A thermodynamic cycle with a quasi-isothermal expansion

Abstract

The combustion of hydrogen and oxygen makes feasible a steam re-heating by mixing rather than by surface exchange. In such a way the use of several re-heaters is possible as well as the increase of re-heating temperature. The performances of steam power-plants with a large number of super-heaters (5–15) have been analyzed. Some theoretical considerations are also given in order to explain expectations, results and perspectives. Using so many super-heaters makes the expansion gradually approach isothermal conditions. A significant reduction of the efficiency gap with respect to the Carnot cycle was therefore expected. A thermal efficiency of 49.2% is achievable. Although this is far from the 61.6% of the Carnot cycle, the study points out some interesting aspects and suggests the basis for further development.