Determination of the Temperature Coefficient of Volume Expansion Heat - Transfer Fluids by Using Refractometer

The aim of the submitted work is in the comparison of the two methods used for determination of the temperature coefficient of volume expansion (β) of heat transfer fluids. Temperature coefficient of volume expansion is one of the fundamental thermo-physical parameters monitored in the heat transfer fluids for solar collectors. A first method is based on commonly used Archimedes law principle and second deals with the determination via Abbe refractometer. Measurement of β using an Abbe refractometer is not very common, but in a practical way simpler and quicker than the methods based on the Archimedes principle. The identified thermal volume expansion coefficient under two different methods was compared and also has been found the relation between refractive index and β of the heat-transfer fluids measured by Abbe refractometer.