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A review of new technologies, models and experimental investigations of solar driers M.V. Ramana Murthy * Department of Mechanical Engineering, Osmania University College of Engineering, Osmania University, Hyderabad 500007, India abstract An attempt is made to review various aspects of solar driers applied to drying of food products at small scale. Popular types of driers in Asia-Pacific region, and new types of driers with improved technologies are discussed. The open sun drying and some alternate solutions are presented. The various aspects considered for modeling and experimental investigations carried out on various food products are also presented. Finally, the performance evaluation of the drier is discussed in detail. It is found that there is a shorter way of estimating the performance of a drier. A review of new technologies, models and experimental investigations of solar driers.pdf

Drying of hot chilli using solar tunnel drier M.A. Hossain a,*, B.K. Bala b a Farm Machinery and Postharvest Process Engineering Division, Bangladesh Agricultural Research Institute, Gazipur-1701, Bangladesh b Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh Received 28 July 2004; received in revised form 9 June 2006; accepted 9 June 2006 Available online 24 August 2006 Communicated by: Associate Editor Istvan Farkas Corresponding author * Abstract A mixed mode type forced convection solar tunnel drier was used to dry hot red and green chillies under the tropical weather conditions of Bangladesh. The drier consisted of transparent plastic covered flat-plate collector and a drying tunnel connected in series to supply hot air directly into the drying tunnel using two fans operated by a photovoltaic module. The drier had a loading capacity of 80 kg of fresh chillies. Moisture content of red chilli was reduced from 2.85 to 0.05 kg kg1 (db) in 20 h in solar tunnel drier and it took 32 h to reduce the moisture content to 0.09 and 0.40 kg kg1 (db) in improved and conventional sun drying methods, respectively. In case of green chilli, about 0.06 kg kg1 (db) moisture content was obtained from an initial moisture content of 7.6 kg kg1 (db) in 22 h in solar tunnel drier and 35 h to reach the moisture content to 0.10 and 0.70 kg kg1 (db) in improved and conventional sun drying methods, respectively. The use of a solar tunnel drier and blanching of sample led to a considerable reduction in drying time and dried products of better quality in terms of colour and pungency in comparison to products dried under the sun. The solar tunnel drier and blanching of chilli are recommended for drying of both red and green chillies. Drying of hot chilli using solar tunnel drier.pdf