Graphite nanoparticles-dispersed paraffin/water emulsion with enhanced thermal-physical property and photo-thermal performance

Wang, Fangxian; Liu, Jian; Fang, Xiaoming; Zhang, Zhengguo

doi:10.1016/j.solmat.2015.12.013

Cited by 76 publications

(28 citation statements)

References 29 publications

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“…Minimum differences between the two µ values (for RT21HC(10 wt.%)/water in the mentioned temperature interval) are~4-6%. In addition, and as previously reported in the literature for other PCM-in-water slurries [13,[15][16][17]57], shear viscosity-temperature curves are affected by melting and recrystallization processes. Such deformations are only appreciated in µ(T) curves of the nano-emulsion with 10 wt.% of paraffin (due to higher content in droplets undergoing the phase change).…”

Section: Shear Viscosity-temperature Sweepssupporting

confidence: 81%

“…However, a slight decrease in shear viscosity with increasing shear rate (pseudo-plastic behavior) was observed for the 10 wt.% paraffin loading in the region of low shear rates. As reviewed in the introduction, PCM nano-emulsions with shear-thinning behaviors were also reported in several studies [4,5,[10][11][12][13][14]. Viscosity values and relative viscosities (defined as the ratio between sample and water viscosities at shear rates around 100 s −1 (Newtonian region) are gathered in Table 1.…”

Section: Surface Propertiesmentioning

confidence: 81%

“…Authors found considerable higher viscosity increases at low temperatures (when PCM droplets are solid) and attributed this behavior to less deformation of solid particles. Wang et al [13] produced water-based PCM emulsions using a mixture of polyvinyl alcohol and polyethylene glycol as emulsifier, 20 wt.% of paraffin (melting point 331-333 K) as dispersed phase (droplet size 2-8 µm) and 0.05-0.1 wt.% of graphite as nucleating agent. Dynamic viscosity slightly decreased with the increasing shear rate (up to 100 s −1 ).…”

Section: Introductionmentioning

confidence: 99%

“…Some rheological studies on PCM nano-emulsions [4,5,9,13,[15][16][17] or suspensions containing micro-encapsulated PCMs [18][19][20][21] also analyzed changes in dynamic viscosity occurring during the solidifyication/melting of phase change material droplets/micro-capsules. Most of those investigations observed deformations in shear viscosity-temperature evolution at temperatures around solid-liquid transitions.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic Viscosity, Surface Tension and Wetting Behavior Studies of Paraffin–in–Water Nano–Emulsions

et al. 2019

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This work analyzes the dynamic viscosity, surface tension and wetting behavior of phase change material nano–emulsions (PCMEs) formulated at dispersed phase concentrations of 2, 4 and 10 wt.%. Paraffin–in–water samples were produced using a solvent–assisted route, starting from RT21HC technical grade paraffin with a nominal melting point at ~293–294 K. In order to evaluate the possible effect of paraffinic nucleating agents on those three properties, a nano–emulsion with 3.6% of RT21HC and 0.4% of RT55 (a paraffin wax with melting temperature at ~328 K) was also investigated. Dynamic viscosity strongly rose with increasing dispersed phase concentration, showing a maximum increase of 151% for the sample containing 10 wt.% of paraffin at 278 K. For that same nano–emulsion, a melting temperature of ~292.4 K and a recrystallization temperature of ~283.7 K (which agree with previous calorimetric results of that emulsion) were determined from rheological temperature sweeps. Nano–emulsions exhibited surface tensions considerably lower than those of water. Nevertheless, at some concentrations and temperatures, PCME values are slightly higher than surface tensions obtained for the corresponding water+SDS mixtures used to produce the nano–emulsions. This may be attributed to the fact that a portion of the surfactant is taking part of the interface between dispersed and continuous phase. Finally, although RT21HC–emulsions exhibited contact angles considerably inferior than those of distilled water, PCME sessile droplets did not rapidly spread as it happened for water+SDS with similar surfactant contents or for bulk–RT21HC.

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Section: Shear Viscosity-temperature Sweepssupporting

confidence: 81%

Section: Surface Propertiesmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamic Viscosity, Surface Tension and Wetting Behavior Studies of Paraffin–in–Water Nano–Emulsions

et al. 2019

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“…The heat transfer coefficients of all the PCMEs were greater than that of water for both laminar and turbulent flow. Wang et al [20] proposed 20 wt% PCMEs containing different mass fractions of graphite nanoparticles as HTFs for a direct absorption solar collector. The experimental results indicated that the dispersion of graphite nanoparticles significantly improved the photothermal performance of the PCME.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Performance Comparison of Solar Water Heating-Phase Change Material System and Solar Water Heating System

et al. 2019

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Phase change material can be used as heat transfer fluid in the solar water heating system, which is the latest way to improve thermal efficiency. In this paper, graphene composite paraffin emulsion is used as heat transfer fluid in a solar water heating-phase change material (SWH-PCM) system. By comparing with the traditional solar water heating (SWH) system, the thermal performance characteristics of SWH-PCM system have been investigated experimentally. The SWH-PCM system has higher heat storage than the SWH system. The heat storage of SWH-PCM system and SWH system all increase with the increase of solar irradiance, while the thermal efficiency has the opposite trend. The flow rate has a greater influence on the thermal efficiency of SWH-PCM system than that of the SWH system. With the flow rate of 200 L/h, the thermal efficiency of SWH-PCM system is 14.21% higher than that of the SWH system. In summary, the SWH-PCM system is a promising solar water heating system with high heat storage and thermal efficiency.

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A MXene‐Based Hierarchical Design Enabling Highly Efficient and Stable Solar‐Water Desalination with Good Salt Resistance

Fan

Yang

Shi

et al. 2020

Adv Funct Materials

269

149

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A solar-thermal water evaporation structure that can continuously generate clean water with high efficiency and good salt rejection ability under sunlight is highly desirable for water desalination, but its realization remains challenging. Here, a hierarchical solar-absorbing architecture is designed and fabricated, which comprises a 3D MXene microporous skeleton with vertically aligned MXene nanosheets, decorated with vertical arrays of metalorganic framework-derived 2D carbon nanoplates embedded with cobalt nano particles. The rational integration of three categories of photothermal materials enables broadband light absorption, efficient light to heat conversion, low heat loss, rapid water transportation behavior, and much-improved corrosion and oxidation resistance. Moreover, when assembling with a hydrophobic insulating layer with hydrophilic channel, the MXene-based solar absorber can exhibit effective inhibition of salt crystallization due to the ability to advect and diffuse concentrated salt back into the water. As a result, when irradiating under one sun, the solar-vapor conversion efficiency of the MXene-based hierarchical design can achieve up to ≈93.4%, and can remain over 91% over 100 h to generate clean vapor for stable and continuous water desalination. This strategy opens an avenue for the development of MXenebased solar absorbers for sustainable solar-driven desalination.

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Graphite nanoparticles-dispersed paraffin/water emulsion with enhanced thermal-physical property and photo-thermal performance

Cited by 76 publications

References 29 publications

Dynamic Viscosity, Surface Tension and Wetting Behavior Studies of Paraffin–in–Water Nano–Emulsions

Dynamic Viscosity, Surface Tension and Wetting Behavior Studies of Paraffin–in–Water Nano–Emulsions

Experimental Investigation on Performance Comparison of Solar Water Heating-Phase Change Material System and Solar Water Heating System

A MXene‐Based Hierarchical Design Enabling Highly Efficient and Stable Solar‐Water Desalination with Good Salt Resistance

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