Mathematical Modeling of Solar Drying of Tomato Slices

Abstract

Solar drying experiments in thin-layer of tomato slices were conducted at Shambat, Faculty of Agriculture, University of Khartoum. The study was conducted to develop a mathematical model for tomato slices solar drying. Then the mathematical model was written into Pascal programming language. An indirect forced convective solar dryer was constructed and used in the experiments. Air was forced into the solar air heater or collector by a suction fan and the resulting hot air was then passed to the drying chamber where the tomato slices were placed in a thin-layer. The change in mass of tomato slices and the drying air parameters were recorded continuously at specified intervals during the experiment. Drying curves obtained from the data were examined to fit into two semi-theoretical mathematical models, Lewis and Page models. The results illustrate that in spite of the high initial moisture content of the tomato slices, the drying takes place only in the falling rate period. The consistency of the two selected models was tested by using statistical parameters, namely reduced chi-square (=539;2), root mean square error (RMSE) and modeling efficiency (EF). The results of these measures have confirmed the consistency of the developed model to describe satisfactorily the thin-layer solar drying characteristics of tomato slices.