• Issue 1 (2012)
• Issue 2 (2012)

The Role of Mathematical Modeling in Understanding the Groundwater Pollution

IJTEE, volume-04 , Issue 2 (2012), PP 171 - 176

Published: 20 Apr 2012

DOI: 10.5383/ijtee.04.02.008

by Fathi M Allan, Emad Elnajjar from Department of Mathematical Sciences, UAEU, AL AIN, UAEU, Department of Mechanical engineering, UAEU, AL AIN, UAEU

Abstract: To understand the process of groundwater contamination diffusion and spreading, mathematical model is usually used. In the present study, a mathematical model based on the transport diffusion will be discussed. The equation is governed by several parameters including the water velocity, permeability and diffusion rate. Fourier transform is employed to obtain the exact solution of the problem. The mathematical model will be totally analysed, programmed and tested using values for the parameters that simulate the actual data. Results suggests the model can bring some insights about the diffusion of the water contaminants as time progress from few days to hundreds of days. read more... read less...

Keywords: Mathematical modeling, underground water pollution, transport equation

Energy Tri-Generation: Combined Gas Cogeneration/Solar Cooling

IJTEE, volume-04 , Issue 2 (2012), PP 157 - 163

Published: 20 Apr 2012

DOI: 10.5383/ijtee.04.02.006

by R. Benelmir, A. Merabtine, D. Descieux from Lorraine Univ. – Fac. Sc. Tech. - LERMAB, Vandoeuvre-les-Nancy, France

Abstract: The article presents an analysis of a tri-generation system using a solar energy as primary energy to provide a reliable alternative to minimize energy consumption in countries with a large solar field as the MENA region. At the University of Nancy, within the faculty of Sciences and Technologies, we are experimenting energy tri-generation through solar cooling of water for air-conditioning and heat/electricity cogeneration using gas fuelled internal combustion engine. The technology used for refrigeration is combined thermal solar-adsorption cooling. The physical principle of an adsorption based refrigerating machine is in some respect similar to the operating principle of a conventional compression based refrigerating machine [1-4]. Both systems rely on a “condenser - expansion valve – evaporator” refrigerant cycle. However, the way the two systems achieve refrigerant’s vapor compression is quite different. While the conventional machine provides a “mechanical” compression of the refrigerant’s vapor (standard refrigerant), the sorption machine achieves rather a “thermal” compression of the refrigerant’s vapor (water) in two steps: in the first stage, the vapor issue from the evaporator is assimilated within a solid adsorbent (silica gel) by rejecting heat; in the second stage, this vapor is resituated back to the system loop at high pressure due to solar heat input through an intermediary fluid (water). read more... read less...

Keywords: Lorraine Univ. – Fac. Sc. Tech. - LERMAB, Vandoeuvre-les-Nancy, France

Modeling Tool for Air Stripping and Carbon Adsorbers to Remove Trace Organic Contaminants

IJTEE, volume-04 , Issue 1 (2012), PP 99 - 106

Published: 19 Jul 2012

DOI: 10.5383/ijtee.04.01.014

by Khaldoon Mourada, Ronny Berndtsson, Wail Abu-El-Sha'r, Abdalla M Qudah from Lund University, Lund, Sweden, 22100, Jordan University of Science and Technology, Irbid, 22110, Jordan

Abstract: Removal of trace organic contaminants from aqueous solutions by air strippers (AS) and fixed bed carbon adsorber (FBCA) has been studied. A trace organic treatment tool has been developed to capture and adapt the best-known design procedures and to have all regulated trace organics, their physical and chemical properties, and the corresponding maximum concentration limits. Outputs include the selected treatment method and the final design parameters of air stripper or fixed bed carbon adsorber. Running the model shows that water temperature is a very important factor in designing AS and FBA. It also shows that the best air pressure values, in AS, ranged between 150 -200 ATM. And there is a big relation between the column size and the packing material. On the other hand, it shows that FBA diameter has an obvious effect on the needed volume, and the best values ranged between 1.2 – 2.5 m. read more... read less...

Keywords: Modeling, Air Stripper, Fixed Bed Adsorber, Trace Organics, Packing Materials

Computational Investigation of Flow and Heat Transfer in a Rectangular Duct with Ribs Mounted in a Staggered Arrangement

IJTEE, volume-04 , Issue 1 (2012), PP 81 - 88

Published: 19 Jul 2012

DOI: 10.5383/ijtee.04.01.012

by M. Alhajeri from Mechanical P& R Engineering Department, Faculty of Technological Studies, PAAET, Kuwait

Abstract: Fluid Flow and heat transfer results are presented from a ribbed U-tube, which models passages used to cool the blades in gas turbine engines. Computational fluid dynamics is used here to predict the air flow behaviour and the surface Nusselt number distributions. The model of the coolant passage consists of two square legs that are connected by a sharp, 180-degree bend with a rectangular outer wall. Four ribs are placed in each side of the leg and mounted in a staggered arrangement. The height and width of the rib are equal to 0.1 duct width, and the rib spacing is 10 times the rib height. Based on inlet flow conditions, the Reynolds number (Re) is 95000. It was found that, after the flow resettles from the disturbances created by the obstacle of the first rib or the effect of the bend, the flow forms two re-circulations, a large one behind the rib and a small one ahead of the rib. The maximum values of the Nusselt numbers are located at a distance of almost one rib height h ahead of the flow reattachment point. read more... read less...

Keywords: Turbine blade cooling, CFD, Rib

A Study on Modification of Knowledge, Attitude and Practice on Vocational High School Electronics Courses Integrated with Nanotechnology Concept

IJTEE, volume-04 , Issue 1 (2012), PP 73 - 79

Published: 19 Jul 2012

DOI: 10.5383/ijtee.04.01.011

by Dai Chien-Yun, Chen Wan-Fei, Yuan Yu-Hsi, Yen Chia-Hung from Department of Industrial Education, National Taiwan Normal University, Taipei, Taiwan, 106

Abstract: The purpose of this study is trying to explore the discrepancy of knowledge (K), attitude (A), and practice (P) before and after the experimental teaching on nanotechnology infused into electronic course in vocational high school. Valid 116 samples were selected from department of electronic of one vocational high school in Taiwan via judgmental sampling. The research result shows that students who received nanotechnology are rise their knowledge test scores dramatically that post-test (M=24.03、SD=2.48) higher than pre-test (M=13.71、SD=3.14); meanwhile, the growth rate around 30%. The analysis result of attitude as 1. The designed materials were suite for students in nanotechnology learning and it will not cause their learning loading rise, hence, students tended to participant nanotechnology related studies and activities initiatively. 2. It is agreed by students that appropriate nano-product can facilitate the convenience of our life. The analysis result of practice as 1. Students either can describe functions at nano-scale within natural world or can identify material physical characteristic at nano-scale. 2. Students learned to search nanotechnology related information and know how to analyse the special function of nano-product. read more... read less...

Keywords: nanotechnology, KAP, vocational high schools electronics courses

Effect of Various Amendments on the Solids Properties and Gas Production of Biosolids

IJTEE, volume-04 , Issue 1 (2012), PP 67 - 72

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.010

by Ayesha Alam Khurram from University of Auckland, New Zealand

Abstract: Four additives namely iron slag (IS), works debris (WD), fly ash (FA), and lime kiln dust (LKD) are added to biosolids and their effects are investigated on the selected properties of biosolids. The biosolids used are final products of the wastewater treatment process at a Wastewater Treatment Plant (WWTP), Auckland, New Zealand. The additives are mixed manually with biosolids at different percentages. Most of the mixtures, finally called amendments has selected amount of lime in them. The amendments are placed separately into respirometer reactors (air tight bottles) for two weeks, measuring gas continuously to find out the total gas production and to analyse methane (CH4) and carbon dioxide (CO2) production to completely understand the biochemical activity. Water content (WC %), volatile solids (VS %), and pH are determined before putting the amendments into the reactors and after two weeks as well. Gases that are being produced from the respirometer reactors are analysed after 5, 10 and 15 days for CH4 and CO2 percentages. After comparing results of all the amendments and comparing results of solids parameters to that of gas analysis, it is concluded that FA 50% with lime 20% inhibited most of the biochemical activities and maintained pH of biosolids at elevated level of 12 or above and thus could be applied to biosolids for stabilization before landfilling. FA 50% with lime 20%, like all the other additives, is added to wet biosolids on the basis of dry weight. Solid content of biosolids is around 25% so the addition of even 70% additive to wet biosolids on the basis of dry weight is very less in amount read more... read less...

Keywords: biosolids, fly ash, gas analysis, biochemical activity.

Fuzzy Implementation for Predicting and Monitoring the Conditions of Transducers for Gas Turbine Cycle

IJTEE, volume-04 , Issue 1 (2012), PP 61 - 66

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.009

by Rustom Mamlook , Omar Badran, Emad Abdulhadi from College of Computer Engineering and Sciences, Al-Kharj University - Saudi Arabia, Mechatronics Engineering Dept, Al-Balqa Applied University, Faculty of Engineering Technology, Amman, Jordan

Abstract: This paper presents a fuzzy logic methodology for predicting the most important parameters that influence the efficiency cycle of the gas turbine and estimates the transducer's condition "health" and its measuring accuracy during the fault. The fuzzy method is implemented here to monitor and predict the working conditions for different sensors and transducers in the gas turbine and to ensure that it is operated at a safe level to prevent equipment deterioration by the correct evaluation of its effective parameters, and save operational costs assuming that there is a single fault occurs at a given time. The fuzzy implementation consisted of two parts, the first one predicts the actual operating parameters based on gas turbine cycle performance calculations, and second part shows the sensor's condition estimates the transducers' accuracy in a percentage scale after any alarm to assure their competence. Fuzzy logic in such applications aids us to condense a large amount of data into smaller set of fuzzy variable rules, to minimize prolonged exposure to downtimes. read more... read less...

Keywords: Fuzzy sets methodology, Turbine fault, Control technology, Sensor's condition, Gas turbine

Impulse Acousitic Enhancement of Flow Boiling in Micro Channels

IJTEE, volume-04 , Issue 1 (2012), PP 55 - 60

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.008

by Yasir M. Shariff from Mechanical Engineering Dept., College of Engineering, P.O. Box 1020, Taibah University, Madina, Saudi Arabia

Abstract: Measurements were done for the heat transfer coefficients h in forced convection refrigerant mixture (R-407C) flow within micro channels enhanced by impulse acoustic vibration. Flow in horizontal micro channels (ID 100.0 length of 50 mm for subcooled and saturated boiling conditions are reported in this study. The heat flux was ranged from 6 kW/m2 for subcooled boiling saturated boiling was carried at heat fluxes of 15 and 29 kW/m2. The mass flow rate varied from 0.45 to 1.85 kg/min. The frequency was maintained at a constant value of 20 kHz. The impulse was varied in three ranges of 20, 40, and 60 dbs. An experimental setup composed of heating elements provided heat flux variations in the micro channels and excitation elements attached to the side of the channels to produce the impulse acoustic vibrations. The heat transfer coefficient found to be dependent on both the heat flux as well as mass flux levels. Results show that impulse acoustic vibration enhanced the heat transfer performance by 12% as compared to regular flow convective boiling process read more... read less...

Keywords: Heat transfer, flow boiling, micro channelsx

Thermodynamics Equilibrium Analysis within the Entrained Flow Gasifier Environment

IJTEE, volume-04 , Issue 1 (2012), PP 47 - 54

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.007

by Shabbar Syed, Isam Janajreh, Chaouki Ghenai from Masdar Institute (MI), Abu Dhabi, 54224, United Arab Emirates, Florida Atlantic University, Boca Raton, FL 33431, USA

Abstract: A thermodynamic equilibrium approach is used to calculate the maximum cold gasification efficiency (CGE) of different feedstock within the entrained flow gasifier. The high temperature (1000 to 1500oK), the small feedstock size (10μm to 0.1mm), and the well mixing environment make them most amenable for equilibrium analysis. Four different feedstocks, i.e., RTC coal, pine needles, ply-wood and lignite, are used for the gasification purpose. Using air as oxidizer a parametric study is conducted to show the behaviour of CGE and product gasification composition by increasing oxidizer input. A gasification model is developed to calculate the seven unknowns in the gasification product. Using four elemental mass balance and three equilibrium constant relations a mathematical code is developed that also incorporate the solid un-burn carbon in product species. Energy equation is used to calculate the temperature of gasification using iterative approach. Result of model shows that the maximum CGE is achieved when all the solid carbon is converted into the carbon monoxide with nearly all hydrogen present in the feedstock converted into the hydrogen gas. Using this result as baseline, a global model to estimate the maximum CGE is developed in reference to Van Krevelen diagram. This model based on minimum requirement of air to convert all the carbon present in feedstock into carbon monoxide. Result shows a growing trend of CGE with the increase O/C and H/C ratio of feedstock read more... read less...

Keywords: Thermodynamics equilibrium, entrain flow gasifier, cold gasification efficiency

Modeling and Simulation of Desiccant Operated Humidity Pump (DOHP)

IJTEE, volume-04 , Issue 1 (2012), PP 39 - 46

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.006

by A. M. Hamed, A. S. Alosaimy from Mechanical Power Department, Faculty of Engineering, Mansoura University, Mechanical Engineering Department, Faculty of Engineering, Taif University, Saudi Arabi

Abstract: In the present work, novel configuration of rotating desiccant wheel using calcium chloride as the working desiccant is presented. The proposed system is called desiccant operated humidity pump (DOHP). Mathematical model, which can be applied for analysis of the proposed system, is developed. The proposed system can be powered by low grade heat sources such as solar energy. Absorption-regeneration cycle for the DOHP is described and analysed. An expression for the efficiency of the simple cycle is introduced. Theoretical analysis shows that strong and weak solution concentration limits play a decisive role in the value of cycle efficiency. System efficiency with consideration of heat and work added to the system is well defined. Dimensionless parameters defining the system design parameters are introduced. The limits of regeneration temperature and mass of strong solution per kg of produced vapor are found highly dependent on the operating concentration of desiccant read more... read less...

Keywords: Desiccant, humidification, absorption, air conditioning, Calcium chloride, humidity pump

Novel Anode Materials for Oxygen Evolution during Seawater Electrolysis for Green Hydrogen Fuel Production

IJTEE, volume-04 , Issue 1 (2012), PP 33 - 38

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.005

by A. A. El-Moneim from Materials Science and Engineering Department, Egypt-Japan University of Science and Technology, P.O. Box 179, New Borg El-Arab City, Alexandria, Egypt

Abstract: Mn1-x-yMoxWyO2+x+y triple oxide electrocatalysts for the anode producing oxygen without forming chlorine in seawater electrolysis were prepared by anodic deposition. The performance of the anode for oxygen evolution in 0.5 M NaCl solutions was examined. The tungsten addition was effective in extending the life of the anode by decreasing the density of pores in electrocatalysts responsible for partial detachment of electrocatalysts, which occurs by high pressure of oxygen formed preferentially at the bottom of pores during electrolysis. Repeated anodic deposition of the electrocatalyst significantly extended the life of the anode, because repeated deposition was able to cover the pores in the underlying electrocatalysts. The potential observed in anodic polarization of an oxide electrode was the sum of the overpotential of the electrochemical reaction and the potential drop as a result of passage of current through the oxide. The potential difference of the two anodes at individual current, Ei, versus the current, i, should show the straight line: The gradient, Ei /i, is the difference of the electrical resistances of the two electrodes, and the activity of the two anodes can be compared from the current, i, at Ei= 0 volt. The tungsten addition enhanced the activity for oxygen evolution. read more... read less...

Keywords: Anode, oxygen evolution efficiency, durability, polarization, SEM

Cassava as a Potent Energy Crop for the Production of Ethanol and Methane in Tropical Countries

IJTEE, volume-04 , Issue 1 (2012), PP 25 - 32

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.004

by B. A. Adelekan from Federal College of Agriculture, Institute of Agricultural Research & Training (IAR&T), PMB 5029, Moor Plantation, Ibadan, Nigeria

Abstract: The ethanol productivity of cassava crop (variety TMS 30555) and the methane productivity of its waste product (peels) mixed with livestock wastes were investigated in laboratory experiments, and the capability of tropical countries in this respect was computed. Cassava tubers were peeled, cut and washed. Five, 15, 25 and 35kg samples of the tubers were weighed in three replicates, soaked in water for a period of 1day, after which each sample was dried, crushed and the mash mixed with 500ml of N-hexane (C6H14). This crushed mash was then allowed to ferment for a period of 8days and afterwards pressed on a 0.6mm aperture size sieve to yield the alcohol contained in it. This alcohol was heated at 79ºC for 5hours at intervals of 1hour followed by 1hour cooling. Ethanol was yielded at the average volumes of 0.73, 2.18, 3.63 and 5.08 litres respectively for the selected masses of cassava sample. The rate of ethanol production was computed to be 145 l/tonne. This study found that a total of 6.77 million tonnes or 1338.77 million gallons of ethanol are available from total cassava production from tropical countries. Methane productivity of cassava peels, were investigated by mixing with poultry, piggery and cattle wastes in ratios 1:1, 2:1, 3:1 and 4:1 by mass, using 12 Nos. 220l batch type anaerobic digesters in a 3x4 factorial experiment using a retention period of 30 days and within the mesophilic temperature range. Methane yield was significantly (P ≤ 0.05) influenced by the different mixing ratios of livestock waste with cassava peels. The cumulative average biogas yield from digested cassava peels was 0.6l/kg-TS. The average cumulative methane yield increased to 13.7, 12.3, 10.4 and 9.0 l/kg-TS respectively for 1:1, 2:1, 3:1 and 4:1 mixing ratios when cassava peel was mixed with poultry waste. For piggery waste, the average cumulative biogas yield increased to 35.0, 26.5, 17.1 and 9.3 l/kg-TS respectively for 1:1, 2:1, 3:1 and 4:1 mixing ratios. For cattle waste, the methane yield increased to 21.3, 19.5, 15.8 and 11.2 l/kg-TS respectively for 1:1, 2:1, 3:1 and 4:1 mixing ratios. For all livestock waste types, mixing with peels in the ratio 1:1 by mass produced the highest methane volumes, and highest was piggery waste. Results show an environmentally safe means of managing the huge wastes produced from cassava processing. The production and use of cassava crop as a potent source of fuel for producing ethanol and methane is recommended in the cassava-growing tropical countries of the world read more... read less...

Keywords: Cassava, Cassava peels, Ethanol, Methane, Cattle waste, Poultry waste, Piggery waste.

DTM- Padé Modeling of Natural Convective Boundary Layer Flow of a Nanofluid Past a Vertical Surface

IJTEE, volume-04 , Issue 1 (2012), PP 13 - 24

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.003

by M.M. Rashidi , O. Anwar Bég, M. Asadi, M.T. Rastegari from Mechanical Engineering Department, Engineering Faculty of Bu-Ali Sina University, Hamedan, Iran, Aerospace Engineering, Department of Engineering and Mathematics, Sheaf Building, Sheaf Street, Sheffield Hallam, University, Sheffield, S11WB, England

Abstract: In this paper, we study theoretically the natural convective boundary-layer flow of a nanofluid past a vertical plate. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. A similarity solution is developed. The similarity transformations are applied to reduce the governing partial differential equations to a set of nonlinear coupled ordinary differential equations in dimensionless form. A mathematical technique, namely the Differential Transform Method (DTM), is used to solve the nonlinear differential equations under appropriate boundary conditions, in the form of series with easily computable terms. Then, Pade approximants are applied to the solutions to increase the convergence of the given series. The combined DTM-Padé procedure is implemented directly without requiring linearization, discretization or perturbation. The solutions depend on a Lewis number (Le), a buoyancy-ratio number (Nr), a Brownian motion number (Nb), a thermophoresis number (Nt), as well as Prandtl number (Pr). Temperatures are shown to be enhanced with Nb, Nr and Nt increasing. Mass fraction function, f, is also reduced with increasing Le. The flow is accelerated with increasing Pr. The computations also indicate that the reduced Nusselt number is a decreasing function of each of Nr, Nb and Nt. Excellent correlation is also achieved between the DTM-Padé results and numerical shooting quadrature. The model has important applications in heat transfer enhancement in renewable energy systems and industrial thermal management read more... read less...

Keywords: Nanofluid, thermal convection, boundary layers, DTM-Padé solutions, Brownian motion, Lewis number, thermophoresis, convergence, heat transfer enhancement

Effect of Nozzle Spacing on Heat Transfer and Fluid Flow Characteristics of an Impinging Circular Jet in Cooling of Electronic Components

IJTEE, volume-04 , Issue 1 (2012), PP 7 - 12

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.002

by M. Anwarullah , V. Vasudeva Rao, K.V. Sharma from Department of Mechanical Engineering, Mehdipatnam, Hyderabad-500028, (Andhra Pradesh), India, Department of Mechanical Engineering, SNIST, Hyderabad. India, Centre for Energy Studies, JNTU College of Engineering, Hyderabad. India

Abstract: An experimental investigation is conducted to study the effect of nozzle-to-surface spacing of the electronic components and Reynolds number on the heat transfer in cooling of electronic components by an impinging submerged air jet. Reynolds number based on nozzle diameter d is varied between 6000 to 23000. Distance from the tip of the nozzle-to-surface of the electronic components H varied from 2 to 10 nozzle diameters. Experiments are conducted with nozzle diameter of 5mm. Local heat transfer rates at a fixed radial location are measured and the stagnation Nusselt numbers for different H/d ratios calculated. They are correlated and compared with the data of earlier investigators. The following correlation for stagnation Nusselt number has been developed based on the experimental data. The results are expected to help the designers in coming up with more effective designs for cooling of electronic components NuCor = 0.8 (Red) 0.5 (PR)0.36 (H/d)-0.0 read more... read less...

Keywords: Heat transfer coefficient, Air jet impingement, Circular jet nozzle, Local Nusselt number, Electronic cooling

Development of an Experimental Apparatus for Demonstrating Vapour Compression Refrigeration System

IJTEE, volume-04 , Issue 1 (2012), PP 1 - 6

Published: 31 May 2012

DOI: 10.5383/ijtee.04.01.001

by B.O. Bolaji , T.O. Falade from Department of Mechanical Engineering, University of Agriculture, P.M.B. 2240, Abeokuta, Nigeria, Department of Mechanical Engineering, Federal Polytechnic, P.M.B. 5351, Ado-Ekiti, Nigeria

Abstract: This paper presents the design, construction and performance testing of a refrigeration system for use as experimental apparatus for demonstrating vapour compression refrigeration cycle and basic concepts of thermodynamic principles. The apparatus shows the visual observation of all-important processes. The experimental data were analysed using the first and second laws of thermodynamics to determine the refrigerating effect, the net heat rejected from the system, the compressor work input and coefficient of performance (COP). During the test, the COPs of the system and Carnot cycle were found to be 3.87 and 6.96, respectively. Also, the steady state discharge pressure and the average refrigeration capacity obtained were 830 kPa and 915.8 W, respectively, while the relative and isentropic efficiencies obtained from the system were 55.6 and 86.7%, respectively. read more... read less...

Keywords: apparatus, experimental, refrigeration system, thermodynamics, refrigerant