Fuel oxidises releasing energy; stoichiometry gives air-fuel ratios.
Fuel reacts with oxygen releasing heat. Stoichiometric reaction CH₄+2O₂→CO₂+2H₂O. Air-fuel ratio and equivalence ratio φ describe mixtures; excess air ensures complete combustion. Heating value (HHV, LHV) quantifies energy. Emissions: CO, NOx, unburnt hydrocarbons, soot.
Burning 1 kg methane releases about 50 MJ (LHV).
Combustion releases chemical energy as heat, and the air-fuel ratio sets efficiency and emissions in every burner, engine and furnace.
Fuel oxidises releasing energy; stoichiometry gives air-fuel ratios.
Combustion releases chemical energy as heat, and the air-fuel ratio sets efficiency and emissions in every burner, engine and furnace.
The exact amount of air needed for complete combustion of the fuel, with no excess oxygen and no unburnt fuel.
A small excess ensures complete combustion, but too much air wastes heat up the stack, so the ratio is carefully controlled.
Typical applications include setting the air-fuel ratio of a gas burner for complete combustion, calculating the flue gas composition from a fuel analysis and estimating the theoretical air needed to burn a given quantity of methane.
Study "Air conditioning and psychrometrics" first (topic 38 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Methane stoichiometric A/F≈17.2. Lean vs rich. Enthalpy of formation.
Burning 1 kg methane releases about 50 MJ (LHV).
The next topic is "Adiabatic flame temperature", which builds directly on this one.
It is classed as Intermediate in Thermodynamics & Fluids (topic 39 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.
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