Journal of Energy and Power Engineering 7 (2013) 1852-1864 Syngas Fuel Combustion in Re-circulating Vortex Combustor Khaled Zbeeb and Chaouki Ghenai Ocean and Mechanical Engineering Department, College of Engineering and Computer Science, Florida Atlantic University, Boca Raton 33431, Florida, United States of America Received: September 29, 2012 / Accepted: January 07, 2013 / Published: October 31, 2013. Abstract: This paper presents results on the combustion of syngas fuel in re-circulating vortex combustor. The combustion stability is achieved through the use of cavities in which recirculation zones of hot products generated by the direct injection of fuel and air are created and acting as a continuous source of ignition for the incoming main fuel-air stream. CFD (computational fluid dynamics) analysis was performed in this study to test the combustion performance and emissions from the vortex trapped combustor using synthetic gas or syngas fuel produced from the gasification process. The flame temperature, the flow field and species concentrations inside the vortex trapped combustor were obtained. Several syngas fuels with different fuel compositions (H 2 , CO, CH 4 , CO 2 , N 2 and H 2 O) and lower heating values were tested in this study. The changes on the flame temperature and species concentrations inside the combustor, the emissions of NO x , CO, CO 2 at the exit of the combustor, the combustor efficiency and the total pressure drop for syngas fuels are presented in this paper. The effect of H 2 /CO ratio and the mass fraction of each constituent of syngas fuels and hydrogen-methane fuel mixtures on the combustion and emissions performances were investigated. Key words: Combustion, alternative fuels, trapped vortex combustor, CFD, mixture fraction/PDF combustion model. 1. Introduction Next generation turbine power plants will require high efficiency gas turbines with higher operating conditions (higher combustor pressures and firing temperatures). This increase in gas turbine operating conditions and firing temperature will tend to increase NO x emissions. As the desire for higher efficiency drives combustor pressures and turbine inlet temperatures ever higher, gas turbines equipped with lean premixed and non-premixed combustors and catalytic reduction eventually will be unable to meet the new NO x emission requirements. The development of new gas turbine combustors with lower emissions than the current state-of-the-art lean premixed and non-premixed combustors is needed. The TVC (trapped vortex combustor) is a novel combustor Corresponding author: Chaouki Ghenai, assistant professor, research fields: combustion, renewable energy and alternative fuels. E-mail: cghenai@fau.edu. geometry which offers stable performance over a wider range of fuel flow rates than current technology. The trapped vortex combustor maintains a vortex of burning fuel and air in a chamber adjacent to the main burner ports. The hot vortex acts as a pilot to the main flame burner. This enables the combustor to operate at leaner premixed fuel with improved stability and lower NO x . Fig. 1 shows a two dimensional TVC combustor with air and fuel flows, the primary and secondary vortex and the wake region [1]. The cavity is obtained by mounting two disks, or bluff bodies, with different size, in tandem. The bigger disk is located upstream of the smaller one and the flow coming from around the first creates a vortex in the cavity between the two. Fuel and primary air are introduced into the cavity generating the pilot flame (Fig. 1). In fact, the aim of the system is to supply a stable and continuous source of ignition for the main stream. If the disks and hence D DAVID PUBLISHING