Excellence in Research and Innovation for Humanity

International Science Index

Commenced in January 1999 Frequency: Monthly Edition: International Abstract Count: 40434

Energy and Power Engineering

Wind Characteristics and Energy Yield in Some Towns in Libya: The Case Study in Derna
In this paper, the wind characteristics of some sites in Libya at multiple levels have been analyzed, wind speed and wind direction were measured every 3 hours at 10 m height for a period of 10 years between 2000 and 2009. These towns which are located on the coast of Mediterranean Sea and others in the desert, which are Derna 1, Derna 2, Shahat, Benghazi, Ajdabya, Sirte, Misurata, Tripoli-Airport, Al-Zawya, Al-Kofra, Sabha, Nalut. The work presented long-term wind data analysis in terms of annual, seasonal, monthly and diurnal variations at these sites. The annual energy yield and wind direction were evaluated for Derna1 town, considering wind turbines ranging between 1.65 MW and 2 MW (power curve considering air density 1.225 Kg/m3). Wind turbine energy production at different heights and different sizes have been calculated using a Weibull distribution (Weibull Statistics Techniques) and Exel sheet.
Investigation of Main Operating Parameters Affecting Gas Turbine Efficiency and Poluttant Releases
This work presents a study on the influence of the main operating variables on the Gas Turbine cycle. A numerical simulation of a gas turbine cycle is performed for a real net power of 100 MW.A calculation code is developed using EES software. The operating variables for values usually adopted for the Tunisian Society of Electricity and Gas. Results show that the increase of ambient temperature leads to an increase of Tpz and NOx emissions rate and a decrease of cycle efficiency and UHC emissions. The CO emissions decrease with the raise of residence time while NOx emissions rate increases and UHC emissions rate decreases. Furthermore, more than the pressure ratio increases more than both of cycle efficiency and NOx emissions rate increase.
Assessing the Ways of Improving the Power Saving Modes in the Ore-Grinding Technological Process
Monitoring the distribution of electric power consumption in the technological process of ore grinding is conducted. As a result, the impacts of the mill filling rate, the productivity of the ore supply, the volumetric density of the grinding balls, the specific density of the ground ore, and the relative speed of the mill rotation on the specific consumption of electric power have been studied. The power and technological factors affecting the reactive power generated by the synchronous motors, operating within the technological scheme are studied. A block diagram for evaluating the power consumption modes of the technological process is proposed, which includes the analysis of the technological scheme, the determination of the place and volumetric density of the ore grinding mill, the evaluation of the technological and power factors affecting the energy saving process, as well as the assessment of the electric power standards.
Influence of Photophysical Parameters of Photoactive Materials on Exciton Diffusion Length and Diffusion Coefficient in Bulk Heterojunction Organic Solar Cells
It has been experimentally demonstrated that exciton diffusion length in organic solids can be improved by fine-tuning the material parameters that govern exciton transfer. Here, a theoretical study is carried out to support this finding. We have therefore derived expressions for the exciton diffusion length and diffusion coefficient of singlet and triplet excitons using Förster resonance energy transfer and Dexter carrier transfer mechanisms and are plotted as a function of photoluminescence (PL) quantum yield, spectral overlap integral, refractive index and dipole moment of the photoactive material. We found that singlet exciton diffusion length increases with PL quantum yield and spectral overlap integral, and decreases with increase in refractive index. Likewise, the triplet exciton diffusion length increases when PL quantum yield increases and dipole moment decreases. The calculated diffusion lengths in different organic materials are compared with existing experimental values and found to be in reasonable agreement. The results are expected to provide insight in developing new organic materials for fabricating bulk heterojunction (BHJ) organic solar cells (OSCs) with better photoconversion efficiency.
Fire Safety Vulnerability Model for Preliminary Design Evaluation with Fuzzy Reasoning
The rapid increase in the amount of information and complexity on building performance systems reveals highly complex decision problems with multiple variables that are stochastic, unknown, and fuzzy. This complexity leads to conflict between building performance criteria due to lack of total fulfillment of every performance standards with an equal degree. Fire safety, with its important performance inputs during the preliminary building design phase, has that conflicting nature and fuzzy character. Thus, the decision-making models in fire safety design need to focus the acceptability of overall fire safety performance by the degree of modifications in other building parameters, since it is not known precisely. Acceptability of fire safety design involves interoperability of fire safety objectives and other design inputs, while the tolerance for imprecision needs to be defined by using fuzzy logic. Fuzzy logic helps the integration of uncountable, undefined, and uncertain information in the decision-making process, with quick-response evaluations based on the decision maker’s intuition, judgment, and experience. This research proposes computer-based fuzzy fire safety vulnerability assessment model, in which most critical building parameters regarding fire safety are identified and visualized. The model framework is developed through literature analysis, while membership functions and rule-based interrelations of parameters are designed through expert opinion. As a result, the fire safety vulnerability assessment tool enables evaluation and visualization of each building variable modifications as well as the total vulnerability of building on the single platform. Thus, point sources of hazardous actions and critical architectural design parameters related to fire safety are detected to get prevention measures in the building design phase.
Enhanced Growth of Microalgae Chlamydomonas reinhardtii Cultivated in Different Organic Waste and Effective Conversion of Algal Oil to Biodiesel
Microalgae are a potential bio-source for rejuvenated solutions in various disciplines of science and technology, especially in medicine and energy. Biodiesel is being replaced for conventional fuels in automobile industries with reduced pollution and equivalent performance. Since it is a carbon neutral fuel by recycling CO2 in photosynthesis, global warming potential can be held in control using this fuel source. One of the ways to meet the rising demand of automotive fuel is to adopt with eco-friendly, green alternative fuels called sustainable microalgal biodiesel. In this work, a microalga Chlamydomonas reinhardtii was cultivated and optimized in different media compositions developed from under-utilized waste materials in lab scale. Using the optimized process conditions, they are then mass propagated in out-door ponds, harvested, dried and oils extracted for optimization in ambient conditions. The microalgal oil was subjected to two step esterification processes using acid catalyst to reduce the acid value (0.52 mg kOH/g) in the initial stage, followed by transesterification to maximize the biodiesel yield. The optimized esterification process parameters are methanol/oil ratio 0.32 (v/v), sulphuric acid 10 vol.%, duration 45 min at 65 ºC. In the transesterification process, commercially available alkali catalyst (KOH) is used and optimized to obtain a maximum biodiesel yield of 95.4%. The optimized parameters are methanol/oil ratio 0.33(v/v), alkali catalyst 0.1 wt.%, duration 90 min at 65 ºC 90 with smooth stirring. Response Surface Methodology (RSM) is employed as a tool for optimizing the process parameters. The biodiesel was then characterized with standard procedures and especially by GC-MS to confirm its compatibility for usage in internal combustion engine.
The Optimal Azimuth and Tilt Angle of BIPV Panels Considering the Prices at Electricity Spot Market
The existing strategies of Building Integrated Photovoltaic (BIPV) power plants planning is to maximize annual electricity production. This approach is motivated by different incentive programs, such as Feed-In Tariff (FIT), which guarantee the price of produced electrical energy, but generally do not take into account the dynamics of electrical energy prices at the market. In perspective, all sources of electrical energy will be equally treated at the electricity market. Under such conditions, profit maximization is not necessarily coincident with production maximization, because the price of produced kWh will depend on the current market price. The profit maximization for the BIPV plant owners will be defined by optimizing the total production of BIPV plants and the correlation degree between the production diagrams and diagrams of electrical energy prices at the market. Under current conditions, price of electrical energy at the market is usually defined by consumption, so that the maximum price is realized mainly in the afternoon hours, which corresponds to the production profile of BIPV plants. With the BIPV plants participation increasing, the electrical energy supply during the traditional load peak hours becomes larger, which leads to decrease of the peak energy price on clear days. Diagrams of electrical energy production of BIPV plants is defined by the path of Sun and azimuth and tilt angle of the panel. The panels which are mounted on the south oriented roofs have the maximum production at solar noon, while south-east oriented panels have maximum production in the morning. The south-west oriented panels have maximum production in the afternoon during clear days. In this paper, the effects of BIPV panels orientation, in the terms of the profit which a BIPV plant owner acquires at the open market of electrical energy, have been analyzed. The analyses have been performed by using real measurement data and prices of electrical energy at The German Electricity Market (EEX and EPEX).
Influence of Bed Depth on Performance of Wire Screen Packed Bed Solar Air Heater
This paper deals with theoretical analysis of performance of solar air collector having its duct packed with blackened wire screen matrices. The heat transfer equations for two-dimensional fully developed fluid flows under quasi-steady-state conditions have been developed in order to analyze the effect of bed depth on performance. A computer programme is developed in C++ language to estimate the temperature rise of entering air for evaluation of performance by solving the governing equations numerically using relevant correlations for heat transfer coefficient for packed bed systems. Results of air temperature rise and thermal efficiency obtained from the analysis have been compared with available experimental results and results have been found fairly in closed agreement. It has been found that there is considerable enhancement in performance with packed bed collector upto a certain total bed depth. Effect of total bed depth on efficiency show that there is an upper limiting value of total bed depth beyond which the thermal efficiency begins to fall again and this type of characteristics behavior is observed at all mass flow rate.
Combined Influence of Charge Carrier Density and Temperature on Open-Circuit Voltage in Bulk Heterojunction Organic Solar Cells
One of the key parameters in determining the power conversion efficiency (PCE) of organic solar cells (OSCs) is the open-circuit voltage, however, it is still not well understood. In order to examine the performance of OSCs, it is necessary to understand the losses associated with the open-circuit voltage and how best it can be improved. Here, an analytical expression for the open-circuit voltage of bulk heterojunction (BHJ) OSCs is derived from the charge carrier densities without considering the drift-diffusion current. The open-circuit voltage thus obtained is dependent on the donor-acceptor band gap, the energy difference between the highest occupied molecular orbital (HOMO) and the hole quasi-Fermi level of the donor material, temperature, the carrier density (electrons), the generation rate of free charge carriers and the bimolecular recombination coefficient. It is found that open-circuit voltage increases when the carrier density increases and when the temperature decreases. The calculated results are discussed in view of experimental results and agree with them reasonably well. Overall, this work proposes an alternative pathway for improving the open-circuit voltage in BHJ OSCs.
Analysis of the Effect of GSR on the Performance of Double Flow Corrugated Absorber Solar Air Heater
This study investigates the effect of Global Solar Radiation (GSR) on the performance of double flow corrugated absorber solar air heater. A mathematical model of a double flow solar air heater, in which air is flowing simultaneously over and under the absorbing plate is presented and solved by developing a computer program in C++ language. The performance evaluation is studied in terms of air temperature rise, energy, effective and exergy efficiencies. The performance of double flow corrugated absorber is compared with double flow flat plate and conventional solar air heaters. It is found that double flow effectively increases the air temperature rise and efficiencies in comparison to a conventional collector. However, corrugated absorber is more superior to that of flat plate double flow solar air heater. The results show that increasing the solar radiation leads to achieve higher air temperature rise and efficiencies.
Evaluation of Electro-Flocculation for Biomass Production of Marine Microalgae Phaeodactilum tricornutum
The commercial production of biodiesel using microalgae demands a high-energy input for harvesting biomass, making production economically unfeasible. Methods currently used involve mechanical, chemical and biological procedures. In this work, a new flocculation system is presented as a cost and energy effective process to increase biomass production of Phaeodactilum tricornutum. This diatom is the only species of the genus that present fast growth and lipid accumulation ability that are of great interest for biofuel production. The algae, selected from the Bank of Microalgae of the Institute of Biology - Federal University of Bahia (Brazil), has been bred in tubular reactor with photoperiod of 12h (clear/dark), providing luminance of about 35 μmol photons m-2s-1, and temperature of 22°C. The medium used for growing cells was the Conway medium, with addition of silica. The seaweed growth curve was accompanied by cell count in Neubauer camera and by optical density in spectrophotometer, at 680nm. The precipitation occurred after stabilization of growth, four days after inoculation, using two methods: centrifugation at 5000rpm for 5 min, and electro-flocculation at 19 EPD and 95W. After precipitation, cells were frozen at -20oC and, subsequently, lyophilized. Biomass obtained by electro-flocculation was approximately 4 times greater than the one achieved by centrifugation. The benefits of this method are that no addition of chemical flocculants is necessary and similar cultivation conditions can be used for the biodiesel production and pharmacological purposes. The results may contribute to improve biodiesel production costs using marine microalgae.
Changes in Institutional Design and Learning-By-Doing: An Empirical Study of Offshore Exploration Drilling Efficiency in South East Asia
Overview: Learning-by-doing has been argued in many literature as a source of productivity and economic growth. By exploring the changes in oil governance in Indonesia, this paper looks at the impact of changes in institutional design to learning-by-doing in offshore exploration drilling. In 2002, Indonesia changed the institutional design of the oil and gas sector (oil governance) by enacting Law No. 22/2001, which created a separate regulatory entity (BPMIGAS) from the national oil company (Pertamina). The main task of BPMIGAS was to regulate the upstream oil and gas sector by entering and managing production sharing contracts with oil companies, including Pertamina. Therefore, this study aims to answer the following research question: Do changes in institutional design enhance learning-by-doing by an agent/company or spillover effect across agents/companies? This study will contribute to the learning-by-doing literature by being the first to provide empirical evidence of the impact of changes in institutional design on the learning-by-doing effect in the oil and gas industry. Methods: To answer the research question, we observe offshore exploration drilling data in South East Asia Region at year of 1992-2012 and run econometric models which contain an interaction term between institutional design dummy and learning variables. Results: This study finds that changes in institutional design enhance learning-by-doing specific to the rig as well as knowledge spillover across oil companies within a basin. The regulatory entity which is created by the changes in institutional design has a greater incentive to capture knowledge created by oil companies and to create positive knowledge spillover across oil companies. The results of this analysis show that the creation of BPMIGAS in Indonesia at the year of 2002 enhanced the positive knowledge spillover effect within a basin such that a doubling increase in experience reduces days needed to drill a meter of well by 18.7%. It also enhances learning-by-doing effect by the rigs also such that a doubling increase in experience reduces days to drill a meter of well by 24.1%. One possible explanation for the increase in the learning-by-doing effect by the rigs is that through procurement approval, BPMIGAS can create competition among rigs. These results are statistically significant at 90% and 95% levels and robust to various specifications.
The Effect of Organic Matter Maturation and Porosity Evolution on Methane Storage Potential in Shale-Gas Reservoirs
Formation of organic matter (OM)-hosted nanopores upon thermal maturation are one of the key factor controlling methane storage potential in unconventional shale-gas reservoirs. In this study, the subcritical CO₂ and N₂ gas adsorption measurements combined with scanning electron microscopy and supercritical methane adsorption have been used to characterize pore system and methane storage potential in black shales from the Baltic Basin (Poland). The samples were collected from a virtually equivalent Llandovery strata across the basin and represent a complete digenetic sequence, from thermally immature to overmature. The results demonstrate that the thermal maturation is a dominant mechanism controlling the formation of OM micro- and mesopores in the Baltic Basin shales. The formation of micro- and mesopores occurs in the oil window (vitrinite reflectance; leavedVR; ~0.5-0.9%) as a result of oil expulsion from kerogenleft OM highly porous. The generated hydrocarbons then turn into solid bitumen causing pore blocking and substantial decrease in micro- and mesopore volume in late-mature shales (VR ~0.9-1.2%). Both micro- and mesopores are regenerated in a middle of the catagenesis range (VR 1.4-1.9%) due to secondary cracking of OM and gas formation. The micropore volume in investigated shales is almost exclusively controlled by the OM content. The contribution of clay minerals to micropore volume is insignificant and masked by a strong contribution from OM. Methane adsorption capacity in the Baltic Basin shales is predominantly controlled by microporous OM with pores < 1.5 nm. The mesopore volume (2-50 nm) and mesopore surface area have no effect on methane sorption behavior. The adsorbed methane density equivalent, calculated as absolute methane adsorption divided by micropore volume, reviled a decrease of the methane loading potential in micropores with increasing maturity. The highest methane loading potential in micropores is observed for OM before metagenesis (VR < 2%), where the adsorbed methane density equivalent is greater than the density of liquid methane. This implies that, in addition to physical adsorption, absorption of methane in OM may occur before metagenesis. After OM content reduction using NaOCl solution methane adoption capacity substantially decreases, suggesting significantly greater adsorption potential for OM microstructure than for the clay minerals matrix.
Electrical and Thermal Characteristics of a Photovoltaic Solar Wall with Passive and Active Ventilation through a Room
An experimental study was conducted for ascertaining electrical and thermal characteristics of a pair of photovoltaic (PV) modules integrated with a solar wall of an outdoor room. A pre-fabricated outdoor room was setup for conducting outdoor experiments on a photovoltaic solar wall with passive and active ventilation through the outdoor room. The selective operating conditions for glass coated PV modules were utilized for establishing their electrical and thermal characteristics. The photovoltaic solar wall was made up of glass coated PV modules, a ventilated air column and an insulating layer of polystyrene filled plywood board. The experimental measurements collected were currents, voltages, electric power, air velocities, temperatures, solar intensities and thermal time constant. The results have demonstrated that: i) glass coated PV module installed on a wooden frame was of more heat generating capacity in comparison to a window glass or a standalone PV module; ii) generation of electric power was affected by operation of vertically inclined PV solar wall; iii) electrical and thermal characteristics were not significantly affected by heat and thermal storage losses; and iv) combined heat and electricity generation were functions of volume of electrical and thermal resistances developed across photovoltaic solar wall. Finally, a comparison of temperature plots of passive and active ventilation envisaged that fan pressure was necessary to avoid overheating of the PV solar wall. The active ventilation was also felt necessary to avoid over-heating of the room and maintain adequate ventilation under mild climate conditions.
Investigation on Unsteady Flow of a Turbine Stage with Negative Bowed Stator
Complicated unsteady flow in axial turbines produces high-frequency unsteady aerodynamic exciting force, which threatens the safe operation of turbines. This paper illustrates how negative-bowed stator reduces the rotor unsteady aerodynamic exciting force by unsteady flow field. With the support of three-dimensional viscous compressible Navier-Stokes equation, the single axial turbines with 0, -10 and -20 degree bowed stator are comparably investigated, aiming to identify the flow field structure difference caused by various negative-bowed degrees. The results show that negative-bowed stator strengthens the turbulence kinetic energy, which is further strengthened with the increase of negative-bowed degree. Meanwhile, the flow phenomenon including stator wakes and passage vortex is shown. In addition, the interaction of upstream negative-bowed wakes contributes to the reduction of unsteady blade load fluctuation. Furthermore, the aerodynamic exciting force decreases with the increasing negative bowed degree, while the efficiency is correspondingly reduced. This paper provides the reference for the alleviation of the harmful impact caused by unsteady interaction with the method of wake control.
Analysis of a Multiejector Cooling System in a Truck at Different Loads
An alternative way of addressing the difficult to recover the useless heat is through an ejector refrigeration cycle for vehicles applications. A group of thermo-compressor supply the mechanical compressor function at conventional refrigeration compression system. The thermo-compressor group recovers the thermal energy from waste streams (exhaust gases product in internal combustion motors, gases burned in wellhead among others) to eliminate the power consumption of the mechanical compressor. These types of alternative cooling system (air-conditioners) present a kind of advantages in both the increase in energy efficiency and the improvement of the COP of the system being studied from their its mechanical simplicity (decrease of moving parts). An ejector refrigeration cycle represents a significant step forward in the optimization of the efficient use of energy in the process of air conditioning and an alternative to reduce the environmental impacts. On one side, with the energy recycling decreases the temperature of the gases thrown into the atmosphere, which contributes to the principal beneficiaries of the average temperature of the planet. In parallel, mitigating the environmental impact caused by the production and handling of conventional cooling fluids commonly available in the market, causing the destruction of the ozone layer. This work had studied the operation of the multiejector cooling system for a truck with a 420 HP engine at different rotation speed. The operation condition limits and the COP of multi-ejector cooling systems applied in a truck are analyzed for a variable rpm range from to 800–1800 rpm.
Thermo-Exergy Optimization of Gas Turbine Cycle with Two Different Regenerator Designs
A thermo-exergy optimization of a gas turbine cycle with two different regenerator designs. A comparison was made between the performance of the two regenerators and their roles in improving the cycle efficiencies. The effect of operational parametric (the pressure ratio of the compressor, the ambient temperature, excess of air, geometric parameters of the regenerators, etc.) on thermal efficiencies, the exergy efficiencies and Irreversibilities was studied using thermal balances and quantitative exegetic equilibrium for each component and for the whole system. The results are given graphically by using the EES software and an appropriate discussion and conclusion was made.
A Dynamic Fault Section Estimation in Power Systems
This paper presents a digital dynamic method for on-line fault location in transmission lines. The method uses digital set of symmetrical short circuit current measurements to locate faults in electrical power systems. The current samples are employed to construct a set of overdetermined system of equations. An estimation problem is then constructed and solved using digital dynamic filter to find the fault distance. The proposed dynamic filter is based on least absolute minimization criteria. The method is tested using practical case study to evaluate the proposed method. Results obtained show that the algorithm can locate the fault point at a very high degree of accuracy.
Existence of Nano Organic Carbon Particles below the Size Range of 10 Nm in the Indoor Air Environment
Indoor air environment is a big concern in monitoring the air quality for the last few decades in the developing countries. In this work an experimental study has been conducted to establish the existence of carbon nanoparticle below the size range of 10 nm in the non-sooting zone of a LPG/air partially premixed flame. Mainly, four optical techniques, UV absorption spectroscopy, fluorescence spectroscopy, dynamic light scattering and TEM have been used to characterize and measure the size of carbon nanoparticles in the sampled materials collected from the inner surface of the flame front. The existence of the carbon nanoparticles in the sampled material has been confirmed with the typical nature of the absorption and fluorescence spectra already reported in the literature. The band gap energy shows the particles are made up of three to six aromatic rings. The size measurement by DLS technique shows the particles below the size range of 10 nm. The results of DLS are also corroborated by the TEM image of the same material.
Composite Distributed Generation and Transmission Expansion Planning Considering Security
During the recent past, due to the increase of electrical energy demand and governmental resources constraints in creating additional capacity in the generation, transmission, and distribution, privatization and restructuring in electrical industry have been considered. So that in most of the countries, different parts of electrical industry like generation, transmission, and distribution have been separated in order to create competition. Considering these changes, environmental issues, energy growth, investment of private equity in energy generation units and difficulties of transmission lines expansion, DG units have been used in power systems. Moreover, reduction in the need for transmission and distribution, the increase of reliability, improvement of power quality and reduction of power loss have caused DG to be placed in power systems. On the other hand, considering low liquidity need, private investors tend to spend their money for DGs. In this project, the main goal is to offer an algorithm for planning and placing DGs in order to reduce the need for transmission and distribution network.
Choosing the Green Energy Option: A Willingness to Pay Study of Metro Manila Residents for Solar Renewable Energy
The energy market in the Philippines remains to have one of the highest electricity rates in the region averaging at US$0.16/kWh (PHP6.89/kWh), excluding VAT, as opposed to the overall energy market average of US$0.13/kWh. The movement towards renewable energy, specifically solar energy, will pose as an expensive one with the country’s energy sector providing Feed-in-Tariff rates as high as US$0.17/kWh (PHP8.69/kWh) for solar energy power plants. Increasing the share of renewables at the current state of the energy regulatory background would yield a three-fold increase in residential electricity bills. The issue lies in the uniform charge that consumers bear regardless of where the electricity is sourced resulting in rates that only consider costs and not the consumers. But if they are given the option to choose where their electricity comes from, a number of consumers may potentially choose economically costlier sources of electricity due to higher levels of utility coupled with the willingness to pay of consuming environmentally-friendly sourced electricity. A contingent valuation survey was conducted to determine their willingness-to-pay for solar energy on a sample that was representative of Metro Manila to elicit their willingness-to-pay and a Single Bounded Dichotomous Choice and Double Bounded Dichotomous Choice analysis was used to estimate the amount they were willing to pay. The results showed that Metro Manila residents are willing to pay a premium on top of their current electricity bill amounting to US$5.71 (PHP268.42) – US$9.26 (PHP435.37) per month which is approximately 0.97% - 1.29% of their monthly household income. It was also discovered that besides higher income of households, a higher level of self-perceived knowledge on environmental awareness significantly affected the likelihood of a consumer to pay the premium. Shifting towards renewable energy is an expensive move not only for the government because of high capital investment but also to consumers; however, the Green Energy Option (a policy mechanism which gives consumers the option to decide where their electricity comes from) can potentially balance the shift of the economic burden by transitioning from a uniformly charged electricity rate to equitably charging consumers based on their willingness to pay for renewably sourced energy.
Influence of Channel Depth on the Performance of Wavy Fin Absorber Solar Air Heater
Channel depth is an important design parameter to be fixed in designing a solar air heater. In this paper, the influence of the channel depth on the performance of wavy fin absorber solar air heater has been investigated using a mathematical model. The channel depth has been varied from 15 cm to 35 cm for the mass flow range 0.01 to 0.11 kg/s. Based on the first law of thermodynamics, the channel depth of 15 cm shows better thermal performance for all the mass flow range. Also, better thermohydraulic performance has been found up to 0.05 kg/s, beyond this thermohydraulic efficiency starts decreasing. It has been seen that, with the increase in the mass flow rate, the difference between thermal and thermohydraulic efficiency increases because of the increase in pressure drop. At lower mass flow rate, 0.01 kg/s, the thermal and thermohydraulic efficiencies for respective channel depth remain same.
[Keynote Talk]: Implementation of 5 Level and 7 Level Multilevel Inverter in Local Trains of Mumbai
Local trains are the lifelines of Mumbai city. Earlier 1500 Volt D.C. supply, is now completely and successfully converted into 25 KV A.C. in central, western and harbour routes. This task is the outcome of the advancement in the area of power electronics. Author has already done the comparative study between D.C. and A.C. supply of traction and predicted the serious problem regarding the harmonics. In this paper, the simulation for 5 level as well as 7 level multilevel inverter has been done which is the substitute for the present cascade type inverter. This paper also showed the reduced level of Total Harmonic Distortion (THD) in the traction system.
Viability Analysis of a Centralized Hydrogen Generation Plant for Use in Oil Refining Industry
The global energy system is experiencing a change of scenery. Unstable energy markets, an increasing focus on climate change and its sustainable development is forcing businesses to pursue new solutions in order to ensure future economic growth. This has led to the interest in using hydrogen as an energy carrier in transportation and industrial applications. As an energy carrier, hydrogen is accessible and holds a high gravimetric energy density. Abundant in hydrocarbons, hydrogen can play an important role in the shift towards low-emission fossil value chains. By combining hydrogen production by natural gas reforming with carbon capture and storage, the overall CO2 emissions are significantly reduced. In addition, the flexibility of hydrogen as an energy storage makes it applicable as a stabilizer in the renewable energy mix. The recent development in hydrogen fuel cells is also raising the expectations for a hydrogen powered transportation sector. Hydrogen value chains exist to a large extent in the industry today. The global hydrogen consumption was approximately 50 million tonnes (7.2 EJ) in 2013, where refineries, ammonia, methanol production and metal processing were main consumers. Natural gas reforming produced 48% of this hydrogen, but without carbon capture and storage (CCS). The total emissions from the production reached 500 million tonnes of CO2, hence alternative production methods with lower emissions will be necessary in future value chains. Hydrogen from electrolysis is used for a wide range of industrial chemical reactions for many years. Possibly, the earliest use was for the production of ammonia-based fertilisers by Norsk Hydro, with a test reactor set up in Notodden, Norway, in 1927. This application also claims one of the world’s largest electrolyser installations, at Sable Chemicals in Zimbabwe. Its array of 28 electrolysers consumes 80 MW per hour, producing around 21,000 Nm3/h of hydrogen. These electrolysers can compete if cheap sources of electricity are available and natural gas for steam reforming is relatively expensive. Because electrolysis of water produces oxygen as a by-product, a system of Autothermal Reforming (ATR) utilizing this oxygen has been analyzed. Replacing the air separation unit with electrolysers produces the required amount of oxygen to the ATR as well as additional hydrogen. The aim of this paper is to evaluate the technical and economic potential of large-scale production of hydrogen for oil refining industry. Sensitivity analysis of parameters such as investment costs, plant operating hours, electricity price and sale price of hydrogen and oxygen are performed.
Electrical Performance Analysis of Single Junction Amorphous Silicon Solar (a-Si:H) Modules Using IV Tracer
The electrical analysis of single junction amorphous silicon solar modules is carried out using outdoor monitoring technique. Like crystalline silicon PV modules, the electrical characterisation and performance of single junction amorphous silicon modules are best described by its current-voltage (IV) characteristic. However, IV curve has a direct dependence on the type of PV technology and material properties used. The analysis reveals discrepancies in the modules performance parameter even though they are of similar technology. The aim of this work is to compare the electrical performance output of each module, using electrical parameters with the aid of PVPM 100040C IV tracer. These results demonstrated the relevance of standardising the performance parameter for effective degradation analysis of a-Si:H.
Economic Development and New Challenges: Biomass Energy and Sustainability
This research was conducted to show the useful source of biomass energy provided from forest waste and the black liquor from the pulping process. This energy source could be able to assist and improve its area environment in a sustainable way. The research will demonstrate the challenges from producing the biomass energy and the implantation of the pulp industry in the city of Três Lagoas, MS. – Brazil. Planted forest’s potential, energy production in the pulp industries and its consequence of impacts on the local region environmental was also studied and examined. The present study is classified as descriptive purposes as it exposes the characteristics of a given population and the means such as bibliographical and documentary. All the data and information collected and demonstrate in this study was carefully analyzed and provided from reliable sources such as official government agencies.
Non-Convex Multi-Objective Economic Dispatch Using Ramp Rate Biogeography Based Optimization
Multi-objective non-convex economic dispatch problems of a thermal power plant are of grave concern for deciding the cost of generation and reduction of emission level for diminishing the global warming level for improving green-house effect. This paper deals with ramp rate constraints for achieving better inequality constraints so as to incorporate valve-point loading for cost of generation in thermal power plant vide ramp rate biogeography-based optimization involving mutation and migration. Through 50 out of 100 trials the cost function and emission objective function were found to have outperformed other classical methods such as lambda iteration method, quadratic programming method and many heuristic methods like particle swarm optimization method, weight improved particle swarm optimization method, constriction factor based particle swarm optimization method and moderate random particle swarm optimization method etc. Ramp rate biogeography-based optimization applications prove quite advantageous in solving non-convex multi-objective economic dispatch problems subjected to nonlinear loads that pollute the source giving rise to third harmonic distortions and other such disturbances.
Modelling of Air-Cooled Adiabatic Membrane-Based Absorber for Absorption Chillers Using Low Temperature Solar Heat
Absorption cooling chillers have received growing attention over the past few decades as they allow the use of low-grade heat to produce the cooling effect. The combination of this technology with solar thermal energy in the summer period can reduce the electricity consumption peak due to air-conditioning. One of the main components, the absorber, is designed for simultaneous heat and mass transfer. Usually, shell and tubes heat exchangers are used, which are large and heavy. Cooling water from a cooling tower is conventionally used to extract the heat released during the absorption and condensation processes. These are clear inconvenient for the generalization of the absorption technology use, limiting its benefits in the contribution to the reduction in CO2 emissions, particularly for the H2O-LiBr solution which can work with low heat temperature sources as provided by solar panels. In the present work a promising new technology is under study, consisting in the use of membrane contactors in adiabatic microchannel mass exchangers. The configuration here proposed consists in one or several modules (depending on the cooling capacity of the chiller) that contain two vapour channels, separated from the solution by adjacent microporous membranes. The solution is confined in rectangular microchannels. A plastic or synthetic wall separates the solution channels between them. The solution entering the absorber is previously subcooled using ambient air. In this way, the need for a cooling tower is avoided. A model of the configuration proposed is developed based on mass and energy balances and some correlations were selected to predict the heat and mass transfer coefficients. The concentration and temperatures along the channels cannot be explicitly determined from the set of equations obtained. For this reason, the equations were implemented in a computer code using Engineering Equation Solver software, EES™. With the aim of minimizing the absorber volume to reduce the size of absorption cooling chillers, the ratio between the cooling power of the chiller and the absorber volume (R) is calculated. Its variation is shown along the solution channels, allowing its optimization for selected operating conditions. For the case considered the solution channel length is recommended to be lower than 3 cm. Maximum values of R obtained in this work are higher than the ones found in optimized horizontal falling film absorbers using the same solution. Results obtained also show the variation of R and the chiller efficiency (COP) for different ambient temperatures and desorption temperatures typically obtained using flat plate solar collectors. The configuration proposed of adiabatic membrane-based absorber using ambient air to subcool the solution is a good technology to reduce the size of the absorption chillers, allowing the use of low temperature solar heat and avoiding the need for cooling towers.
Performance Analysis of MATLAB Solvers in the Case of a Quadratic Programming Generation Scheduling Optimization Problem
Recently, a distributed method for power generation optimization has been published, which uses the decomposition and piecewise linear approximation of generation characteristics. In the case of the proposed method the problem is parallelized by considering multiple possible ‘mode of operation’ profiles, which determine the range in which the generators operate in each period. For each of these profiles, the optimization is carried out independently, and the best resulting dispatch is chosen. For each such profile, the resulting problem is a quadratic programming (QP) problem with a potentially negative definite Q-quadratic term, and constraints depending on the actual operation profile. In this paper, we analyze the performance of available MATLAB optimization methods and solvers for the corresponding QP.
A Deterministic Demand Response Model for Residential End-Users with Home Energy Management System
Demand Response (DR) measures represent one of the demand side management (DSM) strategies used in order to contribute to the improving the sustainability of the electricity grid. DR actions typically refer to altering load consumption patterns in response to signals given by the utility during periods of supply and demand imbalances in the grid. This project aims to provide DR strategies targeted for adoption by the presently passive residential household loads in Singapore. This is also to prepare for the upcoming liberalization of the open electricity market in Singapore. Apart from that, this project also aims to study the viability of these developed strategies by using several indices to determine this. The indices used are consumption indices, monetary indices as well as dissatisfaction indices. Lastly, this project also aims to develop a program on Java NetBeans, that runs a simulation based on the available load consumption profiles. The simulation would show the strategies developed affecting the load consumption curves as well as provide a platform for end- users to predict their day-ahead consumption model by playing with the numbers given.