ACADEMIA ROMÂNĂ Revue Roumaine de Chimie http://web.icf.ro/rrch/ Rev. Roum. Chim., 2014, 59(9), 727-732 KINETICS OF ISOTHERMAL CATALYTIC IGNITION AND COMBUSTION OF LPG-AIR MIXTURES ON PLATINUM WIRE Maria MITU, a Valentin MUNTEANU, b Domnina RAZUS a and Dumitru OANCEA b,* a “Ilie Murgulescu” Institute of Physical Chemistry, Roumanian Academy, 202 Spl. Independenţei, 060021 Bucharest, Roumania b Department of Physical Chemistry, University of Bucharest, 4-12 Elisabeta Bd., 030018 Bucharest, Roumania Received April 29, 2014 The catalytic ignition and flameless steady combustion of lean to stoichiometric gaseous fuel-air mixtures, with equivalence ratios φ = 0.62, 0.71, 0.81, 0.90 and 1.00, resulted from liquefied petroleum gas (LPG) produced in Romania, containing 12 vol % propane, 87 vol % butane, and 1 vol % C5 fraction, were studied on heated platinum wire in isothermal regimes. The critical ignition temperatures at pressures between 20 and 101 kPa and maximum heat release rates, proportional to the rate of the catalytic combustion, within the same pressure range, and temperatures between 570 and 890 K were measured and discussed. The ignition temperature increases with LPG concentration and decreases with total gas pressure. The maximum heat release rate increases with both catalyst temperature and total gas pressure but is apparently independent of LPG content. At 20 kPa pressure the induction delays were measured at several catalyst temperatures. The technique of isothermal combustion allows the evaluation of the overall kinetic parameters on the basis of literature models. 10 30 50 70 90 p0/kPa 550 600 650 700 750 800 850 Tw/K 1 1.5 2 2.5 3 3.5 4 (dQ r /dt) max /(J/s) LPG-air mixtures (dQr/dt)max=a.(p0) n .exp(-c/Tw) r2=0.757 Fstat=216 a=3.356±0.301 b=0.3716±0.0194 c=1310.8±75.5 INTRODUCTION * The liquefied petroleum gas (LPG) represents an increasingly used fuel in both domestic and automotive applications due to the present availability, lower pressure requirements for storage tanks, and associated reduced NO x , CO and unburned hydrocarbon emissions resulted from its combustion. Its main components – propane and butanes – are present in different proportions in many blends according to the country of origin and processing technology. The presence in small amounts of other saturated hydrocarbons, especially pentanes, seems to play no significant role for most applications and consequently the combustion properties of LPG are frequently discussed in connection with those of propane and butanes. The research associated with LPG * Corresponding author: doan@gw-chimie.math.unibuc.ro combustion in various applications is directed to its ignition, propagation and thermal or/and mechanical efficiency on the one hand, and to safety requirements and environment protection on the other. The most important measured properties are the flammability limits, 1 laminar burning velocities and explosion index, 2, 3 quenching distances, minimum ignition currents and minimum ignition energies, 4 maximum explosion pressures and maximum rates of pressure rise, 5 inerting effect of the combustion products, 6 initial pressure and mixture composition influence on the explosivity parameters, 7 effect of the exhaust gas on the laminar burning velocities. 8 Another area of interest is the catalytic combustion of LPG, important for lower temperatures and cleaner operation of micro-combustors, 9, 10 as well as for the development of high performance gas