Modeling of a solar dryer for fruit preservation in developing countries

Abstract: About 25,3 % of the Mozambican population is suffering from undernourishment even though a sufficient amount of food and specifically fruits are produced. Post-harvest losses are estimated to 25 % to 40 % and part of the production is not even harvested due to a short season. A solution has to be found to improve fruit preservation and allow the population to consume what is harvested later. Drying fruits is a solution to preserve them. However, juicy fruits are harder to dry than other fruits since they contain more water. One small-scale solution is drying juicy fruits in a specific membrane which allows water vapour to escape from the fruit or the fruit juice to dry. Those membranes have been proven to provide more efficient drying when place in an airflow or wind. It is possible to couple these membranes with solar dryers technology to control the parameters (temperature, relative humidity, velocity) of such an airflow. Two types of solar dryers are tested : indirect and direct. Both solar dryers are modeled using a CFD tool (COMSOL Multiphysics) and the modeling work is based on former research to elaborate a mathematical model of the dryers physics. The simulations produced by COMSOL allow to study the influence of several parameters (geometry of the solar dryers, ambient conditions, solar dryers materials) and identify the parameters to consider in order to improve the design of the dryers. The results from the modeling are compared to on-site measurements, in Mozambique, in order to calibrate and validate the models.