Nucleate boiling performance on nano/microstructures with different wetting surfaces

A study of nucleate boiling phenomena on nano/microstructures is a very basic and useful study with a view to the potential application of modified surfaces as heating surfaces in a number of fields. We present a detailed study of boiling experiments on fabricated nano/microstructured surfaces used as heating surfaces under atmospheric conditions, employing identical nanostructures with two different wettabilities (silicon-oxidized and Teflon-coated). Consequently, enhancements of both boiling heat transfer (BHT) and critical heat flux (CHF) are demonstrated in the nano/microstructures, independent of their wettability. However, the increment of BHT and CHF on each of the different wetting surfaces depended on the wetting characteristics of heating surfaces. The effect of water penetration in the surface structures by capillary phenomena is suggested as a plausible mechanism for the enhanced CHF on the nano/microstructures regardless of the wettability of the surfaces in atmospheric condition. This is supported by comparing bubble shapes generated in actual boiling experiments and dynamic contact angles under atmospheric conditions on Teflon-coated nano/microstructured surfaces. © 2012 Jo et al.X114146Nsciescopu

Critical heat flux and nucleate boiling on several heterogeneous wetting surfaces: Controlled hydrophobic patterns on a hydrophilic substrate

We used a heating surface composed of a hydrophilic substrate with hydrophobic dots to characterize the effect of spatially-different surface characteristics on critical heat flux (CHF) and nucleate boiling. To ascertain important surface factors that control CHF and boiling on heterogeneous wetting surfaces, we adjusted the hydrophobic dot diameter and the relative pitch between adjacent dots. Based on the dynamics of bubbles on hydrophobic dots, we analyze the trend of CHF on differently-fabricated heterogeneous wetting surfaces. CHFs on heterogeneous wetting surfaces were strongly dependent on ratio R of the area covered by hydrophobic dots to the heated area, but independent on the diameter of hydrophobic dots and the pitch distance. The improvement of boiling heat transfer (BHT) varied according to the conditions, and appeared to be related to the diameter, pitch distance and the number of hydrophobic dots, but the effect of R on BHT was negligible. Based on this study, we propose optimized conditions of a hydrophobic patterned surface. To sustain high CHF of a hydrophilic surface and high BHT of a hydrophobic surface, numerous micron-size hydrophobic dots should be fabricated with small R. (C) 2014 Elsevier Ltd. All rights reserved.X113224Nsciescopu

Development of Fishcake Gripping and Classification Automation Process Based on Suction Shape Transformation Gripper

The surge in demand for automating seafood processing necessitates the development of robotic processes for transportation, packaging, and classification. South Korean companies are actively constructing diverse robots and grippers for fishcake handling, yet small workshops face spatial constraints. To address this, the study focuses on creating a gripper capable of versatile fishcake handling within compact spaces. The gripper, designed for single-robot use, employs three suction cups, adapting its grip based on fishcake shapes. Small fishcakes are gripped at the center with one suction cup, elongated ones with two cups aligned to the slope, and wider ones with three cups. A testbed with the gripper attached to a robot facilitates fishcake gripping, classification, and automation testing. Fishcake recognition and gripping tests revealed challenges based on shape, width, and material. Despite difficulties, a commendable 100% success rate was achieved for the majority of fishcakes, showcasing the gripper’s effectiveness. Identified improvements include reducing the suction cup diameter and increasing pressure for enhanced gripping and classification in confined spaces. The study demonstrates the successful development of a gripper for versatile fishcake handling, particularly beneficial for small workshops. The identified improvements offer pathways to enhance efficiency in fishcake gripping and classification within limited spaces