LAUTECH Journal of Engineering and Technology

SENSITIVITY ANALYSIS OF HYBRIDIZED WIND/PV ENERGY SYSTEM FOR POWERING TELECOMMUNICATION MAST IN LAGOS SOUTH-WEST NIGERIA

O. Olaogun — 2022-06-28

Power delivery micro-grid of hybridized wind and solar system installations keep growing worldwide. There is a great economic advantage in the use of cleaner renewable energy for power generation in the telecommunication industries, especially in remote areas. This studyanalyses the effect of three wind speed fluctuationsor levels on a hybridizedwind energy system’s electricity production for a typical three (3) BTS telecommunication mast using Hybrid Optimization Model for Energy Resources (HOMER)PRO software in Lagos south-western Nigeria as a case study. The economic implication of energy at the different wind speed levels investigated was also derived. From the obtained results, a wind speed of 4, 4.22, and 5 m/s gave an annual electric production of 39,950, 39,050, and 39,250 kWh and energy cost of 195, 192, and ₦175, respectively. This result is useful for the techno-economic operation of hybridized wind/solar system powered by three (3) BTS telecommunication masts.

AN EXPERIMENTAL INQUIRY INTO SURFACE ROUGHNESS OF PAINT-FINISHED MILD STEEL BY SOME TOP AUTOBODY SPRAY PAINTERS IN KADUNA METROPOLITAN AREA, NIGERIA

T. N. Guma — 2022-06-28

Body finish appeal is one of the first noticeable things about any automobile. Most factory autobody painting is highly automated, so aesthetically appealing body finishes of high quality are efficiently achievable with high production rates. However, autobody painting for maintenance or repair in Nigeria is mostly done using manual skills and minimally automated facilities, with a high chance of ending up with low-quality or unappealing body finishes. The purpose of this paper is to present an experimental comparative study about the average surface roughness of paint-finished auto bodies by three top artisanal autobody spray painters, named MA Motors, Alsarafa Body Painters, and IBK Motors in Kaduna metropolis, Nigeria, relative to factory-painted vehicles at Peugeot Automobile Nigeria (PAN) Plc and relevant engineering standards. A cold-rolled mild steel sheet was procured for the study as the most common but corrosion-susceptible autobody material. The sheet was ascertained through nominal composition analysis and was used to produce four similar-sized sheet samples. The samples were individually taken to each of the spray painters and PAN, where they were surface-cleaned, painted, and cured according to the usual methods and standards used there in paint-finishing auto bodies. The surface roughness of the paint-finished samples was measured at 20 different points on each sample with the CRV-135 surface roughness tester and analyzed statistically in terms of the mean value (Ra), root mean square, depth to peak ranges, skewness, kurtosis, and variance. The obtained results indicated that the paint finishes from IBK Motors, Alsarafa Body Painters, MA Motors, and PAN had Ra values of 1.368µm, 1.4725µm, 1.6495µm, and 1.258µm, respectively. The analysis also indicated that all the paint-finished surfaces had minimal roughness, uncharacterized by excessive variations, peaks, and valleys, about their flat average values. The analysis finally indicated that autobody paint finishes by the spray painters are of similar and high quality by engineering standards and comparable to finishes at PAN. The paper provides useful insight into the surface roughness of paint-finished auto bodies by the spray painters as a fundamental quality control parameter that should be imbibed by all in the auto-body painting business, especially in Nigeria, to meet requirements by standards, customers, and users.

THE STRENGTH CHARACTERISTICS OF GLULAM AND BOLT- LAMINATED BEAM

John Wasiu — 2022-06-28

This research presents the strength characteristics of Glulam and Bolted Beam timber specimens. The most common connection method in timber construction is the nail. It is imperative to explore other methods such as glue and bolt in order to avert the disadvantages of nails such as labour intensive and increase in cost. Experimental investigation was carried out on three selected Nigeria timbers; Ceiba Pentandra, Terminalia ivorensis and Tectona grandis. The specimen was prepared in sizes as either glued, bolted or solid connection. Moisture content, density, compression parallel and perpendicular to grain and flexural tests were carried out in the laboratory. The glulam beam specimen; Ceiba Pentandra, Terminalia ivorensis and Tectona grandis showed some positive potentials for application than the bolt-laminated beam connection. It was concluded that bolted connection can be improved by increasing bolt sizes and connection points.

MODELLING AND OPTIMIZATION OF COEFFICIENT OF PERFORMANCE OF LOWER TEMPERATURE CYCLE OF TWO-STEP REFRIGERATION SYSTEMS

A. D. Ogunsola — 2022-06-28

The coefficient of performance (COP) of a single-stage refrigeration system is low, thus there is a need for two-step refrigeration systems when there is a desire to have an evaporator temperature that is below -25 oC. The COP of the lower temperature cycle of the two-step refrigeration systems is a function of the COP of the refrigeration systems.This research aimed at optimizing COP of the lower temperature cycle of two-step refrigeration systems using eco-friendly refrigerants.Thermodynamic analysis of these refrigeration systems was performed by varying seven operating parameters. R-134a was used in the high-temperature cycle (HTC) and R-23 was used in the low-temperature cycle (LTC). The coefficient of performance of the lower temperature cycle (COP.REF[LTC]) of the refrigeration systems was optimized using Half Factorial Design of Design-Expert 12.0.1. The influence of the condensing temperature (TC,HTC),evaporating temperature (TE,HTC), cascade temperature difference (∆TCAS,DIFF), evaporating temperature (TE,LTC), superheating temperature (TSUP,LTC), sub-cooling temperature (TSUB,LTC), and refrigerant mass Flow rate (ṁHTC)was investigated on the values of COP.REF[LTC] of the refrigeration systems. The highest value of COP.REF[LTC] (18.1) was obtained under optimum conditions of the 30 TC,HTCoC , -40 TE,HTCoC, 0 ∆TCAS,DIFFoC, -50 TE,LTCoC, 0 TSUP,LTCoC, 20 TSUB,LTCoC and 0.01 ṁHTC kg/s.The study revealed that all the factors having interaction with TC[HTC] and TE[HTC] have a great influence on the value of COP.REF[LTC]