Performance of Prototype Solar Tunnel Drier Developed by University of Hohenheim Under Local Environmental Conditions in Sri Lanka

Abstract

The solar tunnel dryer developed by University of Hohenheim was studied under local environmental conditions in Sri Lanka to identify necessary improvements so that marketable dehydrated products could be produced. Batch trials were carried using jak fruit (Artocarpus heterophyllus) and brinjal (Solanum melongena). Temperature, relative humidity and air flow rate during the trial period were recorded. Drying duration, physico-chemical and orgonoleptic parameters of the dehydrated products were determined. The dryer was found to be technically feasible and products are hygienically good compared to the open sun drying. Depending on bad weather conditions drying duration varied between 2- 3 days causing to produce organoleptically unacceptable dehydrated products. The reasons identified for unacceptable quality were the long dying periods and keeping the materials inside the drying compartment overnight without drying. Therefore, there is a necessity to shorten the drying period together with maintenance of a correct temperature inside the drying compartment during non solar hours to preserve the quality of dried products.