Fire Dynamics

Recommended Prerequisites

Thermodynamics, Applied Thermodynamics, Fluid Mechanics.

Teaching Methods

The lectures have a traditional format, which is essentially driven by the exposure of the subjects in Powerpoint slides.

The practical classes are devoted to the analysis and solving of practical problems for application of the theoretical knowledge. Some orientations are provided regarding two problems that the student should solve by his own, over the semester, and present the corresponding reports.

Learning Outcomes

Principles of heat conduction. Heat transfer by convection. Basic laws of mass, momentum and energy conservation are presented. The basic principles to calculate convective heat transfer are also presented. The physical nature of thermal radiation is presented as well as the basic laws of emission; Prandl and Stephan-Boltzmann laws together with the concepts of black and grey surfaces. Properties of surfaces relative to incident radiation are defined: absorption, transmission and reflection of radiation. View factors between surfaces. Behaviour of non-transparent media; attenuation coefficient. Radiative properties of gases at high temperature (flames).

Fires in confined spaces (rooms) and consequences for occupants and buildings. Importance of the fuel and the ventilation. Evaluation of temperature level, smoke and carbon-monoxide production. Combustion regimes and losses by thermal radiation. Simulation tools : CFD and zone (1 or 2) models. Propagation of a fire.

Work Placement(s)

No

Syllabus

Heat conduction

Thermal conduction.

Convection

Equations of conservation. Forced and free convection.  Correlations for the calculation of convective heat transfer powers.

Radiation

Nature of thermal radiation and basic laws of emission; Prandl and Stephan-Boltzmann laws. Concepts of black and grey surfaces. Absorption, transmission and reflection of radiation. View factors between surfaces. Non-transparent media and attenuation coefficient. Radiative properties of gases at high temperature (flames).

Mass Transfer

Introduction. Fick's law of diffusion. Diffusion in gases: molecular counter-diffusion; column evaporation. Diffusion in liquids and solids. Mass transfer coefficient. Analogy between heat transfer and mass transfer.

Fires in confined spaces

Importance of the fuel load and the ventilation. Temperature level, smoke and carbon-monoxide production. Combustion regimes and radiation losses. Simulation tools: CFD and zone (1 or 2) models. Propagation of a fire inside and outside a building.

Assessment Methods

Final
Exam: 100.0%

Bibliography

- F.P. Incropera, D.P. DeWitt, T. L. Bergman and A.S. Lavine, Fundamentals of Heat and Mass Transfer, John Wiley & Sons, 6ª ed., 2007.

- Y.A. Çengel, Heat Transfer: a Practical Approach, WCB/McGraw-Hill, 3^th ed., 2006.

- F.P. Incropera and D.P. DeWitt, Fundamentos de Transferência de Calor e de Massa, LTC Ed., 4ªed., 1998.

- M.J. Moran, H.N. Shapiro, B.R. Munson and D.P. DeWitt, Introduction to Thermal Systems Engineering: Thermodynamics, Fluid Mechanics, and Heat Transfer, John Wiley & Sons, 2003.

- F. Kreith, Principles of Heat Transfer, McGraw-Hill, 1986.

- Siegel & Howell, Radiative Heat Transfer, John Wiley & Sons, 1991

- A. R. Figueiredo, J. J. Costa e A. M. Raimundo. Apontamentos de Transmissão Calor.