Exergy loss characteristics of a recuperated gas turbine and Kalina combined cycle system using different inlet guide vanes regulation approaches

This study proposes a novel two-step compressor inlet guide vanes (IGV) method to exploit performance enhancement potential for recuperated gas turbine and Kalina combined cycle (RGT-KCC). The off-design simulation model for RGT-KCC using compressor IGV regulation is constructed on the basis of energy and exergy analysis. The novel two-step IGV method is implemented by decreasing IGV opening to maintain gas turbine inlet temperature constant firstly and then maintain gas turbine outlet temperature (GTOT) at allowable maximum. The effects of novel two-step IGV and two conventional one-step IGV methods on RGT-KCC performance are compared in search for the superiority of novel method. The exergy loss distribution, component exergy efficiency, system exergy efficiency of RGT-KCC under different compressor IGV methods are evaluated with the change of RGT-KCC load. The results indicate that the novel two-step IGV method with the highest GTOT leads to the highest combustion chamber exergy efficiency and topping cycle exergy efficiency. Compared with the conventional one-step IGV methods, the novel method shows 1.37% more combined cycle exergy efficiency at most in RGT-KCC load range of 100-29.3%. As the RGT-KCC load decreases, the component exergy efficiencies of combustion chamber and KCS evaporator go up, while that of compressor and turbine drop. It is interesting to find that exergy loss proportion of combustion chamber drops obviously from 46.79% to 22.31% under novel method, while that of compressor, gas turbine and KCS increase. The novel two-step IGV method with high GTOT is the optimal method to enhance RGT-KCC part-load exergy efficiency in a wide load range.