• R N Pande

Articles written in Pramana – Journal of Physics

• Bounds on the effective thermal conductivity of two-phase systems

The weighted geometric mean of resistors considered for determining the effective thermal conductivityKE of two-phase systems has been optimised. Solutions of the equations lead to a useful set of bounds. When compared with other bounds the present bounds give the better results in estimating the upper and lower values of the effective thermal conductivity of a two-phase system.

• Thermal conduction in a homogeneous two-phase system

Assuming a regular geometry of dispersed phase (λ2) an integrated theory for the effective thermal conductivityλe of all kind of two-phase materials (including loose materials) is developed. The flux modification is carried out by considering the effective neighbouring interactions in the solution of Poisson’s equation. A comparison of calculatedλe values with the reported experimental results over a wide range of two-phase materials shows a good agreement.

• Thermal conduction through loose and granular two-phase materials at normal pressure

The integrated theory derived for the lattice-type dispersions is modified and extended to estimate the effective thermal conductivity of loose and granular two-phase materials at normal pressure assuming an effective continuous media approximation. A comparison of calculated values ofλe with the reported experimental results over a wide range of loose and granular two-phase materials shows a good agreement.

• Effective thermal conductivity of granulated two-phase systems at interstitial air pressures

Considering the htermal conduction through molecular collisions an expression for the effective thermal conductivityλe of loose and granular two-phase materials at different interstitial air pressure has been derived. The dependence ofλe on pore and particle sizes, characteristic pressure and radiative heat transfer is also discussed. Calculated values ofλe of glass beads and loose building materials are compared with reported results.

• Thermal conduction through porous and dispersed three-phase systems

A loose three-phase system made of metal, non-metal and air is considered resulting from small successive dispersions in effective continuous medium (ecm). The effective thermal conductivity of loose three-phase systems is estimated by extending theecm approach to multi-phase systems. The unsteady state line source (needle) method is employed to determine the effective thermal conductivity of some selected three-phase materials. The calculated and observed values show good agreement suggesting that the continuous medium approach can be applied to estimate effective thermal conductivity of multi-phase systems.

• Effective medium in dispersed systems

A structural analysis of effective medium formed by dispersed systems from the viewpoint of flux modification at large dispersions is presented. The effective medium coefficient is investigated for its parametric dependence and the effective properties are estimated through this dependence. This estimation covers all highly dispersed two-phase systems including the effect of container.

• # Pramana – Journal of Physics

Volume 96, 2022
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019