bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparative Study of Different Methods of Correcting Combined Cycle Thermal Performance
Authors: Nanjappa Jagadish 
Published: October 2015

The power output and heat rate (or efficiency) of a combined cycle power plant are expressed in the Power Industry at a specified set of “reference conditions”. Some of these reference conditions pertain to the test boundary (eg. ambient air temperature, barometric pressure etc.) while some others pertain to the operating condition (eg. baseload, evaporative cooler status, etc.) within the plant boundary. The process of measuring the actual thermal performance of a combined cycle plant involves conducting a test wherein the plant is operated at the pre-determined set of operating conditions that enable minimizing deviations from the “reference conditions”. It is a well-known fact that despite all efforts made during such a test, the actual boundary and operating conditions that prevail at the time of the test will not necessarily be identical to the pre-defined set of “reference conditions”. Hence, in order to evaluate the performance levels of the plant, one of the essential steps in the testing process is to “correct” the measured power output and heat consumption (or heat rate) for differences that persist between the actual test conditions and the corresponding set of “reference conditions”. This “correction” can be performed by using either a correction curve-based approach or a model-based approach.
When a correction curve-based approach is used, the effects of the boundary conditions on the relevant performance parameter (output, heat consumption or heat rate) can be depicted as an additive correction term or as a multiplicative correction term. As such, the corrections to the boundary conditions can be applied as either a) additive or b) multiplicative or c) a combination of additive and multiplicative referred to as “hybrid”. The prevailing industry code for testing combined cycle power plants, ASME PTC 46, has adopted the “hybrid” method while the codes for testing individual equipment (such as PTC 22, PTC 6.2, PTC 6) have adopted either the additive philosophy or the multiplicative philosophy or a “hybrid” philosophy similar to PTC 46.
The purpose of this paper is to present the outcome of a study that compares the three different correction methods utilizing the correction curve approach for a combined cycle power plant. The studies were based on thermodynamic simulations performed on different plant configurations. A key result will be the quantification of the errors associated with the different methods, which are primarily a function of the ability of the different methods to inherently capture the interactions between the various boundary parameters in the correction process and are a representation of the uncertainty associated with the particular correction method. Furthermore, the paper will introduce a new calculation method and provide recommendations that will help improve the accuracies of test results.
Analysis and Comparison Between Fixed and Variable Volume Ratio Expander for Micro-Scale ORC
Authors: Gusev Sergei , van den Broek Martijn 
Published: October 2015

Waste heat recovery has become very important in the last decennia. The Organic Rankine Cycle is the most popular technology to transform waste heat into mechanical work or electricity. While large and medium scale installations are widely available on the market for various temperature and power levels, small scale ORCs are still in a pre-commercial phase because of a relatively high specific price.
To make small scale ORCs more attractive for potential customers, the price has to be drastically reduced which means reducing the manufacturing and assembling operations, the number of parts in assemblies and unification of these assemblies. In addition, the performance has to be increased by using advanced cycle architectures and the right fluids. Not only the right choice of the working fluid is important but also the expander built-in volume ratio (BVR) has to be optimal or improved. Neither a fixed volume ratio expander, nor a turbine can provide an optimal expansion of a working fluid in a wide range of operating conditions [1]. In automotive applications, for instance, a strongly fluctuating heat input will be introduced to an ORC unit.
To estimate losses caused by non-optimal operation, a model of a volumetric expander has been developed and verified using the result of extensive test campaigns with a screw expander. The volume ratio of the expander mentioned cannot be physically changed, so under widely changing pressure ratio, caused by varying inlet waste heat and ambient temperatures, it operates mostly far from its design point. The model gives a possibility to vary the BVR in order to compare a fixed-volume ratio expander with a variable one. Benefits from replacement of this expander by an adaptive one are studied. Only steady states are taken into account since there is no dynamic model of this expander developed yet. As a consequence of the results obtained, a concept of a variable volume ratio expander is proposed.
Effect of Inlet Steam Temperature on the HP Section Efficiency of a Steam Turbine
Authors: Fu Yiping , Winterberger Thomas 
Published: October 2015

Steam turbines for modern fossil and combined cycle power plants typically utilize a reheat cycle with High Pressure (HP), Intermediate Pressure (IP), and Low Pressure (LP) turbine sections. For an HP turbine section operating entirely in the superheat region, section efficiency can be calculated based on pressure and temperature measurements at the inlet and exhaust. For this case HP section efficiency is normally assumed to be a constant value over a load range if inlet control valve position and section pressure ratio remain constant.
It has been observed that changes in inlet steam temperature impact HP section efficiency. K.C. Cotton stated that ‘the effect of throttle temperature on HP turbine efficiency is significant’ in his book ‘Evaluating and Improving Steam Turbine Performance’ (2nd Edition, 1998). The information and conclusions provided by K.C. Cotton are based on test results for large fossil units calculated with 1967 ASME steam tables. Since the time of Mr. Cotton’s observations, turbine configurations have evolved, more accurate 1997 ASME steam tables have been released, and our ability to quickly analyze large quantities of data has greatly increased.
This paper studies the relationship between inlet steam temperature and HP section efficiency based on both 1967 and 1997 ASME steam tables and recent test data, which is analyzed computationally to reveal patterns and trends. With the efficiencies of various inlet pressure class HP section turbines being calculated with both 1967 and 1997 ASME steam tables, a comparison reveals different characteristics in the relationship between inlet steam temperature and HP section efficiency. Recommendations are made on how the results may be used to improve accuracy when testing and trending HP section performance.
Impact of Plant Cycling on Availability
Authors: Kumar Nikhil , Ouellette Maria , Miller Kurt , Liu Michael C. 
Published: October 2015

Evidence is mounting that power plant cycling is causing significant additional wear and tear on the units. However, the effects of this additional wear and tear on future maintenance costs, production cost, and equivalent forced outage rate (EFOR) are not accurately quantified at the present time. For example, units that were originally designed for base load operation are now being cycled by many utilities. Typically, such units experience long-term decreases in availability and significantly increased maintenance and capital equipment expenditures because several materials degradation phenomena (creep, fatigue, creep-fatigue interaction, etc.) are accelerated by increased cycling.
The authors will present results of several hundred studies, which highlight the impacts of plant cycling events on short and long term plant availability. The paper will also show the impact of plant cycling design, annual capital and operating expenses which can have a direct impact on plant availability.
Component Test Facility (ComTest) Phase 1 Engineering for 760C (1400F) Advanced Ultra-Supercritical (A-USC) Steam Generator Development
Authors: Weitzel Paul S. 
Published: October 2015

Babcock & Wilcox Power Generation Group, Inc. (B&W) has received a competitively bid award from the United States (U.S.) Department of Energy to perform the preliminary front-end engineering design of an advanced ultra-supercritical (A-USC) steam superheater for a future A-USC component test program (ComTest) achieving 760C (1400F) steam temperature. The current award will provide the engineering data necessary for proceeding to detail engineering, manufacturing, construction and operation of a ComTest. The steam generator superheater would subsequently supply the steam to an A-USC intermediate pressure steam turbine. For this study the ComTest facility site is being considered at the Youngstown Thermal heating plant facility in Youngstown, Ohio.
The ComTest program is important because it would place functioning A-USC components in operation and in coordinated boiler and turbine service. It is also important to introduce the power plant operation and maintenance personnel to the level of skills required and provide initial hands-on training experience. Preliminary fabrication, construction and commissioning plans are to be developed in the study. A follow-on project would eventually provide a means to exercise the complete supply chain events required to practice and refine the process for A-USC power plant design, supply, manufacture, construction, commissioning, operation and maintenance. Representative participants would then be able to transfer knowledge and recommendations to the industry.
ComTest is conceived as firing natural gas in a separate standalone facility that will not jeopardize the host facility or suffer from conflicting requirements in the host plant’s mission that could sacrifice the nickel alloy components and not achieve the testing goals. ComTest will utilize smaller quantities of the expensive materials and reduce the risk in the first operational practice for A-USC technology in the U.S. Components at suitable scale in ComTest provide more assurance before applying them to a full size A-USC demonstration plant. The description of the pre-front-end engineering design study and current results will be presented.
Evaluation for Scalability of a Combined Cycle Using Gas and Bottoming SCO2 Turbines
Authors: Moroz Leonid , Pagur Petr , Rudenko Oleksii , Burlaka Maksym , Joly Clement 
Published: October 2015

Bottoming cycles are drawing a real interest in a world where resources are becoming scarcer and the environmental footprint of power plants is becoming more controlled. Reduction of flue gas temperature, power generation boost without burning more fuel and even production of heat for cogeneration applications are very attractive and it becomes necessary to quantify how much can really be extracted from a simple cycle to be converted to a combined configuration.
As supercritical CO2 is becoming an emerging working fluid [2, 3, 5, 7 and 8] due not only to the fact that turbomachines are being designed significantly more compact, but also because of the fluid’s high thermal efficiency in cycles, it raises an increased interest in its various applications. Evaluating the option of combined gas and supercritical CO2 cycles for different gas turbine sizes, gas turbine exhaust gas temperatures and configurations of bottoming cycle type becomes an essential step toward creating guidelines for the question, “how much more can I get with what I have?”.
Using conceptual design tools for the cycle system generates fast and reliable results to draw this type of conclusion. This paper presents both the qualitative and quantitative advantages of combined cycles for scalability using machines ranging from small to several hundred MW gas turbines to determine which configurations of S-CO2 bottoming cycles are best for pure electricity production.
Water-Ammonia Cycles for the Utilization of Low Temperature Geothermal Resources
Authors: Fiaschi Daniele , Manfrida Giampaolo , Talluri Lorenzo 
Published: October 2015

The research deals with the possibility of effective exploitation of low temperature geothermal energy resources, which are generally much more widespread worldwide compared to conventional high temperature ones, typically available only in limited areas of the Earth. The basic idea is the application of an advanced binary cycle, only thermally coupled to the primary endogen heat source. The selected reference-power cycle is the well-known Kalina, which gives the possibility of optimizing the matching between heat capacities of the geothermal fluid (i.e. typically hot water or saturated steam) and the cycle working fluid, which is a non azeotropic NH3-H2O mixture with variable vaporization temperature at a fixed pressure.
The heat transfer diagrams of the main Kalina heat exchangers, namely the condenser and the evaporator, are analysed with the aim of minimizing the irreversibilities related to the heat transfer. At different fixed NH3-H2O composition and condenser pressures, the evaporator pressure shows an efficiency optimizing value between 40 and 55 bar, generally increasing at higher condenser pressure. At fixed geothermal heat source temperature, condenser/evaporator pressures and working mixture composition, the cycle efficiency increases with increasing evaporator temperature, because of the reduction in the approach temperature difference between the geothermal and the working fluid. Higher efficiencies are found at higher NH3 concentrations.
The proposed Water-Ammonia power cycle is further enhanced introducing a chiller (thus making the power cycle a CCP unit), thanks to the properties of the fluid mixture downstream the absorber, through an intermediate heat exchanger between the condenser and the evaporator.
Mainly due to the better matching of heat capacities between the geothermal and the working fluid, the proposed power cycle offers the possibility of interesting improvements in electrical efficiency compared to traditionally proposed binary cycles using ORCs, at fixed temperature level of the heat source. In the investigated proposal, values of electric efficiency between 15 and 20% are found.
An economic analysis is presented, demonstrating that the CCP system is able to produce electricity at decreased unit cost with respect to the power-only unit.
Developing Green, Highly Efficient Coal-Fired Power Technologies
Authors: Weizhong Feng 
Published: October 2015

Optimization and innovation of all systems are needed to increase the energy saving and reduce emissions in coal-fired power plants. Design changes can be made that are inexpensive, low risk and effective.
A series of optimization and innovation designs have been developed to significantly increase the efficiency of 2×1000MW ultra supercritical (USC) units in China. The turbine efficiency limitations due to solid particle erosion are eliminated by these improvements. The normal deterioration of the turbine efficiency has also been eliminated.
The units net efficiency at the rated operation conditions including the Flue Gas Desulphurization (FGD) and Selective Catalytic Reduction (SCR) systems now exceeds 46.5% for a single reheat system.
Sensitivity estimation in time‐of‐flight list‐mode positron emission tomography
Authors: Herraiz J. L. , Sitek A. 
Published: October 2015

Purpose:An accurate quantification of the images in positron emission tomography (PET) requires knowing the actual sensitivity at each voxel, which represents the probability that a positron emitted in that voxel is finally detected as a coincidence of two gamma rays in a pair of detectors in the PET scanner. This sensitivity depends on the characteristics of the acquisition, as it is affected by the attenuation of the annihilation gamma rays in the body, and possible variations of the sensitivity of the scanner detectors. In this work, the authors propose a new approach to handle time‐of‐flight (TOF) list‐mode PET data, which allows performing either or both, a self‐attenuation correction, and self‐normalization correction based on emission data only.Methods:The authors derive the theory using a fully Bayesian statistical model of complete data. The authors perform an initial evaluation of algorithms derived from that theory and proposed in this work using numerical 2D list‐mode simulations with different TOF resolutions and total number of detected coincidences. Effects of randoms and scatter are not simulated.Results:The authors found that proposed algorithms successfully correct for unknown attenuation and scanner normalization for simulated 2D list‐mode TOF‐PET data.Conclusions:A new method is presented that can be used for corrections for attenuation and normalization (sensitivity) using TOF list‐mode data.
Synthesis, Bioactivity Evaluation, and Toxicity Assessment of Novel Salicylanilide Ester Derivatives as Cercaricides against Schistosoma japonicum and Molluscicides against Oncomelania hupensis
Authors: Wang Weisi , Qin Zhiqiang , Zhu Dan , Wei Yufen , Li Shizhu , Duan Liping 
Published: October 2015

ABSTRACT

A series of novel salicylanilide ester derivatives were synthesized, characterized, and evaluated for cercaricidal potential against
Schistosoma japonicum
and molluscicidal potential against
Oncomelania hupensis
. Four derivatives exhibited remarkable cercaricidal activity superior to that of niclosamide. Among them, the most active compound, 4-chloro-2-((2-methoxy-4-nitrophenyl)carbamoyl)phenyl 4-methoxybenzoate (compound 4c), showed a marked minimum effective cercaricidal concentration as low as 0.43 μM and significant molluscicidal activity, with a 50% lethal concentration (LC
50
) of 0.206 g/m
2
. Particularly, compound 4c displayed 88-fold decreased fish toxicity on
Danio rerio
and 44-fold reduced cytotoxicity on human kidney HEK293 cells in comparison with the toxicity of niclosamide. The results indicated that 4c could serve as a promising drug candidate, with environmental safety properties, against
Schistosoma japonicum
at transmission stages. The preliminary molecular mechanism of target compounds in
Schistosoma japonicum
cercariae was also investigated. Salicylanilide ester derivatives exhibited an inhibitory effect on nitric oxide synthase (NOS) but no effect on lactate dehydrogenase (LDH) and acetylcholinesterase (AChE), and a strong and significant correlation between NOS inhibitory efficacy and cercaricidal activity was observed. In addition, 4c could downregulate the expression of NOS in a dose-dependent manner. These results suggested that NOS was probably one of the drug targets of salicylanilide esters.
Cadazolid Does Not Promote Intestinal Colonization of Vancomycin-Resistant Enterococci in Mice
Authors: Seiler Peter , Enderlin-Paput Michel , Pfaff Philippe , Weiss Maria , Ritz Daniel , Clozel Martine , Locher Hans H. 
Published: October 2015

ABSTRACT

The promotion of colonization with vancomycin-resistant enterococci (VRE) is one potential side effect during treatment of
Clostridium difficile
-associated diarrhea (CDAD), resulting from disturbances in gut microbiota. Cadazolid (CDZ) is an investigational antibiotic with potent
in vitro
activity against
C. difficile
and against VRE and is currently in clinical development for the treatment of CDAD. We report that CDZ treatment did not lead to intestinal VRE overgrowth in mice.
Activity of Tobramycin against Cystic Fibrosis Isolates of Burkholderia cepacia Complex Grown as Biofilms
Authors: Kennedy Sarah , Beaudoin Trevor , Yau Yvonne C. W. , Caraher Emma , Zlosnik James E. A. , Speert David P. , LiPuma John J. , Tullis Elizabeth , Waters Valerie 
Published: October 2015

ABSTRACT

Pulmonary infection with
Burkholderia cepacia
complex in cystic fibrosis (CF) patients is associated with more-rapid lung function decline and earlier death than in CF patients without this infection. In this study, we used confocal microscopy to visualize the effects of various concentrations of tobramycin, achievable with systemic and aerosolized drug administration, on mature
B. cepacia
complex biofilms, both in the presence and absence of CF sputum. After 24 h of growth, biofilm thickness was significantly reduced by exposure to 2,000 μg/ml of tobramycin for
Burkholderia cepacia
,
Burkholderia multivorans
, and
Burkholderia vietnamiensis
; 200 μg/ml of tobramycin was sufficient to reduce the thickness of
Burkholderia dolosa
biofilm. With a more mature 48-h biofilm, significant reductions in thickness were seen with tobramycin at concentrations of ≥100 μg/ml for all
Burkholderia
species. In addition, an increased ratio of dead to live cells was observed in comparison to control with tobramycin concentrations of ≥200 μg/ml for
B. cepacia
and
B. dolosa
(24 h) and ≥100 μg/ml for
Burkholderia cenocepacia
and
B. dolosa
(48 h). Although sputum significantly increased biofilm thickness, tobramycin concentrations of 1,000 μg/ml were still able to significantly reduce biofilm thickness of all
B. cepacia
complex species with the exception of
B. vietnamiensis
. In the presence of sputum, 1,000 μg/ml of tobramycin significantly increased the dead-to-live ratio only for
B. multivorans
compared to control. In summary, although killing is attenuated, high-dose tobramycin can effectively decrease the thickness of
B. cepacia
complex biofilms, even in the presence of sputum, suggesting a possible role as a suppressive therapy in CF.
The C-Terminal Zwitterionic Sequence of CotB1 Is Essential for Biosilicification of the Bacillus cereus Spore Coat
Authors: Motomura Kei , Ikeda Takeshi , Matsuyama Satoshi , Abdelhamid Mohamed A. A. , Tanaka Tatsuya , Ishida Takenori , Hirota Ryuichi , Kuroda Akio 
Published: October 2015

ABSTRACT

Silica is deposited in and around the spore coat layer of
Bacillus cereus
, and enhances the spore's acid resistance. Several peptides and proteins, including diatom silaffin and silacidin peptides, are involved in eukaryotic silica biomineralization (biosilicification). Homologous sequence search revealed a silacidin-like sequence in the C-terminal region of CotB1, a spore coat protein of
B. cereus
. The negatively charged silacidin-like sequence is followed by a positively charged arginine-rich sequence of 14 amino acids, which is remarkably similar to the silaffins. These sequences impart a zwitterionic character to the C terminus of CotB1. Interestingly, the
cotB1
gene appears to form a bicistronic operon with its paralog,
cotB2
, the product of which, however, lacks the C-terminal zwitterionic sequence. A Δ
cotB1B2
mutant strain grew as fast and formed spores at the same rate as wild-type bacteria but did not show biosilicification. Complementation analysis showed that CotB1, but neither CotB2 nor C-terminally truncated mutants of CotB1, could restore the biosilicification activity in the Δ
cotB1B2
mutant, suggesting that the C-terminal zwitterionic sequence of CotB1 is essential for the process. We found that the kinetics of CotB1 expression, as well as its localization, correlated well with the time course of biosilicification and the location of the deposited silica. To our knowledge, this is the first report of a protein directly involved in prokaryotic biosilicification.

IMPORTANCE
Biosilicification is the process by which organisms incorporate soluble silicate in the form of insoluble silica. Although the mechanisms underlying eukaryotic biosilicification have been intensively investigated, prokaryotic biosilicification was not studied until recently. We previously demonstrated that biosilicification occurs in
Bacillus cereus
and its close relatives, and that silica is deposited in and around a spore coat layer as a protective coating against acid. The present study reveals that a
B. cereus
spore coat protein, CotB1, which carried a C-terminal zwitterionic sequence, is essential for biosilicification. Our results provide the first insight into mechanisms required for biosilicification in prokaryotes.