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Predicting Explosive Limits of Flammable Compounds via Phenomenological Relations

Azarnia Fazli, Vahid | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51997 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Nassimi, Ali mohammad; Tafazzoli, Mohsen
  7. Abstract:
  8. In this work, we establish the constancy of expansion ratio (density factor) and adiabatic flame temperature for predicting lower explosive limits and further establish the constancy of expansion ratio for measuring upper explosion limits. Flammability limits are important characteristics of combustion processes. The flame can only propagate in a specific range of ratios of concentration of fuel to oxidant. The maximum of this concentration ratio that make possible propagation of flame in a mixture, is called upper flammability limit. The minimum of this ratio that make flame propagation possible is called lower flammability limit. Limits of flammability change with initial conditions such as initial temperature and pressure. Adding inert gasses into the mixture of fuel and oxidant cause flammability limits to get closer to each other. It is claimed that adiabatic flame temperature is constant for both flammibility limits. Our calculations are based on the assumptions of ideal gas behaviour and equilibrium. We study the reactions at constant enthalpy and pressure in a premixed mixture. Density factor is defined as the ratio of density of the mixture before combustion to the density of mixture after combustion. The claim is that the density factor is constant in both flammability limits for every fuel. We show that density factor varies less than the adiabatic flame temperature in upper flammability limit. This constancy can be used to peredict flammbility limits. We study the change in adiabatic flame temperature and density factor with change in initial temperature. Also the distribution of species of combustion product and thermodynamic quantities are studied
  9. Keywords:
  10. Flammability ; Electroleaching ; Phenomenology ; Adiabatic Flame Temperature ; Expansion Ratio

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