Performance of latent heat stored nano fluid solar water heater

Solar thermal energy is by far the largest exploitable resource. It is a very convenient source of heating. It can be used free of charge, and does not need to be transported. The critical problem for solar thermal utilization is how to improve the efficiency of the solar collector. It can be performed with optimizing the structure of collector or developing a new type of working fluid. Currently, water as a fluid in solar thermal energy system is used widely. But the thermal conductivity of water is not high. With the development of nanotechnology, an innovative heat transfer fluid arise. Nanofluids, a relatively new class of fluids which consist of a base fluid with nano-sized particles (1-100 nm) suspended within them. These particles are generally metals or metal oxides. Nanofluids have been considered as a new-type heat transfer fluid because of their enhanced thermal conductivities. Recently some researchers have put forward to use the nanofluid as the working fluid for the solar collectors. Also, new technological advancements, like phase change materials (PCM), and their integration with solar collectors produced better results in recent years. In this work, an experimental study was performed to determine thermal performance of a two-phase thermosyphon solar water heater, which utilizes heat pipes filled with two different nanofluids and pure water. Al2O3-H2O, CuO-H2O nanofluids and pure water were used in experiments. Also, a latent heat storage unit filled with CaCl2.6H2O was integrated to condenser unit of this two-phase thermosyphon solar water heater system. The highest thermal performance has been obtained for CuO-H2O nanofluid while the lowest thermal performance has been obtained for pure water.