A three-dimensional two-fluid code NEPTUNE_CFD has been validated against the ASU (Arizona State University) [1] and DEBORA [2, 3] boiling flow experiments. Nucleate boiling processes in the subcooled flow boiling regime have been studied on ASU experiments. Within this scope a new wall function is implemented in the NEPTUNE_CFD V1.0.6 code to improve the prediction of flow parameters in the bo...

At the impact of a liquid droplet on a smooth surface heated above the liquid's boiling point, the droplet either immediately boils when it contacts the surface ("contact boiling"), or without any surface contact forms a Leidenfrost vapor layer towards the hot surface and bounces back ("gentle film boiling"), or both forms the Leidenfrost layer and ejects tiny droplets upward ("spraying film bo...

Boiling crisis experiments are carried out in the vicinity of the liquid-gas critical point of H2. A magnetic gravity compensation setup is used to enable nucleate boiling at near critical pressure. The measurements of the critical heat flux that defines the threshold for the boiling crisis are carried out as a function of the distance from the critical point. The obtained power law behavior an...

A newly simplified microstructure model of metal foams was carried out for flow boiling heat transfer in metal-foam filled tube. Fin analysis, heat transfer network and superposition correlation were adopted to obtain the equivalent heat transfer coefficient for flow boiling. Based on annular pattern, fluid can be divided into vapor region in the center of the tube and liquid region near the wa...

An easy-to-implement technique for pool boiling heat transfer enhancement is proposed and evaluated through an experimental investigation. This free-particle technique brings about nucleate boiling at a low degree of superheat by means of metal particles that are not fixed to the heated surface, but rather are free to move with respect to the surface. The effects of copper particles with sizes ...

Nanofluids are engineered colloidal suspensions of nanoparticles in water, and exhibit a very significant enhancement (up to 200%) of the boiling Critical Heat Flux (CHF) at modest nanoparticle concentrations (50.1% by volume). Since CHF is the upper limit of nucleate boiling, such enhancement offers the potential for major performance improvement in many practical applications that use nucleat...

Heat transfer with liquid–vapor phase change in microchannels can support very high heat fluxes for use in applications such as the thermal management of high-performance electronics. However, the effects of channel cross-sectional dimensions on the two-phase heat transfer coefficient and pressure drop have not been investigated extensively. In the present work, experiments are conducted to inv...

The nucleate boiling process is known to be a very efficient mode of heat transfer. It is desirable to operate many engineering applications in this mode since high heat transfer rates and convection coefficients are associated with small values of the excess temperature. Despite its importance, nucleate boiling has not been fully numerically simulated until very recently because of the complex...

Boiling heat transfer rates impact the performance of various processes like quenching, steam generation, desalination, and boiling water reactors. The film boiling regime of the boiling curve has very low heat transfer rates around the Leidenfrost point which corresponds to the formation of a stable and continuous vapor layer at the solid-liquid interface (Leidenfrost effect). This insulating ...

Changes in the physicochemical properties and structure of proteins derived from two malt varieties (Baudin and Guangmai) during wort boiling were investigated by differential scanning calorimetry, SDS-PAGE, two-dimensional electrophoresis, gel filtration chromatography and circular dichroism spectroscopy. The results showed that both protein content and amino acid composition changed only slig...