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Analytical estimation of the effective thermal conductivity of a granular bed in a stagnant gas including the Smoluchowski effect
Date Issued
01-11-2019
Author(s)
Peeketi, Akhil Reddy
Moscardini, Marigrazia
Pupeschi, Simone
Gan, Yixiang
Kamlah, Marc
Indian Institute of Technology, Madras
Abstract
Abstract: An analytical model including the Smoluchowski effect to estimate the effective thermal conductivity of a monosized granular assembly with interstitial stagnant gas from the microstructural parameters of the assembly, as well as the bulk properties of the granules and the gas is proposed in this paper. The discrete element method (DEM) is used for the generation and compaction of the granular assemblies. In the granular systems with interstitial gas, heat transfer occurs through the conduction between particles by solid overlap contacts and through the surrounding stagnant gas. Thermal radiation is included in the analytical model to study the influence of radiation on the thermal behavior of the assembly. The effective thermal conductivity is strongly influenced by the pressure of the gas as the conductivity of the gas decreases with decreasing pressure when confined in small gaps. This influence of the gas pressure is implemented in the analytical model. The effect of cyclic loading on the microstructural parameters is investigated through DEM simulations. Parametric correlations are developed to predict the values of microstructural parameters from experimentally measurable parameters so as to bypass any simulations for the estimation of effective thermal conductivity. A good agreement is observed between the analytical model and the experimental results for different assembly parameters and materials. The proposed analytical model can be used to get a first hand estimate of the effective thermal conductivity of a granular assembly to aid in the design process of such systems. Graphic abstract: [Figure not available: see fulltext.]
Volume
21