Experimental Investigation of Sustainable Low-Cost Thermal Energy Storage Materials for Solar Water Heating

An experimental study was carried out under climatic conditions of Gabes, Tunisia to evaluate the thermal performance of four innovative materials (sand, clay, concrete, PCM) as storage meduim integrated in a solar water heater. The four solar water heaters prototypes are realized then installed on site. The parameters followed in this study are the outlet water and the ambient temperature and the solar flux received according to two different inclinaison angle. A various temperature and thermal performance curves show the experimental results obtained during the measurement day (summer period). The vertical position of the solar collector shows positive results that ensure the hot water needs in the winter and avoid the overheating in the summer. All tested materials give an acceptable thermal effeciencies above 50% similar to that of the conventional system and reach a high water temperature value of 80°C. More than their thermal performance, clay and concrete have other advantages. Clay can be recycled and concrete can be integrated into the facades of a building. Whence, this investigation proves that the thermal storage materials tested during this work present a promising alternative offering the simplicity of manufacture and using low cost, local and available materials.