CONVECTIVE THIN-LAYER DRYING AND REWETTING CHARACTERISTICS OF SESAME SEED

Fundamental information on drying and re-wetting characteristics of agricultural seeds is required in the design and aeration systems as well as in the prediction of drying rate using various mathematical models. Thin-layer drying experiments were conducted using air-ventilated oven to simulate the artificial drying and rewetting processes of sesame seed (6.9 to 18.2% w.b) at three drying temperatures of 40, 50 and 60oC. Five drying models were applied to the thin-layer data. The Page equation fitted the data best after comparing the determination of coefficient (R2), the standard error of moisture content (SEM) and mean relative percent error (e) between the experimental and predicted values. The drying rate of sesame seed under drying and rewetting conditions increased with increased temperature of drying( 40 to 60oC) and initial moisture content of seed( 6.9, 11.5 and 18.2% w.b).  The parameters K and n of the page model was related to the drying temperature and moisture content by two empirical expressions of Page equation for predicting moisture ratio. The coefficient of determination (R2) for parameters K and n were 0.95 and 0.87 respectively.  The effective diffusivity was found to be 2.32 x 10-11 m2s-1

EFFECT OF VARIETY AND MOISTURE CONTENT ON AERODYNAMIC PROPERTIES OF FOUR NIGERIAN COWPEA (Vigna unguiculata) VARIETIES

Knowledge of aerodynamic properties of a crop is important in developing handling, cleaning and processing equipment for the crop. Terminal velocity, drag coefficient and Reynolds number of four Nigerian cowpea varieties namely Ife 98-12, IT90K-277-2, Ife Brown and Drum were studied at moisture levels of 8.2, 12.2, 14.2 and 18.2% wet basis (w.b.), which are levels useful in the design of processing and handling equipment. The terminal velocities of the four varieties ranged from 13.35 to 14.47 m/s, the drag coefficient ranged from 0.446 to 0.454 and Reynolds number ranged from 4768 to 6447. The results showed that both variety moisture content and have significant effect (P≤ 0.05) on both terminal velocity and Reynolds number.Â

EFFECT OF MOISTURE CONTENT ON SOME PHYSICAL PROPERTIES OF COWPEA (Vigna unguiculata)

The effect of moisture content on the physical properties of three of the most popular Nigerian cowpea varieties namely Ife 98-12, IT90K-277-2 and Ife Brown was determined with a view to obtain data useful for the design of handling and processing equipment for the crop. Physical properties such as linear dimensions, geometric mean diameter, sphericity, aspect ratio, bulk density, true density, projected area, porosity and 1000 grain mass were studied in the moisture range of 8 to 18% w.b. which covers the moisture range from harvesting to storage. The length of the grains ranged from 9.36 to 9.74mm, 7.70 to 8.49mm and 8.01 to 8.49mm for the three varieties respectively. The width ranged from 6.34 to 6.53mm, 6.08 to 6.45mm and 6.01 to 6.46mm while the thickness ranged from 5.24 to 5.33mm, 5.00 to 5.24mm and 4.42 to 4.75mm respectively for the three varieties. The results show that variety and moisture content had significant effects (p≤ 0.05) on all the physical properties studied except aspect ratio on which the effect of moisture content was not significant. Regression equations that could be used to express the relationships existing between the physical properties and grain moisture content were established

Energy Expenditure in Gari Processing Activities by Nigerian Women

This work was undertaken to study the energy expenditure by women in Nigeria to produce Gari. Data were collected by direct measurement of height, weight and monitoring of heart beat using stethoscope during operations. In producing gari, a mean energy expenditure of 4.17 kJ/min was spent on cassava peeling and 3.17 kJ/min on mash cake sieving. Frying using traditional method,  improved methods I and II of frying expended 9.75, 2.67 and 1.25 kJ/min of energy respectively. The main activities involved in gari production can be considered to be light grade of work in physiological studies with improved method II, the most appropriate in gari frying in terms of increased capacity and greater efficiency.  &nbsp

Design, Construction and Preliminary Testing of a Beniseed (Sesamum indicum) Air-Screen Cleaner

A beniseed (Sesamum indicum) cleaner was designed and constructed based on the application of some determined physical and aerodynamic properties of the seed. The cleaner was an air-screen type with capacity of 200 kg/h. It consists of a set of vibratory screen made of steel mesh of different sizes. Top screen (2.0mm diameter) prevent foreign material bigger than beniseed while bottom screen (1.2mm diameter) retain beniseed and allow passage of material smaller than beniseed. A centrifugal fan with air speed of 2.5 m/s was incorporated to remove light materials. Preliminary testing of the machine with three varieties of beniseed showed that mean efficiency of separating good product from Yandev-55, E8 and Goza-25 were 66.80 ± 0.54, 61.30 ± 0.85 and 80.08 ± 0.74 % respectively. In Addition, efficiency of separating bad products from Yandev-55, E8 and Goza-25 were 1.47 ± 0.41, 1.61 ± 0.64 and 1.23 ± 0.47 % respectively. Total efficiency of the machine as determined were 98.2 ± 0.98, 98.7 ± 1.24 and 98.5 ± 1.09 % for Yandev-55, E8 and Goza-25 varieties of beniseed respectively. At 95% confidence level, the machine efficiency is acceptable. Therefore, the machine is suitable for cleaning the three varieties of beniseed

Optimization of in-situ Biodiesel Production from Raw Castor Oil-Bean Seed

Optimization of in-situ biodiesel production from raw castor oil-bean seed was carried out from raw castor bean oil seed (37.9% oil content) by alkaline catalyzed in-situ trans-esterification with Sodium hydroxide as catalyst and ethanol as the solvent in a laboratory batch processor.  Response surface methodology and central composite experimental design was applied to evaluate effects of reaction time (30 -120 min), alcohol/seed weight ratio (0.5 – 2.0), Catalyst amount (0.3 – 1.5%) and reaction temperature (40 – 70OC).  Catalyst amount, reaction temperature and time all had significant main effects (p < 0.05) while Alcohol-seed ratio had only slight effects on yield of castor biodiesel as a main effect but was significantly involved in interactions with other factors.  A modified statistical model comprised of all significant factors and interactions (p < 0.05) obtained by multiple regressions predicted that the highest yield of castor ethyl-ester was 99.5% of expressible oil at the following optimized reaction values; alcohol/seed weight ratio of 0.5, a catalyst./seed weight ratio of 1.31, reaction temperature of 60.33oC, and reaction time of 81.7minutes.  A Taguchi L9(3^4)  optimization experimental design used to confirm the modified model at optimum point and two other points within experimental region produced yield that was significantly comparable to model predictions at 95% confidence level using  a paired t-test. Measured properties of the castor ethyl-ester such as viscosity(5.78mm2/s), pour point (-21.5 oC), flash point (177.12 oC), calorific value (47.76MJ/kg), acid value (0.34 mg KOH/g) and cetane number (48.73) were within the ASTM standard D6751-02 but specific gravity. Keywords: Castor oil-bean seed, biodiesel, in-situ trans-esterification, response surface methodology, optimization, Castor ethyl-este

EFFECT OF TEMPERATURE AND PERCENTAGE OF INITIAL CATALYST ON THE IN-SITU PRODUCTION OF BIO-DIESEL FROM CASTOR OIL BEAN SEED USING RESPONSE SURFACE METHODOLOGY

The use of vegetable oil and animal fats for biodiesel production has recently become a great concern because of the competition with food materials.  As the demand for vegetable oil increase tremendously in recent years it has become impossible to justify the use of these oils for fuel production. In-situ trans-esterification process uses the oil (triglycerides) in the oil seed directly without the need for initial extraction as compared with the conventional trans-esterification. Castor oil bean seed contains between 35 and 55% oil and does not compete with food grade oil because of the seed’s toxicity. This study evaluated the effect of temperature and percentage of initial catalyst on yield of castor ethyl ester.  Raw castor oil bean seed kernel at moisture content of 4.68 % (db) was subjected to in-situ trans-esterification in a batch processor with ethanol as the solvent and sodium hydroxide as the catalyst.  Central composite design (CCD) of the Response surface methodology was applied to evaluate the main and interactive effects of initial catalyst amount (0.5 – 1.5%) and reaction temperature (40 – 70OC), on yield of castor ethyl-ester, at reaction time of 120 minutes and alcohol-seed weight ratio of 1:1.  A quadratic non-linear polynomial model was obtained to describe the effect of the factors on yield.  The model was significant (P< 0.05) with a non- significant Lack-of-Fit value (P< 0.05) and R2 value of 0.944. Second order response surfaces and contour plots obtained from the model revealed that initial catalyst amount was the more effective factors on yield while reaction temperature had less effect. The Temperature–percentage of initial catalyst interaction was small and negative, due to the combined effects of formation of by-products (soaps) and saponification. The biodiesel produced from ground castor oil bean seed during this study met the requirements of ASTM standard D6751-02 but specific gravity was higher than the ASTM standard confirming that biodiesel produced from castor bean seed using the in-situ technique can be used as replacement fuel for fossil diesel

PRODUCTION OF BIO-DIESEL FROM JATROPHA CURCAS SEED USING IN-SITU TECHNIQUE: EFFECT OF CATALYST AMOUNT AND ALCOHOL-SEED RATIO

The effect of alcohol seed ratio(0.5,1.5 & 2.0) and initial catalyst amount(0.5,1.0 & 1.5%) on the in-situ production of biodiesel from raw Jatropha Curcas seed was studied at a reaction temperature of 600C and reaction time of 120min.  Central composite experimental design was applied to evaluate effects of alcohol-seed weight ratio (0.5 – 2.0) and initial catalyst amount (0.5 – 1.5%).  Initial catalyst amount and alcohol seed ratio was found to have significant (P<0.05) effects on the yield.  Initial catalyst amount was the more important factor and had a positive influence on the yield than alcohol seed ratio which does not significantly affect the yield as a single factor. Due to formation of by-products (soaps) caused by excessive amount of catalyst and excess alcohol leading to difficult ester separation from glycerol, there was a general reduction in Jatropha Curcas  ethyl-ester as levels of catalyst and alcohol seed ratio increased.  A second-order model was obtained to predict the yield as a function of all factors. The model predicted well the observed data with a R2 value of 0.985 and a non-significant Lack-of-Fit (P<0.05). The biodiesel obtained, compared favorably with the ASTM D6751-02 standard for biodiesel but the viscosity

INFLUENCE OF CATALYST QUANTITY AND REACTION TIME ON IN-SITU PRODUCTION OF BIODIESEL FROM RAW CASTOR BEAN SEED USING RESPONSE SURFACE METHODOLOGY

Trans-esterification is the most commonly used methods of biodiesel production. In-situ trans-esterification process uses oil (triglycerides) in seeds directly without the need for initial extraction. The in-situ production of biodiesel from raw castor bean seed with a batch processor was studied at initial catalyst quantity of 0.1, 0.5 and 1.5%, reaction time of 30, 60 and 90 min with a reaction temperature of 600C and alcohol seed ratio of 1:1 using the response surface methodology.  Initial catalyst concentration and reaction time were subjected to central composite experimental design of the response surface methodology.  Initial catalyst quantity and reaction time were found to have significant (P<0.05) effects on the yield of castor biodiesel produced, with increased catalyst quantity giving a negative effect on the yield after an initial amount of between 1.0 and 1.2%.  The reaction time had a positive effect on the yield until after 90 minutes after which biodiesel yield reduced with increased time. The CA-Time interactions influence was small and negative, due to the superior effect of initial catalyst quantity by the formation of by-products (soaps) leading to difficult ester separation from glycerol. A second-order model was obtained to predict the yield as a function of all factors. The model predicted well the observed data with a R2 value of 0.983. The biodiesel produced had properties comparable to the standards of ASTM while the specific gravity was higher than the specified standards

PRODUCTION OF BIO-DIESEL FROM JATROPHA CURCAS SEED USING IN-SITU TECHNIQUE: EFFECT OF CATALYST AMOUNT AND ALCOHOL-SEED RATIO

The effect of alcohol seed ratio(0.5,1.5 & 2.0) and initial catalyst amount(0.5,1.0 & 1.5%) on the in-situ production of biodiesel from raw Jatropha Curcas seed was studied at a reaction temperature of 600C and reaction time of 120min.  Central composite experimental design was applied to evaluate effects of alcohol-seed weight ratio (0.5 – 2.0) and initial catalyst amount (0.5 – 1.5%).  Initial catalyst amount and alcohol seed ratio was found to have significant (P<0.05) effects on the yield.  Initial catalyst amount was the more important factor and had a positive influence on the yield than alcohol seed ratio which does not significantly affect the yield as a single factor. Due to formation of by-products (soaps) caused by excessive amount of catalyst and excess alcohol leading to difficult ester separation from glycerol, there was a general reduction in Jatropha Curcas  ethyl-ester as levels of catalyst and alcohol seed ratio increased.  A second-order model was obtained to predict the yield as a function of all factors. The model predicted well the observed data with a R2 value of 0.985 and a non-significant Lack-of-Fit (P<0.05). The biodiesel obtained, compared favorably with the ASTM D6751-02 standard for biodiesel but the viscosity