Particle size effects on combustion properties of hardwood charcoal

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

Criteria for the Extraction of Fish Oil

The effect of pre-treatment of mackery (Scomber scombrus) on oil recovery and quality was investigated. Fish oil was extracted using the screw expeller press after heat pre-treatment of the fish sample. The effect of cooking temperatures and cooking times was evaluated. It was observed that the oil yield has a positive relationship with cooking temperature. The oil yield increased with increasing cooking temperature at all the cooking times investigated and also increased with increasing cooking time from 5-15 minutes and then decreased for 20 minutes cooking time at all the cooking temperatures investigated. The results revealed that a highest yield of 22.8 % was obtained when the fish was treated at 90 0C cooking temperature for 15 minutes. The lowest oil yield of 16.5 % was obtained for the conditions of 60 0C cooking temperature and 5 minutes cooking time. Analysis of oil quality indices (e.g. colour, specific gravity, refractive index, free fatty acid value, saponification value. iodine value, peroxide value, unsaponifiable matter and microbiological analysis) of oil extracted by non pre-treatment and heat pre-treatment indicated that mackery oil from both processes has comparatively similar fatty acids composition. In addition, mackery fish oil was extracted by heat pre-treatment and mechanical press had lower lipid oxidation compared to several standards

Design analysis of an existing acha (digitariaexilis) dehulling machine

An existing acha dehulling machine was improved upon by re-designing. The performance of the existing dehulling machine was first evaluated to determine the required modification. Improvements were undertaken in the cylinder speed, cylinder-concave clearance, hopper slope and opening, cylinder type and fan speed. The physical properties, terminal velocities of acha and the acha chaff, velocity of air required for the cleaning were determined and used to re-design the machine. Major component parts were designed using relevant engineering design principles The modified acha dehuller had cylinder speed, cylinder-concave clearance, hopper slope, hopper hole opening and fan speed of 2800 rpm, 10 mm, 57o, 10 mm and 2800 rpm respectively as against the existing dehuller values of 934 rpm, 20mm, 67o, 20 mm and 934 rpm respectively. Terminal velocities of acha and the acha chaff, velocity of air required for the cleaning determined were 3.96 m/s, 1.9 m/s and 2.5 m/s respectively. Keywords: acha, dehulling machine, fonio, performance, terminal velocit

Effect of Selected Hoe Types and Forward Speed on Theperformance of a Developed Mechanical Row Cropweeder

A mechanical row crop weeder was developed to overcome the tedious manual weeding operation experienced in a row crop farming system and its performance evaluated. The machine is made up of a frame, handle, hoeing disk, pneumatic wheel, belt/pulley and power unit. Three different weeding tool types (U-blade, L-blade and Hoe-blade) were developed and used at three different walking speeds of 0.2, 0.4, and 0.6 m/s in three replications. The experimental plots were 27 which measured 800cm by 26cm each. Parameters such as weeding efficiency, weeding index, Field efficiency, effective field capacity and theoretical field capacity were measured using standard known formulae. This weeding machine has a swath-width of cut of 26cm which corresponds to an average furrow width of farm cropping system. Results from field performance showed that both theoretical and effective field capacities increased with increase in the walking speed of the operator while field efficiency decrease with increase in the walking speed. The mean field efficiencies obtained were 93.58 %, 91.91 % and 85.64 % at the walking speeds of 0.2 m/s, 0.4 m/s and 0.6 m/s respectively. ANOVA revealed that the working speed and tool type have significant effect on the weeding index and weeding efficiency of the machine at p<0.05. The results showed that weeding index decreased with increasing walking speeds with all the tool types investigated, the walking speed of 0.2 m/s had the highest weeding index of 0.937 with the L-blade tool type. The least weeding index of 0.580 was obtained at the walking speed of 0.6 m/s with the hoe-blade tool type. The highest weeding efficiency of 93.7 % was obtained for 0.2 m/s walking speed and L-blade tool type. This device will contribute greatly to weeding status of row crop farms for small scale farmer