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An Introduction to Fire Phenomena

Block name: An Introduction to Fire Phenomena

ECTS: 1

Language of instruction: Polish/English

Teaching methods/load: Lecture (4h / semester)

Teacher responsible: Prof. Marek Konecki

 

Prerequisites

The achievement of learning outcomes in the following areas: basic laws of physics, physical chemistry of combustion, thermodynamics and fluid mechanics

 

Description of learning outcomes

The aim of the course is to learn students the basics of dynamics of fire in rooms and buildings including elements of threat modeling (fire).

 

Content:

  • Theory of fires in fire safety engineering. Definitions of terms such as low- and high-temperature environment of fire, fire characteristics of materials, the parameters of the fire. The mechanisms of heat transfer in fire environment – conduction, radiation, convection, determination of heat fluxes and temperature distribution. Bernoulli's Law. The gases movement in case of fire in the buildings. Determination of hydrostatic pressure differences and the gas velocity. Basic mechanisms of the spread of smoke in the buildings – chimney walls, the effect of wind.
  • Parameters (features) fire materials. The mass burning rate and specific mass burning rate. Dependence of mass burning rate on the time in case of fires inside rooms and open space. The basic equation of the flame spread on materials. The thermal inertia of materials and the dynamics of fire. Surface area of fire and combustion. Power (rate of heat release, HRR) and fire power density. Methods of determination of HRR. Example of fire power spread over time - furniture. Classification of fires by ISO. Fire type "t2". The impact of extinguishing on the power of fire.
  • The structure of a fire in the room. The definitions of the fire. Fire risk factors associated with zones of fire. The combustion zone – the average height of the flame, the flame deflection of the ceiling space. Characteristics axisymmetric convection column. The impact of convection column with the borders of the room - ceiling stream parameters. Time to activate a thermal detector. The zone of influence of thermal radiation – radiation flux model of flame. Smoke zone. Changes of visibility during the fire.
  • Changes of gases concentration (oxygen, carbon monoxide, hydrogen cyanide) in fired room. Gas exchange in a room with two small holes and opened door – setting effluent streams and air entering the room. Gas exchange in the room until the fire extinguishing.
  • Basic conditions of transmission between combustion and spread of fire (phase I). Fire spread in room. Phases of fire. Characteristics of the burning rate and heat generation. Fire controlled by the fuel, fire controlled by ventilation. The influence of different factors on the dynamics of fire. The rate of heat release in phase I, phase II and fire vent hole. Emissions of combustion products.
  • The nonlinear phenomenon of internal fire – flashover and backdraft. Symptoms, mechanisms and risk of flashover and the backdraft. Examples of real fires with such effects – analysis of the spread. Prevent methods against flashover and the backdraft. Avoiding of consequences of these effects. Similarities and differences between the these effects.
  • The theory and modeling. Division of fire models, definitions and objectives of modeling. Physical and mathematical models. Deterministic modeling – zone and field. Guidelines and examples of analytical models of fire. Basic fire zone modeling – assumptions, the model equations. Computer programs based on zone models. Examples of applications of modeling  and calculation of the parameters of the fire.

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