Thermal Conductivity Apparatus

Thermal Conductivity Apparatus   

Theory

The Apparatus follows widely accepted theory of heat conduction in liquids based on Debye’s concept in which the hydroacoustic vibrations (phonons) of a continuous medium(base fluid) are responsible for the heat transfer in liquids. Based on this heat transfer mechanism, Bridgman has obtained a formula, characterized by the direct proportionality between thermal conductivity and sound velocity in pure liquids.

where ν_s = ultrasound velocity,

 K_B= (Boltzmann's constant) = 1.3807×10-23 J/K

For Nanofluids it was further modified by J.Hemalatha as under:

where, k_bm is the thermal conductivity value obtained through the modified Bridgman equation, ρnf is the density of nanofluid, and is the molar mass
of nanofluid. x_bf and x_p are the molar fractions of the base fluid
and nanoparticle respectivelywhereas M_bf and M_p are the respective molar masses of the base fluid and nanoparticle.

Working Principle

Ultrasound waves of known frequency are produced and its wavelength is measured. Then sound velocity in Liquid

After calculating velocity of sound in Liquid, one can calculate the thermal conductivity by the formula given by P W Bridgman.

Description

Thermal Conductivity Apparatus consists of following parts: Electronic Unit,Conductivity Cell-2MHz,Stability Cell 4MHz to increase settling time of the suspension,Temperature Controller Unit-To maintain temp.of liquids / nanofluids at desired temp from RT to 70°C.