High-pressure homogenizers are frequently employed for the homogenization of low-viscosity emulsions containing a proportion of disperse phase which is not too high. High-pressure homogenizers essentially consist of a high-pressure pump and a homogenizing nozzle. The design of the homogenizing nozzle influences the flow of the emulsion in the nozzle itself and hence the results of droplet disruption. It is shown which mechanism in frequently used homogenizing nozzles is usually responsible for disruption. Experimental results reveal the effects of the dispersed phase content and the viscosity of the disperse and continuous phases in different nozzles. The results can be explained on the basis of the mechanisms of disruption. Finally, the homogenizing nozzles presented are directly compared with one another.

No abstract

In this study, the thermal conductivity and viscosity of TiO 2 nanoparticles in deionized water were investigated up to a volume fraction of 3 % of particles. The nanofluid was prepared by dispersing TiO 2 nanoparticles in deionized water by using ultrasonic equipment. The mean diameter of TiO 2 nanoparticles was 21 nm. While the thermal conductivity of nanofluids has been measured in general using conventional techniques such as the transient hot-wire method, this work presents the application of the 3ω method for measuring the thermal conductivity. The 3ω method was validated by measuring the thermal conductivity of pure fluids (water, methanol, ethanol, and ethylene glycol), yielding accurate values within 2 %. Following this validation, the effective thermal conductivity of TiO 2 nanoparticles in deionized water was measured at temperatures of 13 • C, 23 • C, 40 • C, and 55 • C. The experimental results showed that the thermal conductivity increases with an increase of particle volume fraction, and the enhancement was observed to be 7.4 % over the base fluid for a nanofluid with 3 % volume fraction of TiO 2 nanoparticles at 13 • C. The increase in viscosity with the increase of particle volume fraction was much more than predicted by the Einstein model. From this research, it seems that the increase in the nanofluid viscosity is larger than the enhancement in the thermal conductivity.A. Turgut · I. Tavman (B)

No abstract

No abstract