LAUTECH Journal of Engineering and Technology (LAUJET)
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MODELLING AND OPTIMIZATION OF COEFFICIENT OF PERFORMANCE OF LOWER TEMPERATURE CYCLE OF TWO-STEP REFRIGERATION SYSTEMS
Get PDFThe 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 (?HTC)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 ?HTC 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
MODIFICATION OF BLADE CHORD INFLUENCE ON THE PERFORMANCE AERODYNAMICS OF VERTICAL AXIS WIND TURBINES
Get PDFPerformance aerodynamics of VAWTs is given important considerations whenchoosing design parameters for the manufacturing of VAWT to effectively and efficiently perform after installation. Blade chord is amongst the many design parameters that can affect the CP of VAWTs in relation to wind harvest and energy yield. This study examines the influenceblade chord modification can have on the PA of wind turbines. The VAWT blade chord of NACA0022 was modified and two configurations of rotors, one with C = 0.03m and the other of C = 0.04m were tested in a low speed and low turbulent intensitytunnel at several wind speeds. An appropriate performance measuring techniques was used to conduct the tests on the two VAWT configurations. The results showed substantial differences in the measured performance efficiency of the two configurations. The two rotorsreached peak performances at the highest tested freestream speed of 8 m/s. The VAWT configuration of C = 0.04m attained higher performance with peak CP = 0.326 at ? = 3.75 while the C = 0.03m showed lower peak CP = 0.26. Changes in the CPwere seen in relation to changes in the free wind speeds.Also the peakperformanceschanged positively as the wind speed is increased. The curves of plot of the CP - ? is observed to close up at region of the peak performances. The CP, the performance efficiency and aerodynamics of the two rotors and configurations are shown tohave been visibly affected bythe modification of the blade chord
EVALUATING THE USERS SATISFACTION ON POST CONSTRUCTION FACILITIES IN SELECTED RESORT HOTELS IN SOUTHWEST NIGERIA
Get PDFPost construction facilities in resort hotel in southwest are known not to fulfill its objectives and thereby affecting the satisfactory state of its users. The challenging state of the post construction facilities coupled with inability to provide its required services has affected the patronization of the resort hotels. The study therefore aims at evaluating the users’ satisfaction on post construction facilities in the selected resort hotels as the hotels has failed to promote its definition and objectives. Literatures revealed the facilities that promote users satisfaction in resort hotels, and established the checklist of recreational facilities for the users’ in resort hotels, these appraised facilities were measured and tested for quality, state of satisfaction and availability. Purposive sampling technique was used to select fifteen (15) resort hotels in the south west Nigeria that has natural landscape elements such as rocks and rivers. (20%) of these hotels were randomly chosen which form the sample population. The study used interviews, observations and questionnaires survey. Thus 425 questionnaires were administered to both staff members (198) and tourists (227) in these hotels. Statistical package for social sciences was used to analyze the data obtained. The result revealed satisfaction state of the users (tourists) and post construction facilities within the resort hotels and conclude that the recreational facilities provided were not maintained and create dissatisfaction for the users. The study concludes that in some of these hotels, users’ satisfaction was rarely incorporated in its design and provision of facilities and therefore the purpose of its state of resort was defeated.
 
REMOVAL OF PHENOL FROM PHARMACEUTICAL EFFLUENTS USING LOCUST BEAN POD AND BENTONITE CLAY
Get PDFThe pharmaceutical industry uses large volumes of fresh water in the process of producing pharmaceutical products and this leads to the generation of large volumes of wastewater. This wastewater is usually profiled for contaminants such as hydrocarbons, dissolved solids and aromatic alcohols such as phenolic compounds which are hazardous to humans. Previous investigations have revealed that the wastewater could be treated by either conventional treatment technologies or biomass treatment systems. However, most of these conventional treatment technologies have higher energy consumption and capital requirement compared to the use of biomass treatment systems. Hence, the current study has employed the use of adsorbents derived from the hybridization of locust bean pod represented as category A, and clay represented as category B for the reduction of phenol from pharmaceutical industry wastewater. The best adsorbent (A3:B3) combination in ratio 1:1, reduced the phenol content to a permissible concentration level of 0.2662 mg/L. This was subjected to an optimization process using Box-Behnken of RSM and lower phenolic concentration of 0.211 mg/L was attained at operating conditions of 45 ºC of temperature, 70 min of contact time, and adsorbent loading of 0.1 g. This study has established that the combination of locust bean pod and clay adsorbent is promising for pharmaceutical wastewater treatment
EFFECT OF PULSED ELECTRIC FIELD ON STRUCTURAL MODIFICATION AND PHYSICOCHEMICAL PROPERTIES OF STARCH-BASED EDIBLE FILMS
Get PDFStarch-based edible film is a novel packaging material that has gained much recognition and attention in the food industry. Its remarkable functional property like microbial deactivation without posing harmful effect on food materials is remarkable. The application of pulsed electric field (PEF) treatment to starch-based edible film is fundamental to ensuring physicochemical changes and structural modifications of films for the purpose of food safety and handling. However, the effectiveness of PEF is affected by process and product parameters, thus information on the effects of PEF treatment on structural modifications and physicochemical properties of starch-based edible film is useful to the food industry.This review provided an overview of the effects of PEF treatment on structural modifications and physicochemical properties such as density, solubility, water activity (aw) and stability of starch-based edible films. The significance of starch-based edible films to the food industry with a focus on potato, cassava, yam and taro starch sources is summarized. The PEF treatment and factors related to process and product parameters affecting its performance and its effects on structural and physicochemical properties of starch-based edible films were succinctly discussed. PEF treatment can cause microbial deactivation, influence the structural and physicochemical properties and produce edible films with much functionality. The future trends of PEF treatment on starch-based edible films should mainly focus on combining other physical treatment as an integrated way of improving the potentials of PEF towards development of a wider range of functionalized films
ALGORITHMIZATION, REQUIREMENTS ANALYSIS AND ARCHITECTURAL CHALLENGES OF TRACONDA
Get PDFGlobally, there are so much information security threats on Internet that even when data is encrypted, there is no guarantee that copy would not be available to third-party, and eventually be decrypted. Thus, trusted routing mechanism that inhibits availability of (encrypted or not) data being transferred to third-party is proposed in this paper. Algorithmization, requirements analysis and architectural challenges for its development are presented
EXERGY PARAMETRIC ANALYSIS AND PREDICTION OF TURMERIC RHIZOME SLICES DRYING USING NEURO-FUZZY, NEURAL-NETWORK AND REGRESSION TECHNIQUES
Get PDFThis study presents exergy parametric analysis and prediction of turmeric rhizome drying using first and second law of thermodynamics as well as soft-computing techniques. The drying experiments were conducted at inlet drying temperature: (40-650C), air velocity (1.5-3m/s), drying time: (30-240 minutes) and sample thickness: (2-5mm). The Neuro-Fuzzy Exhaustive Search (NFES) parametric analysis results revealed that drying time (RMSE=0.0031), temperature (RMSE=0.096), temperature (RMSE=0.046) and sample thickness (RMSE=0.748) are the most single relevant parameters for Exergy Loss (EL), Exergy Efficiency (EE), Exergetic Improvement Potential (EIP) and Sustainability Index (SI) respectively. Whereas temperature-time (RMSE=0.0031), temperature-velocity (RMSE=0.0945), temperature-time (RMSE=0.046) and time-thickness (RMSE=0.7534) are the most important two-input combinations for EL, EE, EIP and SI correspondingly. NFES also revealed that time-temperature-velocity (RMSE=0.004), temperature-velocity-thickness (RMSE=0.082), time-temperature-velocity (RMSE=0.0436) and time-temperature-thickness (RMSE=0.758) are the three-input significant combination for EL, EE, EIP and SI respectively. The ANN results show that two-input combination architectures gave the highest R2 with minimum RMSE for the exergy-sustainability indicators. Therefore, this study shows that NFES and ANN are reliable tools for the analyses of turmeric rhizome drying thermo-sustainability indicators
EVALUATION OF THE RHEOLOGICAL AND PH CONTROL PERFORMANCE OF PLANTAIN PEEL-SNAIL SHELL BIOCOMPOSITE ADDITIVE IN WATER BASED DRILLING FLUID
Get PDFThis study evaluated the applications of Plantain Peel-Snail Shell (PP-SS) bio-composite powder as pH and rheological parameters control additive in Water-Based Drilling Fluid (WBDF). The plant and animal derived wastes were prepared, ground, sieved, and blended together in ratio 1:1 to obtain bio-composite powder. Twelve sets of WBDFs were formulated based on the American Petroleum Institute (API) standard of 25 g bentonite to 350 ml of water. Rheological properties, drilling fluid weight, and pH were conducted on the WBDFs to evaluate the effects of different composite powder concentrations (2, 4, and 6 %w/w) at different temperatures of 30, 50, and 70 oC. The results showed PP-SS bio-composite powder increased the drilling fluid weight by 5.56-15.74% and pH value by 5.56–27.78% as well as improved the rheological properties (apparent viscosity, plastic viscosity, and yield point) of the WBDF as the bio-composite powder concentration increased. The results also revealed that drilling fluid weight did not change with increasing temperature. Apparent and plastic viscosities decreased with increase in temperature while the pH and yield point increased with increase in temperature. Thus, PP-SS bio-composite powder has the potential to be used as a pH and rheological parameters enhancer
INVESTIGATION ON THE EFFECT OF MOISTURE CONTENT ON PHYSICAL AND THERMAL PROPERTIES OF OFADA RICE (ORYZA SATIVA L.) RELEVANT TO POST-HARVEST HANDLING
Get PDFKnowledge of the physical and thermal properties of agricultural products is essential in order to design equipment for processing, sorting, sizing and other post-harvest equipments. Some engineering properties of ofada rice were investigated as a function of moisture content in the moisture range of 9.14 to 25.36% wet basis (w.b.). The increase in moisture content was found to increase the length, width, thickness, arithmetic mean, geometric mean, surface area, volume, sphericity and aspect ratio of the rice grain respectively. Thousand grain mass, bulk density and angle of repose also increased from 19.53 to 25.83 g, 789.33 to 865.33 kg/m3, 35.41 to 42.90º as moisture content increases. Static coefficient of friction carried out on different surfaces include plywood, mild steel, galvanized iron, glass and stainless steel were also found to increase with an increase in moisture content, the values ranged from 0.4951 to 0.5703, 0.5024 to 0.5970, 0.5511 to 0.6371, 0.4350 to 0.5170 and 0.4417 to 0.5206, respectively. The specific heat capacity, thermal conductivity and thermal diffusivity ranged from 1.46 to 1.77 kJ/kgK, 0.137 to 0.198 W/mK and 0.9 to 0.12 × 10-7 m2/s, respectively. The thermal properties were observed to increase as moisture content increases. This study consequently asserts that physical and thermal properties of ofada rice are moisture content dependent and that the results could be exploited by rice processors in the post-harvest processing of ric
DEVELOPMENT AND PERFORMANCE EVALUATION OF A 2kVA FUELLESS GENERATOR
Get PDFElectricity supply has been unreliable for a long period in Nigeria. The energy generating capacity has the potential to generate 12,522 MW of electric power from existing plant, however, approximately 4650 MW is daily generated. Consequently, most homes and industries use internal combustion engine generating sets as an alternative to power grid failure. This does not only contribute to the amount of CO2 that people inhale in the atmosphere but also contributes to ozone layer depletion and climate change. The need for new energy generating sources with no negative impact on our environment had led to several alternatives cleaner source of power that is environmentally friendly and affordable for the masses. In response to this, a fuelless generator was developed using local materials to serve as a standby generator against the incessant power outage. The generator was developed by using a D.C battery, D.C motor, alternator, connecting shaft, charging panel (transformer, diode and capacitor), and a frame. A 12V, 100Ah battery was used to drive a 12V DC motor which in turn spun the alternator to optimal speed to generate electrical power. The output voltage was used to power varying loads of 0W to 2KW, with efficiency reducing with load increase. This paper presents the design and construction procedures, as well as the performance evaluation of the generated result