| Resumo: |
Fish morphormetric parameters namely; length, thickness, width at several points and weight were determined as a prelude and were used to design the furnace-dryer for investigating the effects of hardwood-charcoal particle size on five of its combustion properties under natural convection. The tests were in a dryer at zero load. One-factor experiment at five levels of the charcoal sizes of 10, 20, 28, 37 and 50 mm were used to study four of the properties namely, burn-out time (BOT), burning rate (BR), peak temperature (PT) and the time it takes for the temperature to peak (TTP). For the fifth property which is temperature gradient (TG), a 5×14, two-factor experiment was used. The above charcoal particle sizes form one factor while time after igniting the coal at 20-minutes intervals at 14 levels form the second factor. Each experiment was replicated three times. Temperature readings were taken by calibrating and using a digital multi-meter (MASTERTECH MS8209), at 11 cm spacing interval along the height of the chamber. Charcoal particle size in the range of 10 to 50 mm investigated has linear relationships with the combustion properties of BOT, BR, PT and TTP with high R2 values. The relationship of PT and BOT were directly proportional while that of BR was inversely proportional. Based on the principle of least temperature gradient along the height of the chamber, charcoal in the particle size range of 38 to 50 mm gave a more uniform temperature. Thus for a control requiring uniform temperature in the dryer it would be advisable to use charcoal of 38 to 50 mm particle sizes.
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