Excellence in Research and Innovation for Humanity

International Science Index

Commenced in January 1999 Frequency: Monthly Edition: International Abstract Count: 48522

Energy and Power Engineering

1349
83754
Research on the Development of a Subminiature Turbo-Generator for Supercritical CO₂ Power Generation
Abstract:
One of the most remarkable power cycles is a supercritical carbon dioxide power cycle (S-CO₂). This system can be designed with miniaturization and get higher efficiency than the conventional steam Rankine cycle. To analyze the characteristics of this S-CO₂ power cycle, a subminiature turbo-generator was developed. To design a miniaturization test loop, the subminiature turbo-generator was driven at very low mass flow rate. Assuming a full-admission nozzle, designed rotational speed of the turbine was 800,000 RPM. This was impossible to design a turbo-generator with full-admission nozzle because of limits of bearings and seals. Therefore, the turbo-generator with partial admission nozzle was designed to reduce rotational speed in order to satisfy high-speed rotating condition. It was confirmed that the rotational speed can be reduced to 200,000 RPM. To analyze the rotational stability and vibration of the turbo-generator, a no-load test and cold-gas test was conducted. The cold-gas test was conducted to investigate the vibration and behavior of turbine when the turbine was driven. Before operating the test loop with CO₂ (turbine inlet condition: 130 bar, 200 ℃, turbine outlet condition: 57 bar, 150 ℃), the similarity test was conducted at low pressure condition. The similarity test was essential because it could be operated at low pressure conditions of approximately 30 to 40 bar compared to supercritical CO₂ operation. R134a was used as the working fluid instead of CO₂. As a result, an average turbine electric power of 400 W was obtained.
Digital Article Identifier (DAI):
1348
83522
The Studies of the Sorption Capabilities of the Porous Microspheres with Lignin
Abstract:
Lignin is one of three main constituents of biomass together with cellulose and hemicellulose. It is a complex biopolymer, which contains a large number of functional groups, including aliphatic and aromatic hydroxyl groups, carbohylic groups and methoxy groups in its structure, that is why it shows potential capacities for process of sorption. Lignin is a highly cross-linked polymer with a three-dimentional structure which can provide large surface area and pore volumes. It can also posses better dispersion, diffusion and mass transfer behavior in a field of the removal of, e.g., heavy-metal-ions or aromatic pollutions. In this work emulsion-suspension copolymerization method, to synthesize the porous microspheres of divinylbenzene (DVB), styrene (St) and lignin was used. There are also microspheres without the addition of lignin for comparison. Before the copolymerization, modification lignin with methacryloyl chloride, to improve its reactivity with other monomers was done. The physico-chemical properties of the obtained microspheres, e.g., pore structures (adsorption-desorption measurements), thermal properties (DSC), tendencies to swell and the actual shapes were also studied. Due to well-developed porous structure and the presence of functional groups our materials may have great potential in sorption processes. To estimate the sorption capabilities of the microspheres towards phenol and its chlorinated derivatives the off-line SPE (solid-phase extraction) method is going to be applied. This method has various advantages, including low-cost, easy to use and enables the rapid measurements for a large number of chemicals. The efficiency of the materials in removing phenols from aqueous solution and in desorption processes will be evaluated.
Digital Article Identifier (DAI):
1347
83473
Power Quality Modeling Using Recognition Learning Methods for Waveform Disturbances
Abstract:
This paper presents a Power Quality (PQ) modeling and filtering processes for the distribution system disturbances using recognition learning methods. Typical PQ waveforms with mathematical applications and gathered field data are applied to the proposed models. The objective of this paper is analyzing PQ data with respect to monitoring, discriminating, and evaluating the waveform of power disturbances to ensure the system preventative system failure protections and complex system problem estimations. Examined signal filtering techniques are used for the field waveform noises and feature extractions. Using extraction and learning classification techniques, the efficiency was verified for the recognition of the PQ disturbances with focusing on interactive modeling methods in this paper. The waveform of selected 8 disturbances is modeled with randomized parameters of IEEE 1159 PQ ranges. The range, parameters, and weights are updated regarding field waveform obtained. Along with voltages, currents have same process to obtain the waveform features as the voltage apart from some of ratings and filters. Changing loads are causing the distortion in the voltage waveform due to the drawing of the different patterns of current variation. In the conclusion, PQ disturbances in the voltage and current waveforms indicate different types of patterns of variations and disturbance, and a modified technique based on the symmetrical components in time domain was proposed in this paper for the PQ disturbances detection and then classification. Our method is based on the fact that obtained waveforms from suggested trigger conditions contain potential information for abnormality detections. The extracted features are sequentially applied to estimation and recognition learning modules for further studies.
Digital Article Identifier (DAI):
1346
83411
Optimization of Power Management Strategy for a Grid-Connected Photovoltaic Battery System Considering the Real-Time Pricing by Particle Swarm Optimization Method
Abstract:
Due to the intermittent and fluctuating nature, photovoltaic (PV) power system is always coupled with energy storage. The exchange of power between such a system and the grid becomes important and necessary, especially when the electricity buying/selling cost from the grid is considered. This paper proposed an operational performance optimization for a grid-connected PV system combined with a battery supplying to a residential load. The objective function is to maximize the daily operational benefit of the system. Assuming the day-ahead predicted PV power, the demand, and the electricity price are available, the optimization problem of the power management strategy (PMS) was solved by using Particle Swarm Optimization algorithm. The simulation of the proposed method was carried out for several case studies. The results were analyzed to investigate the economic benefit of the system as well as the obtained discharging/charging profile of battery power and energy.
Digital Article Identifier (DAI):
1345
83406
Theoretical and Numerical Investigation of a Tri-Stable Nonlinear Energy Harvesting System in Rotational Motion for Low Frequency Environment
Abstract:
In order to enhance the energy harvesting efficiency, this paper presents a novel tri-stable energy harvesting system (TEHS), which is realized by the effect of magnetic force, in rotational motion to scavenge vibration energy. The device is meant to provide the power supply for wireless autonomous systems in low-frequency environment. The nonlinear TEHS is composed of the cantilever beam which is mounted on a rotating hub and partially covered by piezoelectric patch, a tip mass magnet in the end and two fixed magnets. A theoretical investigation using the Lagrangian formulation is derived to describe the motion of the energy harvesting system and the output voltage. Additionally, several numerical simulations were carried out to characterize the system under different external excitations and to validate its performance. The results demonstrated that TEHS owns a wide range of frequency of snap-through and high output voltage compared with the bi-stable energy harvesting system (BEHS). Moreover, some sets of experimental validations will be performed in the future work because the experimental setup is in the configuration now.
Digital Article Identifier (DAI):
1344
83269
Batteryless DCM Boost Converter for Kinetic Energy Harvesting Applications
Abstract:
In this paper, a bidirectional boost converter operated in Discontinuous Conduction Mode (DCM) is presented as a suitable power conditioning circuit for tuning of kinetic energy harvesters without the need of a battery. A nonlinear control scheme, composed by two linear controllers, is used to control the average value of the input current, enabling the synthesization of complex loads. The converter, along with the control system, is validated through SPICE simulations using the LTspice tool. The converter model and the controller transfer functions are derived. From the simulation results, it was found that the input current distortion increases with the introduced phase shift and that, such distortion, is almost entirely present at the zero-crossing point of the input voltage.
Digital Article Identifier (DAI):
1343
83237
Assessment of Synchronous Reluctance Motor Design Using Finite Element Method-Circuit Model Considering Cross Magnetic Saturation
Abstract:
In this paper, an approach for achieving the optimum design of Synchronous Reluctance Motor (SynRM) is presented to get the maximum pullout torque and minimum ripples taking into consideration the nonlinearity of core and cross saturation effects. The optimum value of design parameters and their effects on a SynRM performance and dynamic response are identified using iterative Finite Element Method (FEM) solution and circuit models. In this approach, the lumped circuit parameters are calculated numerically using static FEM including cross-magnetic saturation. The used approach combines the accuracy of FEM and ability to include geometrical and physical effects relevant to non-linearity, in addition to the speed of circuit models. Using a computationally efficient approach, the paper demonstrates the importance of including nonlinear effects in design of SynRM, particularly from the point of view of pullout torque and minimum ripples. The approach can be utilized for other motor design applications to include non-linearity.
Digital Article Identifier (DAI):
1342
83160
Techno-Economic Assessments of Small-Scale, Grid-Connected Renewable Power Systems for Generation of Own Power by Small and Medium-Scale Enterprises
Abstract:
Decentralized power generation, from renewables, is an important option for the future energy transition. Encouraging policies, coupled with recent decrease in upfront costs, will attract investments towards power generation from medium and small-scale enterprises (SMEs) alongside large public or private players. In this paper, the potential to produce own power from distributed renewable, to de-carbonize the operations of SMEs was identified and critically analyzed along with a case study. Small-scale, off-site, grid-connected power generation was considered as an alternative for SMEs with space constraint for captive power generation. As a representative of a medium scale industry, one of the leading printing outfits of Sri Lanka was selected to evaluate the techno-economic feasibility and carbon dioxide abatement potential of its operations, through off-site renewable power generation. Solar photovoltaic (PV) and biomass gasification systems were identified as the most cost-efficient and easy to operate technologies for grid-connected, small-scale power generation. An evaluation of the results indicated that local availability of both resource and technology were key components for financial success irrespective of the technologies or resources used. Additionally, identification and utilization of wastes for energy generation from within the material streams of the associated industry was found to add considerable economic benefits to biomass system due to an improved and a more stable supply chain. Socio-political factors would play a higher impacting role for small systems in comparison to large scale units. Technical challenges of grid integration were identified to severely affect the economic viability of small-scale power generation units, irrespective of the technology. Lower capacity factor of solar PV and complexity of the supply chain for a biomass-based power generation were the limiting factors for the small-scale applications of respective technologies. However, a Solar PV-Biomass gasification based hybrid power generation system was established to have superior techno-economic performances with minimized environmental impact than individual technologies. Complementing plant capacity factors of PV and biomass systems, coupled with high part load efficiency of internal combustion engine based power generation would provide a more stable power output from the hybrid system, even with the presence of a fluctuating renewable like solar. Future possibilities for such systems to perform ancillary services were therefore identified and explored in brief. Multi-objective assessments revealed that an equal share of the net power capacity between the technologies was the most suitable combination for a small-scale Solar PV-Biomass gasification hybrid power system. A net carbon dioxide reduction of more than eighty percent of the operations of the SMEs was feasible, based on individual country’s grid emission factors. Additionally, modularity of such hybrid systems would allow system design to be based on, and by taking advantage of, local policies of individual countries or states. An improved economics, together with ease of implementation and operation of a small-scale Solar PV-Biomass gasification hybrid system would therefore, not only provide an attractive investment opportunity for the SMEs, but would ultimately lead to the increase of the share of renewable in the electricity mix.
Digital Article Identifier (DAI):
1341
83063
CO₂ Absorption Studies Using Amine Solvents with Fourier Transform Infrared Analysis
Abstract:
The increasing global atmospheric temperature is of great concern and this has led to the development of technologies to reduce the emission of greenhouse gases into the atmosphere. Flue gas emissions from fossil fuel combustion are major sources of greenhouse gases. One of the ways to reduce the emission of CO₂ from flue gases is by post combustion capture process and this can be done by absorbing the gas into suitable chemical solvents before emitting the gas into the atmosphere. Alkanolamines are promising solvents for this capture process. Vapour liquid equilibrium of CO₂-alkanolamine systems is often represented by CO₂ loading and partial pressure of CO₂ without considering the liquid phase. The liquid phase of this system is a complex one comprising of 9 species. Online analysis of the process is important to monitor the concentrations of the liquid phase reacting and product species. Liquid phase analysis of CO₂-diethanolamine (DEA) solution was performed by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. A robust Calibration was performed for the CO₂-aqueous DEA system prior to an online monitoring experiment. The partial least square regression method was used for the analysis of the calibration spectra obtained. The models obtained were used for prediction of DEA and CO₂ concentrations in the online monitoring experiment. The experiment was performed with a newly built recirculating experimental set up in the laboratory. The set up consist of a 750 ml equilibrium cell and ATR-FTIR liquid flow cell. Measurements were performed at 400°C. The results obtained indicated that the FTIR spectroscopy combined with Partial least square method is an effective tool for online monitoring of speciation.
Digital Article Identifier (DAI):
1340
82985
Wind Farm Power Performance Verification Using Non-Parametric Statistical Inference
Abstract:
Accurate determination of wind turbine performance is necessary for economic operation of a wind farm. At present, the procedure to carry out the power performance verification of wind turbines is based on a standard of the International Electrotechnical Commission (IEC). In this paper, nonparametric statistical inference is applied to designing a simple, inexpensive method of verifying the power performance of a wind turbine. Two statistical tests are examined, and the one with better performance is proposed. The methods use the information that is collected by the SCADA system (Supervisory Control and Data Acquisition) from the sensors embedded in the wind turbines in order to carry out the power performance verification of a wind farm. The study has used data on the monthly output of wind farm in the Republic of Macedonia and the time measuring interval was from January 1, 2016, to December 31, 2016. At the end, it is concluded whether the power performance of a wind turbine differed significantly from what would be expected. The results of the implementation of the proposed methods showed that the power performance of the specific wind farm under assessment was acceptable.
Digital Article Identifier (DAI):
1339
82902
Design and Analysis of 1.4 MW Hybrid Saps System for Rural Electrification in Off-Grid Applications
Abstract:
In this paper, optimal design of hybrid standalone power supply system (SAPS) is done for off grid applications in remote areas where transmission of power is difficult. The hybrid SAPS system uses two primary energy sources, wind and solar, and in addition to these diesel generator is also connected to meet the load demand in case of failure of wind and solar system. This paper presents mathematical modeling of 1.4 MW hybrid SAPS system for rural electrification. This paper firstly focuses on mathematical modeling of PV module connected in a string, secondly focuses on modeling of permanent magnet wind turbine generator (PMWTG). The hybrid controller is also designed for selection of power from the source available as per the load demand. The power output of hybrid SAPS system is analyzed for meeting load demands at urban as well as for rural areas.
Digital Article Identifier (DAI):
1338
82900
Molecular Profiling of an Oleaginous Trebouxiophycean Alga Parachlorella kessleri Subjected to Nutrient Deprivation
Abstract:
Parachlorella kessleri, a marine unicellular green alga belonging to class Trebouxiophyceae, accumulates large amounts of oil, i.e., lipids under nutrient-deprived (-N, -P, and -S) conditions. Understanding their metabolic imprints is important for elucidating the physiological mechanisms of lipid accumulations in this microalga subjected to nutrient deprivation. Metabolic and lipidomic profiles were obtained respectively using gas chromatography-mass spectrometry (GC-MS) of P. kessleri under nutrient starvation (-N, -P and -S) conditions. Relative quantities of more than 100 metabolites were systematically compared in all these three starvation conditions. Our results demonstrate that in lipid metabolism, the quantities of neutral lipids increased significantly followed by the decrease in other metabolites involved in photosynthesis, nitrogen assimilation, etc. In conclusion, the metabolomics and lipidomic profiles have identified a few common metabolites such as citric acid, valine, and trehalose to play a significant role in the overproduction of oil by this microalga subjected to nutrient deprivation. Understanding the entire system through untargeted metabolome profiling will lead to identifying relevant metabolites involved in the biosynthesis and degradation of precursor molecules that may have the potential for biofuel production, aiming towards the vision of tomorrow’s bioenergy needs.
Digital Article Identifier (DAI):
1337
82867
Deep Learning-Based Object Detection on Low Quality Images: A Case Study of Real-Time Traffic Monitoring
Abstract:
The installation and management of traffic monitoring devices can be costly from both a financial and resource point of view. It is therefore important to take advantage of in-place infrastructures to extract the most information. Here we show how low-quality urban road traffic images from cameras already available in many cities (such as Montreal, Vancouver, and Toronto) can be used to estimate traffic flow. To this end, we use a pre-trained neural network, developed for object detection, to count vehicles within images. We then compare the results with human annotations gathered through crowdsourcing campaigns. We use this comparison to assess performance and calibrate the neural network annotations. As a use case, we consider six months of continuous monitoring over hundreds of cameras installed in the city of Montreal. We compare the results with city-provided manual traffic counting performed in similar conditions at the same location. The good performance of our system allows us to consider applications which can monitor the traffic conditions in near real-time, making the counting usable for traffic-related services. Furthermore, the resulting annotations pave the way for building a historical vehicle counting dataset to be used for analysing the impact of road traffic on many city-related issues, such as urban planning, security, and pollution.
Digital Article Identifier (DAI):
1336
82842
Optimization of Water Desalination System Powered by High Concentrated Photovoltaic Panels in Kuwait Climate Conditions
Abstract:
Desalination using solar energy is an interesting option specifically at regions with abundant solar radiation since such areas normally have scarcity of clean water resources. Desalination is the procedure of eliminating dissolved minerals from seawater or brackish water to generate fresh water. In this work, a simulation program is developed to determine the performance of reverse osmosis (RO) water desalination plant powered by high concentrated photovoltaic (HCPV) panels in Kuwait climate conditions. The objective of such a photovoltaic thermal system is to accomplish a double output, i.e., co-generation of both electricity and fresh water that is applicable for rural regions with high solar irradiation. The suggested plan enables to design an RO plant that does not depend on costly batteries or additional land and significantly reduce the government costs to subsidize the water generation cost. Typical weather conditions for Kuwait is employed as input to the simulation program. The simulation program is utilized to optimize the system efficiency as well as the distillate water production. The areas and slopes of HCPV modules are varied to attain maximum yearly power production. Maximum yearly distillate production and HCPV energy generation are found to correspond to HCPV facing south with tilt of 27° (Kuwait latitude-3°). The power needed to produce 1 l of clean drinking water ranged from 2 to 8 kW h/m³, based on the salinity of the feed water and the system operating conditions. Moreover, adapting HCPV systems achieve an avoided greenhouse gases emission by about 1128 ton CO₂ annually. Present outcomes certainly illustrate environmental advantages of water desalination system powered by high concentrated photovoltaic systems in Kuwait climate conditions.
Digital Article Identifier (DAI):
1335
82778
Improving Performance of K₂CO₃ Sorbent Using Core/Shell Alumina-Based Supports in a Multicycle CO₂ Capture Process
Abstract:
The continued increase in the atmospheric concentration of CO₂ is expected to have great impacts on the climate. In order to reduce CO₂ emission to the atmosphere, an efficient and cost-effective technique is required. Using regenerable solid sorbents, especially K₂CO₃ is a promising method for low-temperature CO₂ capture. Pure K₂CO₃ is a delinquent substance that requires modifications before it can be used for cyclic operations. For this purpose, various types of additives and supports have been used to improve the structure of K₂CO₃. However, hydrophilicity and reactivity of the support materials with K₂CO₃ have a negative effect on the CO₂ capture capacity of the sorbents. In this research, two kinds of alumina supports (γ-Alumina and Boehmite) were used. In order to decrease the supports' hydrophilicity and reactivity with K₂CO₃, nonreactive additives such as Titania, Zirconia and Ceria were incorporated into their structures. These materials provide a shell around the alumina to protect it from undesirable reactions and improve its properties. K₂CO₃-based core/shell-supported sorbents were fabricated using two preparation steps. The sol-gel method was applied for shelling the supports. Then the shelled supports were impregnated on K₂CO₃. The physicochemical properties of the sorbents were determined using XRD, SEM and BET analyses, and their CO₂ capture capacity was quantified using a thermogravimetric analyzer. Although modification of the sorbents' structure decreased their BET surface area, new undesirable phases were not detected in their XRD patterns. Thus deactivation phenomena did not occur during the carbonation/regeneration cycles. Based on the obtained results, incorporating nonreactive additives in Boehmite, unlike γ-Alumina, had an outstanding impact on the CO₂ capture performance of the sorbents. Incorporation of Titania into the Boehmite-supported K₂CO₃ enhanced its CO₂ capture capacity significantly. Therefore, further study of this novel fabrication technique is highly recommended. In the second phase of this research project, the CO₂ capture performance of the sorbents in fixed and fluidized bed reactors will be investigated.
Digital Article Identifier (DAI):
1334
82749
The Dynamic of Algeria's Natural Gas Exports to Europe: Evidence from Autoregressive Distributed Lag Bounds Testing Approach with Breakpoints
Abstract:
The purpose of the study is to examine the dynamic of Algeria’s natural gas exports through the Autoregressive Distributed Lag (ARDL) bounds testing approach with break points. The analysis was carried out for the period from 1967 to 2015. Based on imperfect substitution specification, the ARDL approach reveals a long-run equilibrium relationship between Algeria’s Natural gas exports and their determinant factors (Algeria’s gas reserves, Domestic gas consumption, Europe’s GDP per capita, relative prices, the European gas production and the market share of competitors). All the long-run elasticities estimated are statistically significant with a large impact on domestic factors, which constitute the supply constraints. In short term, the elasticities are statistically significant and almost comparable to those of the long term. Furthermore, the speed of adjustment towards long-run equilibrium is less than one year because of the little flexibility of the long term export contracts. Two break points have been estimated when we employ the domestic gas consumption as a break variable; 1984 and 2010, which reflect the arbitration policy between the domestic gas market and gas exports.
Digital Article Identifier (DAI):
1333
82739
Krill-Herd Step-Up Approach Based Energy Efficiency Enhancement Opportunities in the Offshore Mixed Refrigerant Natural Gas Liquefaction Process
Abstract:
Natural gas has become an attractive energy source in comparison with other fossil fuels because of its lower CO₂ and other air pollutant emissions. Therefore, compared to the demand for coal and oil, that for natural gas is increasing rapidly world-wide. The transportation of natural gas over long distances as a liquid (LNG) preferable for several reasons, including economic, technical, political, and safety factors. However, LNG production is an energy-intensive process due to the tremendous amount of power requirements for compression of refrigerants, which provide sufficient cold energy to liquefy natural gas. Therefore, one of the major issues in the LNG industry is to improve the energy efficiency of existing LNG processes through a cost-effective approach that is 'optimization'. In this context, a bio-inspired Krill-herd (KH) step-up approach was examined to enhance the energy efficiency of a single mixed refrigerant (SMR) natural gas liquefaction (LNG) process, which is considered as a most promising candidate for offshore LNG production (FPSO). The optimal design of a natural gas liquefaction processes involves multivariable non-linear thermodynamic interactions, which lead to exergy destruction and contribute to process irreversibility. As key decision variables, the optimal values of mixed refrigerant flow rates and process operating pressures were determined based on the herding behavior of krill individuals corresponding to the minimum energy consumption for LNG production. To perform the rigorous process analysis, the SMR process was simulated in Aspen Hysys® software and the resulting model was connected with the Krill-herd approach coded in MATLAB. The optimal operating conditions found by the proposed approach significantly reduced the overall energy consumption of the SMR process by ≤ 22.5% and also improved the coefficient of performance in comparison with the base case. The proposed approach was also compared with other well-proven optimization algorithms, such as genetic and particle swarm optimization algorithms, and was found to exhibit a superior performance over these existing approaches.
Digital Article Identifier (DAI):
1332
82708
Energy Efficient Retrofitting and Optimization of Dual Mixed Refrigerant Natural Gas Liquefaction Process
Abstract:
Globally, liquefied natural gas (LNG) has drawn interest as a green energy source in comparison with other fossil fuels, mainly because of its ease of transport and low carbon dioxide emissions. It is expected that demand for LNG will grow steadily over the next few decades. In addition, because the demand for clean energy is increasing, LNG production facilities are expanding into new natural gas reserves across the globe. However, LNG production is an energy and cost intensive process because of the huge power requirements for compression and refrigeration. Therefore, one of the major challenges in the LNG industry is to improve the energy efficiency of existing LNG processes through economic and ecological strategies. The advancement in expansion devices such as two-phase cryogenic expander (TPE) and cryogenic hydraulic turbine (HT) were exploited for energy and cost benefits in natural gas liquefaction. Retrofitting the conventional Joule–Thompson (JT) valve with TPE and HT have the potential to improve the energy efficiency of LNG processes. This research investigated the potential feasibility of the retrofitting of a dual mixed refrigerant (DMR) process by replacing the isenthalpic expansion with isentropic expansion corresponding to energy efficient LNG production. To fully take the potential benefit of the proposed process retrofitting, the proposed DMR schemes were optimized by using a Coggins optimization approach, which was implemented in Microsoft Visual Studio (MVS) environment and linked to the rigorous HYSYS® model. The results showed that the required energy of the proposed isentropic expansion based DMR process could be saved up to 26.5% in comparison with the conventional isenthalpic based DMR process using the JT valves. Utilization of the recovered energy into boosting the natural gas feed pressure could further improve the energy efficiency of the LNG process up to 34% as compared to the base case. This work will help the process engineers to overcome the challenges relating to energy efficiency and safety concerns of LNG processes. Furthermore, the proposed retrofitting scheme can also be implemented to improve the energy efficiency of other isenthalpic expansion based energy intensive cryogenic processes.
Digital Article Identifier (DAI):
1331
82643
Analysis of Grid Connected High Concentrated Photovoltaic Systems for Peak Load Shaving in Kuwait
Abstract:
Air conditioning devices are substantially utilized in the summer months, as a result maximum loads in Kuwait take place in these intervals. Peak energy consumption are usually more expensive to satisfy compared to other standard power sources. The primary objective of the current work is to enhance the performance of high concentrated photovoltaic (HCPV) systems in an attempt to minimize peak power usage in Kuwait using HCPV modules. High concentrated PV multi-junction solar cells provide a promising method towards accomplishing lowest pricing per kilowatt-hour. Nevertheless, these cells have various features that should be resolved to be feasible for extensive power production. A single diode equivalent circuit model is formulated to analyze multi-junction solar cells efficiency in Kuwait weather circumstances taking into account the effects of both the temperature and the concentration ratio. The diode shunt resistance that is commonly ignored in the established models is considered in the present numerical model. The current model results are successfully validated versus measurements from published data to within 1.8% accuracy. Present calculations reveal that the single diode model considering the shunt resistance provides accurate and dependable results. The electrical efficiency (η) is observed to increase with concentration to a specific concentration level after which it reduces. Implementing grid systems is noticed to increase with concentration to a certain concentration degree after which it decreases. Employing grid connected HCPV systems results in significant peak load reduction.
Digital Article Identifier (DAI):
1330
82579
Studies on the Feasibility of Cow-Dung as a Non-Conventional Energy Sources
Abstract:
Bio-batteries represent an entirely new long-term, reasonable, reachable and ecofriendly approach to production of sustainable energy. In the present experimental work, we have studied the effect of generation of power by bio-battery using different electrode pairs. The tests show that it is possible to generate electricity using cow-dung as an electrolyte. C-Mg electrode pair shows maximum Voltage and SCC while C-Zn electrode pair shows less OCV and SCC. We have chosen C-Zn electrodes because Mg electrodes are not economical. By the studies of different electrodes and cow-dung, it is found that C-Zn electrode battery is more suitable. This result shows that the bio-batteries have the potency to full fill the need of electricity demand for lower energy equipments.
Digital Article Identifier (DAI):
1329
82434
Cupric Oxide Thin Films for Optoelectronic Application
Abstract:
Copper oxide is a semiconductor that has been studied for several reasons such as the natural abundance of starting material copper (Cu); the easiness of production by Cu oxidation; their non-toxic nature and the reasonably good electrical and optical properties. Copper oxide is well-known as cuprite oxide. The cuprite is p-type semiconductors having band gap energy of 1.21 to 1.51 eV. As a p-type semiconductor, conduction arises from the presence of holes in the valence band (VB) due to doping/annealing. CuO is attractive as a selective solar absorber since it has high solar absorbency and a low thermal emittance. CuO is very promising candidate for solar cell applications as it is a suitable material for photovoltaic energy conversion. It has been demonstrated that the dip technique can be used to deposit CuO films in a simple manner using metallic chlorides (CuCl₂.2H₂O) as a starting material. Copper oxide films are prepared using a methanolic solution of cupric chloride (CuCl₂.2H₂O) at three baking temperatures. We made three samples, after heating which converts to black colour. XRD data confirm that the films are of CuO phases at a particular temperature. The optical band gap of the CuO films calculated from optical absorption measurements is 1.90 eV which is quite comparable to the reported value. Dip technique is a very simple and low-cost method, which requires no sophisticated specialized setup. Coating of the substrate with a large surface area can be easily obtained by this technique compared to that in physical evaporation techniques and spray pyrolysis. Another advantage of the dip technique is that it is very easy to coat both sides of the substrate instead of only one and to deposit otherwise inaccessible surfaces. This method is well suited for applying coating on the inner and outer surfaces of tubes of various diameters and shapes. The main advantage of the dip coating method lies in the fact that it is possible to deposit a variety of layers having good homogeneity and mechanical and chemical stability with a very simple setup. In this paper, the CuO thin films preparation by dip coating method and their characterization will be presented.
Digital Article Identifier (DAI):
1328
82360
Optimization of Cu (In, Ga)Se₂ Based Thin Film Solar Cells: Simulation
Abstract:
Electrical modelling of Cu (In,Ga)Se₂ thin film solar cells is carried out with compositionally graded absorber and CdS buffer layer. Simulation results are compared with experimental data. Surface defect layers (SDL) are located in CdS/CIGS interface for improving open circuit voltage simulated structure through the analysis of the interface is investigated with or without this layer. When SDL removed, by optimizing the conduction band offset (CBO) position of the buffer/absorber layers with its recombination mechanisms and also shallow donor density in the CdS, the open circuit voltage increased significantly. As a result of simulation, excellent performance can be obtained when the conduction band of window layer positions higher by 0.2 eV than that of CIGS and shallow donor density in the CdS was found about 1×10¹⁸ (cm⁻³).
Digital Article Identifier (DAI):
1327
82185
Peltier Air Conditioning System for Preventing Ambient Heating: An Alternative to Gas Air Conditioners
Abstract:
The use of gas cooler has always been associated with high consumption of electrical energy, environmental pollution, and heat production. Therefore, it is not a suitable method for converting electric energy into cold energy. In this paper, an air conditioning system was designed by a creative and scientific method using inexpensive parts with very low energy consumption that produces considerable cold electric energy near the freezing point (without heat generation for the environment) using only 30 watts. This could be a major development in the production of refrigeration systems through which non-fossil or renewable energy cooling systems could be used as the best option for various applications such as industry, buildings, cooling, reduction of urban heating, and so forth. In addition to studying and identifying LEED standards, energy star, and their application in buildings and electrical and electronic devices, the paper investigated and designed an air conditioning system in the building to achieve significant efficiency using the minimum electrical energy so that the consumption of energy is only one eighth of the global average without heat generation for the environment.
Digital Article Identifier (DAI):
1326
81961
Development of Alternative Fuels Technologies: Compressed Natural Gas Home Refueling Station
Abstract:
Compressed natural gas (CNG) represents an excellent compromise between the availability of a technology that is proven and relatively easy to use in many areas of the automotive industry and incurred costs. This fuel causes a lower corrosion effect due to the lower content of products causing the potential difference on the walls of the engine system. Natural gas powered vehicles (NGVs) do not emit any substances that can contaminate water or land. The absence of carcinogenic substances in gaseous fuel extends the life of the engine. In the longer term, it contributes positively to waste management as well as waste disposal. Popularization of propulsion systems powered by natural gas CNG positively affects the reduction of heavy duty transport. For these reasons, CNG as a fuel stimulates considerable interest around the world. Over the last few years, technologies related to use of natural gas as an engine fuel have been developed and improved. These solutions have evolved from the prototype phase to the industrial scale implementation. The widespread availability of gaseous fuels has led to the development of a technology that allows the CNG fuel to be refueled directly from the urban gas network to the vehicle tank (ie. HYGEN - CNGHRS). Home refueling installations, although they have been known for many years, are becoming increasingly important in the present day. The major obstacle in the sale of this technology was, until recently, quite high capital expenditure compared to the later benefits. Home refueling systems allow refueling vehicle tank, with full control of fuel costs and refueling time. CNG Home Refueling Stations (such as HYGEN) allow gas value chain to overcome the dogma that there is a lack of refueling infrastructure allowing companies in gas value chain to participate in transportation market. Technology is based on one stage hydraulic compressor (instead of multistage mechanical compressor technology) which provides the possibility to compress low pressure gas from distribution gas network to 200 bar for its further usage as a fuel for NGVs. This boosts revenues and profits of gas companies by expanding its presence in higher margin of energy sector.
Digital Article Identifier (DAI):
1325
81805
Heating Demand Reduction in Single Family Houses Community through Home Energy Management: Putting Users in Charge
Abstract:
Heating constitutes a major part of the overall energy consumption in Sweden. In 2013 heating and hot water accounted for about 55% of the total energy use in the housing sector. Historically, the end users have not been able to make a significant impact on their consumption on account of traditional control systems that do not facilitate interaction and control of the heating systems. However, in recent years internet connected home energy management systems have become increasingly available which allow users to visualize the indoor temperatures as well as control the heating system. However, the adoption of these systems is still in its nascent stages. This paper presents the outcome of a study carried out in a community of single-family houses in Stockholm. Heating in the area is provided through district heating, and the neighbourhood is connected through a local micro thermal grid, which is owned and operated by the local community. Heating in the houses is accomplished through a hydronic system equipped with radiators. The system installed offers the households to control the indoor temperature through a mobile application as well as through a physical thermostat. It was also possible to program the system to, for instance, lower the temperatures during night time and when the users were away. The users could also monitor the indoor temperatures through the application. It was additionally possible to create different zones in the house with their own individual programming. The historical heating data (in the form of billing data) was available for several previous years and has been used to perform quantitative analysis for the study after necessary normalization for weather variations. The experiment involved 30 households out of a community of 178 houses. The area was selected due to uniform construction profile in the area. It was observed that despite similar design and construction period there was a large variation in the heating energy consumption in the area which can for a large part be attributed to user behaviour. The paper also presents qualitative analysis done through survey questions as well as a focus group carried out with the participants. Overall, considerable energy savings were accomplished during the trial, however, there was a considerable variation between the participating households. The paper additionally presents recommendations to improve the impact of home energy management systems for heating in terms of improving user engagement and hence the energy impact.
Digital Article Identifier (DAI):
1324
81619
Expanding the Evaluation Criteria for a Wind Turbine Performance
Abstract:
The problem of global warming raised up interest towards renewable energy sources. To reduce cost of wind energy is a challenge. Before building of wind park conditions such as: average wind speed, direction, time for each wind, probability of icing, must be considered in the design phase. Operation values used on the setting of control systems also will depend on mentioned variables. Here it is proposed a procedure to be include in the evaluation of the performance of a wind turbine, based on the amplitude of wind changes, the number of changes and their duration. A generic study case based on actual data is presented. Data analysing techniques were applied to model the power required for yaw system based on amplitude and data amount of wind changes. A theoretical model between time, amplitude of wind changes and angular speed of nacelle rotation was identified.
Digital Article Identifier (DAI):
1323
81576
Recirculated Sedimentation Method to Control Contamination for Algal Biomass Production
Abstract:
Microalgae-derived biodiesel, fertilizer or industrial chemicals' production with wastewater has great potential. Especially water from a municipal wastewater treatment plant is a very important nutrient source for biofuel production. Microalgae biomass production in open ponds system is lower cost culture systems. There are many hurdles for commercial algal biomass production in large scale. One of the important technical bottlenecks for microalgae production in open system is culture contamination. The algae culture contaminants can generally be described as invading organisms which could cause pond crash. These invading organisms can be competitors, parasites, and predators. Contamination is unavoidable in open systems. Potential contaminant organisms are already inoculated if wastewater is utilized for algal biomass cultivation. Especially, it is important to control contaminants to retain in acceptable level in order to reach true potential of algal biofuel production. There are several contamination management methods in algae industry, ranging from mechanical, chemical, biological and growth condition change applications. However, none of them are accepted as a suitable contamination control method. This experiment describes an innovative contamination control method, 'Recirculated Sedimentation Method', to manage contamination to avoid pond cash. The method can be used for the production of algal biofuel, fertilizer etc. and algal wastewater treatment. To evaluate the performance of the method on algal culture, an experiment was conducted for 90 days at a lab-scale raceway (60 L) reactor with the use of non-sterilized and non-filtered wastewater (secondary effluent and centrate of anaerobic digestion). The application of the method provided the following; removing contaminants (predators and diatoms) and other debris from reactor without discharging the culture (with microscopic evidence), increasing raceway tank’s suspended solids holding capacity (770 mg L-1), increasing ammonium removal rate (29.83 mg L-1 d-1), decreasing algal and microbial biofilm formation on inner walls of reactor, washing out generated nitrifier from reactor to prevent ammonium consumption.
Digital Article Identifier (DAI):
1322
81532
Fuel Economy of Electrical Energy in the City Bus during Japanese Test Procedure
Abstract:
This paper discusses a model of fuel consumption and on-board electricity generation. Rapid changes in speed result in a constantly changing kinetic energy accumulated in a bus mass and an increased fuel consumption due to hardly recuperated kinetic energy. The model is based on the results achieved from chassis dynamometer, airport and city street researches. The verified model was applied to simulate the on-board electricity generation during the Japanese JE05 Emission Test Cycle. The simulations were performed for several values of vehicle mass and electrical load applied to on-board devices. The research results show that driving dynamics has an impact on a consumption of fuel to drive alternators.
Digital Article Identifier (DAI):
1321
81477
Thermo-Economic Evaluation of Sustainable Biogas Upgrading via Solid-Oxide Electrolysis
Abstract:
Biogas production from anaerobic digestion of organic sludge from wastewater treatment as well as various urban and agricultural organic wastes is of great significance to achieve a sustainable society. Two upgrading approaches for cleaned biogas can be considered: (1) direct H₂ injection for catalytic CO₂ methanation and (2) CO₂ separation from biogas. The first approach usually employs electrolysis technologies to generate hydrogen and increases the biogas production rate; while the second one usually applies commercially-available highly-selective membrane technologies to efficiently extract CO₂ from the biogas with the latter being then sent afterward for compression and storage for further use. A straightforward way of utilizing the captured CO₂ is on-site catalytic CO₂ methanation. From the perspective of system complexity, the second approach may be questioned, since it introduces an additional expensive membrane component for producing the same amount of methane. However, given the circumstance that the sustainability of the produced biogas should be retained after biogas upgrading, renewable electricity should be supplied to drive the electrolyzer. Therefore, considering the intermittent nature and seasonal variation of renewable electricity supply, the second approach offers high operational flexibility. This indicates that these two approaches should be compared based on the availability and scale of the local renewable power supply and not only the technical systems themselves. Solid-oxide electrolysis generally offers high overall system efficiency, and more importantly, it can achieve simultaneous electrolysis of CO₂ and H₂O (namely, co-electrolysis), which may bring significant benefits for the case of CO₂ separation from the produced biogas. When taking co-electrolysis into account, two additional upgrading approaches can be proposed: (1) direct steam injection into the biogas with the mixture going through the SOE, and (2) CO₂ separation from biogas which can be used later for co-electrolysis. The case study of integrating SOE to a wastewater treatment plant is investigated with wind power as the renewable power. The dynamic production of biogas is provided on an hourly basis with the corresponding oxygen and heating requirements. All four approaches mentioned above are investigated and compared thermo-economically: (a) steam-electrolysis with grid power, as the base case for steam electrolysis, (b) CO₂ separation and co-electrolysis with grid power, as the base case for co-electrolysis, (c) steam-electrolysis and CO₂ separation (and storage) with wind power, and (d) co-electrolysis and CO₂ separation (and storage) with wind power. The influence of the scale of wind power supply is investigated by a sensitivity analysis. The results derived provide general understanding on the economic competitiveness of SOE for sustainable biogas upgrading, thus assisting the decision making for biogas production sites. The research leading to the presented work is funded by European Union’s Horizon 2020 under grant agreements n° 699892 (ECo, topic H2020-JTI-FCH-2015-1) and SCCER BIOSWEET.
Digital Article Identifier (DAI):
1320
81400
Useful Effects of Silica Nanoparticles in Ionic Liquid Electrolyte for Energy Storage
Abstract:
Improved energy storage is inevitably needed to improve energy efficiency and to be environmentally friendly to chemical processes. Ionic liquids (ILs) can play a crucial role in addressing these needs due to inherent adjustable properties including low volatility, low flammability, inherent conductivity, wide liquid range, broad electrochemical window, high thermal stability, and recyclability. Here, binary mixtures of ILs were prepared with fumed silica nanoparticles and characterized to obtain ILs with conductivity and electrochemical properties optimized for use in energy storage devices. The solutes were prepared by varying the size and the weight percent concentration of the nanoparticles and made up 10 % of the binary mixture by weight. We report on the physical and electrochemical properties of the individual ILs and their binary mixtures.
Digital Article Identifier (DAI):