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International Heat Transfer Conference 15

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

Study of the Combined Effects of Liquid Properties and Surface Micro-Patterning on Pool Boiling Heat Transfer

Emanuele Teodori
IN+ Center for Innovation, Technology and Policy Research, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisbon 1049-001, Portugal

Ana S. Moita
IN+ Center for Innovation, Technology and Policy Research, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisbon 1049-001, Portugal

Antonio L. N. Moreira
IN+ Center for Innovation, Technology and Policy Research, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisbon 1049-001, Portugal

DOI: 10.1615/IHTC15.pbl.009004
pages 6395-6408


KEY WORDS: Boiling and evaporation, Heat transfer enhancement, surface micro patterning, semi-empirical model

Abstract

The present paper addresses the quantification of the various terms of the pool boiling heat transfer over microstructured surfaces. The micro-structures are composed by regular patterns of quadrangular cavities, with fixed sizes, where only the distance between the center of the cavities, S is varied. The surfaces are made from silicon wafers. The wettability of the surfaces, quantified by the contact angles is not dramatically changed during the structuring process. The The present paper addresses the quantification of the various terms of the pool boiling heat transfer over microstructured surfaces. The micro-structures are composed by regular patterns of quadrangular cavities, with fixed sizes, where only the distance between the center of the cavities, S is varied. The surfaces are made from silicon wafers. The wettability of the surfaces, quantified by the contact angles is not dramatically changed during the structuring process. The The present paper addresses the quantification of the various terms of the pool boiling heat transfer over microstructured surfaces. The micro-structures are composed by regular patterns of quadrangular cavities, with fixed sizes, where only the distance between the center of the cavities, S is varied. The surfaces are made from silicon wafers. The wettability of the surfaces, quantified by the contact angles is not dramatically changed during the structuring process. The The present paper addresses the quantification of the various terms of the pool boiling heat transfer over microstructured surfaces. The micro-structures are composed by regular patterns of quadrangular cavities, with fixed sizes, where only the distance between the center of the cavities, S is varied. The surfaces are made from silicon wafers. The wettability of the surfaces, quantified by the contact angles is not dramatically changed during the structuring process. The The present paper addresses the quantification of the various terms of the pool boiling heat transfer over microstructured surfaces. The micro-structures are composed by regular patterns of quadrangular cavities, with fixed sizes, where only the distance between the center of the cavities, S is varied. The surfaces are made from silicon wafers. The wettability of the surfaces, quantified by the contact angles is not dramatically changed during the structuring process. The The present paper addresses the quantification of the various terms of the pool boiling heat transfer over microstructured surfaces. The micro-structures are composed by regular patterns of quadrangular cavities, with fixed sizes, where only the distance between the center of the cavities, S is varied. The surfaces are made from silicon wafers. The wettability of the surfaces, quantified by the contact angles is not dramatically changed during the structuring process. The The present paper addresses the quantification of the various terms of the pool boiling heat transfer over microstructured surfaces. The micro-structures are composed by regular patterns of quadrangular cavities, with fixed sizes, where only the distance between the center of the cavities, S is varied. The surfaces are made from silicon wafers. The wettability of the surfaces, quantified by the contact angles is not dramatically changed during the structuring process. The The present paper addresses the quantification of the various terms of the pool boiling heat transfer over microstructured surfaces. The micro-structures are composed by regular patterns of quadrangular cavities, with fixed sizes, where only the distance between the center of the cavities, S is varied. The surfaces are made from silicon wafers. The wettability of the surfaces, quantified by the contact angles is not dramatically changed during the structuring process. The independent data required for bubble nucleation and heat transfer characterization are collected coupling high speed camera visualization, PIV (Particle Image Velocimetry) and heat flux/surface temperature measurements. The results confirm the relative importance of the induced bulk convection, particularly in the boiling of liquids with smaller values of the latent heat of evaporation (e.g. refrigerants). In this context, a more detailed characterization of the flow and of the bubble dynamics is presented. Based on this characterization, an alternative approach is suggested to correlate the experimental data with a modified Rohsenow formulation, using a characteristic bubbles’ velocity to compute the Reynolds and the Stanton number, both associated to the bubble detachment and motion in bulk induced convection. Despite the devised relations still have an empirical nature, the work is in progress towards a more mechanistic and objective approach.

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