Sun Tracking Systems: A Review

The output power produced by high-concentration solar thermal and photovoltaic systems is directly related to the amount of solar energy acquired by the system, and it is therefore necessary to track the sun's position with a high degree of accuracy. Many systems have been proposed to facilitate this task over the past 20 years. Accordingly, this paper commences by providing a high level overview of the sun tracking system field and then describes some of the more significant proposals for closed-loop and open-loop types of sun tracking systems

A study of swirling flows in long straight pipes

The paper presents results of a study of the decay process of sw.irl in turbulent pipe flows. The experimental results, obtained using Laser-Doppler techniques, draw attention to a few flow effects not yet described thoroughly in the literature. A numerical analysis fails to predict some of these observed effects. Nevertheless, when a standard k-e : model is used, the rate of decay of the swirl is predicted to a fair degree of accuracy. The performance of second-order turbulence closures is less satisfying