Binary nanofluids, nanoparticle suspensions in binary mixture, are developed to enhance the heat and mass transfer performance of absorption refrigeration cycles. To stabilize the nanoparticles in a strong electrolyte, polymer is used as a steric stabilizer. The effective thermal conductivities of the binary nanofluids with the concentrations of nanoparticle up to 0.1 vol% are measured using the transient hot wire method. Comparing the thermal conductivity change with time, it is found that the dispersion stability of nanofluids is a dominant factor for enhancing the thermal conductivity of binary nanofluids. It is also found that the thermal conductivity of the binary nanofluids (H2O/LiBr binary mixture with Al2O3 nanoparticles) increases with the particle volume concentration and enhances by 2.2% at 0.1 vol% concentration condition. Also a modified dimensionless group is proposed to find the maximum radius of nanoparticles to maintain stable nanofluids. In this study, it was estimated similar to 1.3 mu m. (C) 2011 Elsevier Ltd. All rights reserved.