eng Science and Education Publishing Chemical Engineering and Science 2328-7373 2013-07-15 1 1 55 61 10.12691/ces-1-4-2 CES2013142 article Hassan Al-Haj Ibrahim hasahi123@hotmail.com 1 M. Mourhaf Al-Qassimi 1 Department of Chemical Engineering, Al-Baath University, Homs, Syria Flame and effective gas temperatures are key variables that need to be accurately determined before analysis of heat transfer in the radiant section of fired heaters can be meaningfully undertaken. To facilitate the calculation of these temperatures, appropriate equations were derived using two Computer Matlab programmes specially written for the purpose. A third programme was also written for the solution of the derived equations using the Newton-Raphson method. The whole calculation procedure was illustrated by an example worked out for an actual process heater used in a crude oil topping unit. http://pubs.sciepub.com/ces/1/4/2/ces-1-4-2.pdf effective gas temperature flame temperature radiation section fired heater tubular heater