An experimental investigation and comprehensive modelling of thermal and rheological behaviour of graphene oxide nano platelets suspended mineral oil nano lubricant

Abstract

Suspension of nano additives in lubricants enhances its thermo-physical behaviour and prolongs the compressor durability in eco-friendly refrigeration systems. Therefore, this study investigates the influence of graphene oxide (GO) nano platelet concentration range of 0.05 – 0.75 vol%, temperature range of 30 – 90 °C and shear rate range of 5.48 s−1 to 190 s−1 on the thermal and rheological behaviour of mineral oil lubricant. Field Emission Scanning Electron Microscopy (FESEM) analysis confirms the platelet structure of GO with a maximum sheet thickness of 5 nm. FT-IR result confirms the pure physical interaction of GO with lubricant. Thermal conductivity and dynamic viscosity of nano lubricants ascended with increasing GO concentration and descended with increasing temperature. The maximum thermal conductivity enhancement of 70% was achieved for the nano lubricant with 0.75 vol% at 30 °C with respect to pure oil. Non - Newtonian shear thinning behaviour was possessed by both pure and nano lubricants at all temperatures. The Artificial Neural Networking (ANN) and mathematical correlation were developed to predict the thermo physical properties of nano lubricants. The maximum R-square value of 0.99998 and 0.9988 was achieved for ANN models of thermal conductivity ratio and relative viscosity of nano lubricants. The ANN model outperforms mathematical correlation by achieving maximum R-square and minimum mean square error (MSE).