Investigations on mixture preparation for two phase adiabatic pressure drop of R134a flowing in 5 mm diameter channel

The article presents detailed two-phase adiabatic pressure drops data for refrigerant R134a. Study cases have been set for a mass flux varying from 200 to 400 kg/m2s, at the saturation temperature of 19.4°C. Obtained experimental data was compared with the available correlations from the literature for the frictional pressure drop during adiabatic flow. Influence of mixture preparation on pressure drop was investigated, for varying inlet subcooling temperature in the heated section. The flow patterns have also been obtained by means of a high-speed camera placed in the visualization section and compared with literature observations

Novel approach for modeling the dynamics of fiber breakage in polymer matrix composites during capillary extrusion

In this work, a population balance equation (PBE) model is used to predict the evolution of the fiber breakage inthermoplastic polymer/short-fiber composites during capillary extrusion. The least squares spectral method was used to solve theresulting integrodifferential equation. The differences found between the experimental and simulated data were attributed to theselected breakage and redistribution functions. An experimental setup is proposed to find accurate breakage functions for thisproblem. The results indicate that the application of the PBE for such a breakage process could be a powerful tool for the design ofinjection molding molds.Fil: Sporleder, F.. Norwegian University Of Science And Technology; NoruegaFil: Carella, Jose Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Dorao, C. A.. Norwegian University of Science and Technology; NoruegaFil: Ludueña, Leandro Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentin

Can Wicking Control Droplet Cooling?

Wicking, defined as absorption and passive spreading of liquid into a porous medium, has been identified as a key mechanism to enhance the heat transfer and prevent the thermal crisis. Reducing the evaporation time and increasing the Leidenfrost point (LFP) are important for an efficient and safe design of thermal management applications, such as electronics, nuclear, and aeronautics industry. Here, we report the effect of the wicking of superhydrophilic nanowires (NWs) on the droplet vaporization from low temperatures to temperatures above the Leidenfrost transition. By tuning the wicking capability of the surface, we show that the most wickable NW results in the fastest evaporation time (reduction of 82, 76, and 68% compared with a bare surface at, respectively, 51, 69, and 92 °C) and in one of the highest shifts of the LFP of a water droplet (5 μL) in the literature (about 260 °C)