Convective heat transfer performance of thermal oil-based nanofluids in a high-temperature thermohydraulic loop

Enhancing the performance of heat transfer fluids (HTF) is a key target for improving the efficiency of many industrial processes. Employing nanofluids for this purpose, by dispersing nanoparticles into the initial HTF to improve its thermo-physical properties, is one possible way to increase its heat transfer capacity. However, testing these properties at high temperature is not always easy. An experimental setup consisting of a thermohydraulic loop for high-temperature heat transfer measurements was developed in this work. The accuracy and repeatability of the measurements taken in the heat transfer loop were ensured. A nanofluid consisting of a commercial thermal oil, doped with Sn nanoparticles at 1 wt% and olive oil surfactant used to enhance colloidal stability, was tested and compared to the results obtained for the base fluid and the base fluid/stabiliser mixture employing their experimentally measured thermo-physical properties. The nanofluid generally enhanced the convective heat transfer coefficient in relation to the base fluid with enhancements of up to 7.23% at 200 degrees C and 9.43% at 140 degrees C vs. the pure base fluid.