Teacher

prof.ssa Paola D'AGARO

Credits

6 CFU

Language

Italian

Objectives

Objective of this module is providing students with the necessary background for the analysis of conduction, convection and radiation processes. The acquired notions are utilized for modeling heat transfer processes in components, systems and plants of technical interest.

Acquired skills

- Modeling of steady-state and transient conduction processes.
- Modeling of forced and natural convection processes.
- Thermal design of heat exchangers.
- Modeling of thermal radiation processes.

Lectures and exercises (topics and specific content)

Heat transfer modes: conduction, convection and radiation; thermal conductivity; insulating materials (7 hours).
Conduction rate equations: governing equations for steady-state and transient conduction in two-dimensional geometries; boundary and initial conditions (3 hours).
Steady-state conduction: electrical analogy; one-dimensional plane and cylindrical geometries; extended surfaces; thermal energy generation; shape factors (11 hours).
Transient conduction: the lumped capacity model; one-dimensional plane and radial systems with convection; the semi-infinite solid with constant and time-periodic surface temperatures; multidimensional geometries (8 hours).
Forced convection in external flows: continuity, momentum and energy equations for forced convection in laminar boundary layers; similarity parameters, Nusselt, Reynolds and Prandtl numbers; the effects of turbulence; determination of convection coefficients for non-recirculating and recirculating external flows (11 hours).
Forced convection in internal flows: velocity and temperature distributions in tubes and ducts; determination of convection coefficients for internal flows in tubes and channels (4 hours). 
Free convection: governing equations for laminar free convection from a vertical plate; similarity considerations, Grashof and Rayleigh numbers; determination of convection coefficients (4 hours).
Heat exchangers: heat exchangers types, energy balances and temperature behaviours; log-mean temperature difference and correction factors for multipass and cross-flow exchangers; effectiveness (5 hours).
Radiation: intensity, emissive power, irradiation and radiosity; blackbody radiation; characterization of real surfaces (4 hours).
Radiation exchange: view factors; radiation exchange between black surfaces and between gray surfaces in an enclosure; electrical analogy (3 hours).
Excercises (10 hours).

References

- Comini, G. e Cortella, G., Fondamenti di trasmissione del calore, 4a ed., SGEditoriali, Padova, 2013
- Homework and other information at web page

Type of exam

Written and oral