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Revisiting the Boiling Heat Transfer at Surfaces With Microgrooves Using Lattice Boltzmann Method
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DOI：10.1115/1.4069268.png)
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Abstract
En 中文
Experiments have demonstrated that the boiling heat transfer coefficient may be largely improved by engineering the heating surfaces using micro/nanostructures. While experiments are visually intuitive, the underlying mechanisms for this improvement remain unclear. In this paper, the boiling process on surfaces with various pillar-textured structures and wettability is studied using a two-dimensional lattice Boltzmann model. Our results demonstrate that wettability and surface structures significantly influence the bubble dynamics. The critical heat flux can be effectively increased through vortex generation structures such as pillar-groove structures, which disrupt the vapor film and then enhance the convective heat transfer. Our simulations also show that the width of grooves should exceed the characteristic length of the bubble radius, while not too large, can ensure a continuous bubble release and sufficient nucleation sites. Furthermore, a general relation based on the Arrhenius equation between the average heat flux (qave) and the standard deviation of the velocity field ( sigma ( u ) ) caused by vortexes, i.e., q ave = 6.8 x 10 - 4 exp ( - 3.9 x 10 - 3 / sigma ( u ) ) + 5.8 x 10 - 5 , is proposed. Results show that the convex corner of the pillar-groove structure can maximally enhance the strength of vortex convection within the fluid and maximumly increase the heat flux by 13.8%. Our work here provides a better understanding of bubble behaviors and boiling characteristics on surfaces with different wettability/pillar textures, which may facilitate the design of a strategy to improve the boiling heat transfer.
Keywords:
boiling heat transfer
lattice Boltzmann method
microgrooves
Journal
A
IF:
1.8
Papers:
103
Citations:
382
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