Modeling in situ vapor extraction during convective boiling in fractal-like branching microchannel networks

Salakij, Saran; Liburdy, James A.; Pence, Deborah V.; Apreotesi, Mario

doi:10.1016/j.ijheatmasstransfer.2013.01.004

Cited by 16 publications

(8 citation statements)

References 35 publications

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“…Apreotesi et al [13,14] experimentally investigated flow boiling of water through a fractal-like branching microchannel network with in-situ vapor extraction, showing a decrease in the system pressure drop with increasing extraction pressure differential. A later work by Salakij et al [18], using a one dimensional predictive model validated against the experimental results obtain in [13,14], shows up to a 70% decrease in the overall pressure drop. Moreover, the bulk fluid temperature within the channel was shown to decrease indicating the potential of in-situ vapor extraction to decrease the overall operating temperature of the device.…”

Section: Introductionmentioning

confidence: 94%

“…Apart from the ability to stabilize the flow, several studies suggest that in-situ vapor extraction also has the potential to reduce the system pressure drop while maintaining the benefit of enhanced heat transfer [13][14][15][16][17][18]. Apreotesi et al [13,14] experimentally investigated flow boiling of water through a fractal-like branching microchannel network with in-situ vapor extraction, showing a decrease in the system pressure drop with increasing extraction pressure differential.…”

Section: Introductionmentioning

confidence: 99%

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Modeling Criteria for Extraction Regime Transitions for Microscale In-Situ Vapor Extraction Application

Salakij

Pence

Liburdy

2013

Volume 8B: Heat Transfer and Thermal Engineering

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A major detriment of two-phase microscale flow systems is a relatively high pressure drop, as well as the potential for flow instabilities. A possible mechanism to overcome these disadvantages is vapor extraction through a hydrophobic porous wall in the channel to reduce vapor content and suppress vapor expansion. The vapor extraction may occur either as evaporation, bubble extraction or a mix of both. For the design of vapor extraction systems, it is important to accurately predict extraction regimes, extraction rates and the effect of extraction on the heat transfer and flow conditions. This study focuses on two parts: the development of physic-based models for the transition criteria among (i) the extraction mechanism regimes, and (ii) the extraction flow regimes for microscale flow boiling. The identification and conditions for the various extraction regimes are discussed and criteria for transition are developed based on physical concepts. Six potential extraction mechanism regimes are identified: (a) no extraction, (b) pure evaporation, (c) pure bubble extraction, (d) bubble extraction with partial liquid blockage, (e) bubble extraction with evaporation, and (f) liquid breakthrough. Based on the criteria for the extraction mechanism regimes, the rate of vapor extraction is modeled and used to analyze the effects of vapor extraction on the dynamics of two-phase flow boiling. The results show six extraction flow regimes for two-phase flow boiling: (i) single-phase evaporation, (ii) two-phase evaporation – bubble collapse, (iii) full extraction – stable, (iv) full extraction – unstable, (v) partial extraction – stable and (iv) partial extraction – unstable.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Modeling Criteria for Extraction Regime Transitions for Microscale In-Situ Vapor Extraction Application

Salakij

Pence

Liburdy

2013

Volume 8B: Heat Transfer and Thermal Engineering

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“…For the present study, it is assumed that the extraction process does not influence the rate of growth and that the rate at which mass leaves by extraction is consistent with Darcy's Law, provided in Eq. (9). A transient mass balance considering mass entering and leaving the system yields…”

Section: Regime IImentioning

confidence: 99%

“…In a model developed to assess pressure drop through fractal-like branching channels experiencing in-situ vapor extraction, Salakij et al [9] recognized the drawback of using the entire membrane area for predicting the amount of vapor being extracted. In the model, Darcy's Law was used to predict extraction rates.…”

Section: Introductionmentioning

confidence: 99%

Altering Bubble Dynamics via In Situ Vapor Extraction

Fox

Juarez

Pence

et al. 2016

Heat Transfer Engineering

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Spatio-temporal cooling of electronics using latent energy might be achieved by closely spaced, rapid departure of small bubbles. One means to achieve small diameters during boiling is to provide an additional upward force during bubble formation, such as that from vapor extraction. Experiments were conducted of bubble extraction using constant flow rates of both air and vapor that ranged from 30 to 90 cubic mm per second. Extraction was achieved with a hydrophobic porous membrane sealed to a tube in which a vacuum was drawn. The gap between the extraction and supply surface was varied from 0.5 to 3.25 mm. Only individual bubbles that ruptured at the top surface while still attached to the supply surface were considered. Bubble departure diameters are approximately 80 percent of the gap height. As with unconfined bubbles in pool boiling, the bubble frequency varies inversely with departure diameter. Correlations for bubble rupture, bubble departure and bubble frequency are presented as a function of gap height. Using the three distinct regimes identified in the experimental study, i.e., growth only, growth with extraction, and extraction only, an effective bubble diameter model and an appropriate static force balance were developed. These were used to predict bubble departure frequencies and diameters, respectively, under confined extraction conditions.

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“…It is well documented that [9][10][11][12], the fractal tree-shaped networks, involved in lungs, vasculatures, botanical trees, river networks, and the like, have inherent advantages in the increase of interface-area-to-volume ratios by their repeated branching structure. Due to this attracting feature, the tree-shaped architectures has found to be useful in improving heat sinks [13][14][15], fuel cells [16], chemical reactors [17,18] ever since Bejan [19] firstly put forward the tree-shaped network construction of thermal conduction for electronics cooling. Yu and Li [20] studied the effective thermal conductivity of composites with embedded self-similar fractal-like tree networks via conventional thermal conduction model, and confirmed that the tree networks can significantly reduce the thermal conductivity compared to an equivalent single cylinder.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity of Si/Ge nanocomposites with fractal tree-shaped networks by considering the phonon interface scattering

Chen

Deng

Cheng

2015

International Journal of Heat and Mass Transfer

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Modeling in situ vapor extraction during convective boiling in fractal-like branching microchannel networks

Cited by 16 publications

References 35 publications

Modeling Criteria for Extraction Regime Transitions for Microscale In-Situ Vapor Extraction Application

Modeling Criteria for Extraction Regime Transitions for Microscale In-Situ Vapor Extraction Application

Altering Bubble Dynamics via In Situ Vapor Extraction

Thermal conductivity of Si/Ge nanocomposites with fractal tree-shaped networks by considering the phonon interface scattering

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