Learning outcomes of the course unit
The aim of the course is to give the basic knowledge on the theory of Fluid Machinery, both as stand-alone units and as Power Systems components. Students will be provided with fundamentals required for the understanding of most important energy conversion processes, which will be then used in the analysis of the most widely used power plants.
A basic knowledge of fundamentals of Mathematics, Physics, Thermodynamics and Fluid Mechanics is required.
Course contents summary
Energy demands in Italy and in the world. Fossil and renewable energy sources. Power Systems and Fluid Machinery: characteristics and classification.
Thermodynamics: 1st and 2nd law. Gas and vapours. Mass, energy, momentum conservation equations and their applications. Work done by fluid systems in rotating ducts: radial and axial turbomachinery.
Hydraulic energy: storage and run of river hydro-plants. Hydraulic turbines: Pelton, Francis and Kaplan turbines.
Energy from fossil fuels: combustion processes and fuel properties. Mass balance, combustion products composition, fuel/air ratio.
Thermodynamic cycles. Conversion efficiencies in power plants, overall efficiency and specific fuel consumption. Cost of energy and utilisation coefficient.
Turbomachinery working on compressible fluid. De St.Venant equation, compressibility effects and dynamic pressure, Hugoniot equation, Mach number, ideal and real nozzles and diffusers. Mass flow rate in nozzles. Compression and expansion: representation on thermodynamic diagrams, efficiencies.
Expansion in a stage of an axial turbine: enthalpy changes in stator and rotor, reaction degree, velocity triangles. Conditions for maximum conversion efficiency for an axial stage and influence of the reaction degree.
Compressors and pumps: fundamentals, head, matching with piping system. Centrifugal turbomachinery. Characteristic curves. Pumps: cavitation and NPSH. Dynamic compressors: axial stage, stall and surge, characteristic curves of multi-stage machines, choking and operating range.
Steam plants. Fundamentals: thermodynamic cycles, Rankine and Hirn cycles (superheated). Steam generators: fundamentals and layouts, efficiency of the steam generator, superheaters, air pre-heaters. Condensers and cooling towers. Thermal regeneration and regenerative cycles.
Gas turbines: fundamentals, thermodynamic cycles (ideal and real), efficiency and specific work, cycle optimisation. Combustion chamber and air/fuel ratio. Turbine inlet temperature (TIT): effects on the efficiency, blade cooling, materials and alloys.
Internal combustion engines: fundamentals, ideal thermodynamic cycles, power output. Brake mean effective pressure (bmep). Volumetric efficiency. Characteristic curves.
O.Acton, C.Caputo, Macchine a fluido, vol.1, "Introduzione allo studio delle Macchine", UTET, 1979.
O.Acton, C.Caputo, Macchine a fluido, vol.2, "Impianti Motori", UTET, 1992.
O.Acton, Macchine a Fluido, vol.3, “Turbomacchine”, UTET, 1990.
G.Ferrari, “Motori a Combustione Interna”, Il Capitello, 1990.
C.Caputo, “Gli impianti convertitori di energia”, Masson, 1989.
C.Caputo, “Le turbomacchine”, Masson, 1989.
Lectures and numerical examples on course subjects.
Final evaluation is based on a written exercise on numerical examples and an oral examination.