FC72 and FC87 nucleate boiling inside a narrow horizontal space

A predictive model for confined and unconfined nucleate boiling heat transfer coefficient

“…In the work of Cardoso et al [8], the test section consisted of a copper disc with a 12 mm diameter and 1 mm thickness, with three K thermocouples set in the disc. The copper disc is heated by an electrical resistance skin heater fixed by epoxy resin and is fixed to a piece of PVC.…”

“…In order to better understand the mechanisms responsible for boiling heat transfer in narrow spaces, Cardoso et al [8] performed an experimental nucleate boiling study on a horizontal upward facing heater and on a downward facing heater, by using FC 72 and FC 87 as working fluids and for different gap sizes. The results, according to this study revealed that, for the unconfined case and at low heat fluxes, the heat transfer is higher for a downward facing heating surface than for an upward facing heating surface.…”

“…This paper initially describes the correlations available in the open literature for prediction of pool boiling heat transfer. Subsequently, the database obtained by Cardoso and Passos [1], Cardoso et al [8] and Kiyomura et al [17] for the heat transfer coefficient during pool boiling of FC72, FC87, n-Pentane and DI-water under confined and unconfined conditions are described and compared with the predictive methods from the literature. Then, a new correlation for confined and unconfined nucleate boiling regime, taking into account the heating surface characteristics, the working fluid properties and the interaction between them, is proposed based on the HTC experimental database of these authors.…”

Confined and unconfined nucleate boiling of HFE7100 in the presence of nanostructured surfaces

“…Subscripts l liquid v vapor demonstrated in [28,32], for Bo < 1 there is a gap size effect and the bubbles tend to be coalesced and deformed, while for Bo > 1 the bubbles become isolated. The characteristic most commonly observed is that the HTC increases when the confinement increases, which means a decrease in the distance between the heating and the non-heating surfaces, for low and moderate heat fluxes [28][29][30][31][32]. However, with an increase in the heat flux, the vapor bubbles grow rapidly in the gap region and a large mass of vapor is formed which can reduce the cooling effect of the working fluid because the contact between the fresh liquid front and the heating surface is restricted, leading to a reduction in the heat transfer.…”

“…In these situations, after the formation and growth of vapor bubbles, bubble deformation can occurs and the time for which the vapor bubble remains in the limited space increases. When this occurs, the nucleate boiling process shows a different behavior in relation to the heat transfer (Ishibashi and Nishikawa [28], Katto et al [29], Passos et al [30], Cardoso and Passos [31] and Cardoso et al, [32]).…”