Thermal and Economical Study of Two Solar Water Heaters: the one Using Glass Wool and the other Vegetable Fiber as Thermal Insulator

摘要

Two solar water heaters using a thermosiphon system and each one of them including an internal heat exchanger have been designed and realized at Yamoussoukro (city located at the latitude of 6.58° N and longitude 5.27° W). Each one is made of a solar collector of a 2 m 2 surface and of a storage tank of 95 liters capacity. A comparative study of both thermal performances is realized. The parameters taken into account in the same conditions for the two devices are: the total radiation received by the solar collectors, the ambient temperature, the storage tank hot water temperature, the hot water average temperature in the collector, the hot water average temperature in the heat exchanger, the hot water instantaneous mass flow rate and the instantaneous efficiency of the collector. The level of the average temperature in the storage tank, 45°C for the coconut coir insulation and 55°C for the glass wool insulation, added to the relative simplicity in the realization of these devices and the absence of pumps and other accessories, make them an interesting technological solution. Moreover, the results obtained with the solar water heater by using the coconut fiber as heat insulator show that this system is viable under the local climatic conditions and could be used as a basis for popularization of solar heating water by using local materials as heat insulator. An economic study shows that the solar water heater using coconut fiber makes possible in one year to be more competitive compared to the solar water heater using the glass wood whose gives two years when the imported solar water heater whose investment return ranges between fifteen and sixteen years.