COMPARATIVE STUDY OF GAS TURBINE-HRSG-ORC AND GAS TURBINE-HRSG-SUPERCRITICAL ORC COGENERATION SYSTEMS THROUGH ENERGY AND EXERGY ANALYSIS

Abstract

The comparative study between the ORC and supercritical ORC has been under study in recent time and the comparatively enhanced performance of the supercritical ORC has made a good alternative to the subcritical ORC systems. In this work, the relative feasibility of the supercritical ORC over ORC was studied when they are positioned as the bottoming cycle in a cogeneration system. A comparative study was carried out to analyse two cogeneration systems, first consisting of Gas Turbine- HRSG-ORC cycle and second consisting of Gas turbine-HRSG-Supercritical ORC cycle. The comparative study was carried out though the energy and exergy analysis of the two systems. Though the energy and exergy analysis it was found that in the bottoming cycle supercritical ORC does performs better in compared to the subcritical ORC. The supercritical ORC register an increase in energy and exergy efficiency by 0.6 to 1.2 percentage point depending upon the value of the parameter taken under the parametric study. However, this comes at the expense of comparatively higher exergy destruction observed in the bottoming supercritical cycle up to certain levels of the parameter. The result also establishes that throughout the parametric range the work output of the bottoming supercritical ORC remains considerably higher than the subcritical ORC cycle.