Turbulent convective heat transfer and pressure drop of dilute CuO (copper oxide) - water nanofluid Inside a circular tube

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Turbulent forced convective heat transfer and pressure drop of 0.01 vol.% CuO-water nanofluid was assessed experimentally. The nanofluids were made flow into a heated horizontal tube under uniform constant heat flux within Reynolds number range of 11,500 to 32,000. The first objective is to know how close traditional correlation/formula for, both, heat transfer and pressure drop can predict nanofluid’s heat transfer and pressure drop. The second is to know how nanofluid’s convective heat transfer and pressure drop are compared to those of its base fluid; in this case water. The results showed that the abovementioned characteristics of the nanofluid can be predicted by the traditional correlation available. It is also found that the nanofluid’s Nusselt number and friction factor, which represent the heat transfer rate and pressure drop, respectively, are close to those of water. Hence, there is no anomaly due to the dispersed nanoparticles within the water.KACST (King Abdulaziz City for Science and Technology

Gravity Gradient Effect on a LEO Satellite with an Elliptic Orbit and Unsymmetrical Mass Properties

The study presented in this paper investigates the dynamic behavior of a low earth orbit (LEO) satellite due to gravity gradient disturbances when the product of inertia terms of the spacecraft and the orbit eccentricity are considered. It is shown that the classical stable solution for the gravity gradient disturbance becomes unstable if at least one product of inertia term exceeds a critical value. Dimensional analysis technique is used to develop the significant dimensionless groups which were used to correlate the data generated from the response of the coupled roll, pitch and yaw dynamics. Based on the findings of these groups, stability maps are developed to predict the influence of the product of inertia terms on the long-term behavior of the spacecraft attitude dynamics. The developed stability maps are verified numerically and successful prediction of a spacecraft stability condition due to gravity gradient disturbance is achieved