Numerical simulation of an instrument to determine the thermal conductivity of conductive solids

¹ Centro Nacional de Investigación y Desarrollo Tecnológico, CENIDET-TecNM-SEP, Prol. Av. Palmira S/N. Col. Palmira, Cuernavaca 62490 Morelos, México
² Instituto Tecnológico de Campeche, ITCampeche – TecNM-SEP, Carretera Campeche-Escárcega km 9, Lerma 24500 Campeche, México

^a Corresponding author: jxaman@cenidet.edu.mx

Received: 1 August 2015
Accepted: 14 March 2016

Abstract

In this paper the design of a cut bar system to determine the thermal conductivity of conductive solid materials is presented. The system works under the comparative method, therefore two reference samples with known thermal conductivity are needed. The thermal design consisted on defining the physical configuration of the thermal system, materials to use and their dimensions, in order to evaluate their thermal performance by varying these parameters to calculate the maximum percentage design error. Given that the thermal design was parametric, the finite volume method was used to solve the heat conduction equation in the cut bar system, which allowed us to vary the different parameters that make up the thermal system such as length and diameter of the bars, insulation thickness, type of reference material, etc. The numerical code developed was verified with one analytical solution. It was found that, the thermal design of a cut bar instrument to determine the thermal conductivity of solid materials within the interval 0.58 ⩽ λ ⩽ 429 W.m^-1.K^-1 shows a maximum design error of 3.77% associated to the length of the sample material. The results in this paper allow one to kwon the error by design which can be taken into account as a source of uncertainty when determining the thermal conductivity of solid materials.