AL-QADISIYAH JOURNAL FOR ENGINEERING SCIENCES 15 (2022) 001–008 Contents lists available at http://qu.edu.iq Al-Qadisiyah Journal for Engineering Sciences Journal homepage: http://qu.edu.iq/journaleng/index.php/JQES * Corresponding author. E-mail address: tonyagyemang@yahoo.com (Anthony Agyei-Agyemang) https://doi.org/10.30772/qjes.v15i1.821 2411-7773/© 2021 University of Al-Qadisiyah. All rights reserved. This work is licensed under a Creative Commons Attribution 4.0 International License. Effects of roof angle, inlet gap size and drying time on dryer mass flow rate and moisture content in a chimney-dependent solar crop dryer using design of experiments (DOE) Anthony Agyei-Agyemang a* , Peter Oppong Tawiah a , John K. Afriyie b and Michael K. Commeh c a Department of Mechanical Engineering, College of Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Kumasi, Ghana. b Department of Mechanical Engineering, Kumasi Technical University, Kumasi, +233, Ghana. c Technology Consultancy Centre, College of Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, +233, Ghana. A R T I C L E I N F O Article history: Received 09 February 2022 Received in revised form 6 March 2022 Accepted 15 May 2022 Keywords: Solar dryer Roof angle Inlet gap size Multilevel factorial design Moisture content Ghana A B S T R A C T A chimney dependent solar crop dryer (CDSCD) was designed and developed. Design of Experiments (DOE) was used to carry out experiments using a statistical three level non randomized factorial experimental design in Minitab statistical software version 19.0. The effect of three drying parameters, roof angle (º), Inlet gap size (mm), and time (h) on dryer inlet mass flow rate (kg/s) and moisture content (%) were studied. The regression results showed that there was a satisfactory fit of the model variability for both dryer inlet mass flow rate and crop moisture content. The p-value for each parameter was less than 0.005, which is statistically significant. The R-squared (R 2 ) value was 94.67% for inlet air mass flow rate study and 99.72% for moisture content. It was observed that the optimal values for achieving a low moisture content response (≤ 24%) were roof angle of 81º, inlet to outlet cross-sectional area ratio of 1.08768:1 and a minimum drying time of 24 hours while the optimal values for achieving high inlet air mass flow rate (≥ 0.357 kg/s) were roof angle of 51º, inlet to outlet cross-sectional area ratio of 1.08768:1 and a minimum drying time of 5 hours. The findings could be implemented and utilized for achieving optimum ventilation and drying performances to refine dryer (CDSCD) design. © 2022 University of Al-Qadisiyah. All rights reserved. 1. Introduction MOFA [1] observed that although agriculture is the largest sector of the economy in Ghana, contributing about 39% of GDP, it is still confronted with high post-harvest losses as a result of poor post-harvest management. For instance, Zakari [2] estimates that the average postharvest loss of mango is between 20 % and 50 %. The main causes for the losses being attributed to fruit flies, diseases, poor management and storage during transit to the market. Drying, if used effectively could minimize crop losses. Crop drying refers to the process of removing moisture from a crop. Solar dryer is a solar energy application in drying and conserving agricultural food products and other products [3]. Traditionally, farmers spread their crops on mats in the open sun to dry them, therefore exposing them to environmental conditions such as rain, pest, rodents and different types of unhygienic conditions. Harnessing solar energy is becoming more and more popular in drying. In solar drying, solar energy is the main source of energy used. Recent studies have shown that using solar energy in preserving agricultural products like grains, fruits, and vegetables is economical and ideal for farmers in the developing countries [4]. However, the use of solar energy alone as the source of heat for drying and preservation during the rainy season, is not feasible and therefore proves difficult [5]. As a result, it calls for different ways in which the solar energy is utilized to overcome