Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.
In this work, we present the experimental evaluation of an apparatus that is meant to assess the heat transfer in natural convection conditions for short bars, using water as cooling down fluid. The probe was fabricated in copper, with 150 mm length and 25.4 mm internal diameter. The prototype was completely instrumented to obtain the convective coefficient and the values of the involved physical variables were registered using the Labview software. Heat was supplied with a 500 W electrical resistance regulated by an electronic rheostat. Temperature in different zones was registered using 50 K type thermocouples. The maximum temperature value was registered at the initial extreme of the bar which was 48.3 °C; at a radial distance of 0.003 m it was 43.1 °C and at 0.05 m, 35.2°C. Near the final extreme of the bar, the measured values were 36.6, 35.0, and 31.4 °C respectively. The initial temperature of the fluid and the environment were constant at 20 °C. A simulation of the experiment was performed using the Comsol Multiphysics software, obtaining an acceptable similitude.