6 Analysis of an axial flow expander Text

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COURSE OF ENERGY CONVERSION A 2015/2016 Prof. G. Valenti 6th Project Analysis of an axial-flow expander This project aims at calculating the operating conditions and the stage geometry of an uncooled expander by means of an axial-flow turbine simulation and design tool. Consider: - A) three-stage machine - B) two-stage machine - C) one-stage machine It is required to: i) Calculate the expander efficiencies in the three configurations (A, B and C) as a result of the simulation procedure with the software; moreover, compare the values of the isentropic stage loading (kis), the stage reaction coefficient (r*), his and total temperatures at the inlet and outlet of each stage. ii) For the sole first stage of configuration A, plot the overall efficiency, the specific rotational speed Ns, the mean value of h/d of stator as well as rotor, and the profiles of the stage losses against the rotational speed as it varies between 5000 rpm e 30000 rpm. Moreover, highlight which is the value of rotational speed which guarantees the optimum efficiency. Consider the following 8 losses terms, as reported by the software:  Stator: profile losses, secondary losses and annulus losses  Rotor: profile losses, secondary losses and annulus losses  Kinetic energy losses  Disks losses Design parameters: operating conditions Mass flow rate: 10 kg/s Inlet total pressure: 5 bar Inlet total temperature: 850 °C Working fluid: ideal gas with molecular mass = 30,  =1.31-1.35. Rotational speed base cases: 10000 rpm Maximum blade speed u  350 m/s Note: the simulation software (“Axtur”) works in MS-DOS and Windows environment. The following section provides some guidelines to the use of the input and output files. COURSE OF ENERGY CONVERSION A 2015/2016 Prof. G. Valenti Output file guidelines for…