Effect of nanomaterial properties on thermal conductivity of heat transfer fluids and nanomaterial suspension

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Energy has been rated as the single most important issue facing humanity in the current as well as next 50 years. Securing clean energy has become the top priority of most developed countries. Considering the rapid increase in energy demand worldwide, intensifying the heat transfer process and reducing energy loss due to ineffective use have become an increasingly important task. Fundamentally, energy conversion and transportation occur at atomic or molecular levels, Nanoscience and nanotechnology are expected to play a significant role in revitalizing the traditional energy industries and stimulating the emerging renewable energy industries. Nanofluid is a modern engineering heat transfer fluid with superior potential for enhancing the heat transfer performance of conventional fluids such as water, ethylene glycol and oils. It is consisting of solid nanoparticles with sizes typically of 1–100 nm suspended in base fluids. Many attempts have been made to investigate its important thermal properties, i.e. thermal conductivity; however, no definitive agreements and idea have emerged about this property. This article reports the effect of different nanomaterial on the thermal conductivity enhancement of nanofluids experimentally. TiO2, Fe3O4 and Al2O3 nanoparticles dispersed in water and ethylene glycol with volume concentration of 1 – 7.5 vol. % is used in the present study. A transient hot-wire apparatus (KD2 pro) is used for measuring the thermal conductivity of nanofluids. The results show that all the heat transfer fluids show an increase in thermal conductivity with the addition of nanoparticles in it. The measured thermal conductivity of nanofluids increased as the particle concentrations increased and are higher than the values of the base liquids. This confirms the effect of volume concentration of nanoparticles on the thermal conductivity enhancement