Table of Contents
ISRN Renewable Energy
Volume 2012, Article ID 789324, 8 pages
Research Article

An Experimental Study of Vegetable Solar Drying Systems with and without Auxiliary Heat

1College of Engineering, Nahrain University, P.O. Box 64040, Jadiriya, Baghdad, Iraq
2Department of Mechanical Engineering, University of Technology, Baghdad, Iraq

Received 13 April 2012; Accepted 6 June 2012

Academic Editors: S. Li, R. P. Saini, and S. Salter

Copyright © 2012 Abdul Jabbar N. Khalifa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


An experimental study is conducted to investigate the performance of a solely solar drying system and a system equipped with an auxiliary heater as a supplement to the solar heat. The performances of both are compared to that of natural drying. Beans and peas are dehydrated in a system that consists of two flat plate collectors, a blower, and a drying chamber. Tests with four different airflow rates, namely, 0.0383, 0.05104, 0.0638, and 0.07655 m3/s are conducted. It was found that the drying time was reduced from 56 hours for natural drying to 12–14 hours for solar drying and to 8-9 hours for mixed (solar and auxiliary) drying. The efficiency of the mixed drying system was found to increase by 25% to 40% compared to the solely solar drying. A best fit to the experimental data of peas and beans was obtained by six exponential equations for the various systems with a correlation coefficient in the range 0.933 and 0.997.