Effect of carbon nanofiber additives on thermal behavior of phase change materials

Elgafy, Ahmed; Lafdi, Khalid

doi:10.1016/j.carbon.2005.06.042

Cited by 377 publications

(126 citation statements)

References 9 publications

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“…nanofibers) in PCMs for improved thermal energy storage was reported by Elgafy and Lafdi [23] in 2005. Since then, the efforts have been made on the development and preparation of appropriate nano-enhanced PCMs suitable for various industrial applications, test and characterization of their thermal energy storage performance, and investigation of their melting and solidification characteristics.…”

Section: Introductionmentioning

confidence: 88%

Nano-enhanced phase change materials for improved building performance

Lin

Sohel

2016

Renewable and Sustainable Energy Reviews

168

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Nano-enhanced phase change materials (PCMs) have attracted increasing attention to address one of the key barriers (i.e. low thermal conductivity) to the wide adoption of PCMs in many industrial applications. This paper discusses the generic problem and key issues associated with appropriately using this new class of materials in buildings for effective thermal management and improved energy performance. An overview on major recent development and application of nano-enhanced PCMs as thermal energy storage media is provided. A case study based on a PCM ceiling ventilation system integrated with solar photovoltaic thermal (PVT) collectors is then performed to evaluate the potential benefits due to the dispersion of copper nanoparticles into the PCM base fluid of RT24. The results showed that this nano-enhanced PCM has higher melting and solidification rates than that of the pure PCM. Compared to the use of the pure PCM, 8.3% more heat was charged in and 25.1% more heat was discharged from the nano-enhanced PCM under the three winter test days. More research is needed to understand the fundamental mechanisms behind the PCM thermal conductivity enhancement through the dispersion of nanometer-sized materials and to investigate how these mechanisms drive building performance enhancement. Abstract: Nano-enhanced phase change materials (PCMs) have attracted increasing attention to address one of the key barriers (i.e. low thermal conductivity) to the wide adoption of PCMs in many industrial applications. This paper discusses the generic problem and key issues associated with appropriately using this new class of materials in buildings for effective thermal management and improved energy performance. An overview on major recent development and application of nano-enhanced PCMs as thermal energy storage media is provided. A case study based on a PCM ceiling ventilation system integrated with solar photovoltaic thermal (PVT) collectors is then performed to evaluate the potential benefits due to the dispersion of copper nanoparticles into the PCM base fluid of RT24. The results showed that this nano-enhanced PCM has higher melting and solidification rates than that of the pure PCM. Compared to the use of the pure PCM, 8.3% more heat was charged in and 25.1% more heat was discharged from the nano-enhanced PCM under the three winter test days. More research is needed to understand the fundamental mechanisms behind the PCM thermal conductivity enhancement through the dispersion of nanometer-sized materials and to investigate how these mechanisms drive building performance enhancement.

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Section: Introductionmentioning

confidence: 88%

Nano-enhanced phase change materials for improved building performance

Lin

Sohel

2016

Renewable and Sustainable Energy Reviews

168

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“…It has been reported that CNTs are extremely strong with the strength of tens of GPa and exceptionally stiff with Young's modulus in TPa range, yet remarkably flexible with the breaking strain larger than 5% [18]. Moreover, the CNTs have considerably high thermal conductivity and their density is less than 2,260 kg m -3 , which is lower than that of metals that are usually used as additives [19]. As a result, CNTs are promising additives for heat transfer applications in PCMs.…”

Section: Introductionmentioning

confidence: 99%

Preparation and thermal properties of fatty acids/CNTs composite as shape-stabilized phase change materials

Meng

Zhang

Sun

et al. 2012

J Therm Anal Calorim

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A series of fatty acids/carbon nanotubes (CNTs) composite shape-stabilized PCMs were prepared through infiltration method by using the eutectic mixture of capric acid, lauric acid, and palmitic acid as phase change materials, multi-walled CNTs as a supporting material. Nitrogen adsorption-desorption curves and SEM images of composite shape-stabilized PCMs indicate that the eutectic mixture was effectively absorbed into the porous structure of the CNTs. DSC thermograms show that the composite fatty acids/CNTs possess good phase change behavior. And the latent heat of the sample absorbed with 80 wt% fatty acids can achieve 101.6 J g -1 in the melting process and its phase change temperatures and latent heat almost remain unchanged in 30 times of thermal cycling. Moreover, the thermal conductivity of the composite materials are significantly improved (up to 0.6661 W m -1 k -1 ) due to the addition of the highly thermal conductive CNTs.

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“…For comparison reasons a further time sequence of a volume averaged NaNO 3 temperature of a heat exchanger tube design with longitudinal fins (green colored) is included in Figure 4. Volume of the wire matrix Volume of the PCM  (12) is 0.149 and the surface to volume ratio Surface area of the wire matrix Volume of the wire matrix  (13) is 0.965 m −1 .…”

Section: Results For the Charging Processmentioning

confidence: 99%

“…A widely used method to overcome this heat transport limitation in LHTES is to increase the specific surface of the heat exchanger tubes. Various techniques, like fins [4][5][6][7][8][9][10][11], dispersed high-conductivity particles inside the PCM [12,13], metal and graphite-compound matrices [14][15][16], micro-encapsulation [17][18][19] as well as a combination of metal foam made of copper and sandwich structure fins [20] have been suggested and were analyzed.…”

Section: Introductionmentioning

confidence: 99%

Transient Numerical Simulation of the Melting and Solidification Behavior of NaNO3 Using a Wire Matrix for Enhancing the Heat Transfer

2016

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Abstract:The paper presents the results of a transient numerical investigation of the melting and solidification process of sodium nitrate (NaNO 3 ), which is used as phase change material. For enhancing the heat transfer to the sodium nitrate an aluminum wire matrix is used. The numerical simulation of the melting and solidification process was done with the enthalpy-porosity approach. The numerical analysis of the melting process has shown that apart from the first period of the charging process, where heat conduction is the main heat transfer mechanism, natural convection is the dominant heat transfer mechanism. The numerical investigation of the solidification process has shown that the dominant heat transfer mechanism is heat conduction. Based on the numerical results, the discharging process has been slower than the charging process. The performance of the charged and discharged power has shown that the wire matrix is an alternative method to enhance the heat transfer into the phase change material.

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Effect of carbon nanofiber additives on thermal behavior of phase change materials

Cited by 377 publications

References 9 publications

Nano-enhanced phase change materials for improved building performance

Nano-enhanced phase change materials for improved building performance

Preparation and thermal properties of fatty acids/CNTs composite as shape-stabilized phase change materials

Transient Numerical Simulation of the Melting and Solidification Behavior of NaNO3 Using a Wire Matrix for Enhancing the Heat Transfer

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