Huo et al. [4] studied experimentally boiling heat transfer of R-
134a fluid flowing in small vertical tubes of 2.01 and 4.26 mm
internal diameter. In the range of low vapour quality, the heat
transfer coefficient in both tubes increased with increasing heat
flux and saturated pressure but was independent of vapour quality.
These results were attributed to nucleate boiling being the dominant
heat transfer mode. Over other ranges of vapour quality, however,
the dominant heat transfer mode was not addressed as a