(38c) Low-Cost and High-Throughput Synthesis of Copper Nanopowder for Nanofluid Applications

Cu is low cost and efficient filler for nanofluids. However, commercially available Cu nanopowders are as costly as silver. A few methods are available for synthesis of Cu nanopowder, but the amount of powder produced by these methods are inadequate. Solution based high throughput continuous method for production of kgs of Cu nanopowder has been reported in this work. Cost of production is minimal in this method and nanoparticles are separated from the suspension by a controlled flocculation process. The proposed method relies on the higher solubility of cuprammonium complex in an aqueous medium and its chemical reduction using hydrazine hydrate. The colloid has been stabilized using sodium citrate and obtained as sub 50 nm powder re-dispersible in water and EG. Upon re-dispersion the sub 50 nm clusters have broken down to sub 10 nm particles. Continuous synthesis using a CSTR has been demonstrated, and the quality of particles are similar to that of the batch method. Stable nanofluids have been prepared by re-dispersing the nanopowder in water and EG. Good enhancement (~5%) in thermal conductivity for Cu-EG nanofluids and reasonable enhancement (~1%) for Cu-water nanofluid have been observed with mere 0.6 and 0.3 vol% loading respectively.