Concentration and size dependence of nano-silver dispersed water based nanofluids

► Nano-Ag dispersed water based nanofluids (NFs) are synthesized by one-step method. ► Concentration and size of Ag nanoparticles (NPs) are main variables. ► Microstructure (of NPs) and thermal conductivity (k) of NFs are characterized. ► A maximum 21% enhancement in k at 0.001 M concentration and 55 nm size is noted. ► Brownian motion and clustering of nanoparticles closely predict experimental data.