Development of a multi-purpose solar crop dryer for arid zones

Publication Type

Journal contribution (peer reviewed)

Authors

Lutz, K; Mühlbauer, W; Müller, J; Reisinger, G

Year of publication

1987

Published in

Solar and Wind Technology

Band/Volume

4/4

Page (from - to)

417-424

Abstract--A multi purpose solar crop dryer was developed for drying various agricultural products such
as fruits, vegetables, medicinal plants etc. The newly developed system consists of a small fan, a solar air
heater and a tunnel dryer. The simple design allows production either by farmers themselves, using cheap
and locally available materials, or by small scale industries. Due to the low investment required, the solar
dryer is predestined for application on small farms in developing countries.
Depending on the crop to be dried and the size of the dryer 100--1000 kg of fresh material can be dried
within 1-7 days to safe storage conditions. The solar dryer was successfully tested in Greece, Yugoslavia,
Egypt, Ethiopia and Saudia Arabia drying grapes, dates, onions, peppers and several medicinal plants.
Compared to traditional sun drying methods, the use of the solar dryer reduces drying time significantly
and prevents mass losses. Furthermore, product quality can be improved essentially. During drying, the
crop is protected completely from rain, dust, insects and animals. All these features contribute to the
desired high product quality. The energy costs required for operating the fan are negligible compared to
the additional earnings from reduced mass losses and improved quality. On-farm tests also showed that
the dryer can be easily operated by farmers. However, at present the dissemination of the solar dryer is
limited to electrified areas.