Binary nanoemulsion is defined as the nanoemulsion which basefluid is a binary mixture such as NH3/H2O solution. The objectives of this paper are to estimate the effect of nano-sized oildroplets on the performance of a diffusion absorption refrigerator(DAR) and to find the relationship between the dispersion stability and COP enhancement of the DAR system. The dispersion stability of binary nanoemulsionfluids for each oil concentrations is evaluated from the droplets size and Tyndall effect analysis. The COP enhancement of binary nanoemulsionfluid is compared with that of the conventional refrigerant. It is found that the binary nanoemulsionfluid increased the COP of the DAR system as high as 15% compared with that of the base fluid refrigerator.