This paper presents some results on the performance of hydrogen-based engines. In particular, the following aspects are addressed: benefits associated with specific fuel and energy consumption, net thrust, turbine entry temperature, and hardware changes needed in the upgrading process from kerosene to hydrogen. Hydrogen is a high-energy clean-burning fuel whose main combustion product is water vapour plus traces of nitrogen oxides. This fact suggests that, provided that the technology is available, the use of hydrogen could offer some opportunities for the environmentally friendly development and sustained growth of commercial aviation. The study has been performed in the frame of the Liquid Hydrogen Fuelled Aircraft -System Analysis (CRYOPLANE) project. This is a Fifth Framework Programme, supported by the European Commission, whose objective was to assess the feasibility of using hydrogen as a clean energy source for air transportation systems.
This article presents an optimization study of a semiclosed combined cycle for CO2 capture, based on the combined cycle (CC) gas turbine side, and where the produced water is extracted by condensation; its results are compared with those from the classic open CC. In this study, besides the overall pressure ratio (OPR) influence on the global efficiency, the influence of gas composition is also presented showing that it can change significantly the optimum OPR. Additionally, the sensitivity of the global efficiency to the maximum gas turbine temperature T
4t
, gas turbine components efficiency, and cooling bleeds, the representative parameters of components technology level, is included. The optimum OPR shows that this type of cycles is not out of the current technology. Influence of gas composition on components performance maps is not considered, only some considerations on maps scaling. Also, starting from a baseline concept, some alternatives have been studied looking for a global efficiency improvement; the cooling down of the gas turbine entry conditions and the use of N2 from the air separation unit as high-pressure turbine cooling, by means of the efficiency sensitivity to the blade cooling, are considered. Finally, it also provides efficiency close to the classic open CC and inside the efficiency of related cycles.
Abstract:Emissions are important drivers in the design and use of aero-engines. This paper presents a part of the work carried out in the VITAL (EnVIronmenTALly aero-engine) project; it consists of a parameter study on the application of three innovative thermodynamic cycles to aircraft propulsion, looking for benefits on fuel consumption, carbon dioxide, nitrogen oxides, and noise. These cycles are intercooler-regenerative, the wave rotor topping, and the constant volume combustor cycles. The work, starting from a next-generation ultra-high bypass ratio turbofan, the baseline, and considering two possible design conditions, presents the influence of the application of these new cycles or design changes to the baseline on emissions and on the required technological level, represented by the turbine entry temperature (TET). VITAL is a project supported by the Sixth Framework Programme of the European Communities. The results show that some significant benefits on emissions can be achieved although they are linked to significant technology improvements and in-depth studies of the new components involved in cycle implementation.
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