Parametric analysis of a steam cycle with a quasi-isothermal expansion

Using a hydrogen/oxygen steam generator it is possible to carry out many st eam mixing re-heatings without increasing the complexity of a traditional s team power-plant: steam is not required to re-enter the boiler for each re- heating. An isothermal expansion could thus be approached by means of sever al adiabatic expansions and several steam mixing re-heatings. A theoretical investigation showed that an isothermal expansion could achieve high effic iency (up to 70% of HHV) when the waste heat at the turbine outlet is recov ered for pre-heating water, hydrogen and oxygen. In a real plant the number of re-heatings that can be carried out, although high, is limited and we c an therefore expect an efficiency drop which varies as a function of the nu mber of re-hearings, the re-heating temperature and the maximum pressure. I n order to evaluate real cycle performance, a numerical code. specifically created, was implemented. (C) 2001 International Association for Hydrogen E nergy. Published by Elsevier Science Ltd. All rights reserved.