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Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-6
Measures: 
  • Citations: 

    0
  • Views: 

    306
  • Downloads: 

    301
Abstract: 

The effect of Al (OH) 3 on the hydrogen generation from Al/water system is evaluated. Four synthesized and one commercial Al (OH)3 powders are employed to investigate their assistance to the hydrogen generation from Al/water system at room temperature. It was found that the Al (OH)3 product derived from Al (NO) 3 precursor exhibits the best catalytic effect and exerts the highest hydrogen generation rate.100 % yield of hydrogen (1, 360 ml/g Al at 25oC) can be achieved within 6 min at a proper Al: Al (OH)3: H2O weight ratio (3: 15: 50). That is, by adjusting Al: Al (OH)3: H2O ratio, the highest hydrogen generation rate ever reported so far, without using any alloying elements or corrosive additives, can be achieved.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-15
Measures: 
  • Citations: 

    0
  • Views: 

    346
  • Downloads: 

    128
Abstract: 

The use of industrial cooling for food preservation has been revealed to be an efficient and widely employed technique, from harvest time to final consumption by the customer. However, the most used method to generate that cold (based on the compression refrigeration cycle) requires a considerable amount of electric energy, especially if no appropriate energy efficiency measures are implemented in cold storage chambers.This fact contributes to the increased costs in electricity bills, reduction of competitiveness among companies and also to a negative impact in terms of global warming. To help companies define and implement the right efficiency measures for cold production, this work aims to develop a methodology for simulation and optimization of energy consumption in cold chambers by improving both constructive and operating parameters (external temperature, enclosure insulation, door opening time, etc.), which contribute to the infiltration of heat energy. It is also intended that this methodology determines which of those parameters have greater influence in energy consumptions, as well as to estimate possible savings resulting from the optimization process. Results obtained in a garlic cold chamber showed that it is possible to achieve energy savings of up to 40 % for an initial investment around 1, 500€ in efficiency measures and a payback time among 2 and 5 years. On the other hand, parameters that had the greatest influence in energy consumptions were those directly related with thermal insulation of enclosures and entry of warm air within.Total contribution of these two parameters in the global consumption was about 95%.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-12
Measures: 
  • Citations: 

    1
  • Views: 

    339
  • Downloads: 

    117
Abstract: 

The effect of water application (e.g., through rainfall or sprinkler system) on emissions of greenhouse gases (GHGs), such as nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2), frompen surfaces of open-lot beef cattle feedlots was evaluated under controlled laboratory conditions. Soil/manure samples were collected from several randomly selected pens from two beef cattle feedlots in Kansas and were used as simulated pen surfaces. Three treatments (i.e., dry and loose, moist and loose, and moist and compacted pen surface conditions) were considered, simulating surface conditions in the field after a typical rainfall event or water application with a sprinkler system. Soil/ manure and water were mixed within glass containers and analyzed for GHG emission using a photo-acoustic infrared multi-gas analyzer; emission rates were calculated from measured concentrations. GHG emissions from the dry soil/ manure samples were low, with mean values of 0.02, 0.00, and 45 mg m-2 h-1 for N2O, CH4, and CO2, respectively, compared to moist soil/manure samples. Water application on the dry manure samples resulted in large peaks of GHG fluxes, with peak values of 99.2, 28.6, and 15, 443 mg m-2 h-1 for N2O, CH4, and CO2, respectively.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-10
Measures: 
  • Citations: 

    0
  • Views: 

    311
  • Downloads: 

    126
Abstract: 

Degradation rates and removal efficiencies of different parabens, namely, methylparaben, ethylparaben, propylparaben, and butylparaben using H2O2/Fe2+ advanced oxidation process are studied in this work. With the aim of optimizing the removal of parabens from waters through the Fenton process, a factorial central composite orthogonal and rotatable design (FCCORD) was used.H2O2 and Fe2+ ion initial concentrations were selected as independent variables. The experimental procedure planned according to the FCCORD makes it possible to optimize the removal. The occurrence of interactions between these two variables can also be analyzed with the aid of the experimental design. Fenton process provides conversion efficiencies comprising between 85 and 94% after a reaction time of 48 h, which reveals the appropriateness of this procedure for the removal of parabens from aqueous matrices.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-6
Measures: 
  • Citations: 

    0
  • Views: 

    314
  • Downloads: 

    97
Abstract: 

Swirl flame stabilization is widespread among burners’ manufacturers, but the complex flow patterns are not yet fully understood. The interaction of two confined swirling jets leads to the formation of two recirculation zones being the flame located on the shear layer between the both zones. In such conditions, the lean mixtures can be burned producing low emissions. In the present study, flow structure and turbulent mixing of two isothermal coaxial jets are investigated using Large Eddy Simulation (LES).This is a challenging tool to achieve accuracy but it requests demanding spatial resolution and special treatment of results. By contrasting time-averaged radial profiles with experimental data of a classical benchmark, the model is validated. Results show that LES is able to reproduce the basic features of the flow pattern. Besides, the spectra analysis of instantaneous flow fields provides not only the energy decay but also the most energetic flow structures.

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Author(s): 

KYTE ADAM

Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-7
Measures: 
  • Citations: 

    0
  • Views: 

    329
  • Downloads: 

    139
Abstract: 

Efficiency of domestic ventilation waste heat recovery systems (WHRS) depends not only on the amount of waste heat recovered, but also on the energy involved in running fans to drive air through the system. Computational fluid dynamics (CFD) can be a powerful tool for analysing WHRS losses (thus predicting fan energy usage), but the computational effort involved can limit the value of CFD as a practical design tool. This study presents a range of assumptions and simplifications that can be applied to reduce the computational effort associated with the CFD analysis of a WHRS. The importance of experimental validation to assess the effect of errors introduced by the simplifying assumptions is discussed. In an example case, application of the methods presented have allowed total pressure losses (excluding the fixed losses through the heat exchanger) to be reduced by over 50% in comparison with an initial prototype design, with proportional reduction in fan energy usage. This highlights the value of sufficiently simplified CFD analyses within a typical WHRS product development cycle.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-13
Measures: 
  • Citations: 

    0
  • Views: 

    253
  • Downloads: 

    128
Abstract: 

This paper examines the deficiencies of existing oil spillage remediating techniques and their inabilities to achieve optimal result at maximum efficiency. The development of alternative strategy for remediating oil spillage is an idea conceived from a natural phenomenon based on obvious physical changes between oil and water at lower temperature. The technique involves extensive studies of the physical, chemical and thermodynamic properties of water and hydrocarbons as well as oceans and characteristics of oceans as it is affected by temperature change, climatic condition, heat gradient, salinity, wind speed, and heat stratification. The paper also exploited critical analysis of the thermodynamics of heat transfer between two objects in constant contact as well as the existing oil spillage remediating techniques or devices for sea and land pollution. The new device was designed to generate high quality crude oil continuously from crude oil/ water mixture optimally when the operational conditions are followed strictly. The step by step derivation of equation for the quantity of recovered oil from the empirical data through graphical analyses is a real representation of the conditions for effective operation of the machine in an oceanic environment. The new technique has shown a very high efficiency in quality oil separation and remediation process for a short run as well as optimal efficiency close to one hundred percent for a long run. The results achieved in the operation of the new system are well appreciable when compared with the existing remediating techniques, although, it may be necessary to use an intermediary wave neutralization system in a rough oceanic environment to improve the oil quality and maximize efficiency.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-11
Measures: 
  • Citations: 

    0
  • Views: 

    263
  • Downloads: 

    123
Abstract: 

A life cycle analysis (LCA) for pyrolysis biochar systems was carried out to determine greenhouse gas balance, carbon cycling, and the economics of biochar production from different agricultural residues and wastes.Investigating a range of feedstocks (forest residues, corn stover, etc.) provided insight into the use of biomass residues rather than bioenergy crops as biochar production substrates and the resulting energy and climate change impacts. The analyses were conducted based on various optimized pyrolysis parameters for corn fodder and forest residue. The observed reductions of greenhouse gas (GHG) emissions (CO2 equivalent per Mg dry feedstock) for both corn fodder and forest residue were mainly contributed by the stable carbon in the biochar. Corn fodder showed a greater reduction in emissions than forest residue, indicating the corn fodder’s greater economic potential for soil sequestration of stable carbon. The relative GHG emission analysis found that the optimization of a biomass pyrolysis system for biochar production is better suited for soil sequestration of stable carbon than as a fuel source. The economic viability of the pyrolysis-biochar system is largely dependent on the costs of feedstock production, pyrolysis, and the value of C offsets. The LCA reported in this study can be instrumental in assessing the environmental potential of biochar production and its application in the region.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-11
Measures: 
  • Citations: 

    0
  • Views: 

    362
  • Downloads: 

    173
Abstract: 

In this study, 3-h wind speed data for years 1987-2009 at 10, 20 and 40 m heights have been analyzed for Kurdistan province. Wind energy potential at five stations in this province was investigated. Six types of methods, namely, graphical, empirical, method of moment, energy pattern factor, maximum likelihood and probability weighted moments were used to estimate the parameters.The results showed that MOM was an efficient method among others in the present study because it had the lowest value of the Chi-square statistics. Also, wind speed for Tyear return period was estimated. In the annual time scale, the range of shape parameter, k, was between 0.78 and 1.03 whereas the range of the scale parameter, c, was between 1.84 and 4.37 m/s. Also, the most important characteristics of wind energy were evaluated. Among all the stations, Bijar and Zarineh Obato were found to be the best sites for wind energy harnessing. Bijar had the highest value of wind power density at 10 m height, which was equal to 308 W/m2. In average, the rank of stations according to 100 years return period was as: (1) Zarineh Obato, (2) Bijar, (3) Ghorveh, (4) Saghez and (5) Sanandaj.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-10
Measures: 
  • Citations: 

    0
  • Views: 

    272
  • Downloads: 

    119
Abstract: 

This paper discusses the development of a model of a real cogeneration plant based on Computational Intelligence (CI) algorithms. In particular, two CI strategies are used: one based on artificial neural network and the other one based on a neuro-fuzzy system. Both systems are trained with a data collection from the cogeneration plant.Data mining techniques are applied to remove erroneous and redundant data, and also to obtain information about the variables and its behaviour. This task allows to select only the relevant information and is also a way to decrease the complexity of the model. In this first approach on the work, two separate subsystems of the cogeneration process are considered: an engine and a steam turbine. The obtained models are used to analyze the role of each involved variable and to derive a set of recommendations (i.e., changes in some of the input variables) to optimize the performance of the system. The recommendations applied to the models improve the behaviour of the plant providing higher energy production with a lower cost.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-10
Measures: 
  • Citations: 

    0
  • Views: 

    314
  • Downloads: 

    156
Abstract: 

Nowadays, all research efforts in the field of wet processing of textiles are directed towards shortening and simplification of the processing sequence. To minimise water and energy consumption, it has become necessary to combine several textile processing stages to reduce the number of operations or shorten the process time. An attempt was made to combine the pre-treatment and dyeing processes with optimal quantities of textile auxiliaries in single bath. In this process, individual stages of pre-treatment like desizing, scouring and bleaching followed by dyeing using direct dyes were carried out in a single bath without the usual intermediate washings. This process was carried out without replacing the liquor bath until the end of dyeing. An attempt was also made to dye a woven fabric at different stages, viz., grey, desizing and scouring. These efforts were made to conserve water and energy required for that particular pre-treatment process. The depth of dyeing and the colour fastness properties of all these dyed fabrics were then compared with a bleached fabric which was dyed with conventional method. The properties were at par with the conventional method. Moreover, the combined process saved 83.1% water, 88.6% energy (thermal) and 79.3% time than the conventional processes. Thus, the process has been shown to be ecological, economical and energy conserving.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-9
Measures: 
  • Citations: 

    0
  • Views: 

    344
  • Downloads: 

    106
Abstract: 

The sustainability assessment methods used over the world were the basis of new system development for Slovak conditions. The proposed fields are site selection and project planning; building construction; indoor environmental quality; energy performance; water and waste management. The evaluated indicators were proposed on the basis of available information analysis from particular fields of building environmental assessment and also on the basis of our experimental experiences. The aim of this paper is to present developed building environmental assessment system oriented to energy performance and the significance weight determination. Percentage weight of fields and indicators was determined on the basis of their significance, according to mathematical method.

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Author(s): 

BEIRAO PEDRO JORGE BORGES FONTES NEGRAO, DOS SANTOS PEREIRA MALCA CANDIDA MARIA

Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-11
Measures: 
  • Citations: 

    0
  • Views: 

    515
  • Downloads: 

    125
Abstract: 

This paper describes the design and analysis of several buoy geometries that may be applied to a near-shore floating point-absorber wave energy converter. After the characterisation of the device, a numerical model and a simulator in the time domain were developed and the structural performance of the wave energy converter evaluated for three different buoy geometries. The influence of the buoy dimensions, different submerged conditions and position of hydraulic cylinder piston rod, on the structural performance of the wave energy converter is also analysed. The numerical study was conducted using a commercial finite element code.This software needs, among other parameters, the magnitude of the forces acting upon each buoy. A dynamic model was, therefore, developed assuming that the buoy heave motion is excited by the sea waves. The finite element analysis revealed that a load with a higher magnitude than those computed from the simulator was required. It was shown that, even considering the partially submerged condition, the spherical buoy geometry leads to best structural behaviour.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-9
Measures: 
  • Citations: 

    2
  • Views: 

    450
  • Downloads: 

    163
Abstract: 

Houses in Egypt are often designed without taking the climate into account sufficiently. Consequently, new houses often have a poor indoor climate, which affects comfort, health and building efficiency. In hot and arid climates, passive cooling system employs non-mechanical procedures to maintain suitable indoor temperature. Thus, they have been increasing the influence of the traditional cooling concepts but with new technology. Therefore, these conditions encourage such a concept to enhance natural ventilation with evaporative cooling and save energy in the New Assiut city. In the present study, the effect of solar chimney parameters on wind tower parameters was numerically investigated as a second phase of the new integrated model. All the detailed mathematical equations and system description are presented in phase one. A numerical simulation is implemented in Transient systems simulation program-Conjunction of multizone infiltration specialists program softwares. The parametric studies of the integrated system in phase two were studied to achieve high performance with new compact small design especially for the hottest days in the summer season.The temperature and airflow rates are predicted iteratively taking into account the zone pressure and the pressure drop in the evaporative cooler component. The result shows that the system achieves nearly at least close to 80 % acceptable comfort range according to Adaptive Comfort Standard of American Society of Heating, Refrigerating and Air-Conditioning Engineers with optimum ventilation rate 414 m3/h for the hottest day. The findings show that the system achieves high performance in the hottest day with small solar chimney dimension and is easy to integrate in the building envelope than the proposed system before parametric studies in phase one.

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Author(s): 

KOMALA H.P. | PRASAD ATTIMOGGE GIRIRAJANNA DEVI

Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-7
Measures: 
  • Citations: 

    0
  • Views: 

    262
  • Downloads: 

    133
Abstract: 

Energy is considered as a key factor which determines the economic development in the entire sector of any region. Biomass is one of the primary energy sources in rural areas. The study was carried out to examine the utilization pattern of biomass energy and socioeconomic dimensions associated with rural areas of Yelandur, Karnataka, India. Field studies in these villages covering 645 households were made to collect the data and assess the socioeconomic conditions that govern the biomass utilization pattern for meeting energy requirements.Firewood is the primary energy source (94.78%) for cooking and heating among these rural folk. Most of them are illiterates (60%) with 28.96% of them having a meagre income. Traditional biomass stoves are used predominantly.The study shows that there is a positive correlation (R2=0.98) between the households size and volume of firewood consumption. The study has revealed that the firewood fuels are the dominant source of energy for cooking and heating purposes.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-5
Measures: 
  • Citations: 

    0
  • Views: 

    318
  • Downloads: 

    158
Abstract: 

A high potential of thermosolar power generation systems is the use of thermal storage and/or hybridization to overcome dependability of solar resource availability. The incorporation of these technologies can be of special interest for isolated units intended for distributed generation systems. Among the thermosolar systems, dish-Stirling technology is the one with more possibilities to be used as a system to feed power independently, i.e., due to the modularity of the units that range between 3 and 25 kWe, depending on the supplier. Thus, the present analysis is focused on studying integration of both hybridization and thermal storage in an isolated unit of 10 kWe dish-Stirling. In particular, hybridization will enable a more continuous operation of the system.Hybridization is analyzed both for a conventional fuel, such as natural gas, and for a renewable energy source, biogas. Analysis of performance of the dish-Stirling system enables to determine the interest of introducing the complementary technologies referred above. Regarding the specific case evaluated in this paper, analyzed data show that hybridization has an advantage that depends on the nature of fuel used, being of 20 % for natural gas and 112 % for biogas in relation to output power of solar-only operation. Thermal energy storage system shows no significant benefits when implemented to a variable power system.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-10
Measures: 
  • Citations: 

    2
  • Views: 

    328
  • Downloads: 

    123
Abstract: 

In the framework of CO2 capture and geological storage, risk analysis plays an important role, because it is an essential requirement of knowledge to make up a local, national and supranational definition and planning of carbon injection strategies. This is because each project is at risk of failure. Even from the early stages, it should take into consideration the possible causes of this risk and propose corrective methods along the process, i.e., managing risk. Proper risk management reduces the negative consequences arising from the project. The main method of reduction or neutralizing of risk is mainly the identification, measurement and evaluation of it, together with the development of decision rules. This report presents a methodology developed for risk analysis and the results of its application. The risk assessment requires determination of the random variables that will influence the functioning of the system. It is very difficult to set-up a probability distribution of a random variable in the classical sense (objective probability) when a particular event rarely occurred or even it has an incomplete development. In this situation, we have to determine the subjective probability, especially at an early stage of projects, when we have not enough information about the system. This subjective probability is constructed from assessment of expert judgement to estimate the possibility of certain random events could happen depending on geological features of the area of application. The proposed methodology is based on the application of Bayesian probabilistic networks to estimate the probability of risk of leakage. These probabilistic networks can define graphically the relations of dependence between the variables and joint probability function through a local factorization of probability functions.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-7
Measures: 
  • Citations: 

    1
  • Views: 

    375
  • Downloads: 

    133
Abstract: 

The residual forest biomass (RFB) sector has been experiencing strong development at European level and particularly in Portugal mainly due to the increase of energy production from renewable sources. The aim of this study is to assess the environmental impacts of eucalyptus RFB chips production chain in Portugal. The environmental and economic impact comparison of the processes included in the production chain is presented as well. The environmental impacts were calculated by the life cycle assessment approach described in the ISO 14040 series of standards. The production chain assessed included all processes from eucalyptus forest until the delivery of RFB chips at the power plant. The main conclusion of this study is that eucalyptus wood production is the process that presents the greatest environmental impact through the product life cycle. Considering only emissions and depletion of energy resources, RFB chipping is the process that presents the higher environmental impact followed by transport of RFB by truck and trailer and transport of RFB by forwarder. These operations are responsible for approximately 81 % on ‘‘Respiratory inorganic’’ and 87 % on ‘‘Fossil fuels’’ which are the two most significant normalized impact categories. In economic terms, the transport of RFB by truck and trailer presents the highest cost followed by chipping and processing of trees. These three operations are responsible for approximately 80 % of total costs. A sensitivity analysis showed that a 32 % increase in the transport distance from the forest to the power plant would cause an 8 % increase in ‘‘Climate change’’.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-7
Measures: 
  • Citations: 

    1
  • Views: 

    412
  • Downloads: 

    194
Abstract: 

The uncertainty caused by the discontinuous nature of wind energy affects the power grid. Hence, forecasting the behavior of this renewable resource is important for energy managers and electricity traders to overcome the risk of unpredictability and to provide reliability for the grid. The objective of this paper is to employ and compare the potential of various artificial neural network structures of multi-layer perceptron (MLP) and radial basis function for prediction of the wind velocity time series in Tehran, Iran. Structure analysis and performance evaluations of the established networks indicate that the MLP network with a 4-7-13-1 architecture is superior to others. The best networks were deployed to unseen data and were capable of predicting the velocity time series via using the sliding window technique successfully. Applying the statistical indices with the predicted and the actual test data resulted in acceptable RMSE, MSE and R2 values with 1.19, 1.43 and 0.85, respectively, for the best network.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

MEIER KONRAD

Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-12
Measures: 
  • Citations: 

    0
  • Views: 

    499
  • Downloads: 

    229
Abstract: 

This study looks into possibilities of hydrogen production on an offshore platform in Norway, to capitalize Norway’s offshore wind potential matching political goals to reduce emissions and make Norway’s transportation sector cleaner. The potential power output of a hypothetical offshore wind farm has been assessed using real operating data of other wind farms. The usable electricity was between 258GWh/year and 404GWh/year segmented into three scenarios.Solid oxide electrolysis cell and proton exchange membrane electrolysis are compared. Their function and the necessary technologies to operate them are described in detail. Based on these scenarios the annual hydrogen production was calculated with values between 1530 and 8020 tons per year. The second part of the study estimates the investment to find the production cost per kilogram hydrogen, which was compared to recent fuel prices in Norway to see whether the production of hydrogen was profitable. Prices vary between 5.20 € and 106.10€ per kg hydrogen.

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Author(s): 

PASTOR JEREMIAH | LIU YUCHENG

Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-13
Measures: 
  • Citations: 

    0
  • Views: 

    392
  • Downloads: 

    192
Abstract: 

This paper presents, assesses, and optimizes a point absorber wave energy converter (WEC) through numerical modeling, simulation, and analysis in both frequency and time domain. Wave energy conversion is a technology especially suited for assisting in power generation in the offshore oil and gas platforms. A linear frequency domain model is created to predict the behavior of the heaving point absorber WEC system. The hydrodynamic parameters are obtained with AQWA, a software package based on boundary element methods. A linear external damping coefficient is applied to enable power absorption, and an external spring force is introduced to tune the point absorber to the incoming wave conditions.The external damping coefficient and external spring forces are the control parameters, which need to be optimized to maximize the power absorption. Two buoy shapes are tested and a variety of diameters and drafts are compared.Optimal shape, draft, and diameter of the model are then determined to maximize its power absorption capacity.Based on the results generated from the frequency domain analysis, a time domain analysis was also conducted to derive the responses of the WEC in the hydrodynamic time response domain. The time domain analysis results allowed us to estimate the power output of this WEC system.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-16
Measures: 
  • Citations: 

    1
  • Views: 

    342
  • Downloads: 

    212
Abstract: 

Nigeria is rich in both conventional and renewable energy resources that empower the country with a large capacity to develop an effective national energy policy. The study aims at reviewing the current energy resource structure of Nigeria in terms of production and utilization, comparing sectoral performance and reviewing issues confronting energy growth, sustainability, policies and frameworks towards the actualization of energy efficiency.The total energy consumption in 2011 was 28.8 million tons of oil equivalent about 5.4% of the world value in 2010. Nigeria share of world CO2 emissions in 2011 was 0.32% and a drop of 0.02% in 2010. In addressing the country’s challenges of energy demand, production, consumption and related environmental problems, the government has initiated sustainable and effective energy conservation strategies to improve efficiency.These include: reduction of energy consumption at the household sector, reduction of gas flaring, adoption and maximum renewable energy technologies, reduction of energy intensity in industries by appropriate energy conservation and management system. In addition, the policies also include the development and integration of alternative energy resources such as nuclear, biomass, wind and solar into the total energy mix structure. For all these to be accomplished, the energy development strategy must follow a sustainable framework to balance economic growth, social expansion and eco-friendly protection.

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-6
Measures: 
  • Citations: 

    0
  • Views: 

    360
  • Downloads: 

    94
Abstract: 

The loss of mass of concrete matrix and subsequent corrosion of concrete has been reported very often.Aggressive liquids such acids, bases, solutions of salts or aggressive gases as well as microorganisms penetrate the concrete and cause deterioration and biodeterioration, respectively. Presented paper is aimed at investigation of concrete corrosion (chemical as well as biologically induced) activated by influence of different aggressive media. Concrete cylinder samples of a 32 mm diameter and 15 mm height were formed as a drilled core from prepared concrete cubes. Concrete samples were exposed to different aggressive media under laboratory conditions (acid mine drainage, cultivation media for different bacteria species, sulphuric acid, aluminium sulphate) as well as in situ (waste water of sewage system in Kosice city) for 3 months. Influence of aggressive media and sulphur-oxidising and sulphate-reducing bacteria on concrete samples has been determined in terms of weight and surface changes of investigated concrete samples and leaching of the selected ions. The weight changes varied in the range 0.04–3.7 %. The visual changes of samples surface were observed. Content of Ca, Si and Fe ions in leachates were measured by X-ray fluorescence methods. Higher percentage of calcium ions released has been measured comparing to silicon ions in all media except for distilled water.The results of elements releasing correspond to results of weight changes of investigated concrete samples.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-9
Measures: 
  • Citations: 

    0
  • Views: 

    288
  • Downloads: 

    120
Abstract: 

The optimum thickness of the building envelope insulation materials depends on a large number of parameters. But the optimum thickness is calculated considering only economic arguments. In this paper, life-cycle assessment of the materials used in the building, and specifically the insulation ones, are included in the process to calculate the optimum insulation thickness from both environmental and energetic points of views. Within this frame, the large influence of the parameters associated with the manufacturing of the materials on the determination of the optimum thickness has been demonstrated: For all the studied cases, the insulation thickness depends in a large way on the unitary economic, energetic and environmental costs. The biggest differences in optimum thicknesses between two different insulation materials correspond to the highest differences in the unitary costs, for all the optimization points of views. The study also demonstrates that increasing values of the characteristic parameters of the manufacturing phase, which depend on the nature of the insulation materials, imply a decrease of the impact of the calculation settings, associated with the use phase of the building.

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Author(s): 

SIRINUTSOMBOON BUNPOT

Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-9
Measures: 
  • Citations: 

    0
  • Views: 

    362
  • Downloads: 

    144
Abstract: 

Microbial fuel cell (MFC) is a novel bio-electrochemical system that can use various organic substances as energy source. Computational models of MFC are needed for prediction and optimization of the MFC performance.A comprehensive computational modeling of a membraneless single-chamber MFC, in which bacteria consumed molasses as a substrate, is reported here. The simulated cathode had a layer of polytetrafluoroethylene, which allowed oxygen molecules to diffuse through to take part in the reduction reaction. The substrate molecules diffused through the biofilm, which deposited on the anode surface, and were oxidized by the bacteria localized within the film. The simulation program accepted inputs such as the initial amount of molasses, thickness of the biofilm layer, and dimensions of the MFC chamber. Some outputs of the program include concentration profiles of molasses and oxygen as functions of time and location, and the opencircuit voltage of the MFC as a function of time. As the cathode thickness decreased or the biofilm increased, the voltage increased. To obtain a higher voltage, increasing the biofilm thickness was more effective than decreasing the cathode thickness when the initial COD levels were [5, 000 mg/L.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-14
Measures: 
  • Citations: 

    1
  • Views: 

    390
  • Downloads: 

    77
Abstract: 

Climatic vicissitudes have laid further stress on already dwindling fossil fuels. In response to the emerging energy needs, biofuels can be considered as the safest and sustainable energy resources. At present, ethanol fermentations have been successful in fueling motor vehicles in some countries. However, with the existing population dynamic, obtaining ethanol from food competing resources/ commodities might not be a desirable option. Therefore, non-food competing second-generation biofuels are the right choice to accommodate the increasing energy demand. Regarding the production of biohydrogen, shifting from food competing substrates to non-food competing natural resources would be geared at dawn of biohydrogen productions. In this review potential of lignocellulosic biomass, the largest renewable natural resource for biofuels’generation has been discussed in reference to economical consideration. The strategies will likely involve thermophilic microbes possessing cellulolytic as well as ethanologenic potential. The process economics might be supported to some extent by procuring byproducts of some value from the bioenergy fermentations. Nutritional evaluation of the fermentation residues for animal feed may improve the biofuel economics. The proposed strategies appear promising more specifically in reference to climatic conditions of Pakistan.

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Author(s): 

UGWOHA EJIKEME

Issue Info: 
  • Year: 

    2014
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    1-8
Measures: 
  • Citations: 

    0
  • Views: 

    237
  • Downloads: 

    91
Abstract: 

Lysimeter experiments were conducted to compare the vapour phase transport of 20% ethanol- and butanol-blended gasoline (E20 and B20) compounds in soils using the unblended gasoline (UG) compounds as the standard. Sand containing approximately 0 and 5% organic matter (0 %fom and 5 %fom) was used to simulate the vadose zone. The 5 %fom soil promoted higher vapour phase transport of compounds than the 0%fom soil due to its higher porosity, hence, was used to compare the transport to the groundwater zone of the different gasoline blends. The addition of 20% alcohol by volume to gasoline reduced the retentive capability of the soil for gasoline compound vapours and thus resulted in greater downward transport and higher accumulation of gasoline compounds in the groundwater zone. The transport of gasoline compounds from the vadose zone to the groundwater zone was found to be in the order of E20[B20 [UG, indicating that the risk of groundwater contamination with gasoline compounds after a spill or leak is more likely to be greater for ethanolblended gasoline compared with butanol-blended gasoline.

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