Universidade Federal de Santa Catarina

The heat pipe technology is used in solar flat-plate collectors worldwide mainly when cold weather conditions are found. The main scope of this research is to develop a compact solar heating system using heat pipe technology with costs similar to conventional systems. Heat pipes of the two-phase closed thermosyphon – TPCT type were chosen, so that simple smooth pipes could be used. In the present work, some improvements are added to the TPCTs to reduce their thermal resistance. A liquid retention structure, made with a helicoidal of copper wire, is inserted in the evaporator, providing boiling nucleation sites and increasing the wetted region of the evaporator. Different configurations were tested. Four different filling ratios (0.2, 0.4, 0.6 and 0.8), the insertion or not of the liquid retention structure and the use of ethanol or water as working fluid are combined, resulting in sixteen different configurations