Flow boiling of R410A and CO2 from low to medium reduced pressures in macro channels: Experiments and assessment of prediction methods

Flow boiling heat transfer in minichannels at high saturation temperatures: Part I – Experimental investigation and analysis of the heat transfer mechanisms

“…With R-245fa, they noted that the heat transfer coefficient increased with saturation temperature for a larger vapor quality range. Other studies reported the same trends on the impact of saturation temperature: [1,45,34,4,2,20,8].…”

Peripheral Heat Transfer Coefficient during Flow Boiling: Comparison between 2-D and 1-D Data Reduction and Discussion about Their Applicability

“…For low vapor qualities (zone 1), a slug flow likely occurred, with intermittent passages of vapor in the channel and a different liquid film thickness at the top and bottom walls due to the gravity force. A higher liquid film thickness at the bottom side of the tube involved a higher thermal resistance and therefore a lower heat transfer coefficient, as also shown in the experiments of Grauso et al [35]. For intermediate vapor qualities (zone 2), there were no significant differences in the local heat transfer coefficients, meaning that the flow pattern occurring was likely an annular flow, with the heated wall surrounded by an almost uniform liquid film thickness that eventually became thinner at the top side, leading to slight asymmetries in the heat transfer coefficient at vapor qualities around 0.8.…”

Flow boiling heat transfer in minichannels at high saturation temperatures: Part II – Assessment of predictive methods and impact of flow regimes

“…This correlation is developed for carbon dioxide which explains this discrepancy. Indeed, the heat transfer coefficient for carbon dioxide is higher than that for halogenated refrigerants for a given saturation temperature (as observed by [25]). These correlations fail to achieve any vapor quality effect and fail to reproduce the experimental trend (i.e.…”