New critical heat flux (CHF) and boiling heat transfer data were obtained in the subcooled and low quality regions using refrigerant 113. These data were obtained in a 0.61 cm round tube containing a twisted tape having a twist ratio of 6.25. The new CHF data, plus water data from the literature, were compared to a modified version of the CHF predictive model based on bubble crowding and coalescence in the bubbly layer [Weisman and Pei, Int. J. Heat Mass Transfer 26, 1463-1478 (1983), Weisman and Illeslamlou, Fusion Tech. 13,654-659 (1988)]. Reasonably good predictions were obtained within the range of the model. It was also 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 swirling flow.