Heat transfer and flow characteristics of AL2O3–water nanofluid in a double tube heat exchanger

An experimental study was carried out in order to find out the effects of Al2O3 nanofluid with a mean diameter of 20 nm on heat transfer, pressure drop and thermal performance of a double tubes heat exchanger. The effective viscosity of nanofluid was measured in various temperatures ranging from 27 °C to 55 °C. Experiments were carried out at different Reynolds numbers ranging from 5000 to 20,000, approximately, and in various nanoparticles concentration up to 1% by volume. Results indicate that there is a good potential in promoting the thermal performance of heat exchanger by adding nanoparticles in the investigated ranges where there is not a severe pressure drop penalty. The empirical correlation was created for Nusselt number variation based on the Reynolds number and nanoparticles concentration.