IJTEE, volume-15 , Issue 2 (2017), PP 97 - 102
Published: 26 Sep 2017
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 (2017), PP 87 - 96
Published: 26 Sep 2017
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
IJTEE, volume-15 , Issue 2 (2017), PP 151 - 156
Published: 04 Oct 2017
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
IJTEE, volume-15 , Issue 2 (2017), PP 143 - 150
Published: 27 Sep 2017
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.
IJTEE, volume-15 , Issue 2 (2017), PP 135 - 141
Published: 27 Sep 2017
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 (2017), PP 129 - 133
Published: 27 Sep 2017
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
IJTEE, volume-15 , Issue 2 (2017), PP 123 - 128
Published: 27 Sep 2017
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.
IJTEE, volume-15 , Issue 2 (2017), PP 117 - 121
Published: 27 Sep 2017
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.
IJTEE, volume-15 , Issue 2 (2017), PP 111 - 116
Published: 27 Sep 2017
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
IJTEE, volume-15 , Issue 2 (2017), PP 103 - 110
Published: 27 Sep 2017
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
IJTEE, volume-15 , Issue 1 (2017), PP 9 - 17
Published: 25 Feb 2017
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.
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 (2017), PP 81 - 86
Published: 12 Sep 2017
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