Teacher

prof. aggr. Stefano SAVINO

Credits

6 CFU

Language

Italian

Objectives

The course provides a detailed knowledge of heat transfer through conduction, convection and radiation, and heat transfer in heat exchangers. The aim is to enable students to apply the basic heat transfer principles to common engineering problems.

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 (4 hours).
Conduction rate equations: governing equations for steady-state and transient conduction; boundary and initial conditions (3 hours).
Steady-state conduction: electrical analogy; one-dimensional plane and cylindrical geometries; extended surfaces; thermal energy generation; shape factors (10 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 effects (7 hours).
Convection transfer equations: velocity and thermal boundary layers; continuity, momentum and energy equations for forced convection; similarity parameters, Nusselt, Reynolds and Prandtl number; the effects of turbulence; the Reynolds analogy (5 hours).
Forced convection: determination of friction factors and convection coefficients for, non-recirculating and recirculating external flows, and for internal flows in tubes and channels (7 hours).
Free convection: governing equations for laminar free convection from a vertical plate; similarity considerations, Grashof and Rayleigh numbers; determination of convection coefficients; combined free and forced convection (5 hours).
Seminar: examples of numerical solution of steady-state and transient heat transfer problems (2 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 (6 hours).
Radiation: intensity, emissive power, irradiation and radiosity; blackbody radiation; characterization of real surfaces (5 hours).
Radiation exchange: view factors; radiation exchange between black surfaces, and between grey surfaces in an enclosure; electrical analogy; radiation exchange in a participating medium (6 hours).
Exercises (16 hours).

References

- G. Comini e G. Cortella, Fondamenti di Trasmissione del Calore, SGEditoriali, Padova
- Eserciziario di Trasmissione del Calore (available for download at https://materialedidattico.uniud.it/)

Type of exam

Written and oral

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