volume-12-Issue 2 (2017)
Latest Articles
Numerical Simulation of a Cylindrical Heat Pipe and Performance Study
IJTEE, volume-12, Issue 2 (2017) , PP 135 - 141
Published: 19 Dec 2017
DOI: 10.5383/ijtee.12.02.010
by Mohammed Noorul Hussain, Isam Janajreh from Masdar Institute of Science and Technology, Abu Dhabi, UAE
Abstract: Heat Pipes are passive devices used for transferring heat from a heat source to a heat sink with very small difference in temperature. They have three main sections namely the evaporator, adiabatic section and the condenser. In construction terms, they have three parts, the metal container, the porous wick region which lines the container from inside and the hollow flow chamber. Heat pipe performance is governed by several parameters such as the geometry, dimensions, working fluid, wick and container materials etc. In this study numerical simulation method was used to analyze the performance of the heat pipe. A numerical model based on Navier stokes equation, Energy equation and conjugate heat transfer was developed using COMSOL Multiphysics package. The top wall temperature profile obtained was validated with experimental results, and further the absolute thermal resistance was calculated. A sensitivity study was carried out to study the performance dependency of heat pipe on four parameters namely, porosity, condenser evaporator lengths, radius of heat pipe and the heat input, in terms of the absolute thermal resistance. The results showed that absolute thermal resistance varied directly with respect to porosity of the wick, and inversely in case of radius of the heat pipe. The absolute thermal resistance was maximum in case of equal condenser and evaporator lengths. Interestingly the absolute thermal resistance did not vary with the applied heat rate, demonstrating the practicality in using absolute thermal resistance as a performance characteristic parameter. read more... read less...
Keywords: Heat pipe performance, Absolute thermal resistance, Numerical simulation, Experimental validation.
Voltage Unbalance Reduction of a Local Transformer Area with Domestic Asymmetrical Inverter and Optimal Control Design
IJTEE, volume-12, Issue 2 (2017) , PP 129 - 134
Published: 19 Dec 2017
DOI: 10.5383/ijtee.12.02.009
by László Neukirchner, Attila Göllei, Péter Görbe, Attila Magyar from Department of Electrical Engineering and Information Systems, Faculty of Information Technology, University of Pannonia, Egyetem street 10. H-8200, Veszprém, Hungary
Abstract: The three-phase unbalance problem can introduce additional losses in distribution networks due to both negative and zero sequence components, which leads to inefficient power consumption and increased CO2 emission of low voltage transformer area, moreover it causes safety possible malfunction of energy transportation networks. The aim of this paper is to introduce a new voltage unbalance indicator and a control algorithm that compensates source voltage unbalances. To examine the available measures of voltage asymmetry and make a comparison from the transient behaviors point of view. Analytical and simulation, results are presented to illustrate the effectiveness of the new techniques. read more... read less...
Keywords: voltage, Transformer, inverter
Solar Powered Electrolysis System for Cooking Applications
IJTEE, volume-12, Issue 2 (2017) , PP 119 - 122
Published: 19 Dec 2017
DOI: 10.5383/ijtee.12.02.007
by Evangelia Topriska, Maria Kolokotroni, Zahir Dehouche, and Earle Wilson from Heriot Watt University Dubai Campus, Dubai, United Arab Emirates Brunel University, Uxbridge, United Kingdom University of Technology, Kingston, Jamaica
Abstract: This paper presents a numerical model for a solar-powered Proton Exchange Membrane Electrolyser (PEM) for the generation of hydrogen as a fuel for cooking applications. The model was developed in TRNSYS software and includes a novel FORTRAN numerical component to model the operation of the PEM electrolyzer, based on operational data from a small-scale experimental rig. The numerical model was calibrated using data from the experimental rig powered by operational data from a photovoltaic panel system in the UK and from Jamaica. The calibrated model was used to develop a case study for a small community in Jamaica with a daily cooking demand of 39.6 kWh or 1.68 kg of H2 gas. Simulation results indicate that the H2 production strategy is satisfactory for the cooking needs of the case study and appropriate according to the environmental considerations related to cooking read more... read less...
Keywords: Solar Hydrogen, Electrolysis, Photovoltaics, Integrated Renewable Energy, Cooking
A note on NDT Technology for Detection of Defects in Oil and Gas Pipes
IJTEE, volume-12, Issue 2 (2017) , PP 117 - 118
Published: 19 Dec 2017
DOI: 10.5383/ijtee.12.02.006
by Amjad Omar from School of Graduate Studies and Research, American University of Ras Al Khaimah, UAE
Abstract: This paper provides a general note on the state of the art in the application of nondestructive testing techniques (NDT) for the detection of defects or deteriorations in metallic and nonmetallic oil and gas pipes. The advantages and disadvantages of each technique will be pointed out. read more... read less...
Keywords: NDT, Nonmetallic, Microwave
Scopus-Based Analysis of Solar Energy Research in the United Arab Emirates
IJTEE, volume-12, Issue 2 (2017) , PP 111 - 115
Published: 19 Dec 2017
DOI: 10.5383/ijtee.12.02.005
by Omar Akash from RAK Research & Innovation Center, American University of Ras Al Khaimah, United Arab Emirates
Abstract: This paper examines and presents the solar energy research situation in the UAE using Scopus-database. Like other countries of GCC, the UAE realizes that it has to rely less on oil and gas and start to consider other sources of energy for power production. The country began to support scientific research to be conducted in alternative energy resources such as solar energy since the early Nineties. However, it was very limited. More research was conducted at a somewhat larger scale during the past 10 years. Many researchers worked on various applications of solar energy for electricity production, water desalination, space cooling, etc. This work can be used by researchers, politicians, industry, or decision-makers to see how much the UAE invested in the field of solar energy and how it compares to other countries in the GCC, Arab world, and worldwide. It presents and identifies those active institutions and researchers in the field of solar energy in the UAE using the data collected by Scopus. The progress of solar energy research in the UAE is also presented. read more... read less...
Keywords: Solar energy, Scopus, UAE
Flow Regimes and Heat Transfer Characteristics in Combustion Chambers
IJTEE, volume-12, Issue 2 (2017) , PP 105 - 110
Published: 19 Dec 2017
DOI: 10.5383/ijtee.12.02.004
by Saad A. Mohammed, Essam E. Khalil, Hatem Omar Haridy, and Esmail M. ElBialy from Ministry of Electricity, Baghdad, Iraq Mechanical, Engineering at Faculty of Engineering, Cairo University, Cairo, Egypt
Abstract: This paper presents numerical computations are performed to investigate the convective heat transfer characteristics of a gas turbine that can combustor under non-reacting flow conditions in a Reynolds number range 50,000 to 600,000 with a characteristic swirl number of 0.7. A sample of computational predictions of flow behaviors under reacting conditions is also shown for swirling furnace flow of 0.52. The RNG (K-ɛ Model) predictions are compared with the experimental data of local heat transfer distribution on the combustor liner wall. It was observed that the flow field in the combustor is characterized by an expanding swirling flow, which impinges on the liner wall close to the inlet of the combustor. The peak heat transfer augmentation ratio (compared with fully developed pipe flow) reduces from 10.5 to 2.7. Additionally, the peak location does not change with the Reynolds number since the flow structure in the combustor is also a function of the swirl number. The size of the corner recirculation zone near the combustor liner remains the same for all Reynolds numbers and hence the location of shear layer impingement and peak augmentation does not change. The heat transfer coefficient distribution on the liner wall predicted from the RNG (K-ɛ Model) is in good agreement with experimental values. The location and the magnitude of the peak heat transfer are predicted in very close agreement with the experiments. read more... read less...
Keywords: Furnaces, Modelling, Swirling Flows, Heat transfer
Smoke Spread in Underground Metro Station
IJTEE, volume-12, Issue 2 (2017) , PP 95 - 103
Published: 19 Dec 2017
DOI: 10.5383/ijtee.12.02.003
by Mahmoud A. Ahmed, Mahmoud A. Fouad, and Essam E. Khalil from Mechanical Power Engineering Department, Faculty of Engineering, Cairo University, Giza, Egypt
Abstract: In the event of a subway train, fire smoke is the most fatal factor because smoke spreads in a direction that coincides with a passenger’s evacuation path. It reduces visibility and can cause fatalities by asphyxiation. This research presents a numerical study to investigate the effect of exhausting smoke by single-point extraction and exhausting smoke by multi-point extraction on passengers’ life safety. Also, the effect of adding smoke barriers at the stairs entrance on passengers’ life safety is studied. Fire Dynamics Simulator (FDS) software version 5.5.3 is utilized to simulate 6 case studies in 150 m long, 20 m wide and 13 m height domain with a subway car fire source simulated as a fire with the unsteady heat release rate of 35 MW resulted from burning Heptane as a fuel. Results show that exhausting smoke by multipoint extraction system in underground subway station gives better performance than single point extraction system. By increasing the distance between vents in a multipoint extraction system, tenable conditions improve at a human level. Smoke barrier addition to ventilation system has a great effect on the efficiency of smoke extraction and improving tenable conditions at a human level. read more... read less...
Keywords: Subway train fire, Smoke spread, FDS, Smoke barrier, Life safety.
Investigation of the Current Energy Sector in Jordan: Energy Strategy, Resources and Regulatory Framework
IJTEE, volume-12, Issue 2 (2017) , PP 89 - 93
Published: 19 Dec 2017
DOI: 10.5383/ijtee.12.02.002
by Ahmed Al-Salaymeh, Heba AlZaben, and Nadeen Habash from Mechanical Engineering Department, Faculty of Engineering & Technology, University of Jordan, Amman 11924, Jordan
Abstract: Due to the increase in demand for energy resources and the effect of the ongoing events in the region of Jordan. The energy resources are decreasing over time and that also has a negative effect on the Jordanian economy. Providing energy is always a vital and significant problem in Jordan. Jordan on the other hand is rich in some of the renewable energy resources, which are not fully used until this moment. Therefore, it is essential to find alternative and renewable energy resources. Moreover, there is also a lack in creating clear and long-term future plans in the energy field. In this paper, energy sources and the efficiency of the energy sector in Jordan will be specified, in addition to the determination of the cofounders and sponsors for enhancing and developing the energy sector. The shift in policy that is needed to increase this efficiency will be also investigated. read more... read less...
Keywords: Energy resources. Renewable energy. Energy sector. Energy policy
Performance Study of a Domestic Boiler Fueled By Biodiesel Produced From Rapeseed
IJTEE, volume-12, Issue 2 (2017) , PP 85 - 88
Published: 19 Dec 2017
DOI: 10.5383/ijtee.12.02.001
by Mohammad A. Hamdan and Derar A. Almomani from Faculty of Engineering and Technology, The University of Jordan, Jordan
Abstract: A domestic boiler was used in this work to compare its performance when it is powered by diesel fuel and biodiesel fuel that is produced from rapeseed oil, then blends of both fuels were prepared with different concentrations of biofuel (B5, B10 and B20). The performance measurements included the efficiency of the boiler, the specific fuel consumption in addition to the environmental impact represented by exhaust gases analysis; this included the concentration measurements of main species such as NOX, NO2, NO, SO2, CO2, and hydrocarbon. It was found that there is a small decrease in boiler efficiency resulting from using biodiesel fuel. Moreover, an increase in specific fuel consumption has been noticed. The performance of a domestic boiler when operating using B20, B5, and B10 blends has similar fuel consumption and efficiency when it is powered by petroleum diesel fuel. The regulated emissions from biodiesel fuel found to be more ecological than petroleum diesel, with the concentrations of all pollutants decrease with the percentages of biodiesel in the blends. read more... read less...
Keywords: Boiler, Biodiesel, Rapeseed