Effective thermal conductivity of composite spheres in a continuous medium with contact resistance

Felske, James D.

doi:10.1016/j.ijheatmasstransfer.2004.01.013

Cited by 193 publications

(119 citation statements)

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“…Their utilization in heat transfer was much less frequent until now. Within the last couple of years, some references appeared on using the effective media theories for estimation of thermal conductivity of refractory materials [11], [12], syntactic foams [13], polymer-based composites [14] but not a single reference was found by the authors for cementitious composites, in common sources.…”

Section: Introductionmentioning

confidence: 99%

Effect of Moisture on the Thermal Conductivity of a Cementitious Composite

et al. 2006

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The measurements of thermal conductivity of a cement-based composite material are performed in dependence on moisture content from dry state to fully water saturated state using an impulse technique. Then, the obtained data are analyzed using Brugemann and Wiener homogenization formulas. The validity of applied homogenization techniques is assessed comparing the measured and calculated results. On the basis of the experimental data and the homogenization analyses, the effects of total pore volume, pore distribution and moisture content on the thermal conductivity are discussed. Key words:Thermal conductivity, moisture content, cementitious composites, homogenization IntroductionCementitious composites contain a significant amount of pores of different size. As the thermal conductivity of the air is 0.026 W/mK [1] and the thermal conductivity of cement stone is (depending on the amount and the type of aggregates) in the range of 1-3 W/mK [2], both the total pore volume and the distribution of pores can affect the thermal conductivity of a cementitious material in a very significant way. In usual service conditions, cementitious composites always contain certain amount of water. The thermal conductivity of water is 0.60 W/mK [1], which is more than 20 times higher than of the air. Therefore, if water is present in the pore space, its effect competes with the effect of air, and the thermal conductivity of a composite material can be considered as a result of this competition together with the effect of the cement matrix.

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Section: Introductionmentioning

confidence: 99%

Effect of Moisture on the Thermal Conductivity of a Cementitious Composite

et al. 2006

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“…The effective thermal conductivity can also be calculated by considering the conductivity and the volume fraction of each component as established by Thiele et al [30] and reported by Felske [31] in Eq. 6 as:…”

Section: Theoretical Evaluation Of Proposed Tes Unitmentioning

confidence: 99%

Development of microencapsulated phase change material for solar thermal energy storage

Darkwa

Kokogiannakis

2017

Applied Thermal Engineering

118

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In this paper a novel microencapsulated phase change material (MF-3) has been developed and tested for solar assisted hot water storage systems. Even though the morphology of the sample was affected by the type of emulsifier used for fabrication it recorded the highest energy storage capacity of 126 kJ/kg with encapsulation efficiency of 97.4% as compared with other developed samples. For the purpose of assessing its thermal effectiveness it was theoretically evaluated in a compacted fixed bed TES unit and found to be capable of achieving a higher energy storage density as well as relatively smaller physical storage size than water based system. Despite the overall effective thermal conductivity being slightly less than water, its value was still about twice as high as most current PCM storage units. Experimental evaluation is therefore strongly encouraged.

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“…[14][15][16][17] In SCM, the thermal conductivity of a composite is derived by embedding one filler into an infinite matrix having the average properties of the composite. GSCM employs the same embedding process as SCM, but the embedded filler is different.…”

Section: Gscm For Predicting Thermal Conductivity Of Compositesmentioning

confidence: 99%

“…[14][15][16] Following the same procedures in the above derivations, the thermal conductivity of composite in the transverse direction, eq. (5b), can be derived.…”

Section: Composite With Spherical Fillersmentioning

confidence: 99%

“…12,13) This model has been applied to composites reinforced with simple shapes such as spherical fillers and continuous fibers for predicting the thermal conductivity of the composites, where a contact resistance at the interface between a matrix and fillers is considered. [14][15][16] A research on the thermal conductivity of composites with short fiber using GSCM is very limited. GSCM is presented for particulate composites, but particular emphasis is given to the special case of a cracked body with randomly oriented elliptical cracks.…”

Section: Introductionmentioning

confidence: 99%

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Generalized Self-Consistent Model for Predicting Thermal Conductivity of Composites with Aligned Short Fibers

Lee

Kim

2010

Mater. Trans.

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Thermal conductivities of aligned short fiber composites in the longitudinal and transverse directions are derived by extending the generalized self-consistent model proposed by Benveniste and Miloh. Their final forms are semi-explicitly expressed as functions of constituents' thermal conductivities, fiber aspect ratio, and the aspect ratio of the matrix surrounding the fiber. The results are proved to be consistent with those of composites with extreme shapes of fillers such as sphere and continuous fiber by simply changing a confocality variable. The present results for aligned short fiber composites are compared with Wu's upper and lower bounds to be validated. Finally, the predictions by the present model and modified Eshelby model are compared in terms of the thermal conductivity ratio of constituents, fiber aspect ratio, and fiber volume fraction and their accuracy for the predictions are evaluated by the experimental results from the literature.

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Effective thermal conductivity of composite spheres in a continuous medium with contact resistance

Cited by 193 publications

References 15 publications

Effect of Moisture on the Thermal Conductivity of a Cementitious Composite

Effect of Moisture on the Thermal Conductivity of a Cementitious Composite

Development of microencapsulated phase change material for solar thermal energy storage

Generalized Self-Consistent Model for Predicting Thermal Conductivity of Composites with Aligned Short Fibers

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