DIRECT ILLUMINATED ROCK-BED HEAT STORAGE A POTENTIAL COMPONENT OF A SOLAR THERMAL SYSTEM FOR FOOD PRESERVATION AND SPACE HEATING IN RURAL AREAS OF MOZAMBIQUE

摘要

Sun drying is a well known method of food preservation in countries with high level of solar irradiation and one of the ancient applications of solar energy. This method is widely applied for drying different agricultural products, meat and fish in rural areas of Mozambique. However, sun drying is ineffective method for food preservation and lead to poor product quality and post harvest losses. A more effective method of solar radiation deployment for food preservation is solar drying, which involves solar dryers. But many of them are direct solar dryers. Therefore they exhibit the same intermittent nature as the source of radiation does, which turn them useless devices during off-sun conditions. In order to extend the usefulness of solar dryers even in off-sun conditions, heat storage must be incorporated. In this study, in an in-door test, the potential of a direct illuminated rock-bed heat storage based on natural convection of air is experimentally investigated. The results show a good potential of rock-bed heat storage to supply thermal energy for low-to-medium temperature applications.