The vapour quality at the onset of the dryout
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.