Utilizing Disk Shaped Thermistors to Experimentally Determine the Prandtl Number Dependence Ranging From Vapors to Liquids

The current research utilizes disk-shaped thermistors to indirectly measure the convective heat transfer coefficient in the case of natural convection. Thermistors are resistors which have a resistance that is extremely temperature sensitive, so that experiments can be run with exceptional resolution. Not only can the convective heat transfer be indirectly measured, but so can the surface temperature, without the need for external temperature sensors which can interfere with the phenomena itself. Utilizing these themistors, heat transfer data was taken utilizing a variety of fluids from gasses (Pr = 0.72) to heavy oils (Pr ∼ 1000). From the experimental data, it was shown that the classical Nusselt-Rayleigh type correlation does not accurately predict the Prandtl number dependence for this geometry, and a new dimensionless correlation is proposed.