Estudo experimental da transferência de calor e queda de pressão de nanofluidos a base de óleo em escoamento laminar no interior de tubos horizontais

Abstract

The present work presents an experimental study of the heat transfer and pressure drop of oil based nanofluids, flowing inside horizontal tubes. The nanoparticles used were multi-walled carbon nanotubes. Such nanofluids were produced using the two step method in three different concentrations (0,005, 0,010 and 0,015 wt.%). The stability of nanofluids is analyzed through visual inspection and UVVIS spectroscopy. Thermophysical properties such as thermal conductivity, viscosity and density were measured experimentally. The experimental bench was instrumented and modified to satisfy the established test conditions. The uniform heat flux applied to the tube surface was 8 kW/𝑚􀬶, the mass flow rate varied between 7-17 g/s, the inlet temperature in the test section was kept constant at 55 °C, 60 °C and 65 °C. Based on parameters calculated as heat transfer rate, heat transfer coefficient and pumping power, an analysis of the thermo-hydraulic performance of nanofluids was carried out for their possible use as heat transfer fluid in thermal system applications. Based on the experimental results it was possible to conclude that the use of carbon nanotubes dispersed in oil showed an increase in the heat transfer coefficient compared to the base fluid. On the other hand, the pressure drop of nanofluids increased in comparison to the base fluid.