ICHMT DIGITAL LIBRARY ONLINE
ISSN |
ARTICLE:
Aziz Ungut Andy D. Johnson Lee Phillips Arij I. van Berket ABSTRACT CFD simulation of radiative heat transfer from an under-expanded syngas (10 % CO, 90 % H2) jet fire is reported. The jet emerges from a 2 mm diameter nozzle with a mass flow rate of 13.7 g/s. Turbulent transport equations are solved using the CFX-F3D solver and, the k-ε turbulence model. The combustion process is modelled using the premixed laminar flamelet approach proposed by Leeds university. Radiation heat transfer is estimated using the CFX-RADIATION solver that simulates volume heating, and cooling from the calculated flow grid using a Monte Carlo method. A lookup table is created to estimate the local effective absorption coefficients in a four-dimensional data matrix of local temperature, CO2 and H2O mass fractions, and path length using a narrow band spectral radiation method. A method is proposed to estimate the local CO2 and H2O mass fractions from the flamelet library by assuming that the presence of these molecules outside the flammable region contribute very little to the radiation emissions because of lower local temperatures. Calculated flame size and shape are in reasonable agreement with the experimentally determined values, but the CFD simulation overestimates the lift off height by a factor of two. Calculated total radiation flux from the jet fire show good agreement with the experiments establishing CFD simulation as a useful tool to assess radiation scenarios. We plan to extend the CFD simulation to large scale syngas jet fire release scenarios to estimate the impingement and radiation hazards associated with real situations. |
||||||
download article