Copyright © 2018 Ntwakgolo Marebane 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. International Journal of Engineering & Technology, 7 (4) (2018) 6019-6028 International Journal of Engineering & Technology Website: www.sciencepubco.com/index.php/IJET doi: 10.14419/ijet.v7i4.28739 Research paper Intelligently controlled solar-powered active fruit and vegetable dryer Ntwakgolo Marebane 1 , Immanuel N. Jiya 1 *, Rupert Gouws 1 1 School of Electrical, Electronic and Computer Engineering North-West University, Potchefstroom 2520, South Africa *Corresponding author E-mail: immanueljiya@ieee.org Abstract Due to the impact of consecutive periods of drought recently being experienced in Africa; food storage and shelf life are decreasing rapidly. Food drying increases the shelf and storage life. Electrical dryers are expensive and electricity availability is a challenge in most African countries. To provide high quality and fast drying, a new intelligent automated active solar dryer is proposed in this paper. The dryer mainly operated on a battery system charged by photovoltaic panels. To produce heat in the oven, a heating element was used which was powered by a battery system. Sensors monitored the temperature, humidity and air velocity inside the dryer house and the data was send to a controller which performed automations on the switching of the convection fans and the heating element. The heating element switching was automated to optimise power consumption. Since the main energy source is solar radiation, a backup energy source was needed for worst case situations regarding weather. A port for electrical energy was installed for operations during cloudy and rainy days. From the results obtained, it was observed that the proposed system with temperature control, humidity control, forced hot air convection and forced humidity extraction offered an improved solution in comparison to the already available methods. These improvements observed are in terms of reduced energy usage, faster drying rate and preserved quality in the dried fruits. Keywords: Food shortage; Solar powered dryer, Fruit; Vegetable; Intelligent control; Active dryer. 1. Introduction Africa is currently facing consecutive seasons of drought and most countries are struggling to come to terms with the impact [1]. This has heavily affected the agricultural sector and has resulted in a high demand for food storage and shelves life. Food drying has been identified as one of the effective methods that provide longer stor- age and shelve life [2]. Various food drying methods have been im- plemented but they have side effects which affects production. These available drying methods include electrical dryers, solar pas- sive and active dryers. The issue with the electrical dryer is that it is expensive and that electricity availability is a challenge in most African countries. In some areas, the passive or active solar drying is implemented. These drying methods are less effective in terms of drying rate and quality production. This is due to exposure to dust, bacterial infection, rain and other species which may feed of the products. Both the active and the passive solar dryers have a slower drying rate since their drying process depends on heat intensity from the sun and natural convection. Due to the impact of consecutive periods of drought recently expe- rienced in Africa; food storage and shelf life are in high demand. Food drying increases the shelf and storage life. Various food dry- ing methods like electrical dryers, solar passive and active dryers have previously been implemented, but they inherently contain side effects which affect production [3]. Electrical dryers are expensive and electricity availability is a chal- lenge in most African countries. On the other hand, passive or ac- tive solar drying methods are slow and lack quality control. To pro- vide high quality and fast drying, the automated-active solar dryer is proposed. The dryer uses photovoltaic panels, an energy storage system and a heating element to enable 24 x 7 day operation. The automation of the system optimizes power consumption and drying rate to maintain constant quality. There are various existing solar dryers that were invented to coun- teract this problem [4], but in this project a more effective solar dryer is implemented. The exciting dryers still require more na- tional electricity for effective operation to meet the desired produc- tion for commercial demands and the ones which do not use elec- tricity have a lot of side effects which affects the drying process and the quality of the products. The various existing solar dryers include: Passive Solar Dryers, Active Solar Dryers and Greenhouse Dryers. Passive Solar Dryers are called natural Circulation of natural con- vention systems [5]. These solar dryers use indirect or direct solar for heating and natural air flow for humidity control. Their opera- tion depends entirely on solar energy. Examples of these are the Tent, Box, Seesaw and Cabinet dryers. Tent dryers are normally made of black and transparent polyethylene, where by the black polyethylene is used only on the wall which is opposite the sun for better heat attraction into the dryer house. The main purpose of the polyethylene is protection from shortcomings caused by dust, rain, predators and dirt which may cause bacterial infections [5]. This dryer uses natural convection for drying. It is cheap but takes long drying time. The box dryers are generally used for less quantity dry- ing. The dryer house is generally made of wooden or steel structure with glass coverings. The dryer house is normally painted black on the inside except the top part, for maximum heat concentration. It has holes on the bottom for air inlet and other holes for air outlet on the top. These dryers also use natural convection but are more ef- fective than the Tent Dryers. They can provide a moderate interior temperature (50-60˚C) and airflow rate [6].The temperature can rise to an excess of about 80 ˚C [7]. A Seesaw Dryer normally has two