Experimental investigation into thermal conductivity and viscosity of Al2O3 based engine coolant (nanocoolant)

Abstract

Nanocoolant is an engine coolant produced by mixing, of Al2O3 nanoparticles of various sizes and shape like; 20 nm (spherical), 40 nm (spherical) and 40 nm (elongated) into conventional coolants. Recent investigations into nanofluids show that they have improved thermophysical properties over the conventional fluids like; water, ethylene glycol etc. In spite of best thermal design, materials, the performance of any engine coolant is restricted due to its inherited poor thermal conductivity. Solution to this problem can be sort out from the newly discovered nanomartials based coolants (nanofluids). It has been also observed that nanofluids have potential to improve the performance of cooling medium as, they shows improved themophyiscal properties over the conventional fluids. This paper represents a brief report on the investigations carried out on thermal conductivity and viscosity of Al2O3 based engine coolant, in the temperature range of 25 ºC to 45 ºC. Engine nanocoolant is tested for 0.1, 0.3 and 0.5 volume concentrations of Al2O3 nanoparticles. Thermal conductivity is measured by using KD2 pro a thermal property analyzer and Viscosity of nanofluid is measured by using Brookfield Viscometer LV DV-III CP. Experimental investigation revealed that, at lower temperature increase in thermal conductivity is less,whereas at high temperature (35 ºC to 45 ºC) the enhancement is more. It is also found that viscosity decreases with increases in temperature. At a particular temperature results show increases in thermal conductivity with increase in volume concentration % of nanoparticles and viscosity also increases with the increases in volume concentration % of nanoparticles. Nanoparticles of 20 nm size nanoparticles show higher thermal conductivity than 40 nm. At 0.5% volume concentration , the maximum enhancement in thermal conductivity by 20 nm Al2O3 (spherical) at 40 ºC is 5.7% and maximum value of viscosity at 25 ºC increases 91.7% for 20 nm and 101% for 40 nm compared to base fluid. The nanocoolants with elongated 40 nm particles show highest thermal conductivity than 20 nm & 40 nm (spherical). At 0.5% volume concentration enhancement is shown by elongated Al2O3 nanoparticles compared with base fluid at 45 ºC is 8.4% whereas maximum viscosity enhancement at 25 ºC is 201% compared to base fluid.