A PHENOMENOLOGICAL MODEL FOR BOILING HEAT-TRANSFER AND THE CRITICAL HEAT-FLUX IN TUBES CONTAINING TWISTED TAPES

New critical heat flux (CHF) and boiling heat transfer data were obtai ned in the subcooled and low quality regions using refrigerant 113. Th ese data were obtained in a 0.61 cm round tube containing a twisted ta pe having a twist ratio of 6.25. The new CHF data, plus water data fro m the literature, were compared to a modified version of the CHF predi ctive model based on bubble crowding and coalescence in the bubbly lay er [Weisman and Pei, Int. J. Heat Mass Transfer 26, 1463-1478 (1983), Weisman and Illeslamlou, Fusion Tech. 13,654-659 (1988)]. Reasonably g ood predictions were obtained within the range of the model. It was al so found that the Yang and Weisman [Int. J. Multiphase Flow 17, 77-94 (1991)] extension of the CHF model to boiling heat transfer held for s wirling flow.