LAUTECH Journal of Engineering and Technology

SUITABLE MODEL FOR THIN LAYER DRYING KINETICS OF WHITE AND PINK-FLESHED TANNIA (XANTHOSOMA SAGITTIFOLIUM) CORMELS

B. O. Oyefeso — 2020-06-11

Drying is an essential unit operation in the conversion of fresh tannia (Xanthosoma sagittifolium) cormels into flour with the attendant benefits of improved shelf life and better storability. Information on the drying kinetics of the cormels will foster a good understanding of its behaviour during drying. Rate of moisture loss during the process can also be described by appropriate models. This study therefore, investigated the thin layer drying kinetics of two cultivars of tannia cormels at different temperature levels and determined the most suitable model for its prediction. White and pink-fleshed cormel slices of 3mm thickness were dried at 60, 70 and 80oC temperature levels. Data obtained from the drying experiments were fitted into ten selected models namely Newton, Page, modified Page, Logarithmic, Henderson and Pabis, Midilli, Verma, Two term, Thompson, and Wang and Singh models. The highest and the lowest drying rates were obtained at 80 and 60oC respectively. Page and modified Page models were the most suitable models for describing the drying behaviour of both tannia cultivars with highest R2 in excess of 0.9941 and lowest error estimates (RMSE≤0.0251; χ^2≤0.0008; MBE≤0.0060). The drying took place predominantly in the falling rate period which indicated that moisture removal from tannia cormels occurred mainly by diffusion mechanism.

MONITORING OF PHOTOVOLTAIC PANEL IN A SOLAR-POWERED LAB-SCALE SMART IRRIGATION SYSTEM

O. K. Ogidan — 2020-06-11

The solar photovoltaic (PV) or solar panel is an active transducer whose function in the provision of solar energy cannot be overemphasised. Many solar energy systems perform poorly or fail when the properties of the PV and conditions under which they are implemented are not taken into consideration during system design. Others fail due to environmental conditions such as temperature which might degrade the power generated by the solar PV. As a way of ensuring longevity and healthy operation of the PV, there is the need to do a constant monitoring of it properties and generated power. In this work, parameters such as current, voltage, and ambient temperature of 200 W solar panel are measured in real-time and obtained values used in design of solar power for a lab-scale smart irrigation system. The PV power was determined from the measured current and voltage values using appropriate sensors which are connected to an Arduino-based microcontroller. The PV under a load-OFF test was exposed to the sun from 5:30 am to 7:10 pm. The measured solar power confirms the peak sun hour of 4.5 to 5 hours for Ilara Mokin, Ondo State, Nigeria. Load-ON implementation with a lab-scale smart irrigation testbed reveals that irrigation pumps 2 and 3 maintaining an equal distance each from the water source absorb less power compared with pump 1 at a distance more than double of pumps 2 and 3 from the water source. Thus, the distance of the irrigation pumps and sprinklers from the water source is found to play vital role in the pattern of power consumption by the irrigation system. The maximum power thresholds of irrigation pumps under various load-ON conditions were determined. The power thresholds obtained would be useful parameters for configuring the lab-scale smart irrigation controller for effective performance while the peak sun hour obtained is a useful design parameter for this work and implementation of effective solar system in Ilara Mokin and its environs.

THE STUDY OF RHEOLOGICAL PROPERTIES OF BITUMEN BLENDS MODIFIED WITH DISSOLVED PLASTIC WATER SACHET

M. T. Akinleye — 2020-06-11

Rutting, which is permanent deformation or consolidation of asphalt pavement, is one of the flexible pavement failures. Research has shown that one of the ways of resisting this failure is by modifying the rheological properties of bitumen. This modification can be achieved by the addition of dissolved plastic water sachet (DPWS), a well-known waste in Nigeria, to bitumen. This study was conducted to investigate the effect of DPWS on the rheological properties of bitumen and at the same time reduce the environmental hazard associated with PWS disposal with consequential pavement material improvement. Bituminous blends containing DPWS at various percentages 0, 1, 3, 5, 7, 9, 11, 13, 15 and 17% by weight of conventional bitumen were used for the study. Tests on rheological properties such as dynamic viscosity, phase angle, peak shear stress and peak shear strain were carried out on unmodified and DPWS modified hot and warm bitumen blends to determine the corresponding complex shear modulus and complex shear modulus elastic portion. Results obtained from the tests were compared between control sample (0% DPWS) and DPWS modified bitumen samples. The test results showed that the dynamic viscosity increased upon addition of the DPWS at 135°C and at 165°C, it initially increased upon addition of DPWS up to 7% before it became constant till 17% DPWS addition; and the phase angle decreased upon addition of DPWS at both 135°C and 165°C for hot mix bituminous samples. Likewise, for the warm bituminous samples, the absolute viscosity increased and phase angle decreased upon addition of DPWS at both 135°C and 165°C. The best complex shear modulus elastic portion results occurred upon 9% and 17% DPWS addition for hot mix bituminous samples and upon 5% and 17% DPWS addition for warm mix bituminous samples when subjected to temperatures of 135°C and 165°C respectively. These percentages are the best to resist rutting on our traffic roads from this study.

DEVELOPMENT AND PERFORMANCE EVALUATION OF A MOTORISED PLANTAIN CHIPPING MACHINE USING RESPONSE SURFACE METHODOLOGY

U. J. Etoamaihe — 2020-06-11

A lot of drudgeries and unhygienic processes are involved in manual chipping of plantain. These problems
necessitated the development of a motorised plantain chipping machine with a capacity of 450 kg/h. The
machine is made up of a cutting device, a feeding mechanism, the support frame and an electric motor as a
source of power. The cutting mechanism consists of the stainless steel blades, a connecting rod, a guide
frame for the blades and pulleys. The blades are arranged perpendicular to the plantain fingers. During
performance evaluation of the chipper, the effects of the number of cutting blades, inclination of the angles
of the cutting blades and cutting speed as they affected the chipping efficiency were investigated. Response
Surface Methodology was used in the experiments because it uses very few experimental runs to describe how
the test variables affect the response. It also helps to determine the inter-relationships among the test
variables on the response and also helps to describe the combined effects of all the test variables on the
response. The highest chipping efficiency of 70% was obtained when the machine was operated at the speed
of 975 rpm, with a blade angle inclination of 300
and with nine cutting blades. Generally, it was found that
the chipping efficiency increased as the number of cutting blades are increased. Also the chipping efficiency
increased with the speed of the machine but was not affected by the inclination angles of the blades. The
linear effects of speed, the linear and quadratic effects of the number of blades significantly affected the
chipping efficiency of the machine at 5% probability.

EVALUATION OF THE EFFECT OF PHYSICAL AND MINERALOGICAL CHARACTERISTICS OF SOME ROCK TYPES ON THEIR MECHANICAL PROPERTIES (A CASE STUDY OF EKITI, ONDO AND KWARA STATE)

S. A. Agbalajobi — 2020-06-11

The research work studies the effect of physical and mineralogical characteristics of some rock types on their
mechanical properties. Samples of rock were collected from six locations, Egbejila and Odore (Kwara State),
Ijare and Itaogbolu (Ondo State), Iyin and Awo road, (Ekiti State), in Nigeria. The physical properties (hardness,
density and specific gravity), mineralogical properties (X-Ray Diffraction (XRD) and mechanical properties
(Uniaxial Compressive Strength (UCS); Point Load Strength and Brittleness) were determined in the laboratory
using the required international standard and the equipment used are Impact Testing Machine, Compression
Testing machine, Aggregate Impact Value (AIV) machine, Aggregate Crushing Value (ACV) machine, Global
Positioning System (GPS), Cut-off Saw Machine, and Petrographic Microscope. From the results of the
investigation, it was observed that the concentration of quartz and other minerals as indicated by the X-Ray
Diffraction (XRD) have influence on the highest on the mechanical properties of the rocks under study. Ijare
with the highest quartz content of 69.4% has the highest UCS of 174.4 MPa while Odore with the lowest quartz
content of 33% has the lowest UCS of 120 MPa. Dominance of silica is range of 62.455% – 70.72%). The
physical properties (hardness, density and specific gravity) were found to follow the same trend with the
mineralogical properties in influencing the mechanical behaviour of rock, most especially the UCS. Denser and
harder rock samples were found to have higher UCS. Conclusively, the physical and mineralogical properties of
rock were found to correlate strongly with the mechanical properties.