Experimental Analysis of the Impact of Nanoinclusions and Surfactants on the Viscosity of Paraffin-Based Energy Storage Materials

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Rebecca Weigand ◽  
Kieran Hess ◽  
Amy S. Fleischer
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Thermal Management ◽  
Phase Change Materials ◽  
Positive Impact ◽  
Energy Storage Materials ◽  
Multiwalled Carbon ◽  
Thermal Management Of Electronics ◽  
Transient Thermal ◽  
The Impact

Phase change materials (PCMs) are commonly used in many applications, including the transient thermal management of electronics. For many systems, paraffin-based PCMs are used with suspended nanoinclusions to increase their effective thermal conductivity. The addition of these materials can have a positive impact on thermal conductivity, but can also increase the viscosity in the liquid phase. In this paper, the impact of different nanoinclusions and surfactants on the dynamic viscosity of a common paraffin wax PCM is quantified in order to determine their suitability for thermal energy storage applications. The effect of the nanoparticles on the viscosity is found to be a function of the nanoparticle type with multiwalled carbon nanotubes (MWCNT) yielding the greatest increase in viscosity. The addition of both nanoparticle and surfactant to the base PCM is found to affect the viscosity even when the loading levels of the nanoparticles or surfactant alone are not enough to affect the viscosity, thus the combination must be carefully considered in any heat transfer application.

scholarly journals Enhancement of heat transfer in phase change material using graphite-paraffin composites

2018 ◽  
Vol 172 ◽  
pp. 02001
Author(s):  
R Sathiyaraj. ◽  
R Rakesh. ◽  
N Mithran. ◽  
M Venkatesan.
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Thermal Environment ◽  
Graphite Powder ◽  
Energy Storage Materials ◽  
Melting Period ◽  
Change Material

Phase change materials (PCMs) are energy storage materials which can be used for maintaining a controlled thermal environment for various applications in earth and space. PCMs are used in advanced technologies in aerospace cooling applications like heat exchangers and heat pipes for re-entry vehicles and spacecraft. Paraffin is a phase change material (PCM) commonly used for energy storage-related applications. Paraffin wax exhibits slow thermal response due to low thermal conductivity value (~0.2 W/m K for most paraffin waxes). In the present work, an attempt is made to fabricate a composite PCM using graphite powder. Such a composite material has enhanced thermal conductivity along with reduced melting period which are desirable properties of a PCM during solid to liquid phase change process. The reduction in melting period is indicated by the difference in change in temperature measured by the thermocouples during a specified time. The temperature variation and solid-liquid interface formation during the melting process are experimentally studied. The results showed that composite graphite powder with paraffin can improve the total phase transition time.

scholarly journals Bifunctional biomorphic SiC ceramics embedded molten salts for ultrafast thermal and solar energy storage

2021 ◽  
Author(s):  
Xu Qiao ◽  
Xianglei Liu ◽  
Qinyang Luo ◽  
Yanan Song ◽  
Haolei Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Solar Energy ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Molten Salts ◽  
Phase Change Materials ◽  
Energy Transport ◽  
Energy Storage Materials ◽  
Solar Absorptance

Abstract Phase change materials (PCMs) are regarded as one of the most promising candidates for thermal energy storage due to possessing large energy storage densities and maintaining nearly a constant temperature during charging/discharging processes. However, the intrinsically low thermal conductivity of PCMs has become a bottleneck for rapid energy transport and storage. Here, we present a strategy to achieve ultrafast solar and thermal energy storage based on biomorphic SiC skeletons embedded NaCl-KCl molten salts. A record-high thermal conductivity of 116 W/mK is achieved by replicating cellular structure of oak wood, leading to an ultrafast thermal energy storage rate compared with molten salts alone. By further decorating TiN nanoparticles on SiC skeletons, the solar absorptance is enhanced to be as high as 95.63 % via exciting broadband plasmonic resonances. Excellent thermal transport and solar absorption properties enable designed composites to have bifunctional capabilities of harvesting both thermal energy and solar energy very rapidly. This work opens a new route for the design of bifunctional energy storage materials for ultrafast solar and thermal energy storage.

Thermal Analysis of Phase Change Materials With Embedded Graphite Nanofibers for Thermal Management of Electronics

2006 ◽  
Author(s):  
Thomas C. Kopec ◽  
Randy D. Weinstein ◽  
Amy S. Fleischer ◽  
Elizabeth D'Addio ◽  
Carol A. Bessel
Keyword(s):  
Phase Change ◽  
Thermal Management ◽  
Phase Change Materials ◽  
Thermal Response ◽  
Weight Percent ◽  
Fiber Loading ◽  
Graphite Nanofibers ◽  
Thermal Management Of Electronics ◽  
Cubic System ◽  
Transient Thermal

Phase change materials (PCMs) exhibit excellent thermal storage capacity due to their high latent heat of transformation and have been successfully utilized in small volumes for transient thermal management of electronics. However, their low thermal diffusivity makes it difficult to utilize large volumes of PCMs for transient thermal management of high power density systems. To improve the thermal performance of a paraffin PCM, high thermal conductivity graphite nanofibers are embedded into the paraffin PCM. The thermal effects of graphite fiber loading levels, measured in weight percent, are examined for a 131 cm3 volume cubic system with power loads of 3 and 7 W. It is found that the thermal response of the system improves with increased fiber loading levels.

scholarly journals Multi-Scale Numerical Modelling for Predicting Thermo-Physical Properties of Phase-Change Nanocomposites for Cooling Energy Storage

2021 ◽  
Vol 65 (2-4) ◽  
pp. 201-204
Author(s):  
Alessandro Ribezzo ◽  
Matteo Fasano ◽  
Luca Bergamasco ◽  
Luigi Mongibello ◽  
Eliodoro Chiavazzo
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Phase Change Materials ◽  
Mean Field ◽  
Heat Transfer Process ◽  
Computational Time ◽  
Latent Heat Storage ◽  
Aspect Ratios ◽  
The Impact

One major limitation of phase-change materials (PCM) for thermal energy storage comes from their poor thermal conductivity hindering heat transfer process and power density. Nanocomposites PCMs, where highly conductive nanofillers are dispersed into PCM matrices, have been exploited in the past decades as novel latent heat storage materials with enhanced thermal conductivity. A computational model based on continuum simulations capable to link microscopic characteristics of nanofillers and the bulk PCM with the macroscopic effective thermal conductivity of the resulting nanocomposite is the aim of this work. After preliminary mean-field simulations investigating the impact of the nanofiller aspect ratio on the thermal conductivity of the nanocomposite, finite element simulations at reduced aspect ratios have been performed with corrected thermal conductivity values of the filler, to take into account the thermal interface resistances between fillers and matrix. Finally, the thermal conductivity at the actual aspect ratios has been extrapolated by the results obtained at reduced aspect ratios thus saving computational time and meshing efforts. This method has been validated through comparison against previous literature evidence and new experimental characterizations of nanocomposite PCMs.

Pyrazolium Phase Change Materials for Solar-Thermal and Wind Energy Storage

2019 ◽  
Author(s):  
Karolina Matuszek ◽  
R. Vijayaraghavan ◽  
Craig Forsyth ◽  
Surianarayanan Mahadevan ◽  
Mega Kar ◽  
...  
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
High Efficiency ◽  
Scale Up ◽  
Solar Thermal ◽  
Energy Storage Materials ◽  
Solar Thermal Energy ◽  
Storage Materials

Renewable energy has the ultimate capacity to resolve the environmental and scarcity challenges of the world’s energy supplies. However, both the utility of these sources and the economics of their implementation are strongly limited by their intermittent nature; inexpensive means of energy storage therefore needs to be part of the design. Distributed thermal energy storage is surprisingly underdeveloped in this context, in part due to the lack of advanced storage materials. Here, we describe a novel family of thermal energy storage materials based on pyrazolium cation, that operate in the 100-220°C temperature range, offering safe, inexpensive capacity, opening new pathways for high efficiency collection and storage of both solar-thermal energy, as well as excess wind power. We probe the molecular origins of the high thermal energy storage capacity of these ionic materials and demonstrate extended cycling that provides a basis for further scale up and development.

Assessing the effect of night ventilation on PCM performance in high-rise residential buildings

2019 ◽  
Vol 43 (3) ◽  
pp. 229-249 ◽  
Author(s):  
Shahrzad Soudian ◽  
Umberto Berardi
Keyword(s):  
Thermal Energy ◽  
Phase Change Materials ◽  
Positive Impact ◽  
Residential Buildings ◽  
Solidification Rate ◽  
Operative Temperature ◽  
High Rise ◽  
Ventilation Strategies ◽  
Night Ventilation ◽  
The Impact

This article investigates the possibility to enhance the use of latent heat thermal energy storage (LHTES) as an energy retrofit measure by night ventilation strategies. For this scope, phase change materials (PCMs) are integrated into wall and ceiling surfaces of high-rise residential buildings with highly glazed facades that experience high indoor diurnal temperatures. In particular, this article investigates the effect of night ventilation on the performance of the PCMs, namely, the daily discharge of the thermal energy stored by PCMs. Following previous experimental tests that have shown the efficacy of LHTES in temperate climates, a system comprising two PCM layers with melting temperatures selected for a year-around LHTES was considered. To quantify the effectiveness of different night ventilation strategies to enhance the potential of this composite PCM system, simulations in EnergyPlusTM were performed. The ventilation flow rate, set point temperature, and operation period were the main tested parameters. The performance of the PCMs in relation to the variables was evaluated based on indoor operative temperature and cooling energy use variations in Toronto and New York in the summer. The solidification of the PCMs was analyzed based on the amount of night ventilation needed in each climate condition. The results quantify the positive impact of combining PCMs with night ventilation on cooling energy reductions and operative temperature regulation of the following days. In particular, the results indicate higher benefits obtainable with PCMs coupled with night ventilation in the context of Toronto, since this city experiences higher daily temperature fluctuations. The impact of night ventilation design variables on the solidification rate of the PCMs varied based on each parameter leading to different compromises based on the PCM and climate characteristics.

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