Effects of connecting pipes in thermosyphonic solar systems

Abstract The influence of thermal insulation of pipes in thermosyphonic systems is simulated. In spite of their normally small heat transfer area, these pipes are capable of triggering a reverse flow which causes a substantial drop in the overall efficiency. A clear recommendation of this paper is that at least the upper pipe should be properly insulated. The system's efficiency dependence on the high difference between the collector's top and the tank's bottom is studied. The results indicate that this height should be in the range of 30–80 cm.