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Project

Experimental analysis and macro-scale numerical modeling of a novel solar powered food dehydrator

Agriculture in Ethiopia is the mainstay of livelihood and foundation of the country’s economy. It accounts for 45% of the GDP, 86% of the total foreign exchange earnings, 85% employment and 70% of the raw material requirements for local industries . However, the performance of the agricultural sector has remained weak and heavily influenced by climatic conditions and traditional systems. Studies have shown that Ethiopia is one of the countries heavily impacted by post-harvest losses . Too much of the harvested food is lost by spoilage and infestations on its journey to the consumer. Estimates suggest postharvest losses account up to 30% and the Ministry of Agriculture is striving to minimize losses which are occurring during harvesting, handling, storage, processing, packaging, transportation and marketing. The losses vary according to factors such as the perishability of the commodity, ambient temperature and relative humidity (which affects natural decay as well as fungal and bacterial growth), damage by pests, insects, rodents and birds, the time interval between harvesting and consumption and practices of postharvest handling, storage and processing. This figure is tremendous for a country in which majority of the population is suffering from food insecurity. Hence, food security in Ethiopia is literally a matter of life and death. One of the strategies to increase agricultural production is to minimize postharvest losses. Post-harvest treatment technologies, and more specific drying processes, are of paramount importance as agricultural production is increased and food is transported to areas where it is scarce. Currently, the existing post-harvest processes using solar energy are far from optimized and much needs to be done to increase the efficiency and capacity of these existing small scale installations. Therefore, newly designed solar drying concepts using appropriate farm and village level post-harvest technologies using locally available construction materials, involving building designs and introducing low scale agro-processing technologies will solve the problem of the farming society by reflecting social and cultural traditions. With this, post-harvest losses are minimized and improved nutritional values and an increase in shelf life of agricultural products will improve food security, increase income generation, and achieve sustainable livelihood. To address the needs for good post-harvesting treatment of crops and to improve existing drying installations, the main topic of this PhD is the development of a sustainable drying process to minimize post-harvest losses of several crops, including amongst others potatoes, corn… As the farms in Ethiopia are usually solitaire and far away from public utilities and since there is plenty of sun in the country, the main energy source of the dryer will be solar energy. However, the choice of solar energy brings a lot of difficulties in the design of the drying technology. Challenges like energy storage during the night, the need to use indirect sunlight, the choice of solar panels or boilers … needs to be carefully addressed during the PhD. The PhD will include the following sub-objectives: • Development and validation of a CFD model that can predict the air flow distribution within the drying chamber, as well as the time evolution of the temperature inside. • Applying the developed CFD model in the design of new solar food drier concepts with different inlet configurations and evaluation of the effect of inlet configurations in order to select the most appropriate design configuration. • Development and validation of a lumped capacitance model to model heat and mass transfer of the drying process to replace the need for computational expensive CFD calculations in the design of solar dryers.

Date:27 Sep 2017 →  17 Jan 2022
Keywords:CFD modeling, sustainable food drying technology, solar food drier, transient heat transfer
Disciplines:Ceramic and glass materials, Materials science and engineering, Semiconductor materials, Other materials engineering, Other engineering and technology
Project type:PhD project