volume-15-Issue 1 (2019)
Equivalent Lumped Criterion for Unsteady Heat Conduction in a Vertical Planar Wall with Natural Convection to a Nearby Quiescent Fluid
IJTEE, volume-15, Issue 1 (2019) , PP 81 - 86
Published: 12 Sep 2019
by Antonio Campo from Department of Mechanical Engineering, The University of Texas at San Antonio, San Antonio, Texas, TX 78249, USA
Abstract: Within the framework of the potent lumped model, unsteady heat conduction takes place in a solid body where the mean temperature varies with time. Conceptually, the lumped model subscribes to the notion that the external convective resistance at the body surface dominates the internal conductive resistance inside the solid body. For forced convection heat exchange between a solid body and a fluid, the lumped model criterion entails to the lumped Biot number, Bil < 0.1, in which the mean convective coefficient depends on the impressed fluid velocity. In contrast, for natural convection heat exchange between a solid body and a fluid, the mean convective coefficient depends on the solid-to-fluid temperature difference. As a consequence, the lumped Biot number criterion must be modified to read Bil < 0.1, wherein the maximum mean convective coefficient occurs at the initial temperature Tin and time tin for cooling or at a future temperature Tfut and time tfut for heating. In this paper, the equivalence of the lumped Biot number criterion for a vertical planar wall is deduced employing the thermal conductivity of the solid and the initial or future Rayleigh number as the deciding factors.. read more... read less...
Keywords: vertical planar wall, natural convection, mean convective coefficient, nearby fluid, nonlinear lumped equation, lumped Biot number criterion
IJTEE, volume-15, Issue 1 (2019) , PP 71 - 79
Published: 12 Sep 2019
by Mohamed El Zayat, Sherien Elagroudy, Salah El Haggar from Environmental Engineering, the American University in Cairo, P.O. Box 74, New Cairo 11835, Egypt Environmental Engineering, Ain Shams University, 1 El-Sarayat St., Abassia, Cairo 11517, Egypt
Abstract: The removal of lead, copper, and cadmium from aqueous solution using cement kiln dust (CKD) has been investigated under batch equilibrium technique setup. The adsorption behavior of the target metals is examined as a function of pH, contact time, sorbent dose and initial metal concentration. The metal hydroxide precipitation is studied to determine the separation behavior. The lead hydroxide precipitation is dominant at pH > 6.0 while copper and cadmium precipitation reached 90% at pH > 8.0. A surface titration experiment reveals negative surface charge of the CKD at pH < 10 that means electrostatic attraction is the dominant phenomenon for divalent metals. Langmuir and Freundlich isotherms were performed to show the adsorption capacity of CKD. They show an adsorption order of Pb≥ Cu> Cd which is compatible respectively with their electronegativity; 1.854, 1.85, and 1.52. The sorption capacity of CKD at the optimum conditions is 14.85, 14.65, and 14.1 mg/g for lead, copper, and cadmium, respectively read more... read less...
Keywords: Sorption Isotherms, Heavy Metals; Surface Titration, Cement Kiln Dust (CKD), Batch Equilibrium
Environmental Evaluation of Emissions from Thermal Power Plants in Jordan: Aqaba Thermal Power Plant Case Study
IJTEE, volume-15, Issue 1 (2019) , PP 63 - 70
Published: 12 Sep 2019
by Mohammad Hamdan, Ruba M. Maály from The University of Jordan, Department of Mechanical Engineering, Amman, Jordan
Abstract: Jordan faces a wide variety of environmental problems, most of which are attributable to the inherent of air pollution roused in the last decade, and the cost of ignoring such problem could be exorbitant and the results could be very harmful as well. As thermal power plants are considered the main pollutants emitters, Aqaba city thermal power plant, one of the major thermal power plants in Jordan, is considered as a case study to indicate the impact of main pollutants emitted to surrounding environment. This study is an attempt to generate a correlation that relates amount of emitted pollutants to the amount of the electricity generated of the considered plant. The considered pollutants are carbon dioxide, carbon monoxide, sulphur oxides, and nitrogen oxides. Actual measured data for the amount of fuel used and emission factors for each of these pollutants were provided by Aqaba thermal power station. Amounts of emitted pollutant, electricity generated, and the efficiency for the power was calculated on monthly basis. Correlation was successfully generated that relates the amount of pollutant emitted from the power station to the electrical power generated over the last four years. Using this obtained correlation, it is expected to help in the estimation of future emitted pollutants, and hence to control these amounts in an attempt to establish regulatory frame work for power pollution reduction. read more... read less...
Keywords: Pollutants Activity Data, Emission factor, Pollutant Intensity
Reducing Organic Pollution of Wastewater from Milk Processing Industry by Adsorption on Marlstone Particles
IJTEE, volume-15, Issue 1 (2019) , PP 57 - 61
Published: 12 Sep 2019
by Maher Al-Jabari, Hiba Dwiek, Nareman Zahdeh, Nadia Eqefan from Environmental Technology Engineering, Palestine Polytechnic University, Hebron, Palestine
Abstract: This paper presents a simple technique for controlling industrial pollution of wastewater with organic content. It summarizes results of an experimental batch adsorption work. Samples of real wastewater from milk processing are mixed with marlstone particles and the COD is measured as a function of time for monitoring the performance and kinetics of the adsorption process. Kinetic curves of COD in wastewater and surface concentration (on marlstone particles) as well as equilibrium data are presented. Effects of various parameters are investigated and including stirring rate, pH, solid to liquid ratio (dosage), organic load and contact time. The equilibrium adsorption isotherm is obtained and found to be unfavorable type. Equilibrium adsorption capacity is pH dependent, as adsorption process favors moderate alkaline conditions, i.e. pH range of 5-9. Removal efficiency increases with increasing marlstone particles to wastewater ratio. The adsorption process is relatively fast upon stirring the system as the rate of adsorption increases with stirring rate. Under stirring the final equilibrium adsorption is reached within four hours while without stirring, the adsorption process takes more than 10 days to reach to an equilibrium state. The obtained experimental kinetic adsorption curves are modeled using pseudo first order and second order rate equations. read more... read less...
Keywords: wastewater, chemical oxygen demand, adsorption, kinetic, equilibrium, marlstone
IJTEE, volume-15, Issue 1 (2019) , PP 51 - 56
Published: 12 Sep 2019
by Abdulrahman Th. Mohammad from Baqubah Technical Institute, Middle Technical University (MTU), Baghdad, Iraq
Abstract: This paper describes the design and analysis of space heating system with solar evacuated tube collector using a TRNSYS simulation within the weather data of Baghdad city-Iraq for the period between 1st of November and 31th of March. The first objective summarized in select the main parameters of collect cycle (solar collectors and storage tank) and the main parameters of radiating cycle (fan coil units and pump). The second objective deals with the estimation of the system performance in terms of heat collected by the solar collector, solar fraction in solar cycle and the heat gain in radiating cycle with whole efficiency. The results of simulation show that the maximum radiating heating energy was investigated in December about 985 MJ with solar fraction 0.55 and whole efficiency 35.75%. read more... read less...
Keywords: Solar collector, evacuated tube, TRNSYS
IJTEE, volume-15, Issue 1 (2019) , PP 43 - 49
Published: 11 Sep 2019
by Roberto Alvaro-Hermana, Jesús Fraile-Ardanuy, Julia Merino, Luk Knappen from ORKESTRA-Fundación Deusto, Universidad de Deusto, Av. de las Universidades, 24, 48007, Bilbao Information Processing and Telecommunications Center, ETSI Telecomunicación, Universidad Politécnica de Madrid. Avda. Complutense 30, 28040 Madrid, Spain TECNALIA. Parque Tecnológico de Bizkaia. c/ Geldo, Edificio 700. E-48160 Derio, Spain Institute voor Mobiliteit IMOB, Universiteit Hasselt, Campus Diepenbeek, BE 3590 Diepenbeek, Belgium
Abstract: Electrification of the road transportation sector is one of the ways to reduce the green-house gases (GHGs) emissions worldwide, but an increasing number of electric vehicles (EVs), will impact on the power system, particularly on the residential distribution low-voltage grid. In order to reduce this impact during the peak periods, it is possible for these vehicles to get energy not only from the grid, but also from other EVs parked at the same time in the same place through a peer to peer (P2P) energy trading. In this paper a night charging method that optimizes the recharging process of an EV fleet at regional level depending on hourly energy price in a P2P energy trading system is presented. This algorithm determines how much energy should be recharged in the battery of each EV and the corresponding time slot to do it, avoiding the discontinuities in the charging process and considering the users’ personal mobility constraints. read more... read less...
Keywords: Electric Vehicles; Peer-to-Peer; Optimization
IJTEE, volume-15, Issue 1 (2019) , PP 31 - 41
Published: 11 Sep 2019
by S. Bouzenada, L. Frainkin, A. Léonard from Laboratory of Energy and Environment, department of Architecture, University Constantine 3, Algeria Products Environment Processes Department of Chemical Engineering Sart Tilman, University of Liege, Belgium
Abstract: Liquid desiccant cooling system by solar energy is an energy-conservative and environment-friendly air-conditioning system. Recently, the rapid development of desiccant air conditioning technology has expanded natural fluid to broader applications. To avoid the excessive waste of energy an alternative way to achieve desired electrical energy reduction is the use of liquid desiccant air conditioning system (LDAC) in which a desiccant material absorbs moisture from the humid air. Solar energy is used to regenerate the desiccant material and cycle continues. This system has been considered as a promising application as traditional air-conditioning systems. Its performance is strongly influenced by the thermal properties of liquid desiccant, especially the surface vapor pressure. The vapor pressure of desiccant solutions is the key parameter to select the best desiccant for liquid desiccant air conditioning system. In this paper an experimental study is carried out to calculate the vapor pressure of CaCl2 using regression dependent parameters and evaluate the mass transfer coefficient. The effect of relevant operating parameters, such as air temperature, humidity and air velocity on the mass transfer processes between the air and the desiccant CaCl2 is analyzed. For a detailed study of the dehumidification process and desiccant regeneration, a DVS, a Dryer and Climatic Chamber equipments are used. Several measurements are made in a relatively large range of operating conditions. It is found that the absorption mass rate increased linearly with increasing air humidity. After 6 hour of absorption the mass transfer becomes slow. The mass transfer coefficient is affected by the climatic condition variation. The decrease in mass transfer potential with time is mainly due to vapor pressure rise on the desiccant surface during absorption. The vapor pressure is significantly affected by the air humidity variation. At higher humidity, the concentration decreases while the vapor pressure increases. Vapor pressure of a liquid desiccant is directly proportional to its temperature and inversely proportional to its concentration. As the concentration of the desiccant in the solution increases its vapor pressure decreases. This difference in vapor pressure allows the desiccant solution to absorb moisture from air whenever the vapor pressure of air is greater than that of the desiccant solution. The mass transfer process duration decreased with increasing the air velocity during the desiccant regeneration. It can be pointed out that the CaCl2 is able to absorb moisture and can be regenerated at low temperature then; solar collector can be used in liquid desiccant cooling system. This study allows selecting the best desiccant for use in (LDAC) system. read more... read less...
Keywords: Evaporative air conditioning system, Desiccant, Vapor pressure, Mass transfer coefficient
Connecting Small, Private Independent Hydro Power Plants to Increase the Overall Power Generating Efficiency
IJTEE, volume-15, Issue 1 (2019) , PP 19 - 29
Published: 11 Sep 2019
by Markus Jäger, Markus M. Schwarz, Dagmar Auer, Barbara Platzer, Josef Küng from Institute for Application Oriented Knowledge Processing (FAW), Faculty of Engineering and Natural Sciences (TNF), Johannes Kepler University Linz (JKU), Altenberger Strasse 69, 4040 Linz, Austria, Energieinstitut, Johannes Kepler University Linz (JKU), Altenberger Strasse 69, 4040 Linz, Austria, nextsoft IT GmbH, Grubbachstrasse 42, 4644 Scharnstein, Austria
Abstract: In countries, where many small rivers exist, the geography can be used to implement environment-friendly small hydro power plants for the generation of energy. The smaller such hydro power plants are, the higher is the impact of environmental incidents. Usually, there is more than one small hydro power plant located alongside one river, mostly operated by different owners. To increase the overall power generating efficiency of all hydro power plants alongside one river, a good communication- and cooperating concept is needed. In our work, we propose a system concept and a prototype implementation for several small, private and independent hydro power plants to increase the energy production through a networked intelligent control system. We also show possibilities for avoiding events, which usually induce downtimes of the small hydro power plants. If these events can be minimized in number and duration, the overall energy production time is higher. read more... read less...
Keywords: small hydro power plants, intelligent control system, cooperation, hydro power
IJTEE, volume-15, Issue 1 (2019) , PP 9 - 17
Published: 25 Feb 2019
by Sanaa Y. Saleh from Department of Architecture, Faculty of Engineering, IUG, Gaza, Palestine, P.O. Box 108
Abstract: Various tests are conducted to investigate and compare how both programs (Ecotect and TAS) consider various parameters which affect buildings’ thermal performance including thermal mass, ventilation, and solar gain. The thermal mass comparative tests revealed that the internal air temperature predicted by TAS is higher than that of Ecotect particularly with large thermal mass. A significant difference is observed in the fabrics loss/gain estimated by TAS and that estimated by Ecotect for various fabrics thicknesses in the cases of both free-running and air-conditioning. Further, the fabrics loss/gain estimated by Ecotect in the case of air-conditioning is the same as that in the case of free-running. The solar gain comparative tests indicate that the magnitude of solar gain estimated by TAS is almost two times that estimated by Ecotect. Ecotect does not consider the internal solar absorption of the fabrics in estimating the solar gains, while according to TAS simulation; greater solar gain is associated with higher internal solar absorption of fabrics. Moreover, the ventilation load according to Ecotect rises steadily with the increase of the ventilation rate, while in TAS; the magnitude of increase in the ventilation load fades significantly with higher ventilation rate. Additionally, the ventilation load estimated by Ecotect is extremely higher than that estimated by TAS. In Ecotect, the fabrics loss/gain was found constant for various air change rates. Conversely, in TAS, the fabrics loss/gain decreases with the increase of ventilation rate. read more... read less...
Keywords: Building Thermal Simulation, Computer Modeling, Ecotect, TAS, Thermal Mass, Ventilation.
IJTEE, volume-15, Issue 1 (2019) , PP 1 - 8
Published: 25 Feb 2019
by Rohinikumar Bandaru, Chandrasekharan Muraleedharan from Department of Mechanical Engineering, NIT Calicut, India, 673601
Abstract: The solar thermal pump can be used for handling water where electrical power is not available and solar energy is in plenty. Performance analysis was carried out on a fabricated laboratory scale set up of unconventional solar thermal water pump in Solar Energy Centre of NIT Calicut. The pump employs a flat plate solar collector for converting the working substance (ethyl ether) into vapour and its pressure is adequate to pump water to a fairly high head. The additional storage tank for vapour and a separate condenser cause greater freedom in the pump’s operation leading to improved performance. The performance of solar water pump has been analysed for three different delivery heads 3, 4 and 5 m. The artificial neural network model has been applied successfully to predict the performance of the system at different working conditions. The heating time, efficiency and discharge of the pump have been predicted using three different parameters - solar radiation, ambient temperature and discharge head - by the proposed ANN model based on the feed forward back propagation algorithm. ANN predicted results and estimated values of heating time, efficiency and discharge yield correlation coefficients of 0.99326, 0.99548 and 0.9943, and RMSE values of 0.000126, 0.000087 and 0.000316, respectively. read more... read less...
Keywords: Solar thermal water pump, Experimental analysis, ANN model