Prof. Wilfred I. Okonkwo

My Publications

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Performance study of a solar poultry egg incubator with phase change heat storage subsystem

The performance evaluation of a hybrid solar powered poultry egg incubator is presented in this study. The system consists of a double-glazed flat plate solar collector integrated with a paraffin type phase change material energy storage subsystem and incorporated with a PV subsystem. Results of the study showed that the chamber temperature was within the range of between 36- 39 °C and relative humidity of 50–75%. The temperature ranges of between 42-106 °C and 38–99 °C respectively were ...

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The effect of deteriorative factors on the ascorbic acid level of cashew fruit juice during non-refrigerated storage

Ascorbic acid of cashew apple juice is the major factor used to determine the juice nutrients. It is oxidized easily and the concentration is an index to the retention of the original nutritive quality value. The factors that reduce the ascorbic acid of red and yellow samples of cashew apple juice were estimated and the quality value models based on these factors were developed. It was found that appropriate combination these factors led to satisfactory quality control of ascorbic acid reduction...

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Studies on the Growth Rate, Oil Yield and Properties of Some Indigenous Freshwater Microalgae Species

Freshwater bodies within Nsukka, Nigeria had been shown to be rich in indigenous strains of Desmodesmus armatus, Desmodesmus subspicatus, Chlorella lewinii, Dictyosphaerium sp. and Cosmarium sp. with outstanding growth and bio-oil characteristics. Objective of this study was to undertake studies on the growth rate, oil yield and properties of some indigenous fresh water microalgae species, for biodiesel applications. Materials and Methods: Microalgae species were isolated from freshwater pool...

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Stability analysis of equilibrium for Trombe wall solar chick brooder

Trombe wall solar chick brooder was developed for 150-200 birds’ capacity. System evaluation as well as stability and equilibrium analysis were carried out. A set of linear differential equations were formulated that described the dynamic modeling of Trombe wall solar chick brooder for optimal poultry production. The descriptive models were referred to as system control. The model was transformed into Jacobian matrix and solved for stability and equilibrium. Further tests for stability using R...

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Study of a passive solar air heater using palm oil and paraffin as storage media

This study evaluated a passive solar air heater using different storage media. The heater, which is very useful in low temperature applications like agricultural produce drying and heating of buildings, is made up of a double-glaze solar thermal collector of a flat plate type coupled with thermal storage medium. The heater was replicated using paraffin and palm oil as storage medium for systems 'a' and 'b' respectively. The evaluation of the systems without load under 24-h periods were carried o...

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Modeling the thin Layer Drying Kinetics of Cocoa Beans in a Passive Solar Dryer and under Open Sun

Drying experiments were conducted on cocoa beans using a mixed mode passive solar dryer and open sun drying methods. The drying data obtained from the experiments were fitted into ten different published thin layer drying models. The performance of these models was examined by comparing the coefficient of correlation (R2), reduced Chi-square () and root mean square error (RMSE) between the experimental and predicted values of moisture ratios. Among these models, the Midili-Kucuk model showed goo...

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Experimental Determination of the Drying Rate of Cocoa Beans (Theobroma Cocoa)

Equal samples of cocoa beans (Theobroma cacao) were dried under two different conditions: open-air sun drying method and by using a solar dryer. Their respective weight losses were used to determine the reduction in moisture contents. Drying was assumed to have taken place in the falling rate period, which enabled the use of only one drying rate constant. Graphs of ln(Mo – M) versus time were plotted in each case and used to obtain the drying rate constant, K for the two drying conditions. Thi...

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COMPARATIVE ANALYSIS OF OIL EXTRACTION FROM MORINGA OLEIFERA SEED USING MECHANICAL AND SOLVENT METHODS

This study evaluated the comparative analysis of oil extraction from Moringa oleifera seed using mechanical and solvent methods. Moringa is regarded as nutritive and medicinal source available in the tropics whose seeds possess inherently rich vegetable oil. The seeds for the investigations were obtained locally from market in Enugu state. 120g of the Moringa seeds were used. The seeds were also subjected to proximate analysis to ascertain the physicochemical properties. Thereafter, the seeds we...

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Design, Fabrication and Performance Evaluation of a Portable Hand-Held Refractometer

Refractometer is a simple optical instrument that measures the amount of light refracted in a liquid. It measures on a" Brix" scale and the Brix level determines the flavor and quality of fruits and vegetables. The fabricated refractometer has built-in temperature compensations for Brix measurements and it is only valid for fruit juices solutions The refractometer is equipped with a thermometer and there is a means of circulating water through the refractometer to maintain a given temperature Th...

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My Quote


“Just as Houses are made of stones, so is science made of facts.”
Henri Poincare