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

Vu, Trinh; Xu, Jiajun

doi:10.1186/s11671-017-1984-1

Cited by 14 publications

(9 citation statements)

References 67 publications

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“…5 that for tube diameters below 1 mm, the flow boiling was mostly in the laminar region. Trinh and Xu [85] specified in their experimental study of ethanol/polyalphaolefin nanoemulsion flowing through circular minichannels that the ethanol nano-droplets formed through the nano-emulsion process could significantly enhance the HTC compared to the base fluid. It was suggested that the phase change process of ethanol nano-droplets under flow boiling condition absorbed a relatively large amount of latent heat, which could be one of the reasons for the heat transfer enhancement.…”

Section: Effects Of Reynolds Number and Flow Regimes On Flow Boiling Of Binary Mixturesmentioning

confidence: 99%

A review of boiling heat transfer characteristics in binary mixtures

Wang

Yang

et al. 2021

International Journal of Heat and Mass Transfer

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This paper reviews the state-of-the-art knowledge of boiling heat transfer in binary mixtures, special emphasis is placed on refrigeration industry. The advantage of using refrigerant mixtures over pure refrigerants include the enhancement of coefficient of performance (COP), better match with the desired thermal load and safer, more environmental-friendly refrigerants. In other words, the concept of using mixtures enables more flexibility for the selection of suitable working fluids in particular applications. The purpose of this review article aims to summarize the important published articles on boiling heat transfer in binary mixtures and innovative technologies, as well as to identify limitations to existing studies and directions for future research of this promising thermal management technique. The present article reviews straightforward on both pool boiling and flow boiling in a systematic and comprehensive way. This article maily focus on the review of the effects of mass diffusion, heating surface characteristics, heats from dilution and dissolution on pool boiling heat transfer of binary mixtures, as well as the effects of flow orientation, flow regime and flow instability on flow boiling heat transfer of binary mixtures. Many papers reviewed herein relate to the heat transfer correlations during boiling of binary mixtures. The review reveals that numerical simulations of boiling in binary mixtures, the benefits of surface modification on boiling of binary mixtures and the flow boiling of highly viscous pseudo-plastic mixtures have been scarcely investigated and require further investigation.

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Section: Effects Of Reynolds Number and Flow Regimes On Flow Boiling Of Binary Mixturesmentioning

confidence: 99%

A review of boiling heat transfer characteristics in binary mixtures

Wang

Yang

et al. 2021

International Journal of Heat and Mass Transfer

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“…Recently, the authors have proposed a new type of heat transfer fluid called "nanoemulsion" [47]. Nanoemulsion is a suspension of liquid nanodroplets formed by self-assembly inside another immiscible fluid, as part of a broad class of multiphase colloidal dispersions [48].…”

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

confidence: 99%

“…The droplets typically have a length scale less or equal to 50 nm, which makes the nanoemulsion fluid thermodynamically stable and transparent to natural light. A comparison of nanoemulsion with emulsion (dilute emulsion) is represented in Table 3 [47,48]. Table 3.…”

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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“…Although many experimental studies have been conducted to date to investigate the impact of local vapor quality on boiling heat transfer performance, majority of these studies have taken the similar approach to measure local vapor quality Experimental Approaches to Measurement of Vapor Quality of Two-Phase Flow Boiling DOI: http://dx.doi.org /10.5772/intechopen.94473 only at the outlet of test section mainly under uniform wall heat flux boundary conditions using electrical heating [6][7][8][9][10][11][12]. There are limited studies investigating the effect of local vapor quality for other thermal boundary conditions [13,14], while their techniques to measure local vapor quality are not reported clearly.…”

Section: Introductionmentioning

confidence: 99%

Experimental Approaches to Measurement of Vapor Quality of Two-Phase Flow Boiling

Kabirnajafi¹,

Xu²

2021

Heat Transfer - Design, Experimentation and Applications

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Vapor quality is one of the crucial parameters substantially affecting the flow boiling heat transfer coefficient. Hence, the reliability and accuracy of vapor quality measurements is of a great significance to accurately investigating the effect of vapor quality on the local flow boiling heat transfer coefficients. In the present study, various experimental approaches are represented to measure and control local vapor quality for flow boiling tests. Experimental approaches are classified based on the type of thermal boundary conditions imposed on the tube wall, that is, known constant wall heat flux and constant wall temperature (unknown variable wall heat flux). In addition, in-situ techniques are also investigated to measure local vapor quality regardless of the governing thermal boundary conditions within two-phase flow experiments. Finally, the experimental methodologies are compared based on their level of reliability and accuracy in measurement, costliness and affordability, and simplicity in execution to address their potential merits and demerits.

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

Cited by 14 publications

References 67 publications

A review of boiling heat transfer characteristics in binary mixtures

A review of boiling heat transfer characteristics in binary mixtures

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

Experimental Approaches to Measurement of Vapor Quality of Two-Phase Flow Boiling

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