Propane Combustion
Introduction
This application calculates the adiabatic flame temperature of propane (C3H8) burned with 250% theoretical air, both initially at 298.15 K.
The combustion reaction is
C3H8 (g) + 12.5 O2 (g) + 47 N2 (g) → 3 CO2 (g) + 4 H2O (g) + 7.5 O2 (g) + 47 N2 (g)
The enthalpy of propane, oxygen, nitrogen, carbon dioxide, nitrogen and water are calculated with the empirical data in the ThermophysicalData:-Chemicals package.
restart: with(ThermophysicalData-Chemicals):
Parameters
Enthalpy polynomials
h_C3H8 := Property("Hmolar", "C3H8(g)", "temperature" = T): h_N2 := Property("Hmolar", "N2(g)", "temperature" = T): h_O2 := Property("Hmolar", "O2(g)", "temperature" = T): h_H2O := Property("Hmolar", "H2O(g)", "temperature" = T): h_CO2 := Property("Hmolar", "CO2(g)", "temperature" = T): h_H2O := Property("Hmolar", "H2O(g)", "temperature" = T):
Reference enthalpies
h_r_N2 := eval(h_N2, T = 298); h_r_O2 := eval(h_O2, T = 298); h_r_CO2 := eval(h_CO2, T = 298); h_r_H2O := eval(h_H2O, T = 298);
Enthalpy of formation
h_f_C3H8 := Property("HeatOfFormation", "C3H8"); h_f_N2 := Property("HeatOfFormation", "N2"); h_f_O2 := Property("HeatOfFormation", "O2"); h_f_CO2 := Property("HeatOfFormation", "CO2"); h_f_H2O := Property("HeatOfFormation", "H2O");
Heat Balance
Heat of reactants
H_reac := h_f_C3H8 + 12.5 * (h_f_O2 + 3.76 * h_f_N2)
Heat of products
H_prod := 3 * (h_f_CO2 + h_CO2 - h_r_CO2) + 4 * (h_f_H2O + h_H2O - h_r_H2O) + 7.5 * (h_f_O2 + h_O2 - h_r_O2) + 47 * (h_f_N2 + h_N2 - h_r_N2):
Hence the flame temperature is
fsolve(H_reac = H_prod, T = 1000)
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