Performance Analysis of a 50KW Turbogenerator Gas Turbine Engine

Abstract

This paper describes on/off design performance of a 50KW turbogenerator gas turbine engine for hybrid vehicle application. For optimum design point selection, a relevant pa4rameter study is carried out. The turbogenerator gas turbine engine for a hybrid vehicle is expected to be designed for maximum fuel economy, ultra low emissions, and very low cost. A compressor, combustor, turbine, and a permanent-magnet generator will be mounted on a single high speed (80,000 rpm) shaft that will be supported on air bearings. As the generator is built into the shaft, gearbox and other moving parts become unnecessary and thus will increase the system’s reliability and reduce the manufacturing cost. The engine has a radial compressor and turbine with design point pressure ratio of 4.0. This pressure ratio was set based on calculation of specific fuel consumption and specific power variation with pressure ratio. For the turbine inlet temperature, a rather conservative value of 1100K was selected. Designed mass flow rate was 0.5 kg/sec. Parametric study of the cycle indicates that specific work and efficiency increase at a given pressure ratio and turbine inlet temperature. Off design analysis shows that the gas turbine system reaches self operating condition at about N/NDP = 0.48. Bleeding air for a turbine stator cooling is omitted considering the low TIT in the present engine and to enable the simple geometric configuration for manufacturing purpose. Various engine performance simulations including ambient temperature influence, surging at part load condition; transient analysis were performed to secure the optimum engine operating characteristics. Surge margin throughout the performance analysis were maintained to be over 50% approximately. Present analysis will be compared with performance test result which is scheduled at the end of 1998.

Full Load and Part-Load Performance Prediction for Integrated SOFC and Microturbine Systems

“…The resulting design point turbine isentropic efficiency is therefore 84.5%. These values are in good agreement with the works of Jones (1994) and Kim et al (1998) The other assumptions for the GT cycle calculation are shown in Tab. I.…”

Design and Optimization of Fuel Injection of a 50 kW Micro Turbogas

“…having chosen a pressure ratio β compr = 2.75, a polytropic efficiency η poly = 0.9 and a polytropic coefficient k = 1.4 (as adopted in the literature, e.g., [10]). The combustion chamber operates with strong air excess, defined as the ratio α between the air mass flow rate and fuel mass flow rate, and equal to α = .…”

“…This curvature is realized by an ad hoc shape of both the compressor stator block and the external casing, keeping the section of flow passage constant. Tangential velocity is conserved during flow turning around the compressor stator block, but in order to guide it precisely into the swirlers, some vanes are required to adjust the flow tangential velocity to correctly align with the swirler inlet, since in this design, the swirler is not produced after a wall-rebound effect such as in the KJ-66 model and in [10,20].…”

“…However, while Balje suggests this high efficiency, some considerations are required over this topic; during the calculation, some errors are unavoidably present, since the design of turbomachines is based, as a second design step, on velocity triangle calculations, which are near-1-dimensional calculations representing the fluid behavior, but with no consideration of tridimensional phenomena and motions. For these reasons, and for the fact that pressure losses in the combustion chamber could not be evaluated, we decided to use a conservative turbine efficiency η turb = 0.8, consistent with similar machines' performance [10].…”

The Combination of SOFC and Microturbine for Civil and Industrial Cogeneration

“…Solid Oxide Fuel Cells (SOFCs) have already been considered for integration with gas turbine cycles, projected to achieve extremely high efficiency for electric power production (Bevc et al, 1996;Veyo, 1996;Massardo and Lubelli, 1998;Campanari and Macchi, 1998). The recent proposal of high efficiency recuperated microturbine units generating 50-200 kW and projected to achieve net electrical efficiencies approaching 30% (LHV) (Cana et al, 1998;de Biasi, 1998;Kim et al, 1998;Anon., 1998), together with the recent successful operation of a 100 kW SOFC plant (Veyo and Forbes, 1998) offers the basis for considering the integration of these two technologies in small size plants.…”