31393 - Fluid Mechanics and heat transfer

Learning outcomes

The aim of the Course is to provide a basic knowledge of fluid mechanics and heat transfer, in view of subsequent applications to the design of energy conversion, energy transfer and energy control systems.

Course contents

Fluid Mechanics

Basic definitions. Laminar flow and turbulent flow. Dynamic boundary layer. Viscosity. Newtonian and non-Newtonian fluids. Stresses in a flowing fluid. Time derivative and substantial derivative. Local mass balance equation. Local momentum balance equation. Fully developed laminar flow with constant density in a parallel-plane channel and in a circular tube. Flow with constant density past a cylinder or a sphere, drag coefficient. Integral equation of mechanical-energy balance. Head losses. Friction factor. Moody diagram. Measurements of velocity and of flow rate.

Heat conduction

Fourier law. Fourier equation. Steady heat conduction without generation in plane, cylindrical and spherical geometry. Thermal resistance, thermal resistances in parallel and in series. Heat equation. Example of steady heat conduction with generation, in cylindrical geometry. Measurement of thermal conductivity.

Heat convection

Forced, mixed and natural convection. Local equations of mass, momentum and energy balance. Boussinesq approximation. Convection coefficient and Nusselt number (Nu). Dimensionless equations of mass, momentum and energy balance. Reynolds number (Re), Grashof number (Gr), Prandtl number (Pr). Existence of a relation Nu = Nu(Re, Gr, Pr) for mixed convection. Thermal boundary layer. Forced convection: existence of a relation Nu = Nu(Re, Pr), special cases, examples. Natural convection: existence of a relation Nu = Nu(Gr, Pr), special cases, examples.

Heat radiation

Definitions. Black body. Laws of Kirchhoff, Stefan-Boltzmann, Planck, Wien, Lambert. Grey body. Radiation heat transfer between black bodies and grey bodies. Non-grey bodies. Radiation coefficient.

Composite heat transfer problems

Overall thermal resistance and overall heat transfer coefficient. Examples in plane and in cylindrical geometry. Heat exchangers: plots of fluid temperatures and logarithmic mean temperature difference for coaxial-tube heat exchangers; other kinds of heat exchanger; effective temperature difference; efficiency of a heat exchanger; examples of sizing and verifying heat exchangers.

Readings/Bibliography

S. LAZZARI, B. PULVIRENTI, E. ROSSI DI SCHIO: “Esercizi risolti di Termodinamica, Moto dei Fluidi e Termocinetica” (Esculapio, Bologna, 2006)

Teaching methods

Lectures and exercises in classroom; CFD simulations; discussions in classroom; measurements in the laboratory.

Lessons are taught in italian.

Assessment methods

The assessment aimed to verify knowledge and skills acquired by the student in relation to all the contents illustrated above. The assessment consists of a written exam, which includes a theory question and an exercise.

Teaching tools

In consideration of the types of activities and teaching methods adopted, the attendance of this activity requires all students to carry out Modules 1 and 2 of the Health and Safety Training for Study and Research Areas [https://www.unibo.it/en/services-and-opportunities/health-and-assistance/health-and-safety/online-course-on-health-and-safety-in-study-and-internship-areas] in e-learning mode and to participate in Module 3 of the Health and Safety Training for Study and Research Areas. Information on dates and methods of attendance for Module 3 can be consulted in the specific section of the degree program website.

The course participates to the University project on innovation in teaching.

Office hours

See the website of Eugenia Rossi di Schio