Synergistically-Enhanced Thermal Conductivity of Shape-Stabilized Phase Change Materials by Expanded Graphite and Carbon Nanotube

Liu, Zhang-Peng; Yang, Rui

doi:10.3390/app7060574

Cited by 30 publications

(17 citation statements)

References 38 publications

(43 reference statements)

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“…The relationship between the mass ratios of PCM composites and specific heat was irregular, and the difference was less than 12.5%. The similar conclusions were found in the study of EG-CNT SSPCM by Liu et al [21]. In general, the additives incorporation (HDPE and hybrid CNs) increased the specific capacity of the composite PCM.…”

Section: Comprehensive Evaluationsupporting

confidence: 88%

“…The addition of CNs can enhance the thermal conductivity and further improve the stabilization of the SSPCMs. A few researches explored to use hybrid CN fillers and discussed their synergistic effect on the thermal conductivity enhancement of SSPCM, such as EG-Multiwalled Carbon Nano-tube (EG-MWCNT) and EG-CNF fillers [10], EG/Carbon Fiber (CF) [20], expanded graphite platelets (EGP)/MWCNT fillers [21].…”

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confidence: 99%

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Comprehensive evaluation of Paraffin-HDPE shape stabilized PCM with hybrid carbon nano-additives

Wang

YiShui

et al. 2019

Applied Thermal Engineering

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Thermal energy storage using phase change materials (PCMs) is of great interests in many fields, especially in solar thermal applications. To overcome the leakage problem caused by phase change and the low thermal conductivities of most PCMs, especially paraffin, the current study prepared and tested two Paraffin-HDPE-based composites by adding two hybrid Carbon Nano-additives (CNs) fillers: Expanded Graphite-Multi-walled Carbon Nanotube (EG-MWCNT) and Expanded Graphite-Carbon Nanofiber (EG-CNF). A comprehensive evaluation method was first proposed based on the Efficacy Coefficient Method (ECM) to assess the thermal performance of Paraffin-HDPE shape stabilized PCM (SSPCM). Seven individual indexes, including phase change temperature, latent heat, thermal conductivity, leakage rate, specific heat of both solid and liquid phase, and heat storage/heat release rates, were measured and applied to obtain the overall efficacy coefficients of the prepared SSPCM composites. The results showed that in all studied composites, n-octadecane-HDPE/EG-MWCNT composite exhibited the best comprehensive thermal performance with an optimal mass ratio of EG and MWCNT being 4:1.

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Section: Comprehensive Evaluationsupporting

confidence: 88%

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confidence: 99%

Comprehensive evaluation of Paraffin-HDPE shape stabilized PCM with hybrid carbon nano-additives

Wang

YiShui

et al. 2019

Applied Thermal Engineering

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“…For instance, multiwalled carbon nanotubes (MWCNTs) with outer diameters (2-100 nm) exhibit a significantly high permeability in membrane process applications because of the large surface area [6]. The MWCNT hybrid nanostructure and composite materials with the introduction of polymer chemistry have dramatically attracted attention [8,9]. These nanocomposite materials complement the characteristics of functional polymers and thus provide improved nano-scale dispersing, hydrophilicity, electric properties, etc.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Poly(methyl methacrylate) Grafted Multiwalled Carbon Nanotubes via a Combination of RAFT and Alkyne-Azide Click Reaction

Zhao

Zhu

et al. 2019

Applied Sciences

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An efficient synthesis route was developed for the preparation of multiwalled carbon nanotube (MWCNT) nanohybrids using azide-terminated poly(methyl methacrylate) (PMMA) via a combination of reversible addition fragmentation chain transfer (RAFT) and the click reaction. A novel azido-functionalized chain transfer agent (DMP-N 3 ) was prepared and subsequently employed to mediate the RAFT polymerizations of methyl methacrylate (MMA). The RAFT polymerizations exhibited first-order kinetics and a linear molecular weight dependence with the conversion. The kinetic results show that the grafting percentage of PMMA on the MWCNTs surface grows along with the increase of the reaction time. Even at 50 • C, the grafting rate of azide-terminated PMMA is comparatively fast in the course of the click reaction, with the alkyne groups adhered to MWCNTs in less than 24 h. The successful functionalization of PMMA onto MWCNT was proved by FTIR, while TGA was employed to calculate the grafting degree of PMMA chains (the highest GP = 21.9%). Compared with the pristine MWCNTs, a thicker diameter of the MWCNTs-g-PMMA was observed by TEM, which confirmed the grafted PMMA chain to the surface of nanotubes. Therefore, the MWCNTs-g-PMMA could be dispersed and stably suspended in water. Appl. Sci. 2019, 9, 603 50 ml Schlenk flask. The mixture solution was degassed with nitrogen using a three-way tube (three 95 cycles). Then, a RAFT polymerization reaction was performed at 60 °C for 10 h. After polymerization, 96 the azide-terminated PMMA was obtained when the unreacted MMA monomer was removed with 97 THF for 24 h by Soxhlet apparatus. The resulting polymer was dried at 25 °C in a vacuum oven for 98 12 h. Scheme 1 shows the route of synthesis of azide-terminated PMMA. The resulting polymer was 99 dried at 25 °C in a vacuum oven for 12 h. Scheme 1 shows the route of synthesis of azide-terminated 100 PMMA. 101 102 Scheme 1. The synthetic route for synthesis of azide-terminated poly(methyl methacrylate) PMMA 103 via RAFT polymerization.104 2.3. Alkyne-Modification of MWCNT (MWCNTs-alkyne) 105In total, 2 g of the MWCNTs was subjected to acid treatment with 60 ml of an HNO3:H2SO4 (1:3) 106 mixture using ultrasound at 60 °C for 4 h, and then refluxed at 80 °C for 12 h. After the reaction, the 107 treated MWCNTs (MWCNTs-COOH) were washed until the excess acid was completely removed. 108In total, 1 g of MWCNTs-COOH was dispersed in thionyl chloride (65 mL) for 30 min. Then, 2 109 ml N,N-dimethylformamide (DMF) was added to this reaction mixture and stirred for 24 h at 70 °C. 110Thus, the MWCNT-COCl was obtained after being dried at 50 °C for 24 h. After that, 0.5 g MWCNT- 111COCl and 2 ml anhydrous triethylamine were mixed in 20 mL of trichloromethane. Following this, 3 112 ml of propargyl alcohol was added dropwise to the MWCNT-COCl mixture at 0 °C. The reaction 113 between MWCNT-COCl and propargyl alcohol was carried out at room temperature for 10 h. 114Subsequently, the obtained MWCNTs-alkyne was purified by centrifugation and then dried at 50...

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“…The significantly synergistic enhancement to thermal conductivity of FSPCMs was obtained by using CF and EG. Liu and Yang [12] studied expanded graphite platelets (EGP)/MWCNT-filled SSPCM based on paraffin, HDPE, and styrene-butadiene-styrene (SBS) copolymer. They found 9wt.% of EGP and MWCNT increased the thermal conductivity of SSPCM by 246% and 159% respectively.…”

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confidence: 99%

“…(11), where ρm is the density of matrix, ρp is the density of EG/MWCNT/CNF thermal conductive fillers, and wp is the mass fraction of the fillers. α is defined as a dimensionless parameter indicating the thermal effect of particle dispersion in the matrix, which is determined by thermal conductivity kp, interfacial thermal resistance RBd and dispersion radius r, calculated by Eq (12)…”

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confidence: 99%

Experimental study on thermal conductivity of paraffin-based shape-stabilized phase change material with hybrid carbon nano-additives

et al. 2020

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Thermal energy storage with Phase Change Materials (PCMs) is one of the most potential technologies for energy storage. However the low thermal conductivity of PCMs reduces the heat exchange rate during melting and solidification cycles. This paper studied the effects of two hybrid Carbon Nano-additives (CNs) fillers, that is, Expanded Graphite-Multi-walled Carbon Nano-tube (EG-MWCNT) and Expanded Graphite-Carbon Nano-fiber (EG-CNF), on the thermal conductivity of Paraffin-HDPE SSPCM. From the viewpoints of synergistic thermal enhancement effect and the interfacial thermal resistance, the principle of enhancing thermal conductivity of Paraffin-HDPE/EG-MWCNT and Paraffin-HDPE/EG-CNF composite PCMs was analyzed. A modified Maxwell-Garnett model with a synergy factor η was proposed, which found excellent agreement between model prediction and the experimental data. Compared with the 5wt% loading of single CN additive EG, the thermal conductivities of hybrid CNs fillers (EG-MWCNT and EG-CNF) Paraffin-HDPE SSPCM had increased by 60% and 21.2% respectively. Within the scope of mass ratios of hybrid CNs fillers in this paper, Paraffin-HDPE/EG-MWCNT composite PCM exhibited superior performance than Paraffin-HDPE/EG-CNF in thermal conductivity with the optimal mass ratio of EG and MWCNT being 4:1.

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Synergistically-Enhanced Thermal Conductivity of Shape-Stabilized Phase Change Materials by Expanded Graphite and Carbon Nanotube

Cited by 30 publications

References 38 publications

Comprehensive evaluation of Paraffin-HDPE shape stabilized PCM with hybrid carbon nano-additives

Comprehensive evaluation of Paraffin-HDPE shape stabilized PCM with hybrid carbon nano-additives

Synthesis of Poly(methyl methacrylate) Grafted Multiwalled Carbon Nanotubes via a Combination of RAFT and Alkyne-Azide Click Reaction

Experimental study on thermal conductivity of paraffin-based shape-stabilized phase change material with hybrid carbon nano-additives

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