Academic Year 2021/2022 - 3° Year

ING-IND/11 - 9 CFU - 2° Semester

Provide basic methodology for setting the thermal energy balance of systems. Equation of heat and mass balance. Deepening of the main physical phenomena and their mathematical models. Basic Knowledge for HVAC systems. Design of heating and domestic hot water system for residential users. The knowledge of the features characterizing the architectonic acoustics. Particular attention will be paid to the link between the studied physical phenomena and their applications in the field of energy conservation, the global welfare of the occupants. This course aims to provide the skills that form the basis for a conscious design to issues related to energy and the environment.

The course includes the alternation between theoretical lessons and practical exercises on the issues developed in the classroom.

If the teaching will be given in mixed or remote mode, the necessary changes to what was previously stated may be introduced, in order to comply with the program provided and reported in the syllabus

Fundamentals of Thermodynamics

a) The Thermodynamic System

International System of measurement units. Definitions and measurability of internal energy. Heat energy as a mode of exchange. The first principle of thermodynamics in the expanded form.

b) State of equilibrium.

Magnitudes of physical condition and location. intensive and extensive quantities. Dependence of the work and the heat of the type of thermodynamic process. The entropic postulates. Reversible and irreversible processes. quasi-static transformations. Gibbs equation.

The second law of thermodynamics (Clausius and Kelvin).

c) The ideal gas

State equations. Specific heat at P and V constant. Transformations at T, P, V constant. adiabatic quasistatic. The entropy of an ideal gas. Notes on the behaviour of real gases.

d) The diagrams of physical state.

The diagrams (P-T), (p-v), (t-s). Steam water. Major transformations of the water vapour.

Vapour title. The MOLLIER diagram (h-s) for the water vapour.

e) Direct and inverse cycles.

Cyclical Processes. Direct steam cycles (Rankine and Hirn), gas turbines and Joule Bryton cycles. The refrigerator cycle. isoentropic efficiency. absorption refrigeration cycles.

f) Moist air.

The fundamental values. psychometric diagrams for the humid air. The humid air transformations. The temperature of saturation and dew point temperature. processes for summer and winter conditioning.

HEAT and hints of fluid dynamics

g) fluid dynamics

Bernoulli equation. Similitude, dimensional analysis and modelling. Internal and external flows. Fluid flow in the ducts. Reynolds number. Flow regimes of a liquid in a conduit.

(Regimes: laminar, turbulent and transitional). Friction factor. Coefficients of dynamic and kinematic viscosity. Profiles of velocity.

h) Heat transfer by conduction

The Fourier postulated. steady-state energy balance. The flat plate; the multilayer planar walls (with and without thermal power generation). Electric analogy. The energy balance in the case of cylindrical symmetry. Insulated pipe. electrical analogy. The critical radius. Unsteady conduction: Biot number; method of concentrated capacity.

i) Heat transfer by convection.

external flow and internal flow to the surface. boundary layer. the boundary layer assumptions.

l) Forced convection:

dimensionless groups for forced convection and similarity. experimental dimensionless correlations for the forced heat convection to the main heat exchange configurations of outside and inside surfaces of conduits.

m) Natural convection:

General consideration. constitutive equations for natural convection. Hypothesis Boussinesque. Natural convection in open spaces.

n) heat transfer by radiation

Emissive power. Irradiation. monochrome and overall. The black body: Planck, Stefan-Boltzmann and Wien laws. The coefficients of absorption, reflection, transmission and emission. Kirchhoff's law. The grey body. heat exchange between blacks bodies: the form factor.

ENERGY AND TECHNICAL SYSTEMS

o) HEATING SYSTEM

Heat exchangers. Hydronic distribution networks. Continuous and localized pressure drops. Moody chart.

Darcy-Weisbach formula, Chézy, Colebrook, of Kutter and Darcy. Power of a machine

Operating hydraulic (pump). Calculation of the manometric prevalence and total of a pump. Characteristic curves. emission terminals. Hints on Control Systems

ACOUSTIC

p) Elements of acoustics

TESTI CONSIGLIATI:

- Termodinamica e trasmissione del calore Yunus A. Cengel, - McGraw-Hill
- Elementi di Fisica Tecnica per l’ingegneria Michael J. Moran et al. McGraw-Hill
- Fisica Tecnica Ambientale . Yunus A. Cengel,G. Dell'O', L. Sarto, McGraw Hill
- La progettazione degli impianti di climatizzazione negli edifici –EPC Magrini Anna Magnani Lorenza -
- Dispense del Docente