ABSTRACT
We demonstrate a framework of interpreting data from x-ray photon correlation spectroscopy experiments with the aid of numerical simulations to describe nanoscale dynamics in soft matter. This is exemplified with the transport of passive tracer gold nanoparticles in networks of charge-stabilized cellulose nanofibers. The main structure of dynamic modes in reciprocal space could be replicated with a simulated system of confined Brownian motion, a digital twin, allowing for a direct measurement of important effective material properties describing the local environment of the tracers.
ABSTRACT
Boiling is an efficient heat-transfer mechanism because of the utilization of latent heat of vaporization and has the potential to be used for cooling high-power electronic devices. Surface enhancement is one of the widely used techniques for heat-transfer augmentation in boiling systems. Here, an experimental investigation was conducted on chemical vapor deposition-grown three-dimensional (3D) foamlike graphene-coated silicon surfaces to investigate the effect of pore structures on pool boiling heat transfer and corresponding heat-transfer enhancement mechanisms. 3D graphene-coated samples with four graphene thicknesses were utilized along with a plain surface to investigate boiling heat-transfer characteristics and enhancement mechanisms. A high-speed camera was used to provide a deeper understanding of the bubble dynamics upon departure of emerging bubbles and visualize vapor columns in different boiling regimes. On the basis of the obtained results, in addition to interfacial evaporation, mechanical resonance of the 3D structure had also a considerable effect on vapor column formation. The results indicated that there is an optimum thickness, which exhibits the best performance in terms of boiling heat transfer.
ABSTRACT
Due to its high heat removal capability and exploitation of latent heat, boiling is considered to be one of the most effective cooling methods in industry. Surface structure and wettability are two factors imposing boiling phenomena. Here, we propose an effective and facile method for surface enhancement via crenarchaeon Sulfolobus Solfataricus P2 bio-coatings. The positive effects of such surfaces of bio-coatings were assessed, and enhancements in heat transfer and cooling were obtained. Visualization was also performed, and bubble dynamics of generated bubbles and vapor columns from the tested surfaces with bio-coatings are here presented. Superior performance in terms of boiling heat transfer and cooling was reached with the use of crenarchaeon Sulfolobus Solfataricus P2 coated surfaces. Thus, this study clearly demonstrates the potential of futuristic surfaces with bio-coatings to achieve substantial energy saving and efficiency.
ABSTRACT
Energy harvesting from thermal energy has been widely exploited to achieve energy savings and clean technologies. In this research, a new cost-effective and environment-friendly solution is proposed for the growing individual energy needs thanks to the energy application of cavitating flows. With the aid of cavitating jet flows from microchannel configurations of different sizes, it is shown that significant temperature rise (as high as 5.7 °C) can be obtained on the surface of the thin plate. The obtained heat energy could be integrated to a thermoelectric power generator, which can be used as a power resource for consumer devices, such as cell phones and laptops. To explore the difference in the temperature rise with different microtube diameters, namely, 152, 256, 504, and 762 µm, and also with different upstream pressures of 10, 20, 40, and 60 bar, the cavitation flow patterns are captured and analyzed using an advanced high-speed visualization system. The analysis of the captured data showed that different flow patterns exist for different diameters of the microtubes, including a pattern shift from micro- to macroscale, which accompanied the pattern of temporal results very well.
