Reviewing the experience of solar drying in Algeria with presentation of the different design aspects of solar dryers
No Thumbnail Available
Date
2011
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
Solar drying is one of the processes that have found application in Algeria, because of the important quantities
of solar irradiations that can be exploited in this country. Nevertheless, the experience of Algeria in
solar drying is recent and limited to drying of fruits, vegetables, medicinal and aromatic herbs. The effectuated
review has given an idea about the existing functional dryers in this country with presentation
of their different design aspects and in some cases the mathematical modeling for well describing and
predicting their behaviours. The solar dryers were classified into two classes according to their operation
mode and without taking into account if the dryers are using auxiliary sources of energy. The two classes
are: passive dryers and active dryers. On the other hand, each class was divided into subclasses representing
the type. We have found the direct and indirect types for the passive dryers, but only indirect types
for the active dryers. Mixed types were not developed. The solar dryers were developed and tested in two
different climatic regions which are the north of the country and the Sahara. In the most studied cases,
one or multiple auxiliary sources of energy were used in order to increase the performances of the dryer
or to decrease drying time. Consequently, we register the utilization of pebbles as a heat storage system,
resistances as electrical heater, gas-ring and photovoltaic cells in order to give independency against the
use of the traditional electrical energy. In the case of the active dryers, adding fans and temperature and
flow controllers has permitted the control of the drying conditions. Depending on the dryers, the dried
quantities vary from 200 g to 36 kg. Comparison between many studied cases for different modes and
types and with open sun drying method was furthermore done. With a few exceptions to some solar
dryers which present problems of complexity and was not practical and easy for manipulation to the
agricultural producer, the majority of the developed solar dryers have presented satisfactory results
Description
Keywords
Passive dryers, Active dryers, Auxiliary sources, Food, Herbs, Mathematical modeling