Experimental Setup for Studying the Chain Activation of Low-Temperature Boiling Sites in Superheated Liquid Droplets

Bulanov, N. V.; Gasanov, B. M.

doi:10.1007/s10595-005-0129-x

Cited by 16 publications

(13 citation statements)

References 2 publications

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“…Nanoemulsion fluids are part of a broad class of multiphase colloidal dispersions [15][16][17][18][19]21]. Different from the preparation of the nanofluids and emulsions [23][24][25][26][27][28][29][30][31], the nanoemulsion fluids are spontaneously generated by self-assembly which does not require external shear force. Thus the nanoemulsion fluids are thermodynamically stable [16-19, 23, 32-44].…”

Section: Nanoemulsion Heat Transfer Fluidsmentioning

confidence: 99%

Thermophysical Properties and SANS Studies of Nanoemulsion Heat Transfer Fluids

Yang¹,

Xu²

2016

Neutron Scattering

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Cooling is one of the most important technique challenges faced by a range of diverse industries and military needs. There is an urgent need for innovative heat transfer fluids with improved thermal properties over currently available ones. This chapter discusses the development and characterization of nanoemulsion heat transfer fluids with phase changeable nanodroplets to increase the thermophysical properties and the heat transfer rate of the fluid. Nanoemulsion heat transfer fluids can be formed by dispersing one fluid into another immiscible fluid as nanosized structures such as droplets and tubes, in which those nanostructures are swollen reverse micelles with the dispersed phase and stabilized by the surfactant molecules. In addition to the enhancement of thermophysical properties such as thermal conductivity by mixing another liquid of higher thermal conductivity, an even larger amount of heat can be absorbed or released when these nanodroplets undergo phase transition from liquid to gas or vice versa, and thus enhancing the heat transfer rate. Three types of nanoemulsion heat transfer fluids are introduced: alcohol-in-polyalphaolefin, water-in-FC-72, and water-in-polyalphaolefin. Structural and property characterizations of these nanoemulsion heat-transfer fluids are the two main aspects of this chapter. This chapter also identifies several critical issues in the nanoemulsion heat transfer fluids to be solved in the future.

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Section: Nanoemulsion Heat Transfer Fluidsmentioning

confidence: 99%

Thermophysical Properties and SANS Studies of Nanoemulsion Heat Transfer Fluids

Yang¹,

Xu²

2016

Neutron Scattering

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“…Emulsion and dilute emulsion fluid are essentially similar systems made of a mixture of two immiscible liquids, while the "dilute emulsion" has 5 vol% or less dispersed component. Using emulsion to enhance heat transfer can be dated back to 1959 by Moore [43], and it has attracted interests of researchers [35][36][37][38][39][40][41][42][43][44][45]. One of the most detailed descriptions of how emulsions boil is the work of Bulanov and Gasanov [38-41, 44, 45], in which they proposed chain-reaction boiling of the droplets as an explanation for the observed superheated droplets and bubble dynamics on the heat surface.…”

Section: Ethanol/polyalphaolefin Nanoemulsion: a Novel Heat Transfer mentioning

confidence: 99%

Convective Heat Transfer of Ethanol/Polyalphaolefin Nanoemulsion in Mini- and Microchannel Heat Exchangers for High Heat Flux Electronics Cooling

Rios¹,

Kabirnajafi²,

Gameda³

et al. 2021

Heat Transfer - Design, Experimentation and Applications

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The present study experimentally and numerically investigates the flow and heat transfer characteristics of a novel nanostructured heat transfer fluid, namely, ethanol/polyalphaolefin nanoemulsion, inside a conventionally manufactured minichannel of circular cross section and a microchannel heat exchanger of rectangular cross section manufactured additively using the Direct Metal Laser Sintering (DMLS) process. The experiments were conducted for single-phase flow of pure polyalphaolefin (PAO) and ethanol/PAO nanoemulsion fluids with two ethanol concentrations of 4 wt% and 8 wt% as well as for two-phase flow boiling of nanoemulsion fluids to study the effect of ethanol nanodroplets on the convective flow and heat transfer characteristics. Furthermore, the effects of flow regime of the working fluids on the heat transfer performance for both the minichannel and microchannel heat exchangers were examined within the laminar and transitional flow regimes. It was found that the ethanol/PAO nanoemulsion fluids can improve convective heat transfer compared to that of the pure PAO base fluid under both single- and two-phase flow regimes. While the concentration of nanoemulsion fluids did not reflect a remarkable distinction in single-phase heat transfer performance within the laminar regime, a significant heat transfer enhancement was observed using the nanoemulsion fluids upon entering the transitional flow regime. The heat transfer enhancement at higher concentrations of nanoemulsion within the transitional regime is mainly attributed to the enhanced interaction and interfacial thermal transport between ethanol nanodroplets and PAO base fluid. For two-phase flow boiling, heat transfer coefficients of ethanol/PAO nanoemulsion fluids were further enhanced when the ethanol nanodroplets underwent phase change. A comparative study on the flow and heat transfer characteristics was also implemented between the traditionally fabricated minichannel and additively manufactured microchannel of similar dimensions using the same working fluid of pure PAO and the same operating conditions. The results revealed that although the DMLS fabricated microchannel posed a higher pressure loss, a substantial heat transfer enhancement was achieved as compared to the minichannel heat exchanger tested under the same conditions. The non-post processed surface of the DMLS manufactured microchannel is likely to be the main contributor to the augmented heat transfer performance. Further studies are required to fully appreciate the possible mechanisms behind this phenomenon as well as the convective heat transfer properties of nanoemulsion fluids.

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“…Using emulsion to enhance heat transfer can be dated back to 1959 by Moore [41]. Later on, the emulsion of 5 vol% or less dispersed component is called “dilute emulsion,” and it has attracted interests from several research groups [30–36, 42, 43]. However, the understanding of phase change heat transfer inside emulsion is limited.…”

Section: Introductionmentioning

confidence: 99%

“…However, the understanding of phase change heat transfer inside emulsion is limited. One of the most detailed descriptions of how emulsions boil is the work of Bulanov and Gasanov [33–36, 42, 43], in which they proposed chain-reaction boiling of the droplets as an explanation for the observed superheated droplets and bubble dynamics on the heat surface. To further understand the boiling mechanism of dilute emulsions, Rosele et al [44] carried out an experimental study of boiling heat transfer from a horizontal heated wire, including visual observations in which the heat transfer coefficient is enhanced in dilute emulsions compared to that of water as a base fluid.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study on Flow and Heat Transfer Characteristics of Ethanol/Polyalphaolefin Nanoemulsion Flowing Through Circular Minichannels

2017

Nanoscale Res Lett

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This work experimentally studied the convective flow and heat transfer characteristics of a novel nanostructured heat transfer fluid: “ethanol/polyalphaolefin nanoemulsion” flowing through 12 circular minichannels of 1-mm diameter each. Ethanol/polyalphaolefin nanoemulsion is a thermodynamically stable system formed by dispersing ethanol into a mixture of “polyalphaolefin (PAO)” and surfactants. In this study, ethanol/PAO nanoemulsion is used as the working fluid to study the effect of ethanol nanodroplets on its convective flow and heat transfer characteristics. In addition, the effect of flow regime on its heat transfer is examined. It is found that using ethanol/PAO nanoemulsion fluids can improve convective heat transfer compared to that of pure PAO under both single- and two-phase flow regimes. For single-phase flow, there is no significant difference in Nusselt number between ethanol/PAO nanoemulsion and pure PAO in laminar flow regime. However, when entering transition flow regime, the ethanol/PAO nanoemulsion fluid showed a substantial increase in Nusselt number. Meanwhile, there is an increase in pressure drop and early onset of the laminar-turbulent transitional region for the ethanol/PAO nanoemulsion compared to pure PAO. The heat transfer coefficient of ethanol/PAO nanoemulsion can be further enhanced when the ethanol nanodroplets undergo phase change, which is hypothesized that such an effect is likely related to the enhanced interfacial thermal transport between the nanodroplets and base fluid under elevated temperature and the latent heat of phase changeable nanodroplets inside nanoemulsion. Further studies are needed to fully explore the convective heat transfer properties of nanoemulsion fluids.

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Experimental Setup for Studying the Chain Activation of Low-Temperature Boiling Sites in Superheated Liquid Droplets

Cited by 16 publications

References 2 publications

Thermophysical Properties and SANS Studies of Nanoemulsion Heat Transfer Fluids

Thermophysical Properties and SANS Studies of Nanoemulsion Heat Transfer Fluids

Convective Heat Transfer of Ethanol/Polyalphaolefin Nanoemulsion in Mini- and Microchannel Heat Exchangers for High Heat Flux Electronics Cooling

An Experimental Study on Flow and Heat Transfer Characteristics of Ethanol/Polyalphaolefin Nanoemulsion Flowing Through Circular Minichannels

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