bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Assembly of an Extended Range Electric Vehicle as a University Capstone Project
Authors: Sabatini Vincent J. , Maxson Ryle , Haupfear William , Carter Sean , White Darris , McKisson J. E.
Published: January 2011

The Embry-Riddle HyREV system is an innovative combination of power-split Hybrid and Extended-Range Electric Vehicle technologies, designed to reduce petroleum energy consumption and improve vehicle efficiency across a range of operating conditions on a captured GM fleet vehicle. The HyREV system was developed for the EcoCAR Challenge, and features a high degree of vehicle electrification including all electric accessories, plug-in charging and electric all-wheel-drive through the integration of three electric motors. The proper packaging and integration of components used in the EcoCAR vehicle development process required a comprehensive understanding of element interaction from both a static (space claim) and dynamic (feasibility) standpoint. The research conducted in this competition is used as a capstone project for a wide array of majors, as well as being integrated extensively in several courses in the form of projects and lectures. The overall vehicle design requires expertise in mechanical, electrical, aerospace, computer, software, and controls engineering, as well as incorporating human factors students into the failure modes and effects analysis. The team is split into the different majors for organizational hierarchy; however, there are many tasks that require multidisciplinary ideas and experiences to properly design. The first year of EcoCAR incorporated an entirely virtual design, with the teams receiving hardware in year two. The team is currently in year two, and is assembling the physical components of the vehicle, along with the controls architecture that will drive the vehicle’s power systems. This 65% “mule” vehicle will be tested May 2010 at GM’s Desert Proving Grounds, located in Yuma, Arizona.
Defining a Standard Measure for Whole System EROI Combining Economic “Top-Down” and LCA “Bottom-Up” Accounting
Authors: King Carey W. , Zarnikau Jay , Henshaw Phil
Published: January 2011

Business investments rely on creating a whole system of different parts, technologies, field and business operations, management, land, financing and commerce using a network of other services. Using the example of a wind farm development, a typical life cycle assessment (LCA) focuses upon the primary technology inputs and their countable embodied direct impacts. What LCA omits are the direct and indirect impacts of the rest of the business system that operates the primary technology, the labor, commerce and other technology employed. A total environmental assessment (TEA) would include the physical costs to the environment of the labor, commerce and other technology too. Here a simplified “system energy assessment” (SEA) is used to combine a “top-down” method of measuring implied indirect business impacts using econometric methods, with a “bottom-up” method of adding up the identifiable direct impact parts. The top-down technique gives an inclusive but rough measure. The bottom-up technique gives a precise accounting for the directly identifiable individual parts that is highly incomplete. SEA allows these two kinds of measures to be combined for a significantly improved understanding of the whole business system and its impacts, combining the high and low precision measures indentified by each method. The key is exhaustively accounting for energy uses within the natural boundary of a whole business system as a way of calibrating the measure. That allows defining a standardized measure of complex distributed system energy flows and their energy returns on invested energy resources (EROI). The method is demonstrated for a generic business operation. Starting from the easily accountable inputs and outputs, SEA successively uses larger natural system boundaries to discover a way of finding the limiting value of EROI after all parts of the whole are included. Some business choices and a net present value model of cash flow for the 20 year project help illustrate the related financial issues. The business model used shows that the EROI of a generic “Texas Wind Farm” is 31 when accounting for direct and indirect fuels only, but decreases to 4–6 after accounting for the economic energy consumed by all necessary business units and services.
Development of Alternative Energy Laboratories in Support of a New Green Concentration in Mechanical Engineering
Authors: Dini Said , Mindek Richard B.
Published: January 2011

Alternative energy laboratory experiences have been developed to help support a new Green Concentration recently offered for the first time in the mechanical engineering program at Western New England College. These laboratories, which give students hands-on experience and a better understanding of basic concepts in wind energy, solar energy, and fuel cell technology, utilize an improved Alternative Energy Active Learning Platform, as well as newly developed indoor/outdoor Alternative Energy Laboratory facilities. The alternative energy indoor/outdoor laboratory facility includes six 195 Watt photovoltaic panels, a 30,000 Btu/clear day flat-plate solar collectors, a Thermomax evacuated tubes solar collector, as well as a full scale 1 kW wind turbine, whose scale allows for useful power and heat to be provided to the engineering building. This facility will be fully instrumented for the collection of key performance data and allows for large scale demonstration of alternative energy systems to students. Additionally, the improved Alternative Energy Active Learning Platform, which uses wind and solar energy to power an electrolyzer, which disassociates water into hydrogen and oxygen, and then subsequently uses the hydrogen and oxygen produced within a fuel cell to power a fan, has been automated to allow better visualization of each system in operation and more efficient data collection. This paper describes the development, operation and capabilities of both the new indoor/outdoor Alternative Energy Laboratory facilities, and the improved Alternative Energy Active Learning Platform, and their utilization within the Green Concentration of the undergraduate mechanical engineering program.
Identifying Inefficient Single-Family Homes With Utility Bill Analysis
Authors: Casey Sean , Krarti Moncef , Bianchi Marcus , Roberts David
Published: January 2011

Differentiating between energy-efficient and inefficient single-family homes on a community scale helps identify and prioritize candidates for energy-efficiency upgrades. Prescreening diagnostic procedures can further retrofit efforts by providing efficiency information before a site-visit is conducted. We applied the prescreening diagnostic is applied to a simulated community of homes in Boulder, Colorado and analyzed energy consumption data to identify energy-inefficient homes. A home is defined as efficient if it is compliant with the prescriptive measures of the 2009 International Energy Conservation Code (IECC-2009) for Boulder, Colorado. Previous research indicates a correlation between building operational efficiency and the Heating Slope (HS) regression parameter resulting from the variable-base degree day method. We compared the HS values across a community of houses and those of an IECC-2009-compliant home to identify energy-inefficient homes on a community-scale. To simulate community-wide HS identification, we used DOE-2 energy simulation software for defined home archetypes and corresponding occupant behavior to artificially generate 567 sets of monthly natural gas consumption data Home archetypes were either compliant or incompliant at three conditioned areas; occupant effects were also simulated. Each simulation produced twelve months of natural gas use data. We used monthly energy consumption datasets to estimate the HS values with regression analysis and sorted the homes based on HS values.
Modeling of Wind Power Production Forecast Errors for Wind Integration Studies
Authors: Kemper Jason J. , Bielecki Mark F. , Acker Thomas L.
Published: January 2011

In wind integration studies, accurate representations of the wind power output from potential wind power plants and corresponding representations of wind power forecasts are needed, and typically used in a production cost simulation. Two methods for generating “synthetic” wind power forecasts that capture the statistical trends and characteristics found in commercial forecasting techniques are presented. These two methods are based on auto-regressive moving average (ARMA) models and the Markov random walk method. Statistical criteria are suggested for evaluation of wind power forecast performance, and both synthetic forecast methods proposed are evaluated quantitatively and qualitatively. The forecast performance is then compared with a commercial forecast used for an operational wind power plant in the Northwestern United States evaluated using the same statistical performance measures. These quantitative evaluation parameters are monitored during specific months of the year, during rapid ramping events, and at all times. The best ARMA based models failed to replicate the auto-regressive decay of forecast errors associated with commercial forecasts. A modification to the Markov method, consisting of adding a dimension to the state transition array, allowed the forecast time series to depend on multiple inputs. This improvement lowered the artificial variability in the original time series. The overall performance of this method was better than for the ARMA based models, and provides a suitable technique for use in creating a synthetic wind forecast for a wind integration study.
Seed-Induced Crystallization of Amorphous Silicon for the Formation of Large-Grain Poly-Crystalline Silicon
Authors: Trask Jason , Cui Lin , Wagner Andrew J. , Mkhoyan K. Andre , Kortshagen Uwe
Published: January 2011

A new method for reducing crystallization time of hydrogenated amorphous silicon thin films and more successfully controlling grain structure has been studied through seeding of the bulk matrix with nanocrystallites during film deposition. Films were deposited by a system in which crystallites and amorphous film were synthesized in separate RF-powered plasmas. Average crystallite size was confirmed to be 20 to 50 nm via TEM imaging. Several films with various initial crystallite population densities were produced, and their crystallization kinetics were studied via Raman spectroscopy throughout a staged annealing process. Seeded films consistently displayed a characteristic crystallization time less than the incubation time of unseeded control films. Furthermore, films with larger initial seed densities exhibited earlier crystallization onset. A separate study also was performed in which the dark conductivity was compared between films re-crystallized from various initial seed densities.
Silicon and Germanium Nanocrystal Inks for Low-Cost Solar Cells
Authors: Pi Xiaodong , Holman Zachary , Kortshagen Uwe
Published: January 2011

Silicon is the most widely used material in the microelectronics and photovoltaics industry. Currently it is used in one of two forms: as wafers of single- or polycrystalline material or as CVD deposited thin film material. While crystalline silicon solar cells achieve high efficiencies, the silicon wafer contributes significantly to the module cost. Thin film silicon solar cells can be produced at much lower cost, but they also feature lower efficiencies. In this presentation, we discuss an alternate route to forming silicon (Si) or germanium (Ge) thin films from solution on flexible substrates. Silicon (germanium) nanocrystals are formed in a nonthermal plasma. In the plasma environment a Si/Ge precursor is broken down by electron impact, leading to the nucleation and growth of Si or Ge crystals. By adding dopant precursors, p- and n-doped as well as intrinsic crystals can be formed. Organic ligands can be attached in the plasma such that nanocrystals become soluble in organic solvents. These “nanocrystal inks” can be used to form Si or Ge films with ultra-low-cost printing or coating techniques. Film properties of Si/Ge-ink processed films will be discussed. Proof-of-concept demonstrations of solar cells produced from silicon inks will be presented.
Cumulative Frequency Distributions for Hourly Clearness Indices Through Generalized Parameters
Authors: Satyamurty V. V. , RaviKumar P.
Published: January 2011

The objective of the present investigation is to develop generalized cumulative frequency distributions for hourly clearness indices applicable for different climates. The distributions have been developed in terms of suitable normalized variables relevant on hourly time scale, and include the swing (the difference between the maximum and minimum values of the hourly clearness index for a particular hour over the days in a month) in the hourly clearness index. The adequacy of the distributions developed in predicting the hourly clearness index has been established by comparing with the data values of the 183 secondary locations in addition to the 56 primary locations in USA for which the data are available.
O2 Releasing Reactivity of Ceria-Based Reactive Ceramics on Irradiation of Concentrated Solar Beam for Solar Hydrogen Production
Authors: Tada Masaru , Ishihara Toshihiko , Kaneko Hiroshi , Tamaura Yutaka
Published: January 2011

In the present paper, different types of metal doped ceria CeO2-MOx (M = Sc, Y, Dy, Zr and Hf) with fluorite structures have been prepared with a complex polymerization method. The O2-releasing potential of prepared samples was evaluated at 1773 K for two-step water splitting process. The partially oxygen defected CeO2-MO1.5 mixed oxides (M = Sc3+, Y3+ and Dy3+) exhibited an enhancement of the O2 evolution due to the crystal-chemical effect that cation with smaller ionic radius (Sc3+, Y3+ and Dy3+) mitigate the volume expansion of crystal lattice resulted in the reduction of Ce4+ with smaller ionic radius into Ce3+ with larger ionic radius. The CeO2-MO2 (M = Zr4+ and Hf4+) produced larger amount of O2 than that for CeO2-MO1.5 mixed oxides, since CeO2-MO2 has no oxygen vacancy. While the ionic radii of Zr4+ and Hf4+ are almost equal, the higher O2-releasing reactivity of Ce0.9Hf0.1O2 than that of Ce0.9Zr0.1O2 is explained in terms of ionicity of M-O bond. Thus, it was found that both ionic radius and ionicity play important role in the O2-releasing reaction.
Energy Saving Opportunities Using Building Energy Simulation for a Typical Mosque in Kuwait
Authors: Al Anzi Adnan , Al-Shammeri Basma
Published: January 2011

The weather conditions in Kuwait impose a difficult HVAC building operation due to the hot and arid climate. Most of the time, high ambient temperatures in Kuwait exceed 48° C, which result in difficult indoor comfort condition. Mosques are religious buildings with intermittent occupancy, due to their special cultural and religious requirements. In fact, prayers schedule is scattered throughout five daily times, with a maximum use around noon times on Fridays only. In addition, the number of mosques is increasing, due to population growth, and imposes high electrical load requirements on the public authorities in Kuwait. This paper demonstrates and analyzes thermal behavior of a typical mosque in the state of Kuwait. An energy audit is performed using state of the art building energy simulation software (Visual DOE 4.1). The simulation tool is intended to analyze the thermal behavior of the audited mosques and is used to asses potential energy conservation opportunities for future mosque design in Kuwait. Data collection including drawings, site visits and total daily kWh monitoring are performed to carry out the simulation analysis. It is found that an annual energy use savings up to 72% can be achieved through improvements of buildings envelope designs and operating strategies. In addition, life cycle cost LCC analysis is performed to make economical assessment of the energy conservation measures that are evaluated in this study. It was found that a LCC saving around 40% can be achieved with a simple payback period of less than 4 years.
Colorado Community Benefits From Installing Waste Heat Recovery System
Authors: Strehler Jennifer , Vandenburgh Scott , Parry Dave , Rynders Tim
Published: January 2011

The Town of Avon Colorado and the Eagle River Water and Sanitation District have partnered to design, construct, and operate a mechanical “Community Heat Recovery System” which extracts low-grade waste heat from treated wastewater and delivers this heat for beneficial use. Immediate uses include heating of the community swimming pool, melting snow and ice on high pedestrian areas in an urban redevelopment zone in order to improve pedestrian safety, and space heating for project buildings and an adjacent water plant pump station building. Points of use are located within one mile of the treatment plant. The initial system is sized to extract heat from 170 m3/hr (1.08 mgd) of wastewater plant effluent with a 298 kW (400 hp) heat pump. The heat pump will deliver 1,026 kW (3,500,000 BTU/hr) energy to the heat recovery system. A supplemental natural gas boiler provided to meet peak demands will provide an additional 1,026 kW (3,500,000 BTU/hr) energy. The system is expandable allowing the installation of a second heat pump in the future and roof-mounted solar thermal panels. Power for the waste heat recovery system is provided by wind-generated electricity purchased from the local electric utility. The use of wind power with an electric-powered heat pump enables the agencies to fulfill energy needs while also reducing the carbon footprint. The system will achieve a reduction in the temperature of the treated wastewater, which is currently discharged to the Eagle River during low river flow, fish-sensitive periods. The agencies expect to save tax payers and rate payers money as a result of this project as compared to other alternatives or the status quo because it results in a more sustainable long-term operation. At 2008 utility commodities pricing, delivery of heat generated from this system was estimated to cost about one-third less than that from a conventional natural gas boiler system. This facility is the first of its kind in the U.S. and received a “New Energy Community” grant from the State of Colorado. This project shows how local agencies can work cooperatively for mutual benefit to provide infrastructure which accommodates growth and urban renewal and simultaneously demonstrate strong environmental leadership. The potential application of this technology is broad and global. The installed system is expected to cost about $5,000,000; construction will be completed in 2010.
A Practical Integration Approach and Whole Building Energy Simulation of Three Energy Efficient Building Technologies
Authors: Miller James P. , Deru Michael , Benne Kyle , Zhivov Alexander , Herron Dale
Published: January 2011

Rising energy costs and the desire to reduce energy consumption dictates a need for significantly improved building energy performance. Three technologies that have potential to save energy and improve sustainability of buildings are dedicated outdoor air systems (DOAS), radiant heating and cooling systems and tighter building envelopes. Although individually applying innovative technologies may incrementally improve building energy performance, more significant payoffs are realized when compatible technologies are integrated into an optimized system. Fortunately, DOAS, radiant heating and cooling systems and improved building envelopes are highly compatible. To investigate the energy savings potential of these three technologies, whole building energy simulations were performed for a barracks facility and an administration facility in 15 U.S. climate zones and 16 international locations. The baseline facilities were assumed to be existing buildings with VAV HVAC systems (admin facilities) and packaged HVAC systems (barracks facilities). The energy simulations were adjusted for each location for optimal energy and humidity control performance. The results show that the upgraded facilities realized total building energy savings between 20% and 40% and improved humidity control when compared to baseline building performance.
Numerical Investigation of Separation Control for Wind Turbine Airfoil
Authors: Gross Andreas , Kondaraju Sasidhar , Fasel Hermann F.
Published: January 2011

We simulated the flow over the NREL S822 wind turbine airfoil for a chord Reynolds number of 100,000 and an angle of attack of 5deg. These conditions approximately match the blade element conditions at 80% radius of a 2m turbine that is operating at 300rpm. A simulation of the uncontrolled flow with steady approach flow conditions shows flow separation on the suction side which is consistent with University of Illinois at Urbana-Champaign experimental data. We also investigated the effect of a time-dependent approach flow similar to the conditions encountered during yawed turbine operation. Because the blade rotation frequency is much lower than the frequencies associated with the blade aerodynamics we increased the frequency of the approach flow fluctuations. Nevertheless, the time-dependent inflow was found to have little effect on the separated flow. Finally, we investigated separation control using a plasma actuator located near the maximum thickness on the suction side of the airfoil. Pulsed actuation was found to be very efficient and effective as the disturbance input is amplified by the flow.
Towards a Net Zero Building Cluster Energy Systems Analysis for a Brigade Combat Team Complex
Authors: Zhivov Alexander , Liesen Richard J. , Richter Stephan , Jank Reinhard , Holcomb Franklin H.
Published: January 2011

The Army is required by law (Energy Policy Act of 2005 [EPACT] 2005, U.S. Energy Independence and Security Act of 2007 [EISA] 2007) to eliminate fossil fuel use in new and renovated facilities by 2030 and to reduce overall facility energy usage by 30% by 2015. Army policy is to achieve 25 net zero energy installations by 2025 and to achieve net zero energy (NZE) status for all installations by 2058. Achieving NZE will only be possible if an optimum mix of demand reduction and renewable sources are put in place at a community (installation) or building cluster scale. The Army runs what are essentially small campuses, or clusters of buildings on its installations. The Department of Energy (DOE) is focused on the national grid scale or on individual buildings, while the commercial focus is on retrofits to individual buildings There is a lack of tools and case studies that address dynamics of energy systems at the community scale. The Army’s future building energy requirements are a mixture of ultra-low and high energy intensity facilities. Achieving net zero energy economically in these clusters of buildings will require a seamless blend of energy conservation in individual buildings, combined with building systems automation, utility management and control, and power delivery systems with the capability to integrate onsite power generation (including from renewable energy sources) and energy storage. When buildings are handled individually each building is optimized for energy efficiency to the economic energy efficiency optimum and then renewables are added until the building is net zero. This process works for buildings with a low energy intensity process for its mission, such as barracks and administrative buildings. When the mission of the building requires high energy intensity such as in a dining facility, data center, etc., this optimization process either will not end up with a net zero energy building, or large amounts of renewables will be added resulting in the overall technical solution that is not cost effective. But when buildings are clustered together, after each building is designed to its economic energy efficient option, the building cluster is also energy optimized taking advantages of the diversification between energy intensities, scheduling, and waste energy streams utilization. The optimized cluster will minimize the amount of renewables needed to make the building cluster net zero. This paper describes this process and demonstrates it using as an example a cluster of buildings a Brigade Combat Team Complex at Fort Bliss, TX.
Experimental Study for the Energy Efficiency of Hot-Wall Kang
Authors: Wang Zongshan , Duanmu Lin , Zhu Junliang , Zhao Yang
Published: January 2011

Chinese Kang with two thousand years’ history is a typical heating method using biomass in cold rural areas. It contributes to reducing the demands of coal and to optimizing the energy consumption structure, but its development is limited for low energy efficiency, poor indoor environment and etc. Therefore, we had a study based on experiment on a new reformed hot-wall Kang. The experimental results show that: the hot-wall Kang improved indoor thermal environment to a great extent. The radiation was the main way of heat elimination through the Kang’s surface, and took up about 65% of the total heat supply. The total heat carried by gas was gained by Kang body and chimney, 64.6% and 9.1% respectivley, and the remaining 26.3% was lost by discharged gas. Under the operation simulating residents’ living habit, the heating efficiency of Kang was up to 80.5% in the period of one testing day. The heat loss transferred to the ground through Kang cave and Hot-wall combustion space was 3.17% and 8.27% respectely. It also showed that the dust-ash layer filled in the cave weakened the ground heat loss and had same effect as that of insulation. Other discoveries: the mass flow rate of flue gas during the burning periods varied in the range of 0.04∼0.08 kg/s. It was turbulent flow at a low velocity, companied with two gas temperature layers. Based on the experiment, the thermal and operation character of hot-wall Kang were made clear. Furthermore, a guide for further optimization of the structure was put forward. And the results also supplied some proofs for the study of gas flow and heat transfer with natural ventilation.
Effect of Nonlinear Kinematic Hardening Constants on Cyclic Spherical Indentation Test
Authors: Nayebi A.
Published: January 2011

In the last decade, instrumented indentation test has been widely used to determine the mechanical properties of different materials and especially for metals. The mechanical properties such as Young modulus, yield stress, hardening exponent, and stress-strain curve were determined with the help of the load–displacement curve of the continuous indentation test. The method consists of pushing an indenter in a material sample and the applied load and the indenter displacement are measured. In this research the load on the indenter was considered as cyclic and varied from zero to Fmax. Because of the Bauschinger effect, the hysteresis loops were formed. With the help of these hysteresis loops, nonlinear kinematic hardening parameters of the Armstrong–Freiderick (A-F) model can be determined. Spherical indenter was used and the sample was considered isotropic. The material behavior was modeled by the A-F rule. The test was modeled by the finite element method. An axi-symmetric mesh was used. The A–F model constants, C and γ, were varied to obtain their effects on the hysteresis loops. Maximum applied load was considered constant for different finite element modeling and the maximum and residual displacements were calculated from the simulations results. The normalized maximum and the residual displacements were increased as a function of the cycles. It was shown that these parameters value and their rate are dependent on the material model constants. These dependences were shown for different examples which can help to characterize the A-F model constants by the cyclic spherical indentation tests.
Fundamental Frequency Optimization of Angle-Ply Laminated Plates Using Elitist-Genetic Algorithm and Finite Strip Method
Authors: Sadr Mohammad Homayoun , Ghashochi Bargh Hadi
Published: January 2011

In the present paper, fundamental frequency optimization of symmetrically angle-ply laminated composite plates is studied using the combination of Elitist-Genetic algorithm (EGA) and finite strip method (FSM). The design variables are the number of layers, the fiber orientation angles, edge conditions and plate length/width ratios. The classical laminated plate theory (CLPT) is used to calculate the natural frequencies of laminated rectangular plates. To improve the speed of the optimization process, the elitist strategy is used in the Genetic algorithm. In the E-GA, the fittest individuals in the generation survive and are automatically reinserted in the next generation, right before the next selection process takes place and the fitness function is computed with a semi-analytical finite strip model developed originally on the basis of full energy method. In addition, from the computational economy point of view, combination of E-GA and FSM provides a much higher convergence and reduced the CPU time. To check the validity, the obtained results are also compared with some other stacking sequences.
Optimization of Energy Consumption in Integrated Blast Furnace and BOF Steelmaking Process
Authors: Cayir Emrullah , Egrican Nilufer
Published: January 2011

Energy is one of the main cost components in steelmaking operations. For steel industry, there is big pressure of lowering energy consumption and reducing CO2 emission by energy saving. Decreasing coke rate in blast furnace and increasing amount of liquid steel production per ton of hot metal in basic oxygen furnace (BOF) are the main parameters decreasing energy consumption in an integrated iron and steel plant. In this study, coke consumption and liquid steel production have been predicted through computer simulation of blast furnace and BOF processes. The second law of thermodynamics is very powerful tool in energy optimization of systems. To examine how efficiently energy is consumed in the blast furnace and BOF processes, the following efficiencies have been defined by using second law of thermodynamics: exergetic coke consumption efficiency for blast furnace process and exergetic steel production efficiency for BOF process. Effects of different parameters have been investigated on the energy consumption.
Study on Crashworthiness Characteristics of Several Concentric Thin Wall Tubes
Authors: Hosseini Tehrani Parisa , Pirmohammad Sajad
Published: January 2011

There is a growing interest in the use of thin-wall structures as a means of absorbing the kinetic energy of a moving body. Multi-layered thin-wall structures are more efficient and lighter than thick-wall structures, and show better crashworthiness characteristics. In this task, several concentric aluminum thin wall tubes as energy absorber under axial and oblique loading are studied and optimum combination of these tubes is presented. The weight of the tubes is optimized while crashworthiness of tubes is not compromised. The commercial finite element program LS-DYNA that offers non-linear dynamic simulation capabilities was used in this study.
Influence of Environmental Factors on Corrosion of Machinery at Takoradi Thermal Plant Power Station
Authors: Gbadam Eric K. , Mborah Charles
Published: January 2011

The effects of coastal environment and flue gases are major problems on the operations of industrial machines and the situation is not different at Takoradi Thermal Power Station (TTPS). It was observed that the relative humidity in the area coupled with the production of chloride ions and the formation of ammonium nitrate and ferric hydroxide are the major causes of corrosion at the plant. This paper sought to identify the causes of corrosion and their effects on machinery at TTPS. The major occurrence of corrosion was found to be pitting corrosion and induced stress corrosion cracking occurring on the tanks, pipes and tubes in the Heat Recovery Steam Generator (HRSG). Consequently, this has led to the leaking of pipes, tanks and loss of production. The use of epoxy paint on the pipes and tanks will go along way to reduce the effects.
Effect of Thermophysical Properties Models on the Predicting of Convective Heat Transfer of Nanofluids With Considering Nanoparticles Migration
Authors: Heyhat Mohammad Mahdi , Kowsary Farshad , Alem Saeed
Published: January 2011

In order to study the heat transfer behavior of the nanofluids, precise values of thermal and physical properties such as specific heat, viscosity and thermal conductivity of the nanofluids are required. There are a few well-known correlations for predicting the thermal and physical properties of nanofluids which are often cited by researchers to calculate the convective heat transfer behaviors of the nanofluids. Each researcher has used different models of the thermophysical properties in their works. The aim of the present paper is to study the convective heat transfer of nanofluids containing low volume concentration of Al2O3 nanoparticles with a regard to the migration of nanoparticles due to Brownian diffusion and thermophoresis. To do this, a two-component model has been used and a numerical study on laminar flow of alumina-water nanofluid through a constant wall temperature tube has been performed. Two different models have been adopted for predicting the thermophysical properties of nanofluids. All of the properties are assumed to be temperature as well as particle concentration dependent. The effects of these models on the predicted value of the convective heat transfer of nanofluid and the migration of nanoparticles have been discussed in detail.
Study of Air Bubble Formation Process in Aeration System
Authors: Amano R. S. , Alkhalidi Ammar
Published: January 2011

This paper addresses a study of air bubble creation through an investigation by using CFD (computational fluid dynamic), which were validated to experimental results. Contact angle was also investigated for the air, water interface at a rubber surface to find the contact angle for air exiting diffuser plate. The results show very good comparison with the experimental results.
Experimental Methodologies for the Measurement of Wind Turbines Performance
Authors: Romano` Carlo , Orlando Vincenzo , Mattiazzo Giuliana , Giorcelli Ermanno
Published: January 2011

Wind Turbines are one of the most promising technologies to exploit renewable energy sources, and maybe the one which is the closest to achieve grid parity. Many modeling and experimental research activities are carried out in order to continuously improve devices performance. Another promising sector is small scale turbines, below 100kW installed power, for small installation, domestic use, and to be installed on ships. Moving within this scenario, a 1,5 kW turbine was tested inside a wind tunnel, and the following were measured: forces applied to the tower, angular speed, electric power output, mechanical power involved, and stress induced on the blades. Moreover, the cut in rotor speed and the turbine’s efficiency came as outputs of the activity. After some simple forecast calculations, to establish expected maximum values of physical quantities, the experiment was designed. The method used for acquiring all the values at one time involves a wi-fi device, attached to the rotor, in order to acquire signals coming from strain-gauges placed on the blades, avoiding long and cumbersome transmission lines towards the DAQ, coupled to anemometers, load cells, and a wattmeter. Coordination of operators during the tests had a crucial role in carrying out the procedure correctly. Since the main objects of study were blades, rotor and electric generator, the tower has been replaced with a robust support structure, designed to host and protect load cells and signal conditioners from accidental damage, thus permitting a correct measurement of axial force applied to the rotor and reacting momentum of the generator. The wi-fi device was linked to the rotor, in order to affect its mass and inertia characteristics as less as possible. This required the design of a proper linking structure, which was light and well balanced despite being mechanically resistant. Measured quantities are useful to evaluate the turbine’s performance (efficiency, power curve, cut in speed), and also to validate some fem and multi physics predictive models, that are currently under development, as possible tools for general wind turbines design. The outputs of these tests satisfy the need for a wide range of experimental data. This way of designing tests, the physical quantities involved and the schedule of experiments can be suggested as a valuable operative procedure.
Optimal Control Strategies for Wheeled Mobile Robot With Bounded Inputs
Authors: Zohar Ilan , Ailon Amit
Published: January 2011

This paper presents a simple approach for solving optimal control problems in wheeled mobile robots with bounded inputs. The control objective is to minimize a quadratic index of performance subject to differential constraints (the mobile robot equations of motion). The solution to the problem is obtained by utilizing an explicit trajectory parametrization method, which allows us to establish a sub-optimal control strategy by minimizing a multivariable function subject to a set of algebraic constraints. The approach is based on the flatness property, which allows us to represent the flat output by a polynomial. The bounds on the input signals are taken into consideration in the current analysis.
Laminar Mixed Convection in Horizontal Concentric Annuli With Four Porous Blocks Attached on the Outside of the Inner Cylinder
Authors: Ould-Amer Yacine
Published: January 2011

A numerical study is performed to investigate the performance of an innovative thermal system to improve the heat transfer in horizontal annulus. With attached four porous blocks on the inner cylinder, steady laminar mixed convection is presented for the fully developed region of horizontal concentric annuli. Results are presented for a range of the values of the Grashoff number, the Darcy number and the conductivity ratio between the porous medium and the fluid. Results are presented in the form of contours plots of the streamlines and for the temperature isotherms, and in terms of the overall heat transfer coefficients and friction factor. The average Nusselt number increases significantly with an increase of the conductivity ratio and the Grashoff number. With the use of the four porous blocks, the friction factor is consequently increased compared with the situation without porous blocks. The decrease of the Darcy number leads to an increase of the friction factor. If the fully fluid case is taken as a reference, the use of porous blocks is justified only when the ratio of the average Nusselt number to the friction factor is enhanced. The enhancement occurs for the Darcy number higher than 10−3 and for the higher conductivity ratio.
Semi Active Vibration Control of a Passenger Car Using Magnetorheological Shock Absorber
Authors: Fellah Jahromi Ali , Zabihollah A.
Published: January 2011

A novel semi-active control system for suspension systems of passenger car using Magnetorheological (MR) damper is introduced. The suspension system is considered as a massspring model with an eight-degrees-of-freedom, a passive damper and an active damper. The semi-active vibration control is designed to reduce the amplitude of automotive vibration caused by the alteration of road profile. The control mechanism is designed based on the optimal control algorithm, Linear Quadratic Regulator (LQR). In this system, the damping coefficient of the shock absorber changes actively trough inducing magnetic field. It is observed that utilizing the present control algorithm may significantly reduce the vibration response of the passenger car, thus, providing comfortable drive. The new developed suspension system may lead to design and manufacturing of passenger car in which the passenger may not feel the changes in road profile from highly bumpy to smooth profile.
On the Effects of Water Discharge Through Radial Gates at the Caruachi Dam
Authors: Sanchez Douglas , Salazar Juan E.
Published: January 2011

This paper presents numerical simulation of the water flow through the radial gates of the 2,280 MW Caruchi Dam, in southern Venezuela, and its relation to the vibration of the dam’s spillways and adjacent Control Building. The study is conducted as a contribution in determining the source of vibration of the fore mentioned structures in the case of gates opening above the normal values of up to 5 m, which occur when a larger water discharge is required in order to maintain an adequate level of the reservoir during the rainy season. The aim of the study was to find the pressure distribution and velocity profiles of the discharge flow through one of the dam’s radial gates and determine critical (reduced) velocities that may result in flow-induced vibration of the gates, as they were deemed to be the source of vibration of the whole set of structures in the first place. For this purpose, a commercially available FEM code was used. Three-dimensional CFD models were developed to simulate behavior of the flow when being released to the spillways, for opening values of 2, 5, 10 and 14 m, including the effect of the spillways’ deflectors. Modal analyses of the gate were performed, to take into account natural vibration frequencies in the determination of its critical velocities. After comparison of the gate’s critical velocities and velocity values from the CFD simulations, it is fair to say that the discharge flow does not directly induce vibration on the gates but rather on the spillways’ structure. This conclusion disregards flow through the gates as triggering the vibration phenomena which gave origin to this project, and puts the emphasis now on studying water flow effects on vibration in the spillway which, if not corrected on time, may ultimately lead to its catastrophic failure.
An Application of a Generalized Life Cycle Cost Model to BOXN Wagons of Indian Railways
Authors: Waghmode Laxman Yadu , Sahasrabudhe Anil Dattatraya
Published: January 2011

The objective of this paper is to apply a methodology developed for effective implementation of life cycle costing (LCC) in design and procurement of repairable products/systems to railway wagons. From its origin in defense equipment in US in 1960s, the application of life cycle cost concept has now been extended to other areas of private and public sectors too. This is because the customers are now considering not only the initial product costs but also the cost implications associated with the entire life span of a product. This emerging trend in global markets is gradually forcing the product manufacturers to estimate and optimize the product LCC with reference to performance, safety, reliability (R), and maintainability (M). The life cycle cost of a repairable system is closely coupled to its reliability and maintainability and therefore a careful consideration to the R & M parameters in the product design stage is quite essential from the LCC viewpoint. Taking into consideration these aspects a generalized modeling methodology has been proposed to estimate the life cycle cost of repairable products based on R & M principles. Life cycle costing in railway industry has traditionally been focused on the prediction of investment of railway vehicle. But, today’s mass transit market has rapidly been changed and the suppliers are now forced to treat the LCC of entire railway system. Indian railways are the principle mode of transport for raw materials for steel plants, finished steel from steel plants, coal, oil, iron, cement, petroleum products, fertilizers and food grains in India. To serve this purpose BOXN wagons are used by Indian railways. The BOXN wagons typically have a life span of 35 years and being a repairable system experience multiple failures over their life span. In this paper, a generalized model for LCC of repairable products has been proposed and is applied to BOXN wagon of Indian railways and the results obtained are presented. The methodology presented herein is expected to provide some useful guidelines to the railway industry to predict and analyze the life cycle cost of railway vehicles.
Parallel Mechanism for Precision Sun Tracking
Authors: Mauro Stefano , Scarzella Cristina
Published: January 2011

The paper describes a 2-DOF parallel kinematic machine designed to achieve precise solar tracking. The mechanism has been developed keeping in mind that solar concentration technology requires a precise alignment of photovoltaic modules and sun radiation, with error allowance much lower than those ensured by traditional sun trackers. The paper describes the kinematic structure and discusses its forward and inverse kinematic, providing the tools to design a system that satisfies the requirements for dexterity and workspace.
Generation and Control of Droplet in Cross Microchannel Flow With a Converging-Diverging Nozzle Shaped Section
Authors: Chen Jerry M. , Kuo Ming-Che
Published: January 2011

This paper reports flow visualization experiments of droplet emulsions in the microfluidics that is composed of a flow-focusing (cross-junction) structure with a converging-diverging nozzle shaped section. The channel structure was made of polydimethylsiloxane (PDMS) with a channel of 73 μm in depth and 100 μm in width. Oil as the continuous phase and water as the dispersed phase were injected into the cross-junction inlets to form water-in-oil droplets. It is found that adding the converging-diverging section to the cross-junction significantly reduces the droplet size without largely increases the overall flow resistance and still achieve excellent uniformity (with coefficient of variation less than 3.5%). Throat of the converging-diverging section determines the breakup location of droplet emulsion. The size of droplets is controllable in a wide range (6–116μm) through the variation of throat width between 23 and 100 μm in conjunction with the flow rates of continuous and dispersed phases. This emulsion technique demonstrates that droplets with diameter as small as 10 μm or less can be produced in microchannels having dimensions on the order of 100 μm without use of surfactants.
Using Sliding Mode Control to Adjust Drum Level of a Boiler Unit With Time Varying Parameters
Authors: Moradi Hamed , Bakhtiari-Nejad Firooz , Saffar-Avval Majid , Alasty Aria
Published: January 2011

Stable control of water level of drum is of great importance for economic operation of power plant steam generator systems. In this paper, a linear model of the boiler unit with time varying parameters is used for simulation. Two transfer functions between drum water level (output variable) and feed-water and steam mass rates (input variables) are considered. Variation of model parameters may be arisen from disturbances affecting water level of drum, model uncertainties and parameter mismatch due to the variant operating conditions. To achieve a perfect tracking of the desired drum water level, two sliding mode controllers are designed separately. Results show that the designed controllers result in bounded values of control signals, satisfying the actuators constraints.
Spindle Speed Variation for Regenerative Chatter Suppression in Turning Process With Tool Wear Effect
Authors: Hajikolaei Kambiz Haji , Rahaeifard Masoud , Vossoughi Gholamreza , Movahhedy Mohammadreza
Published: January 2011

Chatter suppression in machining processes results in more material removal rate, high precision and surface quality. In this paper, a single degree of freedom model of orthogonal turning process is used to set up the delay differential equation of motion with considering the tool wear effect as a contact force between the workpiece and tool flank surfaces. Sinusoidal spindle speed variations with different frequencies around the mean speed are modulated to disturb the regenerative mechanism. The optimal amplitudes of the speed modulations are found based on a genetic algorithm such that the input energy to the turning process is minimized. Results of the stability analysis and the controller effect for two distinct cases of one and three sinusoidal speed are presented and compared.