High speed synchrotron X-ray imaging studies of the ultrasound shockwave and enhanced flow during metal solidification processes

The highly dynamic behaviour of ultrasonic bubble implosion in liquid metal, the multiphase liquid metal flow containing bubbles and particles, and the interaction between ultrasonic waves and semisolid phases during solidification of metal were studied in situ using the complementary ultrafast and high speed synchrotron X-ray imaging facilities housed respectively at the Advanced Photon Source, Argonne National Laboratory, US, and Diamond Light Source, UK. Real-time ultrafast X-ray imaging of 135,780 frames per second (fps) revealed that ultrasonic bubble implosion in a liquid Bi-8 wt. %Zn alloy can occur in a single wave period (30 kHz), and the effective region affected by the shockwave at implosion was 3.5 times the original bubble diameter. Furthermore, ultrasound bubbles in liquid metal move faster than the primary particles, and the velocity of bubbles is 70 ~ 100% higher than that of the primary particles present in the same locations close to the sonotrode. Ultrasound waves can very effectively create a strong swirling flow in a semisolid melt in less than one second. The energetic flow can detach solid particles from the liquid-solid interface and redistribute them back into the bulk liquid very effectively

Phase Change Materials in Energy: Current State of Research and Potential Applications

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. Recent research on phase change materials promising to reduce energy losses in industrial and domestic heating/air-conditioning systems is reviewed. In particular, the challenges q fphase change material applications such as an encapsulation strategy for active ingredients, the stability of the obtained phase change materials, and emerging corrosion complications are discussed. Moreover, phase change materials could be employed in refrigerators to increase the efficiency and in storage facilities to reduce evaporative losses of fuels and industrial liquid products. Promising areas for using these materials are highlighted. Ways of solving possible problems are outlined