Energy, Vol.87, 95-103, 2015
Transcritical CO2 power cycle - Effects of regenerative heating using turbine bleed gas at intermediate pressure
For energy utilization from low temperature waste heat, CO2 is a potential working fluid due to its lower critical temperature. In this work, assuming finite quantity of flue gas available at low temperature (200 degrees C), a thermodynamic model is developed for a transcritical CO2 power cycle utilizing turbine bleed gas for regenerative heating. Analysis show that the cycle performance improves with higher value of bleed ratio. However, for a specified bleed pressure and bleed gas temperature at the regenerator exit, maximum practical value of bleed ratio may be fixed by considering the exponential growth of the regenerator size (specified by NTU (number of transfer unit)). Most significant observation is the existence of optimum bleed pressures corresponding to maximum 1st law efficiency or minimum cycle irreversibility for specified values of remaining cycle parameters. (C) 2015 Elsevier Ltd. All rights reserved.
Keywords:Transcritical CO2 power cycle;Regenerative heating;Bleed gas;1st law efficiency;2nd law efficiency