DEVELOPMENT AND IMPLEMENTATION OF TRANSIENT HOT WIRE INSTRUMENT FOR MEASURING THERMAL CONDUCTIVITY AND DIFFUSIVITY OF NANOPARTICLES

Abstract

A transient hot wire instrument for measuring thermal conductivity and diffusivity of nanoparticle was developed. The instrument comprises of heating compartment which houses the nanoparticle sample whose thermal properties are to be measured. The heating compartment was made of tubular metallic material whose diameter and length are 1.8 cm and 10.0 cm respectively. One end of the tube was sealed up and the other end was provided with air-tight adjustable lid so that the content of the heating compartment can be maintained at different compatibility. Openings for two thermocouples, pressure sensor and nichrome wire leads were made on the metallic tube. The nichrome wire of diameter 0.85 mm and length 6cm was installed such that it lies at the centre of the tube. The heating wire was insulated from the metallic tube with the aid of ceramic materials so as to prevent short-circuiting. Thermocouples T1 and T2 were installed at 0.5mm and 5mm respectively away from the line heater. The thermocouples showed excellent performances when evaluated using standard mercury-in-glass thermometer. When used to measure thermal conductivity and diffusivity of free air, the instrument registered 0.2587W/m0C and 20.80 * 10-6 m2/srespectively which agree with the literature values. The instrument was thereafter employed to carry out test on Celtis philipis, Obeche Mahogany powders.