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.