volume-01-Issue 2 (2010)
Latest Articles
Performances Assessment of Natural Refrigerants as Substitutes to CFC and HCFC in Hot Climate
IJTEE, volume-01, Issue 2 (2010) , PP 125 - 130
Published: 26 Jan 2010
DOI: 10.5383/ijtee.01.02.008
by M. Boumaza from Department of Chemical Engineering, College of Engineering, King Saud University, Saudi Arabia
Abstract: Due to the environmental concerns ozone depletion potential (ODP) and global warming potential (GWP) of the existing refrigerants, industry and researchers in this field are investigating long-term solutions. With extensive work on alternatives to chlorofluorocarbons (CFCs) and hydro chlorofluorocarbons (HCFCs), initially hydro fluorocarbons were considered to be long-term solutions. The global warming of HFCs has become a hurdle to accept them as long-term solutions. Now, the focus is on the use of natural refrigerants like hydrocarbons (HCs) such R290, R600, ammonia, carbon dioxide and water. These natural substances have very low GWP, and a zero ODP. This paper presents simulation results through a thermodynamic analysis of R22 and three of its alternatives natural refrigerants (R290, R600a and R717) for A/C and refrigeration purposes operating under various outdoor temperatures, represented by the condenser temperatures. The examined new refrigerants show varying performance, depending on the evaporator temperatures, but in every case, the condenser temperature seems to have an important impact on the performance of the cycle. read more... read less...
Keywords: refrigerants, substitutes, environment, ozone, performances.
Potential for Wind-Powered Desalination Systems in Jordan
IJTEE, volume-01, Issue 2 (2010) , PP 109 - 123
Published: 26 Jan 2010
DOI: 10.5383/ijtee.01.02.007
by Mousa S. Mohsen from Department of Mechanical Engineering, Hashemite University, Zarqa 13115, Jordan
Abstract: Desalination systems driven by renewable energies are limited, and they usually have a limited capacity. They only represent about 0.02% of total desalination capacity. However, many reasons make the use of renewable energies suitable for brackish and seawater desalination. In addition to shortage of fresh water resources, Jordan is suffering from shortages in recoverable commercial energy sources such as crude oil and natural gas. The limited energy sources in Jordan makes considering renewable energy options such as wind power very attractive, especially for remote areas. This will be extremely important for small-scale applications. Due to prevailing tough conditions, such as low water quality and shortage in supplies, there is a large demand for small desalination units, not only in locations not connected to a water supply network, but also as units for additional or independent supply. The coupling of wind energy and desalination systems holds great promise for increasing water supplies in water scarce regions. An effective integration of these technologies will allow countries to address water shortage problems with a domestic energy source that does not produce air pollution or contribute to the global problem of climate change. Meanwhile the costs of desalination and renewable energy systems are steadily decreasing, while fuel prices are rising and fuel supplies are decreasing. This paper specifically seeks to address the enhancement of the overall quantity of freshwater available in Jordan, by exploring the potential for integrating wind power and desalination technologies to increase water supplies. Both desalination and wind technologies are summarized in this paper, including growth trends, costs, and emerging technological advancements. These descriptions provide snapshots of the current status of these technologies and their markets, as both independent and integrated technologies. Meteorological data is then used to generate a map of Jordan wind-powered desalination potential “hotspots”, to give a rough idea where the integration of these technologies might be the most applicable. read more... read less...
Keywords: Wind-Powered Desalination, RO Desalination, Renewable Energy, Jordan
Water-Surrogate Fuel Emulsion Combustion Effect on CO and NOX Emissions
IJTEE, volume-01, Issue 2 (2010) , PP 99 - 108
Published: 26 Jan 2010
DOI: 10.5383/ijtee.01.02.006
by Abdulaziz H. El-Sinawi from College of Engineering, King Faisal University, Al-Ahsa, 31982, Saudi Arabia
Abstract: Water emulsified fuel is one of the few promising emission reduction techniques with the potential to reduce NOX in diesel engines. little effort has been directed towards modelling the combustion of water-in-fuel emulsion. This work provides a better understanding of the effects of the existence of water in fuel in the form of emulsion on spray combustion and pollutant emissions namely NOX and carbon monoxide by modelling the relevant processes and focusing on the variables behind the emission reduction criteria and performance. The commercially available software CHEMKIN IV was used to simulate spray combustion at diesel engine-relevant conditions. Surrogate fuel (80 % heptane and 20 % toluene) was used due to the available detailed kinetic and thermodynamic data needed for modelling. An emulsified fuel with 3, 5, 8 and 20 % water by volume is used as an engine feed for each run separately and the results are compared with that of the dry surrogate fuel of 0 % water. The modelling results show that water has a significant effect on reducing engine operating temperature, and NOX formation. However, the reduction of NOX is at the expense of an increase in carbon monoxide (CO) emissions and elongated ignition delay time, which is disadvantageous for the steady running diesel engines. read more... read less...
Keywords: water-surrogate fuel emulsion, combustion, CO and NOx emissions
Investigation on the Effect of Operating Parameters on the Performance of Solar Desiccant Cooling System Using Artificial Neural Networks
IJTEE, volume-01, Issue 2 (2010) , PP 91 - 98
Published: 26 Jan 2010
DOI: 10.5383/ijtee.01.02.005
by El-Shafei B. Zeidan, Ayman A. Aly, Ahmed M. Hamed from Department of Mechanical engineering, Faculty of Engineering, Taif University, Al-Hawyah, PO Box 888, Saudi Arabia
Abstract: A multiple-layer artificial neural network (ANN) model has been applied to study the performance of a solar liquid desiccant dehumidification/regeneration system. The experimental results of a previous study are used to construct and test the ANN model. Then the model has been utilized to describe the effect of the inlet conditions of the air and calcium chloride (CaCl2) solution on the regeneration process. Good agreement between the outputs from the ANN model and the corresponding results from the experimental data has been found. The proposed model can work well as a predictive tool to complement the experiments. read more... read less...
Keywords: Solar energy, dehumidification/regeneration, absorption, liquid desiccant, ANN, back propagation algorithm
Solar Assisted Gasification: Systematic Analysis and Numerical Simulation
IJTEE, volume-01, Issue 2 (2010) , PP 81 - 90
Published: 26 Jan 2010
DOI: 10.5383/ijtee.01.02.004
by Isam Janajreh, Shabbar Syed, Rana Qudaih, Ilham Talab from Masdar Institute of Science and Technology, Abu Dhabi, United Arab Emirates, P.O. Box 54224
Abstract: Hybrid solar thermo-chemical conversion process is a viable route to produce clean fuel using any carbonaceous material as feedstock and solar radiation to provide energy for endothermic reactions. The steam gasification of carbonaceous material under high energy solar flux provides a thermo-chemical pathway to produce syngas fuel i.e., hydrogen (H2) and carbon monoxide (CO). Therefore, in this study a steady state model of entrained flow gasifier is simulated utilizing direct solar irradiation as process energy for endothermic reactions inside reactor. LaGrange approach is used to inject coal particulates in the reactor which immediately undergoes devolatilization and finally steam (H2O) gasifier. Species transport equations are solved for the concentration of H2, CO2, CO, H2O and nitrogen (N2) as well as the heterogeneous reaction of char (C/fixed carbon) with steam. DO radiation model is applied to simulate 5KW of solar radiation through an optical window inside the reactor. Steady state mass and energy balance are solved to determine the reactor temperature and the composition of product syngas. The resulting problem is then simulated by finite volume method to solve governing mass, momentum, energy and species transport equation. Validation is accomplished by comparing the trends of simulated results with systematic analysis and experiment. The resultant H2: CO and CO: CO2 ratios are computed to be 1.83 and 9.42 respectively. The cold gas efficiency is calculated, which is found to be 105.21% showing the upgraded heating value of product gases by virtue of direct solar radiation read more... read less...
Keywords: CO2 emission, entrain flow gasifier, solar gasification, thermo-chemical
Concept of Overall Thermal Transfer Value (OTTV) in Design of Building Envelope to Achieve Energy Efficiency
IJTEE, volume-01, Issue 2 (2010) , PP 75 - 80
Published: 26 Jan 2010
DOI: 10.5383/ijtee.01.02.003
by J. Vijayalaxmi from Department of Architecture, School of Architecture and Planning, Anna University, Chennai, India- 600025
Abstract: Design of energy efficient buildings is the quickest way to reduce energy consumption. The skin of the building acts as a barrier between the indoor environment and the outdoor environment. The thermal performance of a building depends upon the façade design to a large extent, ranking second to the local climatic characteristics. Potential for energy conservation exists in all building typologies, but it becomes more of a concern in energy intensive buildings such as airconditioned offices and shopping malls. This paper discusses the significance of the Overall Thermal Transfer Value (OTTV) controls as a means of enhancing energy efficiency of buildings. OTTV is a measure of heat gain into the building through the building envelope. It also acts as an index for comparing the thermal performance of buildings. The objectives and need for OTTV controls are discussed. The parameters used in calculating OTTV and therefore the need to customize OTTV calculations based on the location of the building are analysed. The paper also discusses the OTTV standards in countries such as Singapore, Malaysia, Jamaica and Thailand. The application and calculation of OTTV for a case study building is demonstrated. The paper discusses the limitations of OTTV standards, its significance and relevance, and concludes that OTTV is one of the means of achieving energy efficiency of air-conditioned buildings. read more... read less...
Keywords: Air-Conditioned, Energy Efficiency, Energy Intensive, OTTV, Thermal Performance
Energy Rating Windows for Residential Buildings
IJTEE, volume-01, Issue 2 (2010) , PP 67 - 74
Published: 26 Jan 2010
DOI: 10.5383/ijtee.01.02.002
by K. Hassouneh, A. AlShboul, and A. Al-Salaymeh from Architecture Engineering Department, Faculty of Engineering & Technology, Univ. of Jordan, Amman 11942, Jordan, Mechanical Engineering Department, University of Jordan, Amman 11942, Jordan
Abstract: The present paper describes an example of an energy rating windows for residential buildings in Jordan. It focuses on the thermal properties of the available windows in the market in Jordan. Windows have a great effect on the heating and cooling requirements costs of a building, and the comfort level experienced by its occupants. Windows are considered the weakest link in a building envelope for heat gain in the summertime and heat loss in the wintertime. A survey on the most common windows that are used in residential buildings has been carried out. The label of the window describes the type of window, and rates it for many factors such as U-Factor, SHGC, and visible light transmittance. The output of the present work can give the home owners an opportunity to choose the appropriate window for the building taking into consideration thermal performance of the window and its impact on the cooling and heating load of the building. The energy performance of the building and the choice of energy efficient window are dependent on glazing type, number of glazing, frame materials, interior and exterior, shading, and window orientation. Therefore, it is very important to take into consideration all options when determining which energy-efficient window is best and most cost-effective for your needs both now and in the future. The most important reason to select energy efficient windows is to reduce the annual coast of heating and cooling of the buildings. This makes good sense for the most building owners and it also contributes in the efforts to reduce the bad impacts of the non- renewable energy use. read more... read less...
Keywords: Rating Windows, Residential Buildings, Energy Balance
Economic Analysis of Hybrid Renewable Model for Subtropical Climate
IJTEE, volume-01, Issue 2 (2010) , PP 57 - 65
Published: 26 Jan 2010
DOI: 10.5383/ijtee.01.02.001
by GM Shafiullah, Amanullah M.T. Oo, ABM Shawkat Ali, Dennis Jarvis, Peter Wolfs from Faculty of Sciences, Engineering & Health, CQ University, Australia, QLD-4702, Faculty of Arts, Business, Informatics & Education, CQ University, Australia, QLD-4702, Faculty of Science and Engineering, Curtin University of Technology, Australia, WA-6845
Abstract: Current power systems create environmental impacts due to utilization of fossil fuels, especially coal, as carbon dioxide is emitted into the atmosphere. In contrast to fossil fuels, renewable energy offers alternative sources of energy which are in general pollution free, technologically effective and environmentally sustainable. There is an increased interest in renewable energy, particularly solar and wind energy, which provides electricity without giving rise to carbon dioxide emissions. This paper presents economic analysis of a renewable hybrid system for a subtropical climate and also investigated the impact of renewable energy sources to the existing and future smart power system. The daily mean global solar irradiance and three hourly mean wind speeds have been collected from the Rockhampton Aero Weather Station, Queensland (RAWS), Australia for this study. Hybrid Optimization Model for Electric Renewable (HOMER), a computer model developed by National Renewable Energy Laboratory (NREL) has been used to perform comparative analysis of solar and wind energy with diesel and hybrid systems. Initially total net present cost (NPC), cost of energy (COE) and the renewable fraction (RF) have been measured as performances metrics to compare the performances of different systems. For better optimization, the model has been refined with sensitivity analysis which explores performance variations due to wind speed, solar irradiation and diesel fuel prices. From the simulation, it is shown that there are a number of factors that impact the integration and performance of renewable energy sources to the power systems. read more... read less...
Keywords: Renewable Energy, Smart Grid, HOMER, Performances Metrics, Sensitivity Analysis.