THERMAL PERFORMANCE OF A TWO-PHASE CLOSED THERMOSYPHON SOLAR SYSTEM USING DIFFERENT WORKING FLUIDS pp.143-152
Authors: (O. García-Valladares, A. Ordaz-Flores, V.H. Gómez, J. Cadafalch, Centro de Investigación en Energía, Universidad Nacional Autónoma de México, Privada Xochicalco s/n, Temixco, Mor. 62580, México, and others)
Abstract: The increasing interest of preserving the non-renewable resources has led to focus on sustainable growing, based mainly on using renewable energy. Renewable energy sources are the Sun, biomass, hydrogen, wind, etc. Among others, the Sun leads to thermosolar and photovoltaic technologies. The current chapter focus on thermosolar technology, particularly on Solar Domestic Water Heating Systems (SDWHS) to heat water for sanitary purposes. SDWHS permit to diminish the consumption of non-renewable energy (gas or electricity), helping to reduce the quantity of pollutants expelled to the atmosphere. A Two-Phase Closed Thermosyphon Solar Water Heating System consists of a flat plate solar collector coupled to a thermo tank by continuous tubing in which a two-phase working fluid circulates. The working fluid evaporates in the collector and condensates in the thermo tank transferring its latent heat to the water through a coil heat exchanger. Advantages of using a two-phase working fluid, instead of water, include the elimination of freezing, fouling, corrosion and scaling. Also there are no moving parts and there is no much need of maintenance. Disadvantages include the use of a working fluid different from water, higher costs and, in some cases, high pressures in the system. Different fluids must be tested and compared to find the most appropriate one.