Performance Study of Two Circuits Lorenz – Mutzner Vapour Compression Cycle
IJTEE, volume-15 , Issue 2 (2019), PP 151 - 156
Published: 04 Oct 2019
by Abdul Hadi N. Khalifa, Johain J. Faraj, Mahmood H. Khaleel from Engineering Technical College Baghdad, Middle Tech. University, Iraq Engineering Technical College Kirkuk, Southern Tech. University, Iraq
Abstract: The operational parameters for a modified Lorenz – Mutzner refrigeration cycle working with mixed refrigerant were studied experimentally. A Lorenz – Mutzner refrigeration system was designed, built and tested under two types of refrigerants. The first one was pure R-134a refrigerant while the second was a hydrocarbon zeotropic mixture of R290/600a refrigerant in a mass ratio of 60:40. Also, a new control strategy was applied to both refrigerant types. The effects of various parameters on cycle performance were investigated such as refrigeration effect, compressor power consumption, inside freezing and cooling temperatures. It was found that, replacing R-134a by hydrocarbon mixture reducing compressor power consumption by 21%, increasing COP by 16%, and reducing operating time by 25 min. using controlled circuit with the hydrocarbon mixture cycle reduced compressor power consumption by about 20% and the time required reaching the freezing set point by 4 min. While the time required reaching the cooling set point was reduced by about 12 min. The cycle COP was augmented by about 9%. read more... read less...
Keywords: Lorenz – Mutzner cycle, Dual evaporators, Refrigerant mixture, Refrigeration cycle
Study on Adsorption Refrigeration System Using Activated Carbon-Ethanol as Working Pair
IJTEE, volume-15 , Issue 2 (2019), PP 143 - 150
Published: 27 Sep 2019
by Made Astinaa, Ren Sokha, Prihadi S. Darmanto from Faculty of Mechanical and Aerospace Engineering, Institut Teknologi Bandung, Bandung 40132, Indonesia, Department of Industrial and Mechanical Engineering, Institute of Technology of Cambodia, Phnom Penh, Cambodia
Abstract: The adsorption refrigeration system is an alternative refrigeration system powered by thermal source so that it is possible to use waste heat and solar energy. This paper reports the experiment of the ethanol-activated carbon (AC) as the adsorbateadsorbent pair. Experimental work was conducted with two adsorption beds as thermal compressor. Ethanol-AC pair can be operated with the heat source temperatures 90o C and 100o C for different heat sink temperature 20o C, 25o C and 30o C, respectively. The experimental result shows when temperature of the hot water 100o C and the cooling water temperature 30o C, the system give the higher coefficient of performance (COP) than another testing operation condition. Additionally, the COP of the system is varying a long operating in average 0.19 due to manually intermittent operation of both adsorption beds. The maximum adsorption capacity is 0.302 kg/kg·AC while the desorption temperature, desorption pressure and heating time of the adsorption bed are 85o C, 85.52 kPa and 80 minutes, respectively, and the cooling capacity is 23.61 kJ for a operating cycle. The experimental result proved that the ethanol-AC is suitable pair with the adsorption system for cooling application. It can be operated at low temperature driven heat source, and has an environmentally friendly behavior and the working pair is easy to be found in the commercial market. read more... read less...
Keywords: Adsorption, Activated Carbon, Ethanol, Cooling Capacity, Coefficient of Performance.
Holism, Collective Intelligence, Climate Change and Sustainable Cities
IJTEE, volume-15 , Issue 2 (2019), PP 135 - 141
Published: 27 Sep 2019
by Monika dos Santos from Department of Psychology: University of South Africa, PO Box 392, Pretoria 0004, South Africa, Department for Continuing Education: University of Oxford, Rewley House, 1 Wellington Square, Oxford, Oxfordshire OX12JA, United Kingdom
Abstract: As the Earth’s systems are under increasing unsustainable pressures, human security is clearly at stake. Cities are regarded to be increasingly important sites for climate responses, and something can still be solved if humankind acts quickly. Novel methods to long-standing quandaries, such as climate change, can now be applied. It is proposed that city adaptation and mitigation strategies should draw on collective intelligence and an innovative holism multi-systemic approach to the encompassing problem of climate change by breaking it up into smaller, manageable problems and crowdsourcing a way out by means of online argumentation systems, computer simulations, and collective decision making tools. As ‘first responders’, cities with similar location or vulnerability characteristics should also be encouraged to transfer best practices between each other. It is futher argued that the enhancements in efficacy and accessibility of big data can be aggregated at a nationwide level in the shape of economic development and sustainability, and in welfare improvements in developing economies. Furthermore, this critical précis argues that whilst adaptation and mitigation strategies are crucial, at the very crux of it, humankind needs a fundamental change of metaphors: from seeing the world as a machine to understanding it as a holistic network. read more... read less...
Keywords: Climate Change, Cities, Holism, Adaptation, Mitigation, Collective Intelligence, Crowdsourcing, Technological Leapfrogging, Emerging Economies.
Performance Study of Photovoltaic-Water Electrolysis System for Hydrogen Production: A Case Study of Egypt
IJTEE, volume-15 , Issue 2 (2019), PP 129 - 133
Published: 27 Sep 2019
by H.M. El-Sayed, Safie Elden Metwally, E.T. El Shenawy, A. Ramadan, N.M. Farag from Faculty of Science, Ain-Shams University, Cairo, Egypt, Renewable Energy Dept., Desert Research Center, Cairo, Egypt, Solar Energy Dept., National Research Center, Cairo, Egypt, Arab Academy of Science and Technology and Maritime, Cairo, Egypt
Abstract: Solar-hydrogen is expected to play an important role as an energy carrier of the future and is considered an ultimate solution for many energy and environmental problems. Photovoltaic-water electrolysis is a suitable method for solarhydrogen production in Egypt due to the availability of a lot of water sources such as Lake Nasser, Red Sea, and Mediterranean Sea. Moreover, Egypt is endowed with high solar radiation intensity of 2000-3200 kWh/m2/year from north to south. This Paper presents a small photovoltaic-water electrolysis system for the process of water electrolysis and hydrogen production; the system is designed and installed in the solar energy laboratory of desert research Center. The performance of the generation system is investigated under the climatic conditions of Cairo city, Egypt for a sample day. Hourly variation of solar radiation intensity, photovoltaic module output current, and hydrogen production rate are measured accurately and recorded for analysis. It is found that the minimum and maximum hydrogen production rate values are 1.3 ml/min and 3.4 ml/min, respectively. The maximum hydrogen production rate (which is 3.4 ml/min) is obtained at the maximum photovoltaic module output current (which is 0.35 A) that obtained at the maximum solar radiation intensity (which is 980 W/m2) at the solar noon. The effect of solar radiation intensity on the photovoltaic module efficiency and overall system efficiency are also investigated. It was found that the smaller photovoltaic module efficiency decreases the overall system efficiency read more... read less...
Keywords: Hydrogen production, water electrolysis, solar energy
Yatta’s Medium Voltage Network Analysis and Enhancement
IJTEE, volume-15 , Issue 2 (2019), PP 123 - 128
Published: 27 Sep 2019
by Sameer Khader, A.K. Daud, Alaa Abuqubaita, Aladdin Sultan from Palestine Polytechnic University, Power Electronics & Signals Processing Research Unit, Hebron, Palestine, Sultan Smart Technology Company, Jerusalem, Palestine
Abstract: This paper presents analysis and proposes solution scenarios for Yatta city (Y.C.) electrical network which experiences maximum demand exceeds the main feeder capacity and an inferior power factor for the industrial loads of the acceptable range. The maximum demand of the first feeder is covered by proposing new interconnection points and the installation of alternative energy source of photovoltaic (PV) generation units. The power factor of the system was improved by installing capacitor banks for industrial loads. As a result of applied solution related to interconnection points, the total load demand was fairly distributed and the transformer’s life time is increased. Due to distributed PV generation, the utility capacity is also increased and the transformers’ life time is increased by 4-5 years. A Simulation model using ETAP is implemented and the network capacity and load flow are studied that verify the proposed solutions. The obtained simulation results demonstrate the technical feasibility of these proposed solutions. read more... read less...
Keywords: Distribution Network, PV, ETAP, Electrical network, Power Transformers, Power Factor Correction.
Waste and Appendages Percentages of Stone Slabs Cutting Machine
IJTEE, volume-15 , Issue 2 (2019), PP 117 - 121
Published: 27 Sep 2019
by Jawad Al-Haj from Palestinian Stone and Marble Center, Palestine Polytechnic University, PPU, 00972, Hebron, Palestine
Abstract: This paper aims at studying the stone wastage, appendages and defected stone percentages generated from cutting stone slabs into stone pieces with different dimensions (Cut to Size – CTS) using stone slabs cutting machine (Fraiza). Stone wastage represents the stone which were collected in rubbish containers and thrown away while appendages and defected stone represents stone pieces that do not meet the specifications and the requirements of the customer. These are typically at different color or dimensions. Practical data for the Input (stone slabs) and the output (stone tiles or pieces- CTS) for this machine was collected randomly from different stone companies in Palestine. Statistical analysis was carried out for the percentage of wastage, appendages and defected stone in addition to the percentage of ready stone for the customer orders. This study shows that, the average percentage of stone wastage 14.96%, appendages 6.35%, defected stone 7.7%, and the productivity (ready stone for the customer orders) is about 71% of the total stone entering the stone slabs cutting machine. read more... read less...
Keywords: Stone industry, stone slabs cutting machine, stone waste, appendages, defected stone.
Enhancement of Solar Water Disinfection using Nanotechnology
IJTEE, volume-15 , Issue 2 (2019), PP 111 - 116
Published: 27 Sep 2019
by Mohammad Hamdan, Sonia Darabee from The University of Jordan, Department of Mechanical Engineering, Amman, Jordan
Abstract: The main aim of this work is to investigate the effect of adding Titanium and Aluminum Oxides nano-particles on solar disinfection process of contaminated water. Samples of contaminated water were introduced into glass containers containing different concentrations of each type of nano-parrticles, these containers were placed side by side and hence all measurements were conducted at same time for comparison purposes. Having these contaminated water contained glass containers exposed to solar radiation for different time intervals, samples were withdrawn from each one to measure the total counts of both Coliform and E.Coli using IDEXX setup. It was found that the optimum concentration of Al2O3, which reduces the total counts of Coliform and E.coli was 0.06%. However the optimum concentration of TiO2 to minimize the total Coliform was 0.06%, while the concentration to destroy all E.Coli ranges between 0.008 and 0.01%. In general, it was found that TiO2 has more potential to speed up the disinfection process. read more... read less...
Keywords: Solar Water Disinfections, Nano-particles, contaminated water
Desalination by Freeze Crystallization: An Overview
IJTEE, volume-15 , Issue 2 (2019), PP 103 - 110
Published: 27 Sep 2019
by Khadije El Kadi, Isam Janajreh from Mechanical and Materials Eng. Dept., Khalifa University of Science and Technology, Masdar Institute, Masdar City, P.O. Box 54224, Abu Dhabi, United Arab Emirates
Abstract: Desalination by freeze crystallization is a freezing-melting process in which water is crystallized to ice and separated from saline solution. This area is observing a renascence to mitigate the staggering and sea rejected brine that has a negative environmental impact. Phase diagram of NaCl-H2O is the key point of designing freeze desalination systems. All freeze crystallization methods follow the same process, starting from nucleation, crystal growth, separation, and finally melting. Direct contact, indirect contact, vacuum, and eutectic point are the basic methods of crystallization. Furthermore, suspension freezing and freezing on a cold plate by indirect contact with refrigerant are the found to be the most suitable methods for desalination. Initial concentration, refrigerant temperature, growth rate, and flow rate are the main operating parameters that determine the final product properties and desalination efficiency. In this work, a quick review on the subject is brought up as the area is regaining renascence this followed with simulation of an indirect freeze crystallization process in a rectangular enclosure using computational fluid dynamics (CFD) modelling. These modeling are paradigm shift to gain more insight to the complex crystallization process being based on multiple species non-isothermal flow in a two phase flow representing the liquid and the ice formation. Results show that by combined CFD in multiple species modelling much insight into freeze crystallization can be revealed, optimized and re-designed. read more... read less...
Keywords: freeze desalination, crystallization, crystal growth, binary phase diagram, CFD modelling
Analysis of Dissolved Oxygen Deficit in a Flowing Stream
IJTEE, volume-15 , Issue 2 (2019), PP 97 - 102
Published: 26 Sep 2019
by Sunil J. Kulkarni from Department of Chemical Engineering, Datta Meghe College of Engineering, Airoli, Navi Mumbai, India, Pincode:400708
Abstract: The wastewater, domestic or industrial, is commonly disposed off in nearby water streams, rivers and sea. The wastewater, which has high biological oxygen demand (BOD) and chemical oxygen demand (COD) due to presence of organic matter, is also very lean in D.O. content. It is important to know the D.O. deficit and D.O. concentration at various distances to know the length of the flowing stream affected by the discharge and to know the measure of threat to the aquatic life. In the current investigation, the variation in dissolved oxygen content of a river stream is analyzed at various downstream distances from the point of discharge of wastewater. It takes almost 11 days and 100 km to regain initial dissolved oxygen. It can be concluded that the control of pollutants and organic matter needs to be taken care of more effectively. Almost 100 km distance downstream of the mixing point is affected due to discharge. read more... read less...
Keywords: biological oxygen demand, oxygen deficit, critical deficit, critical time, saturation
Analysis of Alternative Cooling Options for a 1000 MWe Power Plant at Reduced Temperature Difference across Ultimate Heat Sink
IJTEE, volume-15 , Issue 2 (2019), PP 87 - 96
Published: 26 Sep 2019
by Shahid Amin, Rashid Ali from Karachi Institute of Power Engineering (KINPOE), Karachi, Pakistan
Abstract: Process heated water from most existing nuclear and fossil fueled power plants is discharged directly to the ultimate heat sink by once through system. This direct discharge increases the temperature of ultimate heat sink in the vicinity of the discharge which has worst biological and ecological effects, leading to legal actions by Environmental Protection Agencies (EPAs). In this paper, an analysis and comparison of alternative cooling options for a typical 1000 MWe Nuclear Power Plant is presented. Several alternative approaches are considered such as cooling canal, various types of cooling towers such as wet, dry and hybrid system, Heller system and cooling pond. The study is divided into three phases, thermal analysis, financial analysis and comparison of the above mentioned options. The quantitative analysis tool developed in MS Excel is validated by benchmarking the results against IAEA water management program (WAMP) tool kit. Financial analysis including investment cost and operation cost is done for each cooling option. Finally, a brief comparison of each technology is done against typical once through system. Results reveal that wet cooling towers are most economical alternative as compared to dry and hybrid cooling towers which high have investment and operation cost. Other alternatives including cooling canal, and cooling pond, also meet the requirement, but they require very large land area. read more... read less...
Keywords: Heat sink, cooling tower, pond, evaporation, environment
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
Equilibrium Sorption Isotherms for Removal of Heavy Metals Using Cement Kiln Dust
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
Design and Analysis of Solar Space Heating System in Iraq
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
Optimization of Night Electric Vehicle Fleet Charging at Regional Level
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
Experimental Investigation on Vapour Pressure of Desiccant for Air Conditioning Application
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
Comparative Tests of Thermal Modeling Computer Program - Ecotect vs. TAS
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.
Performance Prediction of Solar Thermal Water Pump using Artificial Neural Networks
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