impacts as well as to get a better use of natural resources in power generation. The HAT cycle is one of these advanced cycles being considered for use in the next years. This cycle is gas-turbine based, comprises a recuperator and uses water to recover low temperature energy from compressor intercooler, aftercooler and from exhaust gases. However, this cycle requires high-quality water consumption. Consequently, some concerns about water use and costs are being discussed. This work presents an exergetic analysis of the HAT cycle, for different total pressure-ratio on compressor train. The effect of pressure ratio over the water use is also shown. The turbine inlet temperature was kept fixed, to simulate the same technological level on blade cooling and metal alloys. All sub-systems are analyzed from irreversibility viewpoint. An exergy-based thermoeconomic evaluation is made, regarding only fuel and water costs and their impacts on power cost. This methodology can highlight not only the final electric power cost (result that could be also achieved by conventional economic analysis), but also the internal costs of each stream and sub-system of the plant. The complete exergoeconomic analysis of the HAT cycle will depend on reliable economic data, as investment costs of each sub-system, operation and maintenance costs and the operational profile of the plant (base or peak load, yearly operation hours), as well as financial conditions.