Unit 4 Assignment: Case Study: Heat Flux Review the case study file and write a 2-page paper that explains heat flux and its implications in the danger of fire heat transfer. After reviewing the pic

Heat Transfer Case Study Assignment Heat Transfer • Major factor in the ignition, growth, spread, decay and extinction of a fire. • Heat energy transferred to an object increases the object’s temperature • Heat energy transferred from an object decreases the object’s temperature • Heat is always transferred from the hotter object to the colder object. Mechanisms of Heat Transfer • Conduction - heat transfer within solids or between contacting solids • Convection - heat transfer by the movement of liquids or gasses • Radiation - heat transfer by electromagnetic waves Radiative vs Convective HRR • Most fuels release the majority of their heat via convection and followed by radiation. • 60 to 75 % Convective • 25 to 40 % Radiative Fuel • Organic Fuels – typically contain carbon, hydrogen, oxygen – wood, plastics, gasoline, natural gas • Inorganic Fuels – typically contain no carbon – magnesium, sodium Forms of Fuel • Gaseous – Methane • Liquid – gasoline or LP • Solid – Wood • What is actually burning? Heat Release Rate • Heat release rate from an object is controlled by: – the chemical and physical properties of the fuel – geometry of fuel and containment – ventilation – surrounding fuels Heat Release Rate • The heat release rate of an object or a room is important to understanding how the energy released from that item would change the thermal conditions in a room or how it might ignite other nearby fuels via heat transfer. Geometry of Fuel • Liquids – Spray vs Spill • Solids – Thin vs Thick – Low density vs high density – Flat, convex vs concave Pool Evaporation vs Spray Pool fire vs Spray Fire Thermally Thin vs Thick Low Density vs High Density Flat vs Convex vs Concave Work Station Arrangements 2 -sided 3 -sided 4 -sided 30 sec 100 kW 180 sec 350 kW 300 sec 1.4 MW 360 sec 2.2 MW 420 sec 3.0 MW 2-Sided Workstation 60 sec 90 kW 180 sec 280 kW 330 sec 1.7 MW 360 sec 2.3 MW 480 sec 3.8 MW 3-Sided Workstation 60 sec 140 kW 150 sec 400 kW 180 sec 700 kW 240 sec 1.5 MW 360 sec 6.9 MW 4-Sided Workstation