Analysis of flow and heat transfer characteristics of micro-pin fin heat sink using silver nanofluids

Silver nanofluids with three different volume fractions are prepared by a one-step chemical reduction method (Ultrasound-assisted Membrane Reaction (UAMR)). The convective heat transfer and friction characteristics of silver nanofluid in micro-pin fin heat sink are investigated experimentally. The results indicate that the pressure drops of nanofluids with different volume fractions have little difference. Compared to the base fluid (polyvinylpyrrolidone (PVP) solution), the pressure drop of nanofluids increases slightly at the same volume flow rate. When the flow rate is small, the increment is not obvious. The introduction of surfactant increases the fluid viscosity, so the pressure drops of nanofluids are larger than those of pure water, under the same flow rate. However, the maximum difference is no more than 10%. The volume fraction of silver nanoparticles significantly affects the convection heat transfer coefficient of micro-pin fin heat sink. The presence of nanoparticles improves significantly the heat transfer performance. However, high viscosity of the nanofluids hinders the heat transfer strengthening effect of nanofluids. In the present work, when the volume fraction of silver particles reaches to 0.012%, the thermal resistance of nanofluid gradually becomes lower than that of deionized water, which indicates the integrated heat transfer enhancement of nanofluids.