Influence of particle concentration and temperature on thermal conductivity and viscosity of Al2O3/R141b nanorefrigerant

Refrigerant-based nanofluids are termed as nanorefrigerants. They have the potential to enhance the heat transfer performances of refrigeration and air-conditioning systems. In this paper, thermal conductivity and viscosity of the Al2O3/R141b nanorefrigerant for 0.5 to 2 vol.% concentrations at temperatures of 5 to 20 degrees C have been investigated. Al2O3 particles with average diameters of 13 nm were used with the R141b refrigerant The experimental results show that, thermal conductivity of the Al2O3/R141b nanorefrigerant increased with the augmentation of particle concentrations and temperatures. Besides, viscosity of the nanorefrigerant increased with the increase of volume fractions. However, this parameter decreased accordingly with the increment of temperature. The highest thermal conductivity and viscosity were observed to be 1.626 and 179 times greater than the base fluid for 2 volume concentration (%) of particles, respectively. Therefore, optimal concentrations of nanoparticles need to be dispersed in the refrigerant considering the thermal conductivity and viscosity for better heat transfer performance. (C) 2013 Elsevier Ltd. All rights reserved.