nano materials have been widely used in laboratory and industrial scales in order to improve various properties of concrete and concrete mixture. the mainstream practice of the researches in this field is to add metallic nano-particles into the concrete mixture. the present research focuses on adding micro-nano air bubbles (mnab) into water before mixing it with aggregate and cement mixtures. i...

The miniaturization boiling (micro-bubble emission boiling [MEB]) phenomenon, with a high heat removal capacity that contributes considerably to the cooling of the divertor of the nuclear fusion reactor, was discovered in the early 1980s. Extensive research on MEB has been performed since its discovery. However, the progress of the application has been delayed because the generation mechanism o...

In this research, the effect of micro turbulence on the flotation rate of quartz particles was investigated. The maximum particle Reynolds number (Rep) was obtained at 60.25 with a particle size of -500+420 µm, impeller speed of 900 rpm, bubble surface area flux of 10.21 1/s and micro scale turbulence size of 162 µm. When the micro turbulence size was equal to the particle size, ...

The standard treatment of altitude decompression sickness (aDCS) caused by nitrogen bubble formation is oxygen breathing and recompression. However, micro air bubbles (containing 79% nitrogen), injected into adipose tissue, grow and stabilize at 25 kPa regardless of continued oxygen breathing and the tissue nitrogen pressure. To quantify the contribution of oxygen to bubble growth at altitude, ...

computational scheme is used to study the bubble trajectories. The 2D averaged Navier stokes equations are solved. The SIMPLEC algorithm is used to relate the pressure to velocity. A one-way coupling is assumed and the effects of the bubbles on carrier flow are neglected. The bubble equation of motion includes the drag, buoyancy, pressure gradient, Saffman lift and bubble volume change forces. ...

Abstract: To improve the stability and reliability of the piezoelectric micro-pump, the cause of air block phenomenon is analyzed on the structure of wheel check valve. During the movement of the bubble in the micro-channel, pressure drop occurs, the main factor which influences the bubble going through is opening height of the wheel check valve. Five groups of wheel check valves with different...

Experiments were performed to measure the incipient boiling heat flux in a heat sink containing 21 rectangular (231 lm wide and 713 lm deep) micro-channels. Tests were performed using deionized water with inlet liquid velocities of 0.13–1.44 m/s, inlet temperatures of 30, 60 and 90 C, and an outlet pressure of 1.2 bar. Using a microscope, boiling incipience was identified when the first bubbles...

The micro capillary pumped loop system (MCPL) is a highly efficient device for heat transfer because the main driving force is a result of thermo-bubbles in micro-channel. In this study, the scaling effect with respect to the dimensional geometry of MCPL was studied for improving the heat transfer performance. The results showed that when a larger heating power was provided by microheater, the ...

Numerical and experimental results show that during the collapse phase of a vapor bubble near a rigid boundary, in the absence of strong buoyancy forces, a liquid micro jet is developed on the side of the bubble far from the rigid surface and directed towards it. Numerical and experimental results also show that, in the case of a bubble near a free surface, during the collapse phase of the bubb...