Effect of the distance between the micro/nanostructures on pool boiling heat transfer with water on a copper heater

Copper heaters were made. On the surface of these heaters the arrays of micrococoons were synthesized from silicon oxide (SiOx) nanowires with different concentrations of micro/nanostructures and hence different average distances between them. Boiling curves were obtained for these samples and it was found that heat transfer enhancement during boiling occurs on them in comparison with a smooth copper surface. It was shown that the effect increases with decreasing concentration of micro/nanostructures and reaches a maximum for microrelief with an approximate concentration of microstructures equal to unity per square micron. It was found that surfaces with micrococoons are sufficiently stable and suitable for enhancing heat transfer during boiling.

Review: The flow and heat transfer investigation inside tapered and straight two pass channels with rib turbulators

This paper is a review of the number of experimental and CFD experiments performed with rib turbulators about the heat transfer and the at two pass channel. In respect to achieve higher thermal efficiency of gas turbines, efforts are made to raise the inlet temperature. The secondary fluxes resulting from the rib and U-shaped curvature play an important role enhancing heat transfer in the two pass ribbed channels. The ribs on the internal surface of cooling passage will increase the strength of heat transfer. This paper deals with the effect of tapered and straight two-pass channels with the influence of the variable rib cross-section on flow and heat transfer enhancement

ENHANCING HEAT TRANSFER COEFFICIENT AND BREAKDOWN STRENGTH OF MINERAL OIL BY (AL2O3 AND TIO2) NANOPARTICLES

The aims of this paper study the effects of two types of nanoparticle on dielectric strength and heat transfer coefficient within mineral oil used in an electrical transformer. These nanoparticles (NPs) including (semi conductive TiO2 and insulating Al2O3), have been prepared with the same size and surface modification, it is shown that nano-particles enhance insulating and thermal properties of mineral oil as well as the degree of enhancement is dependent on the NPs concentration.