Manufacturing and Evaluating of Indirect Solar Dryers

A Case Study for the Kurdistan Region of Iraq

Keywords: Drying efficiency, Eggplant, Experimentation, Indirect solar dryer, Solar energy


–Indirect solar drying uses solar radiation to heat air and dry agricultural products in harvest time to store them for a longer time and reduce waste. The dryer consists of a solar air heater collector, a drying chamber, and an air ventilation system. In this study, an indirect solar dryer system is constructed and ventilated with an electrical fan. Experiments are conducted on the system using eggplant as an agricultural sample on 2 consequent days (29th and 30th October 2022), to evaluate the system data recorded during the drying process in terms of the temperature for points in the system, solar radiation, and the sample mass. The temperature measurements are ambient, collector, and dried chamber outlet temperatures. The results show that the most effective time for solar drying is between 9:00 and 16:00, and the drying system air temperature is raised to about 40°C when solar radiation reached more than 600 W/m2 in the noon time. The weighted mass is used to
evaluate the drying process, and maximum drying rate and drying efficiency are obtained on the 1st day of the drying before noon time.


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Author Biography

Dara K. Khidir, Department of Manufacturing and Industrial Engineering, Faculty of Engineering, Koya University, Koya, KOY45, Kurdistan Region - F.R. Iraq

Dara Khalid Khidhir is an assistant  lecturer at the Department of Petroleum at Koya University, since 2014. He has a B.Sc. degree in Mechanical Engineering in 1998 and M.Sc. degree in Mechanical Engineering (Thermal Power) in 2013. His main research area is Energy and Renewable Energy analysis, Internal combustion engines, and simulation of Thermal Systems. Mr. Dara is a Mechanical Engineer at the Presidency of Koya University and He is member of Kurdistan Engineering Union and He has an experience in maintenance of Heavy duty machines. 


Brenndorfer, B., Kennedy, L., Bateman, C., Trim, D. S., Mrema, G. C., and Wereko-Brobby, C., 1987. Solar Dryers-their Role in Post-harvest Processing. 1st ed. Commonwealth Science Council, London.

Cherotich, S., and Simate, I. N., 2016. Experimental investigation and mathematical modelling of a natural convection solar tunnel dryer. International Journal of Scientific and Engineering Research, 7(5), pp.597-603.

Chouicha, S., Boubekri, A., Mennouche, D., and Berrbeuh, M. H., 2013. Solar drying of sliced potatoes. an experimental investigation. Energy Procedia, 36, pp.1276-1285. DOI:

Díaz, R.I., Gómez, R.A.J., Danguillecourt, O.L., de Paz, P.L., Vázquez, N.F., and Duharte, G.R.I., 2017. Design, construction and evaluation of a solar dryer for Ataulfo mango. Revista Mexicana de Ciencias Agrícolas, 8, pp.1719-1732. DOI:

Ertekin, C., and Yaldiz, O., 2004. Drying of eggplant and selection of a suitable thin layer drying model. Journal of Food Engineering, 63(3), pp.349-359. DOI:

Fernandes, L., Fernandes, J.R., and Tavares, P.B., 2022. Design of a friendly solar food dryer for domestic over-production. Solar, 2(4), pp.495-508. DOI:

Hii, C.L., Jangam, S.V., Ong, S.P., and Mujumdar, A.S., 2012. Solar Drying: Fundamentals, Applications and Innovations. TPR Group Publication, Singapore. Available from: [Last accessesd on 2022 Oct].

Jadallah, A., Alsaadi, M., and Hussien, S., 2020. The hybrid (PVT) double-pass system with a mixed-mode solar dryer for drying banana. Engineering and Technology Journal, 38(8), pp.1214-1225. DOI:

Jassim, N.A., and Hassan, S.S., 2018. Thermal Performance Evaluation of Solar Air Dryer for Food Drying in Iraq. Available from: https://www.researchgate. net/publication/324991813 [Last accessed on 2022 Nov].

Khan, Y., Kasi, J.K., and Kasi, A.K., 2018. Dehydration of vegetables by using indirect solar dryer. Techno-Science Scientific Journal of Mehmet Akif Ersoy University, 1(1), pp.22-28.

Karami, H., Kaveh, M., Golpour, I., Khalife, E., Rusinek, R., Dobrzański, B. Jr., and Gancarz, M., 2021. Thermodynamic evaluation of the forced convective hybrid-solar dryer during drying process of rosemary (Rosmarinus officinalis l.) leaves. Energies, 14(18), p.5835. DOI:

Khalil, M. H., Ramzan, M., Rahman, M. U., and Khan, M. A., 2012. Development and evaluation of a solar thermal collector designed for drying grain. Iranica Journal of Energy and Environment, 3(4), pp.380-384.

Krabch, H., Tadili, R., Idrissi, A., and Bargach, M., 2022. Indirect solar dryer with a single compartment for food drying. Application to the drying of the pear. Solar Energy, 240, pp.131-139. DOI:

Kumar, A., Singh, K. U., Singh, M. K., Kushwaha, A. K. S., and Kumar, A., 2022. Design and fabrication of solar dryer system for food preservation of vegetables or fruit. Journal of Food Quality, 2022, p.6564933. DOI:

Leon, M.A., Kumar, S., and Bhattacharya, S.C., 2002. A comprehensive procedure for performance evaluation of solar food dryers. Renewable and Sustainable Energy Reviews, 6(4), pp.367-393. DOI:

Lingayat, A.B., Chandramohan, V.P., Raju, V.R.K., and Meda, V., 2020. Areview on indirect type solar dryers for agricultural crops-dryer setup, its performance, energy storage and important highlights. Applied Energy, 258, p.114005. DOI:

Mahmood, F.H., and Al-Hassany, G.S., 2014. Study global solar radiation based on sunshine hours in Iraq. Iraqi Journal of Science, 55(4), pp.1663-1674.

Montero, I., Miranda, M.T., Sepúlveda F.J., Arranz, J.I., Rojas, C.V., and Nogales, S., 2015. Solar dryer application for olive oil mill wastes. Energies, 8(12), pp.14049-14063. DOI:

Ramirez, C., Palacio, M., and Carmona, M., 2020. Reduced model and comparative analysis of the thermal performance of indirect solar dryer with and without PCM. Energies, 13(20), p.5508. DOI:

Ssemwanga, M., Makule, E., and Kayondo, S.I., 2020. Performance analysis of an improved solar dryer integrated with multiple metallic solar concentrators for drying fruits. Solar Energy, 204, pp.419-428. DOI:

Wankhade, P. K., Sapkal, R. S., and Sapka, V. S., 2014. Design and performance evaluation of a solar dryer. Journal of Mechanical and Civil Engineering, 11, pp. 70-73.

Zaredar, A., Effatnejad, R., and Behnam, B., 2018. Construction of an indirect solar dryer with a photovoltaic system and optimised speed control. IET Renewable Power Generation, 12(15), pp.1807-1812 DOI:

How to Cite
Khidir, D. K. (2023) “Manufacturing and Evaluating of Indirect Solar Dryers: A Case Study for the Kurdistan Region of Iraq”, ARO-THE SCIENTIFIC JOURNAL OF KOYA UNIVERSITY, 11(2), pp. 89-94. doi: 10.14500/aro.11127.