Specific Heat of Nanocrystalline Materials

Malinovskaya, T. D.; Sachkov, V. I.

doi:10.1023/b:rupj.0000028157.40453.35

Cited by 3 publications

(3 citation statements)

References 1 publication

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“…The decrease in heat capacity for the CB NEIL may be due to the increased thermal conductivity of the system, because carbonaceous materials are known to have very high thermal conductivity . In nanocrystalline materials, a larger grain size will also correlate to a higher heat capacity . VP-1-containing nanoparticles could not be tested in this study because of the high volatility of the fluid.…”

Section: Resultsmentioning

confidence: 99%

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Potential of Nanoparticle-Enhanced Ionic Liquids (NEILs) as Advanced Heat-Transfer Fluids

2011

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803-507-8560 RECEIVED DATEKEYWORDS. Nanoparticle enhanced ionic liquid, heat transfer fluid, concentrating solar power, 1-Butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, nanofluid INTRODUCTIONInterest in capturing the energy of the sun is rising as demands for renewable energy sources increase. One area of developing research is the use of concentrating solar power (CSP), where the solar energy is concentrated by using mirrors to direct the sunlight towards a collector filled with a heat transfer fluid (HTF). 1 The HTF transfers the collected energy into pressurized steam, which is used to generate energy. The greater the energy collected by the HTF, the more efficent the electrical energy production is, thus the overall efficiency is controlled by the thermal fluid. Commercial HTFs such as Therminol ® (VP-1), which is a blend of biphenyl and diphenyl oxide, 2 have a significant vapor pressure, especially at elevated temperatures. 1 In order for these volatile compounds to be used in CSP systems, the system either has to be engineered to prevent the phase change (i.e., volatilization and condensation) through pressurization of the system, or operate across the phase change. 3 Over thirty years ago, a class of low-melting organic compounds were developed with negligible vapor pressure. 4 These compounds are referred to as ionic liquids (ILs), which are organic-based compounds with discrete charges that cause a significant decrease in their vapor pressure. 5 As a class, ILs are molten salts with a melting point below 100 o C and can have a liquidus range approaching 400 o C, and in several cases freezing points being below 0 o C. 6 Due to the lack of an appreciable vapor 1 pressure, volatilization of an IL is not possible at atmospheric pressure, 5 which would lead to a simplification of the design if used as a thermal fluid and for energy storage materials. 7 Though the lack of a vapor pressure does not make the use of ILs a better HTF, the lack of a vapor pressure is a compliment to their higher heat capacity, higher volummetric density, and thus higher volumetric heat capacity. 8 These favorable physical properties give ILs a pontential advantage over the current commerically used thermal fluids. Also within the past decade nanofluids have gained attention for thermal conductivity enhancment of fluids 9 , but little analysis has been completed on the heat capacity effects of the nanoparticle addition.The idea of ILs or nanofluids as a HTF is not new, as there are several references that have proposed the idea. 8, 10 However, the use of ionic liquid nanofluids containing nanomaterials other than carbon nanotubes has never before been studied. Here, for the first time, nano-particle enhanced ILs (NEILs) have been shown to increase the heat capacity of the IL with no adverse side effects to the ILs' thermal stability and, only at high nanoparticle loading, are the IL physical properties affected. An increase of volumetric heat capacity translates into a better heat transfer fluid as more energy i...

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Section: Resultsmentioning

confidence: 99%

“…13 In nanocrystalline materials, a larger grain size will also correlate to a higher heat capacity. 14 Energy & Fuels COMMUNICATION volatility of the fluid. We are currently devloping methods to measure heat capacity and thermal stability in a pressurized environment to characterize VP-1-containing nanoparticles for comparison to NEILs.…”

Section: ' Introductionmentioning

confidence: 99%

Potential of Nanoparticle-Enhanced Ionic Liquids (NEILs) as Advanced Heat-Transfer Fluids

2011

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“…However, if nanoparticles reduces to a cluster of, say, 100 atoms, the bulk-like arrangement of atoms is lost, and the vibration modes of the atoms are influenced by their spatial locations, see e.g. [10][11]. Therefore, only above a certain limiting size of a nanoparticle the heat capacity can be described by ρ e c F,e .…”

Section: Heat Transfer In Nanoparticlesmentioning

confidence: 99%

Temperature fields in particles and in their environment due to sudden phase transformations

Fischer¹,

Leindl

Dirschmid³

et al. 2010

Z Angew Math Mech

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Heat can be released or consumed in particles in a nearly adiabatic way due to phase transformation, thermal fluctuation, etc. In this case a temperature field, strongly varying in space and time, develops in the particle in addition to the global temperature field. Analytical as well as numerical solutions for this additional temperature field are presented for identical and different thermal properties of both the particle and its environment. The case of heat conduction and of heat transfer is dealt with. Consequences for nanoparticles are discussed.

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On the role of surface energy and surface stress in phase-transforming nanoparticles

Fischer

Waitz

Vollath

et al. 2008

Progress in Materials Science

236

155

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Specific Heat of Nanocrystalline Materials

Cited by 3 publications

References 1 publication

Potential of Nanoparticle-Enhanced Ionic Liquids (NEILs) as Advanced Heat-Transfer Fluids

Potential of Nanoparticle-Enhanced Ionic Liquids (NEILs) as Advanced Heat-Transfer Fluids

Temperature fields in particles and in their environment due to sudden phase transformations

On the role of surface energy and surface stress in phase-transforming nanoparticles

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