The effect of structured roughness on the heat transfer of water flowing through minichannels was experimentally investigated in this study. The test channels were formed by two 12.7 mm wide 94.6 mm long stainless steel strips. Eight structured roughness elements were generated using a wire electrical discharge machining (EDM) process as lateral grooves of sinusoidal profile on the channel wall...

An experimental and theoretical energy and exergy analysis was conducted for a cylindrical cavity receiver employed in a parabolic dish collector. Based on simultaneous energy and exergy analysis, the receiver average wall temperature and overall heat transfer coefficient were determined. A simplified Nusselt number for Heat Transfer Fluid (HTF) through the receiver as a function of Reynolds an...

The liquid motion induced by surface tension variation, termed the thermocapillary or Marangoni effect, and its contribution to boiling heat transfer has long been a very controversial issue. In the past this convection was not the subject of much attention because, under terrestrial conditions, it is superimposed by the strong buoyancy convection, which makes it difficult to obtain quantitativ...

Convective heat transfer of MgO-water nanofluid in a microchannel heat sink is experimentally investigated in various concentrations of 0.01, 0.05, 0.1, and 0.6 wt%. The microchannel consisted of 48 parallel rectangular cross section channels with the height of 800 µm, width of 524 µm and length of 52 mm. A well stability duration (ca. 1 month) was resulted by a 180 min ultra-sonication of the ...

in this article cuo/water nanofluid was synthesized by using polyvinylpyrolidone (pvp) as the dispersant.  thenanofluid stability period and the heat transfer enhancement were determinedby measuring the thermal conductivities. to study the nano-fluid stability, zeta (ζ) potential, and absorbency were measured under different ph values and pvp surfactant concentrations; also thermal conductivity...

In this paper, we present our recent experimental results on buoyancy-induced convection in aluminum metal foams of different pore densities [corresponding to 5, 10, 20, and 40 pores per in. (PPI)] and porosities (0.89–0.96). The results show that compared to a heated surface, the heat transfer coefficients in these heat sinks are five to six times higher. However, when compared to commercially...

magnetohydrodynamic (mhd) mixed convection flow of cu–water nanofluid inside a two-sided lid-driven square enclosure with adiabatic horizontal walls and differentially heated sidewalls has been investigated numerically. the effects of moving lids direction, variations of richardson number, hartmann number, and volume fraction of nanoparticles on flow and temperature fields have been studied. th...

Boiling is considered an important mode of heat transfer (HT) enhancement and has several industrial cooling applications. the potential to minimize energy losses from HT devices, compared with other convection or conduction modes enhancement. The purpose this review article was analyze, discuss, compare existing research on boiling techniques last few decades. We sought understand effect nucle...