FISICA TECNICA A - L

The aim of the course is to provide a structured knowledge on:

- applied thermodynamics, with a main concern on its fundamental theoretical principles and, in particular, on its applications to the design, analysis and characterisation of the main components of energy plants, of the direct and inverse thermodynamical cycles and of air conditioning plants;

- the fundamental heat transfer mechanisms and their interactions, as well as the operative tools for the analytical description and characterisation of heat transfer in basic geometrical configurations and in heat exchangers.

APPLIED THERMODYNAMICS

Thermodynamics and energy; heat transfer; the units of the IS; The thermodynamic system and the control volume; the state variables; the thermodynamic equilibrium. The zeroth law of thermodynamics. Gibbs’ rule or the equation of state; definitions of pressure, volume and temperature; thermodynamic processes and thermodynamic cycles; Energy: internal energy, kinetic and potential energy, the energy exchange at the boundary of the system: heat and work; Phase changes; diagrams and tables for saturated vapour; The ideal gas model and other state equations. Thermodynamic behaviour of real gas; The energy balance; specific heats at constant pressure and at constant volume; The thermodynamic analysis of the control volumes and steady flow processes, definitions of enthalpy and work exchanged in flows; The first law of thermodynamics for closed and open systems, the main devices operating in stationary flow condition; Definition of thermal engines and refrigeration systems; statements of the second law of thermodynamics. The direct and the inverse Carnot cycle; the Carnot theorems; the thermodynamic temperature scale; The concept of irreversibility; the definition of entropy; entropy diagrams; Gibbs equations and their applications to the case of ideal gas and of incompressible liquid and solid; the balance of entropy for open and closed systems; the isentropic efficiency; Energy and entropy balance for the analysis and characterisation of the basic components of technological plants; Direct gas and vapour Carnot cycles; direct gas cycles; the internally reversible Brayton-Joule cycle; the effect of irreversibilities; the regenerative Brayton-Joule cycle; basic concepts on other evolutions and on application in aeronautics; basic concepts on the Otto, Diesel and Sabathé cycles; The internally reversible Rankine cycle; the superheated Rankine cycle; technological and physical limits for vapour cycles; the effects of irreversibilities; regeneration, cogeneration and combined cycles; Inverse cycles for refrigerators and heat pumps. Vapour compression cycles; the effect of irreversibilities; Mixtures of ideal and real gases, moist air; definition of thermodynamic variables and diagrams used in psychometrics, the main transformations and devices for the treatment of moist air.

HEAT TRANSFER

Introduction to heat transfer: the modes of heat transfer by conduction, convection and radiation. Temperature field and heat transfer; Fourier’s law of thermal conduction and the thermal conductivity of materials; the steady-state conduction in homogeneous and isotropic materials; the electric-thermal analogy and the definition of conductive and convective thermal resistance; the evaluation of the stationary heat transfer for one-dimensional geometries: plane walls, cylinders and spheres; the critical radius of insulation; Heat transfer by external forced convection; dimensionless parameters of forced convection; the regimes of motion and flow on a flat plate; insight to other geometries; Heat transfer in bounded forced convection; the flow within ducts and channels; the heat exchange, the pressure drops and the Moody’s chart; Heat transfer in natural convection; Basic principles of radiation, black body and its fundamental laws, the radiative properties and the grey body model; Heat transfer by radiation; view factors; the heat exchange between black and gray surfaces; Heat exchangers; the overall coefficient of heat exchange; design criteria; the average logarithmic temperature difference; the e-NTU method; Mixed conduction and convection problems: finned surfaces and definitions of effectiveness and efficiency of a fin and of a finned surface; unsteady heat conduction; lumped parameter modelling and Heisler’s diagrams.

1. Y.A. CENGEL - TERMODINAMICA E TRASMISSIONE DEL CALORE - MCGRAW-HILL​

2. M.J. MORAN, H.N. SHAPIRO, B.R. MUNSON, P.D. DE WITT - ELEMENTI DI FISICA TECNICA PER L'INGEGNERIA - MCGRAW-HILL