Thermal performance of a micro heat exchanger (MHE) working with zirconia‑based nanofuids for industrial cooling

An experimental investigation was performed with the view to assess the heat transfer characteristics of a water-based nanofuid in a micro heat exchanger employed to quench a high heat fux heater for industrial and microelectronic cooling applications. The experiments were conducted at heat fuxes 10–70 kW/m2 and for nanofuids at various mass concentrations of 0.1–0.3% and passing fow rates of 0.1–5 l/min. Thermo-physical properties of the nanofuid including thermal conductivity, heat capacity, density and viscosity of nanofuid were experimentally measured at 40 °C close to the temperature of the experiments. Results showed that the heat transfer coefcient and pressure drop were augmented by 40.1% and 67% at wt%=0.3 compared to the base fuid, respectively. The enhancement in the heat transfer coefcient was associated with the improvement in the thermal conductivity of the base fuid together with the intensifcation of Brownian motion and thermophoresis efect. The increase in the pressure drop was also attributed to the increase in the viscosity of the working fuid which induces layer–layer frictional forces in the bulk of the coolant in micro heat exchanger.