Objective Thermal Conductivity of Liquids & Nanofluids & Engine Oils etc.
Thermal Conductivity Apparatus
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 νs = ultrasound velocity,N (Avogadro's number) = 6.02×1023 and V (molar volume) =
KB= (Boltzmann's constant) = 1.3807×10-23 J/KFor Polyatomic Liquids it was modified as:
For Nanofluids it was further modified by J.Hemalatha as under:
where, kbm is the thermal conductivity value obtained through the modified Bridgman equation, ρnf is the density of nanofluid, and is the molar mass
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.
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.