| The work presented here describes a method for calibrating a recently designed device that will measure the thermal conductivity of liquids at elevated temperatures. Molten salts are specifically the liquids addressed in this research, as they are becoming a highly researched topic in relation to thermal energy storage as phase change materials and heat transfer fluids in the solar industry. Because there is no conclusive experiment in which the thermal conductivity of molten salts has been measured, a device has been designed and calibrated for this specific task. The function introduced herein, for calibration purposes, is an asymptotic solution to the transient diffusion equation and is used to curve fit the experimentally determined temperature versus time data to calculate the thermal conductivity of the test liquids at various elevated temperatures. Experiments were conducted on water and propylene glycol as part of the calibration procedure. For water at 23 C, the measured thermal conductivity values were within 3 % of the literature value for all experimental trials. For propylene glycol over a temperature range from 24 C to 100 C, percent errors of up to 19 % were found. The high error found in the propylene glycol experiments is due to the poor temperature control of the available test furnace. In order to reduce error a furnace with a higher degree of temperature control must be used in order to achieve equilibrium within in the test liquid. |
