volume-13-Issue 1 (2018)
Latest Articles
Heat and Mass Transfer in Partially-Layered Cavity with Inner Square conductive Body
IJTEE, volume-13, Issue 1 (2018) , PP 67 - 74
Published: 24 Dec 2018
DOI: 10.5383/ijtee.13.01.010
by Hassan S. Ghalib, Muneer A. Ismael from Mechanical Engineering Department, Engineering College, University of Basrah, Basrah, Iraq
Abstract: This paper investigates the double diffusive natural convection in a partially porous layered enclosed cavity with a thermally conductive square body. The horizontal walls are thermally insulated, the left wall adds heat isothermally into the porous layer, while the right wall is cooled isothermally. The center of the square conductive body is positioned in the center of the cavity in such a way it lays on the porous-fluid interface. The governing equations have been solved using up-wind scheme finite difference method. The Parndtl number, thermal conductivity ratio of the body to fluid, Darcy number, aspect ratio of the square body to the cavity sides have fixed at 6.26, 1, 10-3, 0.5, respectively. The study has been governed by three parameters namely, Lewis number (Le = 1–50), buoyancy ratio (-10 – 10), and Rayleigh number (103 - 106 ). The results have showed that the mass diffusivity ratio, which takes into account non-unity tortuosity ratio (Deff/D = 0.53) has a significant effect on the mass transfer than the unity value. It is found also that Sherwood number is minimal when the buoyancy ratio equals to -0.5, otherwise, it increases with increasing the absolute value of the buoyancy ratio. read more... read less...
Keywords: Double-diffusive, partitioned cavity, porous medium, inner body, finite difference
Numerical Simulation of Heat Transfer during Solidification of Al–Cu Alloy Ingots Cast in a Cylindrical Mold for Different Conditions
IJTEE, volume-13, Issue 1 (2018) , PP 59 - 66
Published: 24 Dec 2018
DOI: 10.5383/ijtee.13.01.009
by Farouk M. Mahdi , Sami R. Aslan, Mahmud H. Ali from Department of Mechanical Engineering, College of Engineering, Tikrit University, Tikrit, Iraq Electronic and Control Engineering Technology, Technical College Kirkuk, Kirkuk, Iraq Department of Mechanical Engineering, College of Engineering, Kirkuk University, Kirkuk, Iraq
Abstract: In this paper, two dimensional numerical simulation of heat transfer during solidification of Al- 4.5 wt. % Cu alloy cast in a cylindrical mold was carried out to specify the optimum solidification conditions. The mold has the dimensions of 150 mm height, 38 mm outer radius, and 8 mm thickness. Four cases were studied for the solidification process; first case is the solidification in the mold without applying any thermal effects at four different mold temperatures of 25, 50, 100 and 200 Ԩ respectively. The second case is insulating the cast from the top. The third case is insulating the upper portion of the mold wall. The last case is adding heat to the upper portion of the mold wall for specific time. For the last three cases, the mold temperature is set to 25Ԩ. The results have shown that the increase in mold temperature only increases the solidification time and it does not significantly affect the temperature distribution and the final cast shape. Insulating the top of the mold made the last solidification region to be at the top of the cast, which leads to get ingot free from the secondary cavity. Insulating a portion of the upper wall of the mold made the cast surface to be more homogeneous with smallest secondary cavity. Heat addition to a portion of the upper wall of the mold leads to obtain a cast with approximately flat surface that is free from secondary cavity in addition to the primary cavity. read more... read less...
Keywords: Al 4.5 wt. % Cu alloy ingot casting; heat transfer; numerical simulation; cylindrical metal mold
Feasibility study on HYSOL CSP
IJTEE, volume-13, Issue 1 (2018) , PP 49 - 58
Published: 26 Nov 2018
DOI: 10.5383/ijtee.13.01.008
by Lars Henrik Nielsen, Mattia Baldini, Klaus Skytte, Cristian Hernán Cabrera Pérez, Eduardo Carrajero García, Diego Lopez Barrio, Lucía González Cuadrado, Alberto Rodríguez Rocha from Technical University of Denmark (DTU), Copenhagen, Denmark Investigación, Desarrollo e innovación en energía, Madrid, Spain COBRA Technology & Innovation, Madrid, Spain
Abstract: Concentrating Solar Power (CSP) plants utilize thermal conversion of direct solar irradiation. A trough or tower configuration focuses solar radiation and heats up oil or molten salt that subsequently in high temperature heat exchangers generate steam for power generation. High temperature molten salt can be stored and the stored heat can thus increase the load factor and the usability for a CSP plant, e.g. to cover evening peak demand. In the HYSOL concept (HYbrid SOLar) such configuration is extended further to include a gas turbine fuelled by upgraded biogas or natural gas. The optimised integrated HYSOL concept, therefore, becomes a fully dispatchable (offering firm power) and fully renewable energy source (RES) based power supply alternative, offering CO2-free electricity in regions with sufficient solar resources. The economic feasibility of HYSOL configurations is addressed in this paper. The analysis is performed from a socio- and private- economic perspective. In the socio-economic analysis, the CO2 free HYSOL alternative is discussed relative to conventional reference firm power generation technologies. In particular the HYSOL performance relative to new power plants based on natural gas (NG) such as open cycle or combined cycle gas turbines (OCGT or CCGT) are in focus. In the corporate-economic analysis the focus is on the uncertain technical and economic parameters. The core of the analyses is based on the LCOE economic indicator. In the corporate economic analysis, NPV and IRR are furthermore used to assess the feasibility. The feasibility of renewable based HYSOL power plant configurations attuned to specific electricity consumption patterns in selected regions with promising solar energy potentials are discussed. read more... read less...
Keywords: Feasibility analysis; CSP, Hybridization; Storage; Steam turbine; Firm power; HYSOL; OCGT; CCGT
Glass Properties Selection Effect on LEED Points for Core and Shell High Rise Residential Building in Jordan, Ammar Alkhalidi, Hasan Jarad, Mohammad Juaidy
IJTEE, volume-13, Issue 1 (2018) , PP 29 - 35
Published: 27 Jul 2018
DOI: 10.5383/ijtee.13.01.006
by Ammar Alkhalidi, Hasan Jarad, Mohammad Juaidy from Department of Energy Engineering, German Jordanian University, P.O. Box 35247, Amman 11180 Jordan Mechanical Engineering, JEA Associate engineer, Arabtec Jardaneh Engineers and Architects, Amman, Jordan
Abstract: Green building concept is flourishing in developing countries due to the high-energy cost. To meet the green building requirement, this paper investigate the effect of glass properties on 4 and 20 story building total, heating and cooling, loads for variable glass-wall ratios using HAP4.5 . The ratios considered are 20%, 40%, 60%, 80% & 100% glass to wall. The simulations were carried out for both building under moderate climate, Amman, Jordan was the selected city from this climatic zone. The glass overall heat transfer (U-value) & shading coefficient (S.C) are paired in nine combinations, these pairs are called Combination Number (CN). Combination Number simulate all range of glass properties, CN 1 is the worst case to 9 the best glass properties. Results showed that the minimum impact of glass properties was on 20-percentile glass to wall ratio and maximum at 100 Percentile. On the other hand, a Maximum of 10 LEED point could be achieved in the 20-percentile and 16 point in the case of 100-persentile for both 20 and 4 story building. Data found in this paper where formulated in the following equations with R2 = 0.949.4 Story Total Load = 915514 - (63546 * CN) + (9770 * Glass to wall) 20 Story Total Load = 7638346 - (540386 * CN) + (84090 * Glass to wall) read more... read less...
Keywords: Green Building, LEED Points, Glass Properties Effect
Prospects of Wind Energy for Power Generation in University of Benin
IJTEE, volume-13, Issue 1 (2018) , PP 23 - 28
Published: 27 Jul 2018
DOI: 10.5383/ijtee.13.01.005
by H.O. Egware, U.P. Onochie, O.O. Ighodaro from Department of Mechanical Engineering, University of Benin, Benin City, Nigeria National Centre for Energy and Environment, Energy Commission of Nigeria, University of Benin, Benin City, Nigeria
Abstract: Wind is a renewable energy resource by nature. It is clean, abundant, inexhaustible and environmentally friendly. Essentially, this study investigated the prospects of wind energy for power generation in University of Benin. Wind data from Jan 31st – Dec 31st 2013 (at 10m height) was collected from National Centre for Energy and Environment, University of Benin. Accordingly, the annual and monthly wind speed and density are estimated using the 2- parameter Weibull probability density function. From the analysis, results obtained shows that the highest mean wind speed of 1.975m/s occurred in March and the lowest monthly mean speed of 0.977m/s occurred in November. Also, the annual mean wind speed is 1.496m/s while the annual mean power density based on Weibull distribution function is 2.692W/m2 . Further results shows that the mean annual most probable wind speed and wind speed carrying maximum energy are 1.535m/s and 1.761m/s respectively. Thus, it is recommended that the institution can tap on the available wind power potential to augment its power supply. read more... read less...
Keywords: Prospects, wind energy potential, Weibull distribution, wind speed, wind power density.
Thermal Depolymerization of Lignin
IJTEE, volume-13, Issue 1 (2018) , PP 17 - 22
Published: 27 Jul 2018
DOI: 10.5383/ijtee.13.01.004
by Bilal A. Akash from American University of Ras Al Khaimah, Ras Al Khaimah, United Arab Emirates
Abstract: Lignin can be considered as a clean source of renewable energy, which may be a substitute to fossil fuel and thus reduce some of the environmental pollution. This paper presents a review of the thermal process of depolymerization of lignin; which results in production of oil and gaseous fuels from such important renewable energy source. Also, thermal hydro-cracking of lignin enhances the liquefaction of other solid fossil fuels such as coal, by producing intermediates which then react further with coal producing lower molecular weight material, which is more desirable. read more... read less...
Keywords: Lignin, depolymerization, thermal hydrocrackingd
Combined Production of Biofuels from Locally Grown Microalgae
IJTEE, volume-13, Issue 1 (2018) , PP 7 - 12
Published: 27 Jul 2018
DOI: 10.5383/ijtee.13.01.002
by N. Adam, A. Shanableh from Department of Civil and Environmental Engineering University of Sharjah, Sharjah, United Arab Emirates Research Institute of Sciences and Engineering, University of Sharjah, PO Box 2727, Sharjah, United Arab Emirates
Abstract: The purpose of this study was to assess the potential of combining the production of three types of biofuels (i.e., biodiesel, bioethanol, and biogas) from Nannochloropsis sp. microalgae. Cellulase enzyme, produced from Trichoderma viride fungi was used to convert algal hydrocarbons into sugars for bioethanol production and to improve lipids extraction for biodiesel production. The procedure for producing the three biofuels consisted of initially mixing predetermined quantities of cellulose with the algae to hydrolyze the complex hydrocarbons and produce sugars, followed by oil extraction from the hydrolyzed algae, and finally producing biogas through co-digesting the hydrolyzed and oil-extracted algae residual with wastewater treatment sludge. Without enzyme, the total sugar yield following hydrolysis for 6 hours with distilled water at 37°C and pH 5 reached 38 mg/g algae. Using the enzyme, total sugar production increased in the range of 42 mg/g algae to 74 mg/g algae with increasing enzyme use. Similarly, the reducing sugar production increased from 36 mg/g algae without enzyme to 60 mg/g algae with increasing enzyme dose. Following hydrolysis, the lipids yield reached 59% of the extracted algae weight, which represents almost all of the lipids in the algae. The residual algae mixed with sludge generated significant amounts of biogas in excess of the quantities generated by sludge alone. The results demonstrated the technical feasibility of producing three biofuels from algae; however the economic aspects of the process require significant further careful consideration. read more... read less...
Keywords: Biofuels, Biogas, Biodiesel, Ethanol, Enzymatic Hydrolysis, Sugars, Oil, Renewable Energy, Microalgae.
Impact of Date Palm Seed Size on Biogas Production from Date Seeds/Wastewater Treatment Sludge Mixtures
IJTEE, volume-13, Issue 1 (2018) , PP 1 - 6
Published: 27 Jul 2018
DOI: 10.5383/ijtee.13.01.001
by W. Radeef, A. Shanableh, T. Merabtene from Department of Civil and Environmental Engineering, University of Sharjah, Sharjah, United Arab Emirates Research Institute of Sciences and Engineering, University of Sharjah, PO Box 2727, Sharjah, United Arab Emirates
Abstract: Biogas in the form of methane can be produced from wastewater treatment sludge mixed with a variety of biodegradable organic feedstocks through anaerobic digestion. In this study, biogas was produced from date palm seeds, which are locally available, and wastewater treatment sludge mixtures. The objective of the study was to assess the effect of date palm seed additives with different sizes on biogas production from the mixtures. In the study, two locally available types of date seeds, Khalas and Khudari, were anaerobically co-digested with wastewater treatment sludge in 50 mL serum bottles under mesophilic conditions. Date seeds with three different sizes; 1.18– 3.75 mm, 0.6 –1.18 mm; and 0.425 – 0.6 mm, were added to the sludge at date seeds to sludge total solids (TS) weight ratios of 0%, 2.5%, 5%, 7.5%, and 10%. The experimental results confirmed that the addition of date seeds significantly enhanced biogas production up to 20% to 30%. The results indicated that the date seed size slightly affected biogas production, with the order of cumulative biogas production and biogas production rates, expressed in terms of date seed sizes, being as follows: 0.425 – 0.6 mm > 0.6 – 1.18 mm > 1.18 – 3.75 mm. However, the results showed no major difference in biogas production between the two different date seed types read more... read less...
Keywords: Khalas Date Seed, Khudari Date Seed, Wastewater Sludge, Biogas Production, Methane Production, Biofuel