ACADEMIA ROMÂNĂ Revue Roumaine de Chimie http://web.icf.ro/rrch/ Rev. Roum. Chim., 2012, 57(3), 215-222 NUMERICAL STUDY OF DILUENT INFLUENCE ON BURNING VELOCITY OF ACETYLENE-AIR MIXTURES Codina MOVILEANU, a Maria MITU, a Venera GIURCAN, a Adina MUSUC, a Domnina RAZUS a* and Dumitru OANCEA b a Roumanian Academy, ”Ilie Murgulescu” Institute of Physical Chemistry, 202 Spl.Independentei, 060021Bucharest, Roumania b Department of Physical Chemistry, University of Bucharest, 4-12 Regina Elisabeta Blvd., 030018 Bucharest, Roumania Received November 1, 2011 In the present paper, the numerical study of 1-D adiabatic laminar premixed flames of acetylene-air and acetylene-air-diluent (stoichiometric acetylene-air mixtures containing various amounts of Ar, N 2 or CO 2 ) was carried out at room temperature and atmospheric pressure, using two software packages (INSFLA, based on Warnatz mechanism and COSILAB, based on GRI mechanism). The kinetic modelling provides the normal burning velocities and the profiles of temperature and heat release rate across the flame front. For the stoichiometric acetylene-air mixture, the burning velocities computed with GRI mechanism agree well with experimental values from literature while the burning velocities computed with the Warnatz mechanism are underestimated. Dilution by increasing amounts of diluents determines the decrease of burning velocity, of maximum flame temperature and of heat release rate, determined by decrease of overall reaction rate between fuel and oxidant in the reaction zone and of heat and mass transfer rates between the burnt and unburnt gases. INTRODUCTION * The acetylene combustion with air or oxygen has a considerable chemical and industrial interest and importance. The high enthalpy of formation of acetylene determined by the presence of the triple C≡C bond results in flame temperatures higher than those normally obtained from other hydrocarbon fuels; therefore acetylene is widely used in industrial welding and cutting and also in other applications where high temperature flames are required, such as photometry and atomic absorption. 1 The combustion reactions of acetylene are of wider significance, since acetylene is formed as an intermediate in the combustion of fuel-rich mixtures of other hydrocarbons and plays an important role in soot formation. 2 Knowledge of acetylene combustion is important also with respect to industrial hazards presented during acetylene manufacture and its wide using for chemical synthesis. This is particularly so since acetylene is capable of sustaining a self- * Corresponding author: drazus@icf.ro; drazus@yahoo.com decomposition flame, while in mixture with oxygen it readily detonates. 3 The laminar burning velocities for acetylene-air mixtures are also substantially higher than those of any other hydrocarbon mixture for the same equivalence ratio. 4, 5 Among characteristic propagation parameters, the normal burning velocities are key properties for modelling the turbulent combustion, optimization of internal combustion engines and the design and construction of venting devices. Reliable values of burning velocities for gaseous acetylene-air mixtures are found in literature, from various measurements on premixed flames, under stationary or non-stationary conditions. 6-12 The burning velocities of acetylene with air over lean to rich fuel concentrations, at various initial pressures between 0.5 and 20 atm were measured by means of the spherical bomb technique. 6-8 For the stoichiometric mixture at ambient initial pressure and temperature, burning velocities ranging within 125 cm/s 6 and 135 cm/s 8 were reported. Other