Influence of temperature on thermal conductivity of CuO nanofluid

Abstract

In the present article we report the synthesis of pure phase of CuO nanoparticles using Cu(NO:)z xH2O as precursor. The technique of synthesis is very fast, cheap and green materials technique. The CUO nanoparticles used in the experiment are rod-like, with a mean length of about 23-26 nm. They can be stably suspended in ethylene glycol for several months. Also stability of nanofluid prepared by such technique is better than that obtained by two step process. The effect of particle volume fraction and temperature on thermal conductivity of CuO-EG nanofluids developed using continuous chemical technique is studied. The thermal conductivity of the nanofluids was studied using the LAMBDA system based on the principle of instationary heat-wire instrument with a very small sensor. The output of the instrument is highly stable and reproducible. Experimental data indicates that the size, volume fraction and properties of nanoparticles (shape, nano layer thickness and material properties) influence the heat transfer characteristics of nanofluids. The experimental results show that the increase in therrnal conductivity with volume fraction is non-linear while that with temperature is linear. Further, the effect of temperature change on the thermal conductivity of nanofluids is greater than that of volume fraction change. For 1.78 percent of the volume fraction the rise in temperature from 25"C to 75oC enhances thermal conductivity by 10.5 percent to 20 percent. Therefore, when the copper oxide nanofluids are applied to the heat exchange device under medium and high temperature, an optimal radiation effect can be acquired.