Characteristics of microencapsulated PCM slurry as a heat‐transfer fluid

Yamagishi, Yasushi; Takeuchi, Hiromi; Pyatenko, Alexander; Kayukawa, Naoyuki

doi:10.1002/aic.690450405

Cited by 252 publications

(155 citation statements)

References 16 publications

(14 reference statements)

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“…The PCM nanofluids reach higher Nu than water with an equal Re in both laminar and turbulent regimes, and the deviation increases with increasing concentration. Similar behavior has also been widely reported in literature for nanofluids, nanoemulsions and PCM fluids [5][6][7][8]12,19,[21][22][23][24]34]. However, this presentation method has been criticized in several recent publications, since it does not take the pumping power into account [21][22][23][24][25][26].…”

Section: Convective Heat Transfermentioning

confidence: 64%

“…Therefore, the fluids studied herein do not exhibit penalties in pressure losses, which is advantageous in terms of performance in practical applications. Previously, pressure loss penalties of various magnitudes have been reported for both nanofluids and PCM fluids [3,5,12,21,22,29]. In addition, even decreased pressure losses have been reported for PCM fluids in some cases, but that phenomenon can be mostly attributed to turbulence suppression i.e.…”

Section: Friction Factors and Pressure Lossesmentioning

confidence: 99%

“…In several studies, suspensions containing micro-sized PCM particles (typically 1-200 μm) have shown significant improvement in convective heat transfer performance [1][2][3][4][5]. However, the convection performance of such fluids containing nano-sized PCM particles has not been experimentally evaluated so far.…”

Section: Introductionmentioning

confidence: 99%

“…Naturally, more unexpected results might be obtained with yet higher concentrations. The particle fractions studied herein (5-10 w-%) are rather high for nanofluids, but even higher concentrations are often studied in the class of micro PCM fluids (~30%) [2,5,28]. …”

Section: Convective Heat Transfermentioning

confidence: 99%

See 3 more Smart Citations

Thermal properties and convective heat transfer of phase changing paraffin nanofluids

Mikkola

Puupponen

Saari

et al. 2017

International Journal of Thermal Sciences

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THERMAL PROPERTIES AND CONVECTIVE HEAT TRANSFER PERFORMANCE OF SOLID-LIQUID PHASE CHANGING PARAFFIN NANOFLUIDSWe aim to combine these two concepts for the first time by studying fluids containing nano-sized phase changing particles. In this study, the convective heat transfer performance and the thermal properties of solidliquid phase changing paraffin nanofluids are experimentally examined. Three water-based paraffin nanofluids with particle mass fractions of 5-10% are prepared and measured with an annular tube heat exchanger. The heat transfer measurements cover both laminar and turbulent regimes with Reynolds numbers varying in the range of 700-11000. The measurements also include pressure losses in order to study the suitability of the fluids for practical forced convection applications. In addition, the fluids are characterized: latent heats, specific heats, viscosities, thermal conductivities, densities and particle size distributions are all determined experimentally. In agreement with previous studies, the nanofluids are found to exhibit Nusselt numbers clearly higher than water when compared on the basis of equal Reynolds numbers. However, the differences in Prandtl numbers are shown to explain these deviations in Nusselt numbers. Indeed, the well-known Gnielinski correlation is able to explain the results quite adequately and thus, significant anomalies in the convection heat transfer caused by neither the melting of the phase change material nor the presence of the nanoparticles are observed. However, the nanofluids have systematically slightly higher Nusselt numbers than the correlation would predict, but the deviations are within the accuracy of the correlation (10%). When compared by using equal pumping powers, the nanofluids exhibit heat transfer performance poorer than that of water. The positive impact of the latent heat is outweighed by the negative effects of the increased viscosity and decreased specific heat.

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Section: Convective Heat Transfermentioning

confidence: 64%

Section: Friction Factors and Pressure Lossesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Convective Heat Transfermentioning

confidence: 99%

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Thermal properties and convective heat transfer of phase changing paraffin nanofluids

Mikkola

Puupponen

Saari

et al. 2017

International Journal of Thermal Sciences

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“…In the two past decades, microencapsulated Phase Change Materials (PCM) have drawn an increasing interest to provide enhanced thermal functionalities in a wide 30 variety of applications [1][2][3][4]. When the encapsulated PCM is heated to the melting point, it absorbs heat as it goes from a solid state to a liquid state.…”

Section: Introductionmentioning

confidence: 99%

Polymer nanoparticles to decrease thermal conductivity of phase change materials

et al. 2008

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Microparticles including paraffin are currently used for textiles coating in order to 15 deaden thermal shocks. We will show that polymer nanoparticles embedded in those microsized capsules allow for decreasing the thermal conductivity of the coating and enhance the protection in the stationary regime. A reasonable volume fraction of polymer nanoparticles reduces the conductivity more than predicted by Maxwell mixing rules. Besides, measurements prove that the polymer nanoparticles do not 20 affect the latent heat and even improve the phase change behaviour as well as the mechanical properties.

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Microencapsulation

Thies¹

2005

Kirk-Othmer Encyclopedia of Chemical Technology

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This article discusses the concept of microencapsulation, many processes by which microcapsules are produced, and a number of microcapsule applications. Nomenclature and selected materials used to form microcapsules are summarized briefly. Encapsulation processes discussed include complex coacervation, polymer–polymer incompatibility, interfacial and in situ polymerization, solvent evaporation, extractive drying, submerged stationary nozzle, centrifugal nozzle, spray drying, fluidized bed, and rotational suspension separation. Microcapsule applications discussed include graphic arts, including carbonless copy paper; prolonged herbicides and insecticides; oral and injectable pharmaceuticals; live cell immobilization for biomedical and biotechnological applications; enhanced performance of food ingredients, such as flavors and vitamins; and several general consumer uses, such as cosmetics and adhesives.

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Characteristics of microencapsulated PCM slurry as a heat‐transfer fluid

Cited by 252 publications

References 16 publications

Thermal properties and convective heat transfer of phase changing paraffin nanofluids

Thermal properties and convective heat transfer of phase changing paraffin nanofluids

Polymer nanoparticles to decrease thermal conductivity of phase change materials

Microencapsulation

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