FH-2 Considerations of Flow Patterns in Fired Heater Tubes

K. J. Farrell

This study addresses the accuracy of adiabatic HTRI flow regime maps for diabatic flows in large diameter fired heater tubes. In the absence of relevant experimental data, HTRI investigated the diameter and heat flux dependence of two recent mechanistic models and compared the results to HTRI flow regime maps for horizontal and vertical upflows.

The results plotted on a map of the HTRI flow regime parameter versus the homogeneous liquid volume fraction showed favorable comparison for horizontal flows in both 0.051-m and 0.254-m diameter tubes. For vertical upflows, the Fair map was deficient in both tube sizes. The inclusion of heat flux in the flow regime map substantially alters the stratified wavy-toannular transition boundary for horizontal flows. Experimental data from large diameter pipes are required to validate necessary improvements in the HTRI flow regime maps so that our software can include a unified mechanistic flow regime model, independent of inclination angle.