H 2 ∕ O 2 Cycles: Thermodynamic Potentialities and Limits

Abstract

In this paper, the thermodynamic potentialities and limits of the H2∕O2 turbine cycles (afterward named only H2∕O2 cycles) are investigated. Starting from the conventional gas turbine and steam turbine technology, the paper qualitatively tackles problems related to a change of oxidizer and fuel: from these considerations, an internal combustion steam cycle is analyzed where steam, injected into the combustion chamber together with oxygen and hydrogen, is produced in a regenerative way and plays the important role of inert. A proper parametric analysis is then performed in order to evaluate the influence of the main working parameters on the overall performance of H2∕O2 cycles. All the results are carried out by neglecting the energy requirements for O2 and H2 production systems, but taking into account the work required by the O2 and H2 compression. This choice permits a great freedom in the definition of these thermodynamic cycles; moreover, it is possible to come to some general conclusions because the H2 and/or O2 production systems and their integrations with thermodynamic cycles do not have to be specified. Therefore, this paper can be framed in a context of centralized production of oxygen and hydrogen (by nuclear or renewable energy sources, for example) and their distribution as pure gases in the utilization place. By adopting some realistic assumptions, for example, a top temperature of 1350°C, the potentialities of H2∕O2 cycles are very limited: the net efficiency attains a value of about 50%. Instead, by adopting futurist assumptions, for example, a top temperature of 1700°C, a different H2∕O2 cycle scheme can be proposed and its performance becomes more interesting (the net efficiency is over 60%). The paper tackles the main thermodynamic and technological subjects of the H2∕O2 cycles: for example, it is underlined how the choice of the working parameters of these cycles strongly influences the attainable performance.

Energy and exergy analysis of steam cooled reheat gas–steam combined cycle

“…Macchi and Chiesa [3], El Masri [4], Bannister et al [5], Rice [6][7][8], Gambini et al [9], Bhargava and Perotto [10], Poullikkas [11] have studied and predicted performance of reheat gas turbine using air as coolant. In the light of the above works the present work is aimed at: To identify and quantify the sources of losses in the selected configuration (R3PR) with different means of cooling and hence to try for minimizing these losses to achieve maximum efficiency in R3PR.…”

Comparative analysis of H/O cycle power plants based on different hydrogen production systems from fossil fuels

“…The reference cases were studied [1] varying the maximum pressure and temperature. Also in this paper we have analyzed the in uence of these parameters on power plant overall performance.…”

“…For this scheme, a proper parametric analysis was performed [1] in order to evaluate H2=O2 cycle performance as a function of the most important working parameters (oxygen and hydrogen are pure gases at ambient conditions). This cycle sustains itself, adopting a top temperature of 1350 • C. In this case, with a total pressure ratio of 30, the maximum e ciency attains the value of about 50%.…”

Superimposition of Elementary Thermodynamic Cycles and Separation of the Heat Transfer Section in Energy Systems Analysis

“…The concept of superimposition of cycles derives from the observation that many advanced power cycles are built upon an integration of elementary cycles, which are individually "optimized" for given temperature ranges [18][19][20][21]. Such integration is realized, for example, by mixing the working fluids and performing portions of elementary cycles in a common transformation, and by a high degree of system thermal integration [22,23]. This paper shows the advantages of combining the HEATSEP methodology with the analysis and superimposition of elementary cycles to enhance the comprehension of advanced gas turbine cycles and to find directions for design improvement.…”