University of Central Lancashire UC 13. Performance-based regulations for the fire safety and the increased complexity of building design have led to a dramatic increase in the use of computer modelling

of smoke and heat movement in buildings. Critically review zone and field models used for compartment modelling. Your report should cover main assumptions, differences between the two models, limitations and prose and cones of both models. Include examples and critically analyse the main assumptions, limitations, advantages and disadvantages of these models. Target word count is 300 words. 18 Marks) 14. Critically analyse the effect of ventilation on the composition of smoke using equivalence ratio Compare over ventilated and under vantilated combustion. Target word count is 300 words. (8 Marks) 15. A small wooden crib burns on the floor in the middle of a room. With a total energy release rate of 250 kW. Calculate the mass flow in the plume at heights of 1.0 m and 1.9 m above the floor. Also calculate the plume temperatures at these heights. Assume the radiative fraction of energy loss is 22%. Assume ambient room temperature of 18 °C. Explain your answers. (5 Marks) 16. Analyse the process of liquid and solid fuel combustion. What is the role of radiative feedback? Compare the mechanisms of liquid and solid fuel combustion. Target word count is 300 words. (Marks) 17. Mixed fuel is composed by methane (volume fraction is 0.25), propane (0.15), carbon monoxide (0.35) and hydrogen (0.25). Calculate the lower fiammability limit for the mixture loxidiser is air). Provided the mixture is at LFL, calculate the concentration of each component in the (4 Marks) mixture. 18. A new type of insulating board has been developed by that esteemed construction organisation Kaput Co. They warn that at extremely high heat fluxes it could be ignited, but they don't think it's very likely and it would take hours, so there's no real risk! As an expert on the gritability of materials, you are asked to perform a thick/thin calculation given the following data on the material: Density Thermal conductivity Specific heat capacity Thickness of board Initial/ambient laboratory temperature Ignition temperature 2300 kg ³ 0.85 W²¹ 847JkK Sem 18 °C 415 C Muit Cra/n1. Discuss the factors that will influence fire development within a compartment. 2. Discuss the term "spill plume" and the two categories "adhered" and "balcony". 3. How does the development of a tunnel fire differ from that in a building? (6 Mar 4. Consider a 2.5 m diameter pan fire of methyl alcohol with a heat release rate intensity of 6 kW/m³ of surface area. Calculate the mean flame height under normal atmospheric condition (2 Mark (8 Ma (8 Ma 5. Calculate the heat release rate necessary to cause flashover, using two different approache Consider the room 8.1 m x 5.2 m in floor area and 1.9 m in height with a door opening 1.8r height and 0.75m width. The boundary material is Gypsum. Explain the limitations of you chosen approaches. (6 marks, 6. Calculate the rate constant at 35 "C and 65 °C in a reaction where the Arrhenius constant (A) is 2.5 x 10s and the activation energy (Ea) is 75 kJ mol. Explain how the temperature difference has affected the rate of reaction. (4 marks) 7. Write out the balanced equation for the complete combustion of polymethyl methacrylate (PMMA) CO₂H, The determine how much carbon dioxide is produced when 650 g of PMMA is completely combusted. (3 Marks) 8. Assume that a sample of burning PMMA was weighed as it burnt, giving the average mass loss rate of 5.2g/s. The complete heat of combustion for PMMA has been found to be roughly 25kJ/g. Assuming that the combustion efficiency is 85%, estimate the resulting energy release rate. Also, give a rough estimate of the size of the burning PMMA slab (assume an average burning rate per unit area of 25g/(m²). (5 Marks) 9. Estimate the calorific power of the flame above a burning methanol spillage, diameter of pool 4.5 m, mass burning rate is 42 g/(m's). Net Heat of the combustion is 32.6 MJ/kg fuel, combustion efficiency is 0.80. (4 Marks) 10. Calculate the laminar burning velocity for the propane-air mixture under the pressure of 7.30 atm. (4 Marks) 11. What are free radicals? What is their relevance to fires? (4 Marks) 12. Estimate the extinction coefficient of the smoke produced by flaming combustion of 1.5 kg of polystyrene-foam in a square 6 m room of 1.5 m height (5 Marks)