Catalytic ignition and heat release of fuel/air mixtures

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5713794

Cho, P

Ignition and heat release rates of fuel/oxygen/nitrogen over platinum wires are experimentally studied using micro-calorimetry, aiming to gain additional understanding on the complex transport and kinetic processes involved during catalytic oxidation so as to relate the macroscopic observables with the microscopic behavior. The fuels studied are propane, butane, propylene, ethylene, carbon monoxide, and hydrogen. Parameters investigated include catalyst surface temperature, fuel and oxygen concentrations, and flow velocity. Results show that for very low Reynolds number flows the flow velocity has negligible influence on the ignition temperature. Its influence on the heat release rates is also negligible but only for the reactions in kinetically controlled regime. Variation of fuel concentration is found to be an important factor in that the ignition temperatures of propane and butane decrease as their concentrations are increased from lean to rich mixtures while the opposite trend is observed for propylene, ethylene, carbon monoxide and hydrogen. The effect of oxygen concentration on the ignition temperature of propane display a minimum on the lean side of stoichiometry whereas for carbon monoxide the ignition becomes progressively easier as the oxygen concentration is increased. The heat release rate shows that the highly-reactive hydrogen/air mixture is usually diffusion-limited but, propane/air is not limited by mass transport rate. Other fuel/air mixtures show both trends - kinetically controlled at low temperature range but diffusion limited at higher temperatures. Based on the above results a qualitative correlation is made between the ignition temperature and the chemisorption strength of the fuel molecules relative to oxygen.

• OSTI ID: 5713794
• Country of Publication: United States
• Language: English

Related Subjects

090110* -- Hydrocarbon Fuels-- Properties-- (1979-1989)
10 SYNTHETIC FUELS
AIR
ALKANES
ALKENES
BUTANE
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSIS
CATALYTIC EFFECTS
CHALCOGENIDES
DISPERSIONS
ELEMENTS
ENERGY TRANSFER
ETHYLENE
FLUIDS
GASES
HEAT TRANSFER
HYDROCARBONS
HYDROGEN
IGNITION
METALS
MIXTURES
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
PROPANE
PROPYLENE
TRANSITION ELEMENTS