Pool boiling heat transfer has been extensively studied over decades, but the effect of boundary heating conditions on boiling received little attention. In this work, heat transfer coefficients during pool boiling of five different refrigerants (R123, R245fa, R236fa, R134a, and R22) on the outside surface of a smooth copper tube were measured at the saturation temperature of 6.7 C; water flows...

Flow boiling in microchannels and minichannels is being investigated for its potential for high heat flux removal in electronics and other devices. The small channel dimensions characteristic of these channels result, under most circumstances, in laminar flow at the flow rates used in these applications. The present work investigates the applicability of the correlation developed by Kandlikar a...

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...

Steady state pool boiling heat transfer coefficients have been obtained experimentally for acetone–isopropanol–water and acetone–MEK (methyl ethyl ketone)–water ternary systems. The data show that, for a given heat flux, the heat transfer coefficients of mixtures are lower than those obtained for pure components constituting the mixture. The measured heat transfer coefficients were compared wit...

The present paper is an experimental investigation of roughness effects on nucleate pool boiling of refrigerant R113 on horizontal circular copper surfaces. The copper samples were treated by different sand paper grit sizes to achieve different surface roughness. The average surface roughness of the four samples was 0.901, 0.735, 0.65, and 0.09, respectively. The experiments were performed in t...

Flow boiling in microchannels has received considerable attention from researchers worldwide in the last decade. A scaling analysis is presented to identify the relative effects of different forces on the boiling process at microscale. Based on this scaling analysis, the flow pattern transitions and stability for flow boiling of water and FC-77 are evaluated. From the insight gained through the...

Experiments are conducted with a perfluorinated dielectric fluid, Fluorinert FC-77, to investigate the effects of channel width, depth, and aspect ratio on flow boiling heat transfer and flow patterns in microchannels. Experiments are performed for a fixed mass flux of 630 kg/ms with eleven different silicon test pieces containing parallel microchannels of widths ranging from 100 μm to 5850 μm ...

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 ...

In this paper, we present an experimental investigation of pool boiling heat transfer on multiscale (micro/ nano) functionalized metallic surfaces. Heat transfer enhancement in metallic surfaces is very important for large scale high heat flux applications like in the nuclear power industry. The multiscale structures were fabricated via a femtosecond laser surface process (FLSP) technique, whic...