bluuebunny/crossref_metadata_2025 huggingface dataset:
Torque and Power Coefficients of a Vertical Axis Wind Turbine With Optimal Pitch Control
Authors: Chen Jim Shih-Jiun , Chen Zhi , Biswas Saroj , Miau Jiun-Jih , Hsieh Cheng-Han
Published: January 2011

Vertical axis wind turbines (VAWT) have been valued in recent years for their low manufacturing cost, structural simplicity and convenience of applications in urban settings. Despite their advantages, VAWTs have several drawbacks including low power coefficient, poor self-starting ability, negative torque and the associated cyclic stress at certain azimuth angles. Using pitch control ideas, our research is aimed at solving the above problems. In this study, a small-scale Giromill VAWT using three NACA-0015 airfoils with a cord length of 0.09 m and a wind turbine radius of 0.6 m is investigated. During each rotation, the angle of attack depends on the wind velocity, angular velocity and current azimuth angle for each turbine blade. Negative torques at certain angles are attributed to the inherent unsteady aerodynamic behavior at high angles of attack. Without optimal pitch control, the Double-Multiple Streamtube (DMS) model predicts negative torques at certain azimuth angles and very low power coefficients for tip speed ratios below 2.5. The unfavorable negative torques are eliminated using an optimal pitch control strategy, which maximizes the tangential force coefficients and thus the torque coefficients by iterations of all possible relative angles of attack for various tip speed ratios. As a result, the power coefficient is significantly improved especially at low tip speed ratios in the range of zero to three (λ = 0 – 3). Blade pitch control can also solve the self-starting problem and reduce the vibration of vertical axis wind turbines.
Nuclear Power and Coal: An Unexpected Marriage
Authors: Keller Michael F.
Published: January 2011

America possesses hundreds of years of low-cost coal resources that are becoming increasingly unpopular due to climate-change concerns. The promise of the nuclear gas reactor also remains out-of-reach as a result of technical and cost considerations, while the high cost of conventional nuclear power greatly hampers the building of new facilities. Hybrid-nuclear power is an unexpected breakthrough solution to the growing energy and climate change dilemmas. The emerging hybrid technology can help revitalize the coal as well as nuclear industries while also significantly helping the United States achieve energy independence.
Blisk Life Prediction for Twin-Shaft Turbo Engines by Using a Two-Dimensional Thermal Off-Design Model
Authors: Chen Ying , Koul Ashok , Zhao Jun
Published: January 2011

Understanding the off-design engine behavior is very important for the life cycle management of gas turbines because overhaul interval must be predicted accurately to minimize engine down time and maintenance costs. An off-design thermodynamic model has been developed for twin-shaft engines to obtain mean-line temperature distribution to be used in a prognostics system. A semi-empirical projecting approach was adopted to compute the two-dimensional temperature distribution for the gas path components. This temperature profile was then fed into the structural analysis and damage modeling modules of the prognostics system to predict the fracture critical location and crack initiation life of an A 250 integrally cast bladed disc (blisk). Comparison of the twin shaft model with GasTurb results showed that the model predicts the temperature profile within +/− 8K. The life prediction results from the prognostics system also match closely with the field data.
Increasing Condenser Capacity Without Adding Tubes to Support a Station Uprate
Authors: Welch Warren C. , Harpster Timothy J. , Harpster Joseph W.
Published: January 2011

A station uprate provides an economical opportunity to improve the generation capacity of a power plant if all the major system components are able to handle the effects of increased generation. The magnitude of uprate from increased steam generation will be limited by the maximum capacity of the weakest link in the cycle, which for many plants is the condenser. The condensers on many units are already pushed to their limit. This is especially true if a cooling tower is employed, where the condenser inlet cooling water temperatures are high on high wet-bulb temperature days. This condition forces many units to throttle down load to prevent excursions above the backpressure limits on their turbines. For condensers limited by the present duty, however, the options have been historically limited to rebundling the whole condenser with a larger surface area design and perhaps changing the tube material to a material with a higher heat transfer coefficient. Recently, a very low cost option has been demonstrated that should be considered by any plant looking to increase condenser duty or prevent station power reductions. Advances in the proper management of steam, condensate and noncondensable flows have permitted an upgrade for almost all vintage condensers, unlocking inactive surface area without a bundle replacement or complete redesign. This paper reports the results of a condenser retrofit effort, with emphasis on an upgrade applied to a load limited condenser concurrent with a major reduction in its operating backpressure. The performance of the condenser is presented before and after the upgrade showing significant backpressure reduction and heat transfer improvement accompanied by exceptional condensate chemistry results. It will be shown that 30% of the effective condenser surface area (or similarly, an additional 30% average heat transfer coefficient) was unlocked by activating the previously idle surface area.
Flashback Propensity in Swirl Stabilized Burner With Syngas Fuels
Authors: Dam Bidhan , Corona Gilberto , Choudhuri Ahsan
Published: January 2011

In swirl stabilized burner, combustion induced vortex breakdown (CIVB) flashback is a significant phenomenon. This paper presents experimental measurements of CIVB flashback propensity for hydrogen (H2)-carbon monoxide (CO) flames. The effects of H2 concentration, and swirl number on the flashback propensity of H2-CO flames are discussed. For a given air mass flow rate, the stoichiometric ratio (%F) at which the CIVB flashback occurs decreases with the increase in H2 concentration in fuel mixtures. However it appears that near the CIVB flashback limit, the swirl strength plays a more dominating role over the H2 concentration in the fuel mixture. The flashback propensity decreases with the increase in swirl number. An analysis of the nonreacting flow field (Air 6 g/s) as well as reacting (CH4-Air and H2-CO-Air) flame near the CIVB transient velocity field was conducted. The analysis revealed that a complex vortex-chemistry interaction leading to vortex breakdown and flashback occurred. The vector flow field showed that the high swirling flow generates a more stabilized and wider recirculation zone. It also showed that the presence of H2 dictates the intensity of the flashback process.
Reducing the Cost of Fan Performance Testing When Evaluating Reduced Load Fan Input Power: Revisiting PTC 11 Mandatory Appendix I
Authors: Kaufman Steven G.
Published: January 2011

This paper presents alternative methods for evaluating how field tested power compares to a fan vendor’s rated power when the tested operating point is marginally off the specified reduced load operating point. ASME PTC 11-2008 Mandatory Appendix I requires four separate field test points be obtained to verify a single reduced load operating point. Each of the four test points must fall within two to four separate and relatively precise target windows that adjoin and surround the specified operating point. This approach will involve numerous system adjustments, fan control adjustments and accompanying field performance tests just to verify a single specified operating point. A methodology is proposed in this paper for which it is postulated that only a single field test point needs to be obtained within a flow-pressure target window of ±3% of the specified flow and ±2% of the specified pressure rise to accurately evaluate reduced load power. Three different evaluation methods are presented that compare the field tested power to the fan vendor’s rated reduced load power; i) power evaluation – 4-point distance weighted interpolation ii) power evaluation – 2-point linear interpolation and iii) efficiency evaluation. The proposed power evaluation methods require that in addition to identifying the rated power at the specified operating point, the fan vendor will be asked to identify what the rated power is at each of the four corners of the flow-pressure target window. These rated powers are used to interpolate the rated power that corresponds with the single field test point which can then be compared directly to the field tested power. This approach will result in significant reductions in field testing time and expenses. In addition, working with a single field tested power value for a single test point should reduce the potential combined uncertainty associated with interpolating test power from multiple field tested powers. It is opined that applying an interpolation method to the fan vendor’s rated reduced load power predictions rather than field test data may be more agreeable to the fan vendor. In effect, the fan vendor is being asked to guarantee the reduced load power for a relatively narrow flow-pressure target window.
Limitations of 439 SS in HP Feedwater Heater Application
Authors: Khurrum Silvia , Catapano Michael
Published: January 2011

This paper presents a case history of problems experienced with a replacement HP feedwater heater that was manufactured with Type 439 stainless steel tubing. The subject heater was installed after numerous problems during manufacturing and was commissioned for service in February 2007. The first failures were experienced after only 2 years of operation. Reports indicate that after the discovery of the first leaks, maintenance groups servicing the heater were never able to get the heater completely leak-tight. Ultimately, the frequency and magnitude of subsequent leak incidents that followed caused the power generating company to fully bypass the heater in September 2009. The paper offers a full chronology of events that ultimately led to the demise of subject heater. The primary objective of the paper is to share the lessons learned during the root cause analysis of the problem, including the inherent limitations related to subject tube material. Specific steps identified herein were taken by the power generating company to ensure that the technical specification for the next replacement heater would preclude any similar problems from occurring.
Technical and Economic Analysis of Cogeneration Systems for Refinery Power Plant Applications
Authors: Rodri´guez Marti´nez J. Hugo , Alcaraz Caldero´n Agusti´n , Ruiz Flores Luis Iva´n , Valdez Vargas Roberto
Published: January 2011

This paper shows the main results from a technical and economical study for the implementation of new cogeneration systems in Mexican refineries. At least three cogeneration alternatives to match a 50% additional energy requirement (thermal and electric) for a refinery are analyzed. A balance simulator tool developed specially for the electric and steam refinery systems is used in order to obtain the technical parameters for the alternatives, which allows obtaining system performance indicators such as fuel consumption, cooling water requirement, electric and combined efficiency. Standard techniques as net present value, internal rate of return, and payback period are used for the economic analysis. According to the results, the best alternative was a gas turbine-heat recovery steam generator arrangement fueled by natural gas, including the respective adjustments of the refinery electrical and steam systems.
Improvements in Fuel Flexibility and Operating Cost Reduction at CSU Drake Station With Targeted In-Furnace Injection™ Technology
Authors: Towell James , Martinez Tom , Hightower David , Maxey Richard , Snow Gerry , Gonzalez Hector , Rians Robert
Published: January 2011

Power generating stations are under continuous pressure to achieve maximum availability, highest efficiency, and minimum environmental emissions at the lowest possible cost. In recent years, increased fuel flexibility has become more critical financially and operationally than ever before. Colorado Springs Utilities (CSU) has been very progressive in adopting and implementing benchmark technologies and operating strategies to help achieve these goals across their diversified generation portfolio, and in particular at four operating coal units representing 462 megawatts in the system. One key strategy employed at CSU’s Martin Drake Station has been to continuously evaluate and test alternative coal feedstocks which have potential to reduce cost while maintaining capacity, fuel supply security, availability, and efficiency. These tests would not have been possible without the use of Fuel Tech’s Targeted In-Furnace Injection™ (TIFI®) technology to control slagging and fouling, reduce forced outages and load drops, and enhance unit efficiency. The TIFI process involves the use of two different forms of fluid dynamics modeling coupled with a virtual reality engine. Together, these simulation methods create a running duplicate of a given furnace with injection overlays and dosage maps to predict the precise trajectory of an injected chemical, helping to ensure as close to 100% coverage of the targeted zones as possible. With TIFI installed on Units 6 and 7 at Martin Drake Station, the operators were able to blend Powder River Basin coal with design fuel up to double the percentages previously achievable. Using TIFI, the plant was able to maintain full load generation, better control slagging deposits, show improvements in heat absorption, and reduce attemperator spray flows over previous blend trials. Including the cost of the TIFI program, the station has demonstrated a potential annual operating cost reduction approaching $4.9 million. Effective return on TIFI program investment is 4:1.
Hot Windbox and Combined Cycle Repowering to Improve Heat Rate
Authors: Tawfik Tarek A. , Smith Thomas P.
Published: January 2011

Retrofitting existing power generation plants by repowering is becoming an attractive option to improve plant performance with less cost. “Hot Windbox Repowering” involves utilizing the hot exhaust gas from a combustion gas turbine and using it as combustion air for an existing fossil-fuel boiler. “Combined Cycle Repowering” or “Full Repowering” involves completely replacing the existing boiler with a combined cycle consisting of a gas turbine(s) and a heat recovery steam generator (HRSG). The existing steam turbine will be used in both repowering scenarios. This paper discusses an engineering study and summarizes the results obtained from repowering an existing heavy-oil / natural gas fired steam power plant in the north east of the United States. The plant consists of a 600 MW boiler and steam turbine. Several engineering studies were considered and evaluated thermodynamically and economically to retrofit such plant. Several options were considered involving different gas turbines, gas turbine combinations, and different repowering methods. The best option is based on retrofitting the unit by a combination of both, hot windbox repowering and combined cycle repowering. The proposed design consists of one gas turbine repowering the windbox of the existing boiler, and a second gas turbine operating in a separate combined cycle configuration with the generated superheated steam tying into the main steam line and expanding in the existing steam turbine. Several heat balances were developed to assist in obtaining meaningful results for this feasibility study. Actual costs were obtained for the gas turbines and heat recovery steam generators (HRSG), as well as installation costs for a more accurate evaluation. The results indicate that the combined output of the repowered unit will generate an additional 295 MW and reduce the heat rate by more than 11 percent at full load and annual average ambient conditions. The estimated capital cost of the project is expected to range from $235 to $245 millions.
Using SmartPlant® Foundation to Commission and Operate a New Nuclear Plant
Authors: Hess Charles W.
Published: January 2011

Most modern nuclear power plants are being designed using advanced design tools for both CAE and CAD. The SmartPlant® suite of programs, now called the SmartPlant Enterprise, is one of the most widely used and comprehensive of these programs. It is currently being used to design all nuclear Generation III+ designs by Westinghouse, GE-Hitachi, Mitsubishi, Toshiba, and AECL. The SmartPlant® Enterprise is a complete integrated solution capable of capturing all engineering, design, and construction data in a product called SmartPlant Foundation®. Once construction begins on these plants, however, the challenge for the operating companies becomes how to take the data contained within SmartPlant Foundation and use it for commissioning and operation. In this paperless environment, there is increased reliance on the software to make this transition in a nuclear operating company. This paper describes the benefits of this new paradigm, and provides a roadmap for the steps necessary to accomplish this goal. It also provides recommendations for the resources and for the cost and schedule required to make the conversion from design tool to operations tool.
A Micro Combined Heat and Power Thermodynamic Analysis and Optimization
Authors: Gholizadeh Ali , Shafii M. B. , Saidi M. H.
Published: January 2011

In modeling and designing micro combined heat and power cycle most important point is recognition of how the cycle operates based on the first and second laws of thermodynamics simultaneously. Analyzing data obtained from thermodynamic analysis employed to optimize MCHP cycle. The data obtained from prime mover optimization has been used for basic stimulus cycle. Assumptions considered for prime mover optimization has been improved, for example in making optimum operation condition by using genetic algorithms constant pressure combustion chamber was considered. The exact value of downstream and upstream pressure changes in the combustion chamber reaction has been obtained. After extraction of the appropriate relationship for the primary stimulus cycle, data required for the overall cycle analysis identified, By using these data optimum total cycle efficiency and constructing the first and second laws of thermodynamics has been calculated for it. After reviewing Thermodynamic governing relations in each cycle and using the optimum values that the prime mover has been optimized with, other cycles have been optimized. In best performance condition of cycle, electrical efficiency was 41 percent and the overall efficiency of the cycle was 88 percent, respectively. After using the second law of thermodynamics mathematical model Second law of thermodynamics efficiency and entropy production rate was estimated. Second law of thermodynamics yield best performance against the 45.14 percent and the rate of entropy production in this case equal to 0.099 kW/K respectively.
Investigation of Distributed Combustion for Gas Turbine Application: Forward Flow Configuration
Authors: Arghode Vaibhav K. , Gupta Ashwani K.
Published: January 2011

Colorless Distributed Combustion (CDC) has been investigated here for high efficiency and ultra low pollution gas turbine combustors applications. In this paper forward flow configurations have been examined. Basic requirement for CDC is carefully tailored mixture preparation prior to ignition through a combination of product gas recirculation, controlled mixing between the fresh combustion air and recirculated gases to form hot and diluted oxidizer. Rapid mixing between the injected fuel and hot oxidizer is desirable prior to spontaneous ignition of the mixture in the entire combustion zone to achieve distributed combustion reactions. Distributed reactions can also be achieved in premixed mode of operation with sufficient entrainment of burned gases and faster turbulent mixing between the reactants. In the present investigation forward flow modes are considered in which three non-premixed and one premixed combustion mode have been examined that showed favorable CDC combustion conditions. In the forward flow configurations the air injection port is positioned at a location opposite to the combustor exit. The location of fuel injection ports is changed to give different configurations. The thermal intensity for the present investigation is 28MW/m3-atm simulating gas turbine conditions. Increase in thermal intensity (lower combustion volume) presents many challenges, such as, lower residence time, lower recirculation of gases and confinement effects on the jet characteristics. The results are presented on the global flame signatures, exhaust emissions, and emission of radical species using experiments and flowfield dynamics using numerical simulations. Ultra low NOx emissions are found for both the premixed and non-premixed combustion modes investigated here. The reaction zone is observed to be significantly different in different combustion modes.
Applying the X-Ratio Correction to Calculated Air Heater Efficiency: An Alternate Method
Authors: McLaughlin David C. , Nasal Joseph R.
Published: January 2011

ASME PTC 4.3 on testing Air Heaters provides guidance for the calculation of gas-side efficiency as a measure of air heater performance. This code also provides for calculation of air heater X-ratio (XR), which is the ratio of the heat capacity (mass flow times specific heat capacity) of the air flowing through the heater to that of the flue gas. The code acknowledges the impact of XR on air heater efficiency, and dictates that the gas temperature leaving the air heater (and hence, air heater efficiency) be corrected for deviation from design XR by the use of “appropriate design correction curves” [1]. Unfortunately, such curves are rare, and therefore this important correction is usually ignored in routine air heater test calculations by power plant testing personnel, resulting in an incorrect calculation of air heater efficiency. This is particularly true for balanced draft boilers burning coal that are aged and have a significant amount of air leakage into the boiler setting. On these boilers, the ratio of combustion flue gas mass flow to combustion air mass flow is changed significantly from the original design, and therefore applying an XR correction factor is essential to calculating and reporting accurate air heater efficiency. This paper presents a method to calculate and correct for a deviation from design X-ratio based on standard heat exchanger analysis techniques, namely the ε-NTU method, which utilizes the concept of heat exchanger effectiveness (ε). A solution that results in applying the ratio of the design to actual XR’s as the correction factor is developed. The paper also provides empirical data from testing on a coal-fired boiler to validate the alternate correction method.
Load Cycling of a 242 MW Coal Fired Steam Turbine Plant Designed for Base Load Operations
Authors: Mutama Kuda R. , Duperron Norm
Published: January 2011

The TS Power Plant (TSPP) is a 242 MW gross coal fired power plant designed to operate base loaded. The plant is new and began commercial operations in June 2008. Due to high volumes of snow fall in the northwest the availability of low cost hydropower in 2009 reduced power demand from TSPP and other coal based generating stations. Moreover in 2009 natural gas prices fell to the lowest point in years making energy from newer more efficient combined cycle power plants very favorable. This paper examines the performance of TSPP under varying load output conditions with regard to key plant equipment such as the boiler, steam turbine generator and air quality systems for the flue gas. The plant was being operated from minimum load without firing oil (80 NMW) to sometimes full load conditions (218 NMW). Load changes were experienced on an hour to hour basis for several months. Load changes varied from 40 NMW increasing to 60 NMW decreasing during the 20 minute load change window during the hour. The boiler has three coal pulverizers. The boiler can achieve full load operations with two pulverizers, however all three pulverizers are ran at times for reliability. At loads less than 140 NMW the plant can operate one pulverizer but operations at loads lower than 80 NMW requires oil burners for flame stabilization. Transition points from one pulverizer to two pulverizer operations also cause challenges during load changes. However examining plant operating data over the load ranges has shown that TSPP has performed very well despite the varying load schedule. The plant heat rate is a good indicator as to how well the plant has performed. The heat rate has varied from under 10,000 Btu/kwhr at low loads (< 100 MW net) to around 9,400 Btu/kWhr at higher loads (> 175 MWnet). A summary of plant boiler and turbine data under various loads is also presented in this paper as well as balance of plant equipment.
Integrated Exhaust System for Simple Cycle Power Plants
Authors: Buzanowski Mark A. , McMenamin Sean P.
Published: January 2011

Simple cycle power plants are frequently utilized as peaking power plants which generate electricity typically during a high demand. To comply with environmental standards simple cycle power plants are equipped with emission control catalysts reducing emissions of nitrogen oxides, carbon monoxide and other pollutants. In some applications ambient air (so called tempering air) is injected into the exhaust duct to control temperature of the flue gas prior to entering environmental catalysts. Such catalytic treatment of pollutants present in the flue gas requires exhaust systems with substantial footprints to accommodate the emission control catalysts and tempering air injection systems. This paper discusses a new compact exhaust system and efficient arrangement of the tempering air system for simple cycle power plants. The proposed system includes transitioning hot exhaust flue gas into pre-oxidation section of the exhaust system, passing hot exhaust gas through the oxidation catalyst for the CO emissions control, injecting tempering air stream into the post-oxidation section of the exhaust system, and passing cooled flue gas through the reduction catalyst for the NOx emissions control. The resultant benefit of this newly designed process is a more effective use of catalysts, a smaller exhaust footprint of equipment and a lower capital cost to the end user.
Effective Expansion and Repair of Tube-to-Tubesheet Joints in a High Pressure Feedwater Heater
Authors: Holderness Darcy , Bruno Joe
Published: January 2011

This paper demonstrates the extensive detail in initial testing, specification preparation, and final in-plant repair of seal welded and hydraulic expanded tube-to-tubesheet joints. The feedwater heater in question included T22 tube material and was installed new in 2002. With a little over 6 years of service, SaskPower realized that the tube-to-tubesheet joints on the PR1 (Poplar River Unit 1) number six high pressure feedwater heater had a significant number of leaks. After considerable investigation, 87 tube-to-tubesheet joint leaks were identified. No tubes were plugged based on actual tube failures. Rather than perform continued plugging of leaking joints, several repair strategies were developed. After a detailed review of the options, the repair procedure selected included repair to the tube-to-tubesheet joint seal welds that were leaking, followed by a full strength re-expansion of a 100% of the tubes. The initial recommended repair procedure was not deemed appropriate due to physical constraints. SaskPower worked closely and contracted with American Exchanger Services to complete a full strength explosive re-expansion of the tube-to-tubesheet joints, seal weld repair any remaining leaking joints as needed, and perform NDE necessary to assure tight tube joints. This paper will define the details of the initial investigation into the extent of the leaking, the development of the testing sequence and methods, and finally the preparations and repair strategy to bring this heater back to full operating status with minimal expense.
Malaysian Biomass Resources: Green Renewable Contribution in the National Energy Mix
Authors: Shamsuddin Abd Halim
Published: January 2011

Being a major agricultural commodity producer in the region Malaysia is well positioned amongst the ASEAN countries to promote the use of biomass as a renewable energy source in the national energy mix. The palm oil industry, the second largest in the world, has over 4 million hectares of plantation. The palm oil milling industry produces large amount of solid residues, the volumes of which for the year 2007 are: empty fruit bunches EFB (16.7 million tonnes), fruit fibres (12.2.million tonnes), and palm kernel shell (4.9 million tonnes). Besides the oil palm milling industry residues, other biomass contributors includes, the timber industry, rice industry and bagasse. These biomass residues, if fully utilized as fuel for power generation, would have the potential of annual generation of 31,900 GWh, with maximum generating capacity of 3,600 MW. Under the National Energy Policy set in 1979, three principal energy objectives, which are instrumental in guiding the future energy sector development, were established. These are Supply, Utilization and Environmental Objectives. In 2001, the beginning of the Eighth Malaysian Plan, Renewable Energy (RE) was regarded as the fifth fuel in the new Five Fuel Strategy in the energy supply mix. The target is that RE contributes 5% of the country’s electricity demand by the year 2005. Malaysia’s Five Fuel Diversification Policy provides the renewable energy policy guidance while the current grid-based small renewable energy programmes (SREP) and the renewable energy power purchase agreement (REPPA), embodies the national renewable energy strategy. To reinforce these policy instruments, the Malaysian Ministry of Energy, Green Technology and Water launched the National Green Technology Policy in the middle of 2009 that include Green Energy Technology. This paper presents the overall scenario of the Malaysia’s biomass resources, the status of biomass contribution to the nation’s energy mix, the challenges faced by the biomass promoters, and future research and development activities in developing optimized and efficient technologies at the Centre for Renewable Energy, Universiti Tenaga Nasional.
Process Control and Design Issues in a Concentrated Solar Power Trough Plant With Thermal Storage
Authors: Bullington Brad
Published: January 2011

The power block for a conventional Concentrated Solar Power (CSP) Plant without thermal storage follows standard power block design practices. A closed loop heat transfer fluid (HTF) is heated in the solar field, which consists of multiple solar collector assemblies (SCAs). Heat exchangers use the heat from the HTF to generate and superheat steam. The steam is sent to a steam turbine, which generates electricity. The cooled HTF is recirculated back to the solar field. In an effort to shift the period of power generation or to maintain full power output during non-peak periods of operation, a thermal energy storage (TES) system can be added. This entails adding a second closed loop fluid that is heated by the HTF during sufficient radiation hours, which in turn can heat the HTF that is supplied to the power block during periods of non-peak radiation. This article discusses the process control and design issues for the integrated solar field, TES system and power block for these plants. The article will address the following: 1) Operations with the Solar field on-line, TES system off-line, and STG on-line. 2) Operations with the Solar field on-line, TES system charging, and STG on-line. 3) Operations with the Solar field on-line, the TES system discharging, and STG on-line. 4) Operations with the solar field off-line, the TES system discharging, and the STG on-line. 5) Operations with the Solar field on-line, the TES system charging, and STG off-line. 6) Steam Turbine Issues. 7) Freeze protection. 8) HTF/TES Heat Exchanger. 9) Circulating Water and Surface Condenser.
Modeling Dispersion of PM10 and PST in the Cesar Department Mining Region, Colombia by Using ISC and AERMOD
Authors: Huertas Jose I. , Izquierdo Sebastia´n , Gonza´lez Enrique D.
Published: January 2011

The mining region of the Cesar Department, Colombia, is made up of 6 mining companies with an approximate coal production of ∼3.5×107 tonnes/year through open cut exploitation. The region has an air quality monitoring network that reports readings exceeding the standard for the daily and annual concentration of PST and PM10. In order to orient the efforts of the decontamination program that has been implemented in the region, the environmental authority needs tools to model the PST and PM10 dispersion. Initially a unified PST and PM10 emission inventory methodology was developed and the topographic and meteorological information available for the region was collected. The dispersion of particled material was then modeled in ISC and AERMOD with meteorological data collected by 3 local stations during 2008. The results obtained were contrasted against the values measured by the air quality monitoring network that is operating in the region. Correlation coefficients were obtained exceeding 0.7, which is acceptable considering the high degree of uncertainty in emission inventory data. Based on the modeling results, the regions were delimited that, according to the local laws, correspond to areas with high, medium and moderate pollution levels. Finally, new actions were presented that make it possible to control PST and PM10 pollution in the mining region.
A Modified Double Reheat Cycle
Authors: Kjaer Sven , Drinhaus Frank
Published: January 2011

DONG Energy owns and operates seven power stations in Denmark fueled by internationally traded bituminous coal. Since the early 1980s, competitiveness has been supported by an efficient conversion from coal to wire in super critical boilers and turbines. DONG Energy also operates a double reheat plant with ultra super critical steam parameters, and based on experience from this plant, a revised concept for the double reheat steam cycle has been developed. The revised design (named the Master Cycle or MC) solves the problems with the very strong superheating of the bleed steam from the IP turbines and paves the way for an affordable double reheat technology. The core component of the revised design is a small separate turbine (named the tuning turbine or T-turbine) driving a 100% boiler feed pump in combination with a balancing motor/generator and delivering relatively cold bleed steam for the heaters normally bleeding on the IP turbines. The T-turbine is fed with steam from the first cold reheat steam line meaning reduced steam flow through the reheaters and higher main steam flow which is advantageous for cooling of the furnace walls. Based on the Master Cycle and Ultra Super Critical (USC) steam parameters, net efficiency of a single reheat plant can be improved from 47% to 48.5% without any deterioration of availability. Many double reheat plants with elements similar to those of the Master Cycle are in operation in the USA and their operational records are excellent. Higher net efficiency of a Master Cycle plant would mean solid CO2 reductions of 4% by comparison with a new single reheat plant. Much higher reductions could be achieved by replacing an old plant.
A measure that relates to elementary school children's risk of injury: the supervision attributes and risk-taking questionnaire (SARTQ)
Authors: Morrongiello Barbara A , Corbett Michael R , Kane Alexa
Published: January 2011

Objectives

The aim of this study was to examine the psychometric properties of the supervision attributes and risk-taking questionnaire (SARTQ), which is a new measure of caregiver supervision and child risk-taking that applies to elementary school children 7–10 years of age.

Methods

Using a prospective design, scores on the SARTQ were related to children's recent and long-term history of injuries and to parents' supervision scores that were derived based on measuring their home supervision practices over 8 weeks.

Results

Subscale scores on the SARTQ related differentially to measures of supervision and child injury scores, providing support for the criterion validity of this new measure.

Conclusion

Results from this initial test of the SARTQ suggest that it holds promise as a measure that is relevant to understanding injury risk for elementary school children.
Explaining regional disparities in traffic mortality by decomposing conditional probabilities
Authors: Goldstein Gregory P , Clark David E , Travis Lori L , Haskins Amy E
Published: January 2011

Background

In the USA, the mortality rate from traffic injury is higher in rural and in southern regions, for reasons that are not well understood.

Methods

For 1754 (56%) of the 3142 US counties, we obtained data allowing for separation of the deaths/population rate into deaths/injury, injuries/crash, crashes/exposure and exposure/population, with exposure measured as vehicle miles travelled. A ‘decomposition method’ proposed by Li and Baker was extended to study how the contributions of these components were affected by three measures of rural location, as well as southern location.

Results

The method of Li and Baker extended without difficulty to include non-binary effects and multiple exposures. Deaths/injury was by far the most important determinant in the county-to-county variation in deaths/population, and accounted for the greatest portion of the rural/urban disparity. After controlling for the rural effect, injuries/crash accounted for most of the southern/northern disparity.

Conclusions

The increased mortality rate from traffic injury in rural areas can be attributed to the increased probability of death given that a person has been injured, possibly due to challenges faced by emergency medical response systems. In southern areas, there is an increased probability of injury given that a person has crashed, possibly due to differences in vehicle, road, or driving conditions.
Cranial dural arteriovenous fistula: transarterial Onyx embolization experience and technical nuances
Authors: Hu Yin C , Newman C Benjamin , Dashti Shervin R , Albuquerque Felipe C , McDougall Cameron G
Published: January 2011

Introduction

Traditional endovascular treatment of cranial dural arteriovenous fistulas (DAVFs) consists of a transarterial approach with n-butylcyanoacrylate (nBCA) or a transvenous approach with coil embolization. The advent of Onyx in the endovascular arsenal potentially offers a high probability of obliteration of these vascular lesions through a purely transarterial route.

Methods

A retrospective review of the Barrow Neurological Institute endovascular database between October 2005 and November 2009 highlighted 50 patients with 63 cranial DAVFs that were treated with transarterial Onyx, with and without adjuvant embolysates, for a total of 76 embolization procedures. Hospital records, cerebral angiography and other diagnostic imaging and clinical visits were reviewed.

Results

At a median follow-up of 5 months (range 0–25 months), complete angiographic cure was obtained in 41 patients with 50 (79%) DAVFs after transarterial embolization using Onyx combined with other embolysates. When Onyx was used as the sole embolic agent, 32 of 37 DAVFs (87%) in 29 (of 33) patients achieved angiographic cure. Subgroup analysis showed that by using the middle meningeal artery (MMA) as a conduit for primary Onyx embolization, angiographic cures were achieved in 27 of the 37 DAVFs (73%). Periprocedural complications occurred in six (7.9%) sessions in one patients (8%). Only one patient had a permanent complication (2%) with unimproved cranial nerve palsies.

Conclusion

Transarterial Onyx embolization of cranial DAVFs, particularly using the MMA as a conduit, is a safe and effective curative therapy.
Endovascular treatment of a pial arteriovenous fistula of a posteroinferior cerebellar artery with a double origin
Authors: Guimaraens Leopoldo , Casasco Alfredo , Sola Teresa , Cuellar Hugo , Miralbes Salvador , Cambra Francisco Jose
Published: January 2011

Pial arteriovenous fistulas (pAVF) of the posterior fossa are rare and may present with symptoms secondary to mass effect, venous hypertension or hemorrhage, among others. A case is presented of a previously healthy 2-year-old boy with neurological deficit arising from pAVF of the posteroinferior cerebellar artery. The pAVF was successfully treated with endovascular occlusion.
The first genetic linkage map of Luohanguo (Siraitia grosvenorii) based on ISSR and SRAP markers
Authors: Liu Lihua , Ma Xiaojun , Wei Jianhe , Qin Jiaming , Mo Changming
Published: January 2011

In this study, the first genetic map of Luohanguo ( Siraitia grosvenorii (Swingle) C. Jeffrey) was constructed with 150 F2population individuals using inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) markers. A total of 100 ISSRs and 196 SRAP primer combinations generated 51 and 222 polymorphic markers, respectively. Among the 273 markers obtained, 199 markers (29 ISSRs and 170 SRAPs) were mapped to 25 linkage groups. The map covered 1463.3 cM with a mean map distance of 7.35 cM between adjacent markers and a maximum map distance of 52.6 cM between two markers. The markers were distributed randomly in 25 groups except for minor clusters in the distal region of linkage groups. All 25 linkage groups consisted of 2–36 loci ranging in length from 19.5 to 152.6 cM and accounted for 59.8% of the total map distance. This map provides reference information for future molecular breeding work on Luohanguo.
New insights into the mycorrhizal status of Cyperaceae from ultramafic soils in New Caledonia
Authors: Lagrange Alexandre , Ducousso Marc , Jourand Philippe , Majorel Clarisse , Amir Hamid
Published: January 2011

In New Caledonia, a hot spot of biodiversity, plants from the Cyperaceae family are mostly endemic and considered pioneers of the nickel-rich natural serpentine ecosystem. The aim of the study was to highlight the mycorrhizal status of these Cyperaceae and to bring new insights into the role of this symbiosis in plant tolerance to ultramafic soils. Nine Cyperaceae species were studied and presented evidence of root colonization by arbuscular mycorrhizas (AMs), with frequencies ranging from 8% to 57%. The highest level of AM colonization was observed in plants from the endemic dominant genus Costularia . Molecular evidence demonstrated the presence of Glomus sp. inside the roots. In a controlled greenhouse assay, AM inoculation of Costularia comosa grown under ultramafic conditions significantly enhanced plant growth, with an increase in biomass by up to 2.4-fold for shoots and 1.2-fold for roots, and also reduced nickel content in roots by 2.5-fold, as compared with the controls. All these data support our hypotheses (i) that a relationship exists between the mycorrhizal status of Cyperaceae and their habitat, and (ii) that AM have a positive role in plant tolerance to ultramafic soils (mineral nutrition and metal tolerance), suggesting the use of these pioneer plants with AM management as potential tools for nickel mine site rehabilitation in New Caledonia.
Production and characterization of monoclonal antibodies against the hemagglutinin of H5N1 and antigenic investigation of avian influenza H5N1 viruses isolated from China
Authors: Wei Jie , Yan Bing , Chen Ze , Li Tianxian , Deng Fei , Wang Hualin , Hu Zhihong
Published: January 2011

Eight monoclonal antibodies against hemagglutinin of influenza A virus A/Chicken/Henan/01/2004(H5N1) were produced by a DNA prime and inactivated virions-boost immunization strategy. Among the monoclonal antibodies, 3 (H50, H56, and H57) exhibited hemagglutination inhibition activity. Western blot analyses revealed that all the monoclonal antibodies reacted to the prokaryotically expressed HA1 of A/Chicken/Henan/01/2004(H5N1). The monoclonal antibodies were then used to characterize 10 avian influenza H5N1 viruses isolated from China during 2004 to 2007, by using the hemagglutination inhibition test and the antigen-capture enzyme-linked immunosorbent assay. The isolates could be divided into 4 different antigenic groups according to their responses to the monoclonal antibodies. The antigenic grouping of these 10 H5N1 isolates, using these antibodies, did not completely match their phylogenetic classification based on the hemagglutinin sequences. The results showed there were antigenic variations within the subclade 2.3.4 of H5N1, which is predominant in China.
Diversity and decay ability of basidiomycetes isolated from lodgepole pines killed by the mountain pine beetle
Authors: Son E. , Kim J.-J. , Lim Y.W. , Au-Yeung T.T. , Yang C.Y.H. , Breuil C.
Published: January 2011

When lodgepole pines ( Pinus contorta Douglas ex Louden var. latifolia Engelm. ex S. Watson) that are killed by the mountain pine beetle ( Dendroctonus ponderosae ) and its fungal associates are not harvested, fungal decay can affect wood and fibre properties. Ophiostomatoids stain sapwood but do not affect the structural properties of wood. In contrast, white or brown decay basidiomycetes degrade wood. We isolated both staining and decay fungi from 300 lodgepole pine trees killed by mountain pine beetle at green, red, and grey stages at 10 sites across British Columbia. We retained 224 basidiomycete isolates that we classified into 34 species using morphological and physiological characteristics and rDNA large subunit sequences. The number of basidiomycete species varied from 4 to 14 species per site. We assessed the ability of these fungi to degrade both pine sapwood and heartwood using the soil jar decay test. The highest wood mass losses for both sapwood and heartwood were measured for the brown rot species Fomitopsis pinicola and the white rot Metulodontia and Ganoderma species. The sap rot species Trichaptum abietinum was more damaging for sapwood than for heartwood. A number of species caused more than 50% wood mass losses after 12 weeks at room temperature, suggesting that beetle-killed trees can rapidly lose market value due to degradation of wood structural components.
VERY SPECIAL RELATIVITY IS INCOMPATIBLE WITH THOMAS PRECESSION
Authors: DAS SURATNA , MOHANTY SUBHENDRA
Published: January 2011

Glashow and Cohen make the interesting observation that certain proper subgroups of the Lorentz group like HOM(2) or SIM(2) can explain many results of special relativity like time dilation, relativistic velocity addition and a maximal isotropic speed of light. We show here that such SIM(2) and HOM(2) based VSR theories predict an incorrect value for the Thomas precession and are therefore ruled out by observations. In VSR theories the spin-orbital coupling in atoms turn out to be too large by a factor of 2. The Thomas–BMT equation derived from VSR predicts a precession of electrons and muons in storage rings which is too large by a factor of 103. VSR theories are therefore ruled out by observations.
THE HOLOGRAPHIC SCREEN AT LOW TEMPERATURES
Authors: KISELEV V. V. , TIMOFEEV S. A.
Published: January 2011

A permissible spectrum of transverse vibrations for the holographic screen modifies both a distribution of thermal energy over bits at low temperatures and the law of gravitation at small accelerations of free fall in agreement with observations of flat rotation curves in spiral galaxies. This modification relates holographic screen parameters in de Sitter spacetime with the Milgrom acceleration in MOND.
ANALYSIS OF AN ABSORPTION CHILLER DRIVEN BY THE HEAT RECOVERY ON A SOLID OXIDE FUEL CELL
Authors: LONGO GIOVANNI A. , BAGGIO PAOLO
Published: January 2011

This paper studies an absorption machine driven by the heat recovered from a Solid Oxide Fuel Cell (SOFC). The absorption unit was first evaluated by a cycle analysis determining the sensitivity to the main boundary conditions and to the internal parameters. Then a specific simulation code of all the different devices of the absorption machine was developed to evaluate the performance and size of the unit together with its operating condition limits.