Comprehensive modeling of heat and mass transport in a micropillar evaporator

Download

index.pdf

Date

2022-4-05

Author

Yuncu, Göksel

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

688
views

294
downloads

Thin-film evaporation and the replenishing capillary liquid flow have paramount importance for various technological applications spanning from desalination to electronics cooling. With the developments enabling faster and cheaper yet more precise fabrication, evaporators with micropillar arrays have attracted substantial attention to sustain efficient evaporation fed by passive liquid transport. Although considerable effort has been devoted to designing optimized wicks, the full picture is still blurry due to complexities in modeling the liquid-vapor interface and the flow around the micropillars. Fundamentally, the heat transfer from a micropillar wick evaporator is a problem governed by various interfacial phenomena such as the capillarity-induced liquid flow, thin-film evaporation intensifying near the contact lines, and thermocapillarity-induced Marangoni flow. In this work, we develop a comprehensive model for the evaporation from a micropillar wick evaporator by coupling the liquid flow with the energy transfer in both liquid and solid domains at both cell- and device-levels. The model is successfully validated with previous experiments. When Marangoni number is sufficiently high, the model identifies a sharp reduction in the evaporator temperature attributed to the thermocapillary convection creating circulations beneath the liquid-vapor interface. This temperature drop cannot be identified when thermocapillarity is switched off in the model and the prediction of the model substantially deviates from the experimental measurement. Therefore, the current study reveals a hitherto unexplored role of Marangoni flow in the evaporation of water from micropillar wick evaporators. The proposal modeling framework can be a guide to engineers for the optimization of micro-post evaporators by accounting for all the relevant interfacial phenomena.

Subject Keywords

thin-film evaporation, capillary flow, Marangoni flow, micropillar wick, dryout heat flux

URI

https://hdl.handle.net/11511/96810

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Interplay of capillary and Marangoni flows in micropillar evaporation Yuncu, Goksel; Akkus, Yigit; Dursunkaya, Zafer (2023-2-01) The evaporation from a micropillar evaporator is a problem governed by various interfacial phenomena such as the capillarity-induced liquid flow, thin-film evaporation intensifying near the contact lines, and thermocapillarity-induced Marangoni flow. However, past research has not been able to assess the effect of Marangoni flow due to the missing coupling between cell-and device-level modeling. In this work, we develop a comprehensive model for the evaporation from a micropillar evaporator by coupling the ...
Experimental investigation of single phase liquid flow and heat transfer in multiport minichannels Altınöz, Mesru; Güvenç Yazıcıoğlu, Almıla; Baker, Derek Keıth; Department of Mechanical Engineering (2013) This thesis aims to experimentally investigate pressure drop and heat transfer characteristics of single phase water flow in rectangular minichannels. The small channels are an area of interest in heat transfer field since 1970’s owing to their enhanced heat transfer characteristics. However, the heat transfer and pressure drop characteristics of these channels are not fully established as there is a wide number of studies in literature showing inconsistent results with each other. In order to investigate t...
A theoretical framework for comprehensive modeling of steadily fed evaporating droplets and the validity of common assumptions Akkus, Yigit; ÇETİN, BARBAROS; Dursunkaya, Zafer (Elsevier BV, 2020-12-01) A theoretical framework is established to model the evaporation from continuously fed droplets, promising tools in the thermal management of high heat flux electronics. Using the framework, a comprehensive model is developed for a hemispherical water droplet resting on a heated flat substrate incorporating all of the relevant transport mechanisms: buoyant and thermocapillary convection inside the droplet and diffusive and convective transport of vapor in the gas domain. At the interface, mass, momentum, and...
PERFORMANCE ASSESSMENT OF COMMERCIAL HEAT PIPES WITH SINTERED AND GROOVED WICKS UNDER NATURAL CONVECTION Atay, Atakan; Sariarslan, Busra; Kuscu, Yigit F.; Saygan, Samet; Akkus, Yigit; Gurer, A. Turker; Cetin, Barbaros; Dursunkaya, Zafer (2019-01-01) Heat pipes are widely used in thermal management of high heat flux devices due to their ability of removing high heat loads with small temperature differences. While the thermal conductivity of standard metal coolers is approximately 100-500 W/m.K, effective thermal conductivities of heat pipes, which utilize phase-change heat transfer, can reach up to 50,000 W/m.K. In industrial applications, commercially available heat pipes are commonly preferred by thermal engineers due to their low cost and versatility...
Numerical analysis of laminar forced convection with temperature-dependent thermal conductivity of nanofluids and thermal dispersion Özerinç, Sezer; Kakac, S. (2012-12-01) Nanofluids are promising heat transfer fluids due to their high thermal conductivity. In order to utilize nanofluids in practical applications, accurate prediction of forced convection heat transfer of nanofluids is necessary. In the first part of the present study, we consider the application of some classical correlations of forced convection heat transfer developed for the flow of pure fluids to the case of nanofluids by the use of nanofluid thermophysical properties. The results are compared with experi...

Citation Formats

G. Yuncu, “Comprehensive modeling of heat and mass transport in a micropillar evaporator,” M.S. - Master of Science, Middle East Technical University, 2022.