D irector of Project : Dr. Venera Giurcan

1. Postdoctoral Research Project PN-II-RU-PD-2011-3-0053 Contract No. 36/05.10.2011 Limiting conditions of explosion propagation in gaseous fuel-air and fuel-air-inert mixturesDuration: 05.10.2011 – 04.10.2013 Director of Project: Dr. Venera Giurcan Mentor of Project: Dr. Domnina Razus

2. Project Budget:

3. Project Summary: The main objective of research is the examination of deflagration propagation in gaseous fuel-air and fuel-air-inert mixtures with the scope to map the flammability range of fuel in air in the presence of various inert additives. The project will be realized by an experimental and a computational study of fuel-air explosions in the vicinity of flammability limits, in confined conditions. Ethylene and ethane are chosen as representative fuel. The objectives of the project are: (1) the experimental determination of explosion limits of ethylene-air and ethylene-air-inert mixtures, at ambient initial conditions. Nitrogen, argon or carbon dioxide will be used as inert gases. (2) calculation of LOC (limiting oxygen concentration) for ethylene-air-inert mixtures using an original method based on the correlation between adiabatic flame temperature at LOC and adiabatic flame temperature at the lower explosion limit; (3) development of a new method to predict LOC based on examination of normal burning velocities of fuel-oxidizer limit-mixtures and of fuel-oxidizer-inert mixtures at the apex of the flammability range. The new method uses the concept of threshold value of the normal burning velocities for gaseous systems at the lower explosion limit and at the apex of the flammability range. The flammability limits are essential safety parameters in industry or domestic fields. Inerting a fuel-air mixture is also a method to limit the pollutant emissions generated by the combustion process.

4. Project Objectives 1. The experimental determination of lower explosion limit (LEL) of fuel-air and fuel-air-inert mixtures, at ambient initial pressure and temperature. Important parameters will be derived from the LEL of fuel-air-inert mixtures: limiting oxigen concentration (LOC) and (minimum intert concentration (MIC). Several inert additives will be used: nitrogen, argon, carbon dioxide. 2. The calculation of adiabatic flame temperature (AFT) of fuel-air mixtures and fuel-air-inert mixtures at ambient pressure and temperature, using available computing packages, in order to realize the mapping of the flammability zone by means of flame temperatures. Besides AFT calculated assuming the thermodynamic equilibrium, the maximum temperatures from flame front calculated by the kinetic modelling of flames accompanied by energy losses (non-adiabatic propagation) will be examined. 3. The calculation of LOC of fuel-air-inert mixtures at ambient pressure and temperature using the recently developed original method based on AFT computation in limit mixtures. 4. The examination and the possible extension of the validity of the linear correlation between the adiabatic flame temperature of mixtures at apex of the flammability range (AFTLOC) and the adiabatic flame temperature of mixtures at lower explosion limit (AFTLEL) for different inert gases (nitrogen, argon, carbon dioxide) using the new measured data (determined at objective 1) or literature data from our scientific partners and from literature. 5. The examination of the normal burning velocities of premixed laminar flames of gaseous fuel-oxidizer mixtures in order to develop new correlations valid for fuel-oxidizer mixtures at LEL and fuel-oxidizer-inert mixtures at the apex of the flammability range.

5. Experimental set up

6. Dissemination of project results • Papers in ISI Journals: • 1. V.Giurcan, D.Razus, M.Mitu, V.Schröder, Limiting oxygen concentration and minimum inert concentration of fuel-air-inert gaseous mixtures evaluation by means of adiabatic flame temperatures and measured fuel-air lower flammability limits,accepted atRev. Chimie, 2013. • V.Giurcan, D.Razus. M.Mitu, D.Oancea, Numerical study of the laminar flame propagation in ethane-air mixtures, submitted to Central Eur. J. Chemistry, 2013. • B. Papers in Proceedings: • V.Giurcan, D.Razus, M.Mitu, C.Movileanu, D.Oancea, Experimental and numerical investigation of laminar burning velocitiy of fuel/air/inert gaseous mixtures of variable initial temperature and pressure, Proceedings of the 6th European Combustion Meeting 2013, 6 pagini, Lucrarea 1-74.

7. Dissemination of project results C. Conferences 1. V.Giurcan, D.Razus, M.Mitu, C.Movileanu, D.Oancea, Experimental and numerical investigation of laminar burning velocity of ethane/air gaseous mixtures of variable initial composition, temperature and pressure, 34th Intern. Symposium on Combustion, Warsaw, Poland, Aug. 2012. 2. V.Giurcan, D.Razus, M.Mitu, Limiting oxygen concentration and minimum inert concentration of fuel/air/inert gaseous mixtures evaluation by means of adiabatic flame temperatures and measured fuel/air lower flammability limits, 34th Intern. Symposium on Combustion, Warsaw, Poland, Aug. 2012. 3. V.Giurcan, D.Razus, M.Mitu, C.Movileanu, D.Oancea, Experimental and numerical investigation of laminar burning velocitiy of fuel/air/inert gaseous mixtures of variable initial temperature and pressure,6th European Combustion Meeting, Lund, Sweden, June 2013. 4. V.Giurcan, D.Razus, M.Mitu, D.Oancea, Flame propagation in near-limit fuel-air-inert gaseous mixtures, 15th Intern. Conf. on Physical Chemistry ROMPHYSCHEM-15, Bucharest, Romania, Sept. 2013. 5. V.Giurcan, M.Mitu, D.Razus, C.Movileanu, D.Oancea,Inert gas influence on propagation parameters of propane-air mixtures, 15th Intern. Conf. on Physical Chemistry ROMPHYSCHEM-15, Bucharest, Romania, Sept. 2013. 6. V.Giurcan, D.Razus, M.Mitu, D.Oancea, Correlations of Laminar Burning Velocities for C2 Hydrocarbon/Air Gaseous Mixtures, 8th Mediterranean Combustion Symposium, Cesme –Izmir, Turkey, Sept. 2013.

8. Training of the Project Director 1. “2012 Princeton Combustion Summer School”, Princeton University, NJ, USA, June 2012. 2. “2013 Tsinghua-Princeton Summer School on Combustion”, Tsinghua University, Center for Combustion Energy, Beijing, China, July 2013. 3.“The Combustion Institute Summer School 2013”, Lund University, Lund Sweden, Aug. 2013.