A study was conducted to evaluate the parameters affecting the dewatering of cassava mash during processing. First, studies on the pressure distribution within the mash during the dewatering were carried out. Experimental equipment consisting of tyre tube filled with water, a copper tube, and a pressure gauge was designed and fabricated to measure pressure used in expressing the juice contained in the grated cassava mash. It also included a cylindrical dewatering tank made of galvanized steel plate and a sack which was used as control. The tank had 7mm holes drilled at the base to allow the flow of juice. The volume of juice was measured using a measuring cylinder and the stopwatch measured the time. IITA TMS 4(2) 1425 variety of cassava at three levels of maturity age of 9, 12 and 15 months was utilized in the study. The dewatering pressure is from hydraulic jack used to press the grated mash. The dewatering parameters investigated were pressure drop, face area of the filter medium and mash resistance. The results showed that mash resistance varied with the age of the cassava with the highest value of 54,000,000,000 m/kg recorded. Medium Resistance also varied with the age, 33,000,000,000/m was the highest value recorded for 15 months old sample. 0.00371m3 volume of filtrate was obtained from the 12 months old sample with 0.0945 kg mash cake deposit on the filtering medium as the highest deposit. The Kozemy constant value for TMS 4(2) 1425 variety of cassava was found to be 11400000 and Porosity 0.0181, the result presents the distribution and values of identified parameters numerically for equipment designers use.

Cocoa (Theobroma cacao L.) is widely produced in West Africa and South America and is a great economic tree crop, with so many industrial uses. In this work, the experimental drying kinetics of foreign species was investigated, and the experiments were carried out under isothermal conditions, using heated batch drier at 55, 70 and 81 ºC. The moisture ratio data obtained from change of moisture content with the drying time was fit to two thin layer drying model with good results. A faster drying process was observed at a higher drying temperature resulting in higher drying rates which is advantageous when evaluating costs. Fick's second law of diffusion was used to predict effective diffusivity using experimental data assuming that the variation of diffusivity with temperature can be expressed by an Arrhenius type function, and the values of diffusivity obtained ranged from 6.137 x 10-10 to 2.1855 x 10-9 m 2 s-1 for the temperature used. The Arrhenius constant (D) is predicted at 8.64 x 10-4 m 2 s-1 while the activation energy was predicted at 39.94 kJ mol-1 .

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In this study, a mobile, indirect passive solar drying system was designed and constructed on the principles of convective heat flow using locally sourced materials to dry cassava chips. The performance of the dryer was evaluated and the results obtained showed that the system is to a large extent effective in dehydrating food items reasonably and rapidly to a save moisture level. The maximum temperatures obtained in the collector, lower and upper parts of the drying chamber were 78.5, 71.0 and 68.5 o C, respectively during the validation test at noload operating condition, while maximum temperature of 71.0, 62.5 and 60.0 o C, respectively were obtained during the dehydration test. The maximum ambient air temperature was 33.5 o C. The dryer was able to reduce the moisture content of 500 g cassava chips from 74.5 to 20.3% (dry basis) in 6 hours of effective dehydration time. The system overall thermal efficiency and average drying rate were found to be 58.4% and 0.083 kg/h, respectively.

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