Fig. 12. Comparison between the calculated and experimental vapour quality at the onset of the dryout for the correlation of Mori et al.  and of Padovan et al. . HF Z-IETD-FMK expressed in (kW m−2).Figure optionsDownload full-size imageDownload as PowerPoint slide
The heat transfer coefficients have been compared against the values estimated by a correlation recently proposed by the present authors . Fig. 13 reports the comparison among experimental and empirical values for R1234yf and R134a. R134a data are taken from Mancin et al. . This correlation is subatomic particles an updated version of the original model by Cavallini et al. , then modified by Padovan et al. . The model is valid for D = 3.4 mm, for vapour qualities prior to the onset of the dryout, and for mass velocity from 150 to 940 kg m−2 s−1. The correlation well predicts the experimental values, with mean, absolute, and standard deviations of 1.7%, 4.9%, and 6.0%, respectively, for R1234yf, and of 3.3%, 7.5%, and 8.5%, respectively, for R134a.