bluuebunny/crossref_metadata_2025 huggingface dataset:
Experience From Burning Highly Aromatic Fuels in GT35, 17 MW, Gas Turbine
Authors: Nilsson Nils G.
Published: December 2014

The aromatic hydrocarbon content in a gas turbine fuel has a great influence during combustion. The aromatic hydrocarbon content governs the hydrogen content and has an indirect effect on fuel burning characteristics like the luminometer No and the smoke point.

ABB Stal got an oportunity to sell a standard GT35 gasturbine set for electrical generation to a refinery in Thailand, provided the customers prefered fuel, a naphtha containing up to 75 vol% aromatics, could be used.

A theoretical “state of the art” study indicated that 75 vol% aromatics certainly was in the unexperienced area.

Most gas turbine fuel specifications set an upper limit for the aromatic content at 30–35% for industrial GT and at 20–25% for aero engines. Higher values could result in smoke formation during combustion.

This paper describes a full scale test with the ABB GT35 standard industrial gas generator operating on a liquid fuel containing up to 75% aromatic hydrocarbon content. The measurements of CO, UHC, NOx and the smoke number, in Bacharach, taken from the exhaust during the test, will be presented as well as the influence of the combustion on the combustor wall temperature. The effect of the unique standard design on the GT35 air and fuel mixing of the primary combustor section (patented 1965) will be discussed to show how a very complete combustion was obtained also with a 75% aromatic content in the fuel.

After the test that showed that GT35 was able to burn 75% aromatics whitout smoke formation - the set was sold and delivered.
Prediction of 3-D Viscous Flow of Centrifugal Impeller With Tip-Clearance: Part 2 — Mixed-Flow Water Pump
Authors: Ng E. Y. K.
Published: December 2014

This paper describes an extension of 3D time-marching compressible Navier-Stokes solver (Part 1) for an incompressible application through the pseudo-compressibility technique suggested by Chorin. Effect of tip clearances on the mixed-flow pump is investigated. Static pressure distribution and intricate internal flow pattern is reasonably well predicted. Fine-tuning of the pseudo-compressibility parameter and grid size is required for improve convergence and stability.
Finite-Time Thermodynamic Performance for a Class of Irreversible Heat Pumps
Authors: Wu Chih , Chen Lingen , Sun Fengrui
Published: December 2014

The effect of heat resistance and heat leak on the performance of irreversible heat pumps using a generalized heat transfer law is analyzed in this paper. The relationship between the optimal cooling load and the cop (coefficient of performance) for a steady-state irreversible heat pump is derived.
Performance Study of Finned Tube Evaporators in a Humid Environment
Authors: Liu M. , Liang S. Y. , Wong T. N. , Nathan G. K.
Published: December 2014

Finned tube evaporators are commonly used as cross flow heat exchangers in air conditioning and refrigeration systems for cooling and dehumidification. A simulation model for the steady-state performance of evaporator coils is developed in this paper. The coils are simulated as equivalent, parallel refrigerant circuits. The governing equations for heat and mass balance across the tube are presented. Local heat and mass balances are applied to a control volume of infinitesimal tube length along the surface of each row for different heat transfer zones, and the uneven distribution of air temperature inside the coils and the local flow characteristics of the refrigerant are simulated. The effects of evaporating temperature, coil face velocity, inlet air temperature and relative humidity on the evaporator performance are presented. The simulation results related to the humid environment with a fixed coil geometry are discussed.
Film Condensation of R-22 and R-410A on Horizontal Enhanced Tubes
Authors: Cheng W. Y. , Hu Y. Z. Robert , Wang C. C.
Published: December 2014

This study experimentally investigates the film condensation of R-22 and R-410A on two horizontal enhanced tubes. The test tubes include a GEWA-C and a GEWA-TWX. Data was measured at three different saturation temperatures (35°C, 40°C and 45°C) in accordance with the range of practical condensation conditions in the air-conditioning and refrigeration applications. Average heat transfer coefficients were determined by overall heat transfer coefficients based on energy balance. The comparisons of heat transfer coefficients between R-22 and R-410A for both test tubes were presented.
Second Law Analysis of an Automobile Air-Conditioner With R22/R124/R152a Refrigerant Mixture
Authors: Kiatsiriroat T. , Euakit T.
Published: December 2014

In this paper the irreversibilities and second law efficiency of an automobile air-conditioner with R22/R124/R152a refrigerant blend have been carried out. The engine is 1,300 c.c. capacity and operated at different compressor speeds between 13–55 rps. The irreversibility at each component of the air-conditioner increases with higher compressor speed. Significant irreversibilities have been found at the condenser and the compressor. In the case of the cycle second law efficiency, the unit with 30% mass fraction of R22 shows better performance than those with 20 and 40% mass fraction.
Development of a Virtual Simulation System for Crane-Operating Training
Authors: Lai Jiing-Yih , Doong Ji-Liang , Hwang Jiun-Ren , Jeng Ming-Chang , Gau Chung-Yun
Published: December 2014

The purpose of this work is to develop a virtual simulation system for crane-operating training. It includes an operating chamber to simulate the driving chamber of a truck crane and a motion chair to offer additional vibrating effect. The virtual scenes, generated by a VR software, is displayed on a screen in front of the operating chamber through a 3D projector. A data communication structure is proposed to deliver the information among three personal computers. The hardware configuration of the simulator is discussed and the VR techniques used to generate the virtual scenes are addressed. A performance evaluation in terms of the frame rate is provided also.
Parallel Projection Beams for Non-Contact 3D Profile Measurement
Authors: Lee Shuo-Jen , Fan Tien-Jung
Published: December 2014

In this paper, a non-contact 3D profile measurement technique was presented which is based on the projection of parallel beams. An arc light which was assumed to be point light source was positioned in the focal point of an parabolic mirror. After it was reflected by the parabolic mirror, uniform parallel beams were projected. These parallel beams, passing through LCD, produce 27 coded patterns. The purpose of these coded patterns is to ensure their relative positions. CCD images where then taken on these coded patterns in order to perform space coding on each of the measurement points. It was followed by the calibration process with special designed model to obtain the internal and external parameters of the CCD such as focal length and ratio of pixel size. Using the triangulation theory, coordinate transformation between the measured object and the CCD will transform the 2D image plan into 3D coordinate profile. The parallelism of these projection beams eliminates the disadvantages of diffused projection light patterns, simplifies the mathematical algorithms, and reduces image processing error of the projected patterns. This can be more efficient and accurate technique for 3D profile measurement as compared with other non-contact structured light techniques.
Extension of Vectorial Tolerances for Coordinate Measurement Analysis
Authors: Yau Hong-Tzong
Published: December 2014

In recent years, vectorial tolerancing has emerged as a new alternative of representing workpiece tolerances. In contrast with conventional geometric tolerances that originated from hard gauging practice, vectorial tolerancing follows the working principle of coordinate measuring machines and CAD/CAM systems. Moreover it provides feedback from measurement directly to manufacturing process control. Many believe it is a better tolerancing method to tie design, manufacturing, and measurement together. However, current proposal of vectorial tolerancing has several limitations. First, the current orientation vector is inadequate for representing true 3D orientation. As a result, the orientation of a free form surface can not be properly established. Second, there has not been much discussion on the subject of vectorial tolerance evaluation. This paper proposes a new orientation vector which provides a more general mathematical basis for representing vectorial tolerances. It enables true 3D orientation representation and relates tolerances to functional requirement. With the mathematical definition, a systematic evaluation approach becomes possible for both analytical geometric elements and free form surfaces. Computer simulation and real-world application were studied to validate this new approach.
Gas to Liquids (GTL) Conversion: A New Option for Monetizing Natural Gas
Authors: Agee Mark A.
Published: December 2014

A new process for converting natural gas into liquid fuels and other petroleum products is described, as is the increased market opportunity this technology portends for gas turbine manufacturers. The GTL technology, developed by Syntroleum Corporation, utilizes Autothermal Reforming with air to produce a nitrogen-diluted synthesis gas having a near ideal ratio for converting into synthetic hydrocarbons via Fischer-Tropsch synthesis. A proprietary catalyst system achieves conversion rates comparable to conventional F-T processes without the need for recycling. This results in plant capital costs low enough to make conversion of remote and/or sub-quality gas into synthetic fuels economical at current oil prices. The process is energy self-sufficient and compact enough to be constructed in small sizes for plants in remote areas, including floating or platform facilities to utilize offshore gas reserves. It can also be scaled up for 50,000 BPD or larger applications.
High Vibration Problem in Compressor Piping Systems: A Case Study
Authors: Kumar G. Vijaya , Chary S. Raghava , Rajamani A.
Published: December 2014

High vibration problems resulting in damage to supports, instrument stubs etc. have been experienced in many compressor piping systems installed at different fertilizer plants. Investigations aimed at a solution to the problem included vibration measurements on the suction and discharge piping, and mathematical modeling of the piping. The measurements indicated presence of an excitation frequency in the range of 30–35% of the compressor running speed. Dynamic analysis of the piping system showed the presence of natural frequencies coinciding with or very near to the excitation frequencies. This has been further confirmed by impact tests. Analytical mode shapes clearly show that the antinodes match with high vibration zones observed at the site. The mathematical models were used to determine optimum configurations which would separate mechanical responses from excitation frequencies. These modifications have been implemented at site and the piping vibrations are within normal limits.
Evaluation of Delaminations in Aluminium Honeycomb Structures Using the Mechanical Impedance Technique
Authors: Wong Brian Stephen , Tui Cheng Guan
Published: December 2014

This paper describes an evaluation of the capability of a mechanical impedance instrument, for detecting delamination defects in aluminium honeycomb structures. The resonant frequency was found to decrease as the centre of a defect was approached. The defects have been found to be accurately represented by a model for a vibrating plate, which is rigidly clamped at its edges. It was also possible to use resonant frequency to determine the size of the defects in the specimens used in this paper. An irregularly shaped defect showed that the rate of drop in resonant frequency across an extremity of the defect was affected by the radius at the extremity and the proximity to the main central area of the defect. An important result was that an ellipsoidal shaped defect would be sized as a circular defect of diameter equal to the minor diameter of the ellipse. Also a boron skinned honeycomb was found to behave similarly to a glass fibre skinned honeycomb.
Composition and Performance Optimization of Catalyst Layer in a Proton Exchange Membrane Fuel Cell
Authors: Marr Curtis , Li Xianguo
Published: December 2014

The composition and performance optimisation of cathode catalyst platinum and catalyst layer structure in a proton exchange membrane fuel cell has been investigated by including both electrochemical reaction and mass transport process. It is found that electrochemical reactions occur in a thin layer within a few micrometers thick, indicating ineffective catalyst utilization for the present catalyst layer design. The effective use of platinum catalyst decreases with increasing current density, hence lower loadings of platinum are feasible for higher current densities of practical interest without adverse effect on cell performance. The optimal void fraction for the catalyst layer is about 60% and fairly independent of current density, and a 40% supported platinum catalyst yields the best performance amongst various supported catalysts investigated. An optimal amount of membrane content in the void region of the catalyst layer exists for minimum cathode voltage losses due to competition between proton migration through the membrane and oxygen transfer in the void region. The present results will be useful for practical fuel cell designs.
Catalytic Control of SI Engine Emissions Over Ion-Exchanged X-Zeolites
Authors: Das Randip K. , Ghosh B. B. , Bhattacharyya Souvik , DuttaGupta Maya
Published: December 2014

Three catalysts based on X-zeolite have been developed by exchanging its Na+ ion with Copper, Iron and Nickel metal ions and tested in a SI engine exhaust for a wide range of exhaust and operating conditions. Of the three catalysts, the Cu-X catalyst exhibits the best NOx and CO conversion performance while Ni-X shows slightly better performance compared to the Fe-X catalyst at any catalyst temperature. Unlike noble metals, the doped X-zeolite catalysts, studied here, exhibit significant NOx reduction for a wide λ range and exhibit a slow rate of decrease with increase in λ ratio. Back pressure developed across the catalyst bed is found to be well-afford able and power loss due to back pressure is only 0.216% at space velocity of 52500 /h. During 30 hours of testing of each catalyst, no significant deactivation of any catalyst is observed.
Coupled Soot Formation and Radiation in a Laminar Diffusion Flame
Authors: Chan S. H. , Lei Xiaoyan
Published: December 2014

The effect of soot formation on a flamelet structure and radiation in a laminar methane flamelet is presented in this paper. A new kinetics mechanism, GRI-Mech2.1, for methane combustion is used. TDMA computer code is used to solve the coupled mass conservation, momentum, energy, species, and soot transport equations to determine the properties of the flamelet. The flamelet structure and soot concentration profiles are presented over the entire range of mixture fraction. The soot enhancement by preheating is examined. Effects of soot formation and gaseous species on flame radiation are also investigated.

The calculations show that the methane/air flamelet is a light sooting flame, and that the soot formation does not have a profound effect on flame radiation and flamelet structure. It is shown that preheating the combustion air can lead to a great enhancement in soot formation but not in flame radiation. While the soot formation contributes to larger Planck mean absorption coefficient for emission, the emission lowers the flame temperature. These opposing effects dampen the effectiveness of soot formation on flame radiation enhancement in methane/air flames.
Tribology of High Speed Aerodynamic Foil Journal Bearings
Authors: Reddy D. Sudheer Kumar , Swarnamani S. , Prabhu B. S.
Published: December 2014

Foil journal bearings come under the category of air lubricated journal bearings where the lubricant is atmospheric air. In this type of bearings the pressure developed is due to the aerodynamic wedge developed between the rotating shaft and the foil bearing surface. This paper is concerned with the analysis of the bending dominated type foil bearing, in which the compliance is effected mainly through the bending of foils. The nonlinear Reynolds equation has been used for the aerodynamic pressure solution. Effect of elastohydrodynamics on foil journal bearing has been studied. The problem has been formulated using incremental finite element method. Two types of bending dominated foil bearings have been considered for analysis, namely straight foil type and curved foil type bearings. The equations for the dynamic coefficients were obtained by a perturbation technique and the results were computed using the finite element method. The effect of bearing compliance and the bearing number on performance parameters has been studied, the results were compared with the available literature.
Energy Saving in Processes Using Simple Thermodynamic Models of Utilities
Authors: Stehlík Petr , Fiaia Aleš , Hajný Zdeněk
Published: December 2014

Maximizing heat recovery in the heat exchanger network has to be considered as one of basic steps in a process design. Heating and cooling duties not serviced by heat recovery must be provided by external utilities. Simple thermodynamic models of various types of utilities (furnaces, steam boilers, steam turbines, gas turbines) are described in this paper. These models provide us with a tool for the analysis of utilities selection (provided the process heat and power demand are given), enable us to evaluate fuel burnt, power generated, costs for fuel and for exported/imported power and emissions (CO2, SO2) flowrates on a “local” or a “global” basis. This approach is convenient at the targeting stage of a design and can contribute to a substantial energy saving and flue gas emissions reduction.
Vibration and Buckling of Square Plates Containing Central Holes
Authors: Sabir A. B. , Davies G. T.
Published: December 2014

The finite element method is used to determine the natural frequencies of flat square plates containing centrally located circular or square holes. The plates are subjected to either inplane uniaxial, biaxial or uniformly distributed shear along the four outer edges. These edges are either simply supported or clamped.

To determine the stiffness and mass matrices, non conforming rectangular and triangular displacement elements are used to model the out of plane behaviour of the plate. The inplane stress distribution within the plates, which are required in the analysis are determined by using inplane finite elements having displacement fields based on assumed strains. These satisfy the exact requirements of strain free rigid body modes of displacements.

The natural frequencies of simply supported and clamped plates are initially determined when no inplane loads are applied. This showed the influence of the size of the hole on the natural circular frequency. These plates were then subjected to inplane loads and the effect of these forces on the natural frequencies are given. The results show the natural frequencies of square plates with central circular holes decrease with increasing compressive forces, and that the frequencies become zero when the compressive forces are equal to the elastic buckling loads of the plates.

By repeating this process for all boundary conditions and applied loads a comprehensive set of results is obtained for the buckling and vibrational properties of square plates containing centrally located holes.
A Nodal Load Model of 3-D Finite Element Analysis for a Crankshaft of a Truck-Mounted Compressor
Authors: Zhou Si-zhu , Dang J. G. , Chen Jacob Jen-Gwo
Published: December 2014

In order to analyze the stresses and deformations of a crankshaft of a truck-mounted compressor by means of finite element method, the most important and difficult thing is how to determine the external force model on a crankshaft. The objective of this paper is to present a new load model of 3-D finite element analysis for a crankshaft of a truck-mounted compressor used in an oil field, i.e., the contacting-distribution forces are transferred into equivalent nodal forces. Firstly, the contacting-distribution forces between the crankshaft and the links are analyzed; secondly, formulations of equivalent node forces for the working conditions of 0° and 75° are deduced; finally, the crankshaft of a gas-engine driven truck-mounted compressor is taken as an illustration.
Natural Frequency Analysis of Elastic Plate
Authors: Saijo O. , Eto H.
Published: December 2014

Large scale floating structures, such as floating airport and amusement park having two dimensional expanse in horizontal direction, which structural concept can be considered as plate-type structural system. This structural system has a great deal of potential to be applied to oceanic structures like a artificial ground. This practical fabrication will be done by a combination of units. The hydroelastic interaction problem and structural design have attracted the attention of researchers and structural engineers.

This paper presents consideration and conclusion through the numerical calculation results of the natural frequency studied under the various supporting conditions by developed computer program. The theoretical development is obtained by a way of combination of finite element method (FEM) and boundary integral equation method (BIEM). As to natural frequency analysis of oceanic structures based on the fluid-structure interaction, in general, there is an assumption to make it possible by estimating properly the added mass of the structure surrounding by water. The added mass of floating plate obtained by BIEM is modified and transformed into mass matrix of plate in FEM analysis. Herein, FEM analysis is based on the bending vibration assumption.
Analysis and Design of a Cyclone Separator for CFBC Boilers
Authors: Prasad P. M. L. , Rajamani A. , Chandrasekhar N. V.
Published: December 2014

Cyclones are the most common dust-removal systems used in combined cycle fluidized bed combustion boilers. Analysis of a cyclone separator combining flow and structural aspects is carried out using detailed three dimensional finite element modeling including stiffeners and supporting arrangement. The fluid flow study involves the solution of continuity, energy and Navier-Stokes equations. The fluid analysis gives the variation of pressure on cyclone shell, which in turn is imparted on the structural model using fluid structure interface routine. The pressure distribution obtained from the fluid-flow analysis is mapped on to the structure. Then a linear static analysis is performed considering thermal, wind and seismic loads besides the pressure loads. The results for various loads include the reaction forces at the supports and stress levels in the cyclone. The stresses are checked against the allowable values as per Indian Standard Structural Codes. A separate computer code is developed and is interfaced with the FEM program. Results indicate higher stresses in some of the beam stiffeners and at support locations. These are suitably modified and a reanalysis confirmed the stresses to be within limits. The analysis methodology combining the fluid, structure and code requirement developed shall be very useful for the design improvement and safe operation of a cyclone separator.
Modeling Procedures for Estimation of Extensional Stiffness of Knitted Fabric Reinforced Composites
Authors: Ramakrishna S. , Lim S. K. , Teoh S. H.
Published: December 2014

This paper presents effective extensional stiffness of plain-weft knitted fabric reinforced composites obtained from finite element analysis and analytical calculations. For micro-mechanical analyses, a unit cell, enclosing the characteristic periodic repeat pattern in the knitted fabric, is isolated and modeled. Psuedo three-dimensional finite element model is constructed using laminated shell elements. Composite extensional stiffness is estimated for plane-stress and plane-strain conditions. Further, stiffness and compliance averaging methods have been used to determine the upper and lower limits of composite stiffness. The models are explicitly based on the properties of fiber and matrix materials and orientation of yarns. Results obtained from the models are compared with experimental values.
Green’s Functions for Timoshenko Beam Problems
Authors: Wang C. M. , Lam K. Y. , He X. Q.
Published: December 2014

In this paper, a unified formulation is given for the bending, buckling and vibration problems of uniform Timoshenko and Euler-Bernoulli beams resting on various models of elastic foundation. Canonical Green’s functions have been derived for these beams which can be readily used to furnish exact solutions. In addition to elucidating the behaviour of the beams, the exact solutions serve as important benchmark results for checking the convergence and accuracy of various solutions obtained from numerical methods.
Kinematics and Dynamics of a Multibody System of an Oilfield Pumping Unit by Means of Finite Element Method
Authors: Zhou Si-zhu , Chen Jacob Jen-Gwo
Published: December 2014

Taking a multibody system of the oil field pumping unit into a multibody elastic system, this paper analyzes its kinematics and dynamics by means of finite element method, deduces the kinematics and dynamics function after doing the element’s and global analysis, and puts forward the procedures of this method, i.e., (1) dividing the system into elements; (2) calculating for the elements; (3) calculating the matrix of external force; (4) piling the element stiffness and mass matrixes up; and (5) solving the function. As an example, this paper illustrates the process of analyzing the multibody system of a PUMPING UNIT used in an oil field.
A Preliminary Analysis on the Vortical Structure of a Coaxial Geometry With a Central Lobed Nozzle
Authors: Yu S. C. M. , Low S. C.
Published: December 2014

The vortical structure of the turbulent, confined, coaxial geometry with a central lobe forced mixer have been determined by measurements using a two-component fibre-optic laser-Doppler anemometer at a Reynolds number of 5.1 × 104 (based on the baseline circular nozzle diameter, Di = 30 mm, and bulk mean velocity, Ur, of the two streams at 1.7 m/s). Ratios of the annular mean to the core mean velocity (λ) were kept at 0.4, 1.1 and 2.0 respectively. Results showed that the mixing processes were greatly enhanced by the formation and interactions of the normal and streamwise vorticity. In particular, the deformation and the subsequent stretching of the normal vortices shed at the nozzle walls by the streamwise vortices played a crucial role in the mixing processes. The higher speed stream appeared to determine the form of mixing downstream. For all the cases considered, strength of the streamwise vorticity were dissipated within 6Di from the nozzle exit plane.
Real Time Linear Simulation and Control for the Small Aircraft Turbojet Engine
Authors: Kong C. D. , Kim S. K.
Published: December 2014

The performance of the aero gas turbine engine requires optimization because it is directly related to overall aircraft performance.

In this study, a modified DYNGEN, a dynamic simulation program with component maps of the small aircraft turbojet engine, was used. Nonlinear dynamic simulation was performed to predict overall engine performance.

Each response characteristic of various cases, such as the 6% rpm step model, the 5% rpm step model, the 3% rpm step model, and the real-time linear model of the interpolation scheme within the operating range were compared. Among them, the real time linear model was selected for the turbojet engine with nonlinear characteristics.

Finally control schemes such as the PI (Proportional-Integral Controller) and the LQR (Linear Quadratic Regulator) were applied to optimize engine performance.

As a result of comparison of the PI and the LQR controller, the overshoot of the turbine inlet temperature was effectively eliminated by the LQR controller with the proper control gain K.
Phase 1 Testing of the Redundant Internal Mechanical Start System for the Ship Service Gas Turbine Generator Sets on the U.S. Navy’s DDG-51 Class Ships
Authors: Russom Dennis M. , Masincup William E. , Eghtessad John
Published: December 2014

The Redundant Independent Mechanical Start System (RIMSS) is a gas turbine powered, mechanically coupled start system for the Allison AG9140 Ship Service Gas Turbine Generator Sets (SSGTGs) of the U.S. Navy’s DDG-51 Class ships. The system will be original equipment on DDG-86 and follow. It will also be a candidate for backfit onto earlier DDG-51 Class ships.

This paper describes RIMSS and details a very successful phase of the RIMSS program. All U.S. Navy testing was conducted on an Allison AG9140 located at the Carderock Division, Naval Surface Warfare Center-Ship Systems Engineering Station, DDG-51 Gas Turbine Ship Land Based Engineering Site (NSWCCD-SSES LBES), Figure 1. The test agenda included 516 SSGTG starts and 75 SSGTG motoring cycles. The primary goal was to validate engine life predictions for the Allison 250-C20B gas turbine engine in the RIMSS application. A secondary goal was to evaluate the overall RIMSS system during an extended period of operation.
Pressure Drop Distribution in a Rotating Rectangular Channel With One Ribbed Surface
Authors: Prabhu S. V. , Vedula R. P.
Published: December 2014

A modified geometry for the internal cooling passages of a gas turbine rotor blade is suggested here. In this modified geometry, the Coriolis force induced enhanced heat transfer coefficients are experienced by both the coolant channel walls adjacent to the blade pressure and blade suction surfaces. This is made possible by permitting the flow to have a radially outward and a radially inward direction at different locations along the blade thickness at a given chordwise location. However, the flow geometry is complex and the corresponding pressure losses are also likely to be larger. The present investigation is a preliminary study of the pressure drop characteristics for the modified channel suggested above and the simplest case of a straight channel with ribs on only one surface is reported here. The pressure drop in a rectangular cross-sectioned duct with an aspect ratio of 2.0 rotating about an axis normal to the free-stream direction in the presence of rib turbulators glued on one of the surfaces of the test section with ribs normal to the flow direction is measured. The study has been conducted for Reynolds number varying from 10000–17000 and the rotation number varying from 0–0.21. Experiments were carried out for various pitch-to-rib height ratios (P/e) of 3, 5, 7.5 & 10 with a constant rib height-to-hydraulic diameter ratio (e/D) of 0.15. A significant increase of the friction factor is observed when the ribbed surface is the coolant channel trailing (pressure) surface in the presence of rotation. The highest friction factor is observed in a channel with a P/e ratio of 5 which would imply that there could be a significant increase in the heat transfer coefficient for this configuration. A pitch-to-height ratio of about 10, which is the most preferred choice for a stationary configuration, no longer appears to be the optimum in the presence of rotation.
Lessons Learned From Durability Surveillance of Advanced Gas Turbines
Authors: Touchton George L. , Quentin George H. , Mastrodonato Bart
Published: December 2014

New high temperature materials and improved blade cooling techniques have led 10 design of advanced models of industrial gas turbines with inlet or “firing” temperatures of 2350 degrees F. and higher. All major vendors now offer large new commercial gas turbine-generators, with outputs of 150 megawatts and higher, based on these new designs. These new turbine units offer higher overall performance and fuel efficiencies, with promise of better reliability and availability, as well as lower operating and maintenance costs.

EPRI began to assess the durability of early models of these advanced gas turbines (AGT) in 1991, by closely monitoring their performance during electric utility operation. The durability surveillance program, involving several AGT installations outlined below, will be described. However, only the first two sites involving GE units have produced a substantial operating history for discussion. The latter two sites have only recently had new AGT units installed by ABB and Siemens respectively. At the time of this writing, those new units are still being readied for utility operation. Their operating history under the durability surveillance program will be monitored, and discussed in a future paper.

• General Electric Gas Turbine Model MS7001F in peaking service at Potomac Electric Power Co. Station H at Dickerson, Maryland.

• General Electric Gas Turbine Model MS7001FA in baseload service at Florida Power & Light Co. Martin Plant at Indiantown, Florida.

• ASEA Brown Bovert Gas Turbine Model GT 24 initially in peaking service at Jersey Central Power & Light Co.(now GPU GenCo) Gilbert Station at Milford, New Jersey.

• Siemens Gas Turbine Model V84.3A in peaking service at Kansas City Power & Light Co. Hawthorn Station at Kansas City, Missouri.

The purpose is to determine the prospects for improved unit life cycle costs as a result of higher levels of performance, availability, reliability, and mantainability achieved by adding these engines to the industry fleet. This paper will describe the initial results from the Durability Surveillance studies, including observations from unit maintenance inspections as well as the output of advanced diagnostics and monitoring systems.
Object Oriented Programming and Expert Systems in Rotating Machinery
Authors: Kumar M. Sarath , Prabhu B. S.
Published: December 2014

In any rotating machinery, unbalance and misalignment of the rotor are the two major malfunctions. Perfect alignment of shafts never exists. Improper aligning of shafts through couplings often leads to severe vibration problems in many rotating machines. In the present work effect of flexible coupling misalignment on lateral vibrational characteristics of a rotor-bearing system has been studied in an Object Oriented Programming framework using finite element method. An off-line rule based expert system has been developed for condition monitoring of a gas turbine, which predicts the machine condition severity and the cause of the problem. The system is implemented in C++.
Influence of the Control Logic on Gas Turbine Operation
Authors: Bettocchi R. , Spina P. R.
Published: December 2014

This paper presents an analysis of the influence of control logic on gas turbine operation, when machine load adjustments are carried out.

An examination is made of the control logics that are possible for a two-shaft gas turbine with variable power turbine nozzle in order to reach the following objectives:

- operation in maximum efficiency conditions;

- operation in the conditions of maximum thermal power of exhaust gases at the turbine outlet;

- operation at constant turbine outlet temperature;

- operation with the maximum Surge Margin.

The control logics necessary for reaching the predetermined objectives in the part-load operation are provided by the map of gas turbine’s main performance, thermodynamic and control parameters.
A Techno-Economic Computational Tool for Power Generation Project Assessments and Life Cycle Risk Management
Authors: Gayraud Stéphane , Singh Riti
Published: December 2014

The growing desire for sponsors of power generation projects to share risk with the lenders has promoted the use of computational tools, simulating and evaluating from a techno-economic viewpoint long-term, high-risk projects. Such models need to include reliable engine diagnostics, life-cycle costing and risk analysis technique.

This paper presents a Decision Support System (DSS) for the assessment of power generation projects using industrial gas turbines. The software, programmed in Visual Basic in Excel, runs the object-oriented software Pythia which has been developed by the Department of Propulsion, Power and Automotive Engineering at Cranfield University and which can perform gas turbine performance calculations, including off-design conditions, with or without degradation effects providing thus very reliable engine diagnostics. Moreover, a life cycle cost, assessed using manufacturer methodology for instance, can be integrated into the economic model. The degree of uncertainty relating to technical and economic factors is assessed using a normal distribution and the level of risk can then be evaluated using a risk analysis technique based upon the Monte Carlo Method. The DSS therefore provides charts and result tables to support the decision making, allowing the user to achieve a good level of confidence using new techniques of risk management.
Properties and Applications of an Advanced Austenitic Fe-Ni-Cr Alloy
Authors: Ishwar Venkat R. , Johnson William C. , Lai George Y.
Published: December 2014

Many modern industrial processes require high-temperature alloys with superior environmental resistance and high-temperature mechanical properties. This paper describes a recently developed Fe-Ni-Cr-Nb-N alloy (HAYNES® HR-120® alloy) which is being used in several modern high-temperature industries. This alloy utilizes niobium (columbium) nitride and carbide strengthening mechanisms for its excellent tensile and creep-rupture strength characteristics. These properties are significantly higher than those of regular Fe-Ni-Cr alloys and some Ni-base alloys. The alloy also exhibits excellent resistance to oxidation and sulfidation needed for applications in many of these industrial processes. This alloy is increasingly being used in the petroleum refinery, waste incineration, oil and gas recovery, heat treating and land base gas turbine industries. Major properties, alloy characterization and industrial applications for this alloy are reviewed in this paper.
The Sensitivity Analysis for Life Estimation of Turbine Blades
Authors: Repetski O. , Zainchkovski K.
Published: December 2014

The proposed algorithm permits one to determine the sensitivity coefficients of natural frequencies and dynamic displacements and stresses in the free- and forced vibration analysis. This algorithm is presented in a computer program with the help of finite element method (FEM). The design variables is the thickness of the blades. Usually a maximum resonance accounts more than half the damage and deterioration of machine components. The analysis of dynamic stress sensitivity distribution for this resonance permits us to control for both the endurance of machines and their components based on the thickness. In this study the sensitivity coefficients for both free vibration, dynamic resonances are investigated by acceleration and braking the regimes.
Environmental Upgrading of GTN-16 Gas-Pumping Unit Combustion Chamber
Authors: Soudarev A. V. , Zakharov Yu. I. , Vinogradov E. D. , Gutnik M. N.
Published: December 2014

The results of research into development of engineering approaches to environmental update of the GTN-16 16 MW gas-pumping unit combustor are presented. The built-in “disc” combustor of the GTN-16 is noted for having a small length and very low hydraulic resistances. The multi-burner low-NOx combustor design was developed in a test rig. The “lean” fuel/air premix combustion was adopted as the basis for the design.

The proposed environmental update of the GTN-16 combustor does not bring about any changes in the most costly material-intensive and labour-consuming components of the combustor, viz. casing, frame, liners. No changes were also made in the automatic control system. It is noteworthy that a similar approach is appropriate for the “Turbomotorny Zavod” (Ekaterinburg, Russia) GTN-25 type 25 MW unit.
High Efficiency-Coal and Gas (HE-C&G): A Hybrid Power Plant Concept Iintegrating ABB’s GT24/GT26 Gas Turbines With Conventional Steam Power Plants for Competitive Power Generation With High Dispatch Flexibility
Authors: Fetescu Mircea
Published: December 2014

The electric power generation world is currently confronted with new challenges: deregulation, open competition, new players entering the business, new regulations governing the return on investment, increased complexity and risk.

In order to maintain or enhance their competitive position the electricity generators have as main objectives to lower generating costs, increase operating and dispatching flexibility and manage fuel related risks: availability, supply diversification, prices and price escalation and finally to capture value added profits.

In order to meet new requirements of electricity generators, ABB has developed a hybrid power plant concept integrating the sequential combustion gas turbines GT24/GT26 with existing or new conventional steam power plants: the High Efficiency Coal and Gas (HE-C&G).

The HE-C&G, with its unique design, operating and dispatching flexibility, provides our customers with the benefits of competitive power generation: the owner/operator can optimise — on line — the plant fuel and O&M costs, increase the availability, extend economic life and lower the environmental impact of the power plant. And even more, the HE-C&G creates the ability to benefit of the market opportunities: buy cheaper fuels and sell the electricity when profitable.

This paper evaluates the feasibility of combining conventional steam power plants with sequential combustion gas turbines GT24/GT26 and recommends the HE-C&G as one of the most competitive alternatives for power generation, especially for re-evaluation of existing assets and positioning in the competitive environment.
Effects of Tigecycline and Vancomycin Administration on Established Clostridium difficile Infection
Authors: Theriot Casey M. , Schumacher Cassie A. , Bassis Christine M. , Seekatz Anna M. , Young Vincent B.
Published: December 2014

The glycylcycline antibiotic tigecycline was approved in 2005 for the treatment of complicated skin and soft tissue infections and complicated intra-abdominal infections. Tigecycline is broadly active against both Gram-negative and Gram-positive microorganisms, including
Clostridium difficile
. Tigecycline has a low MIC against
C. difficile
in vitro
and thus may represent an alternate treatment for
C. difficile
infection (CDI). To assess the use of tigecycline for treatment of established CDI, 5- to 8-week-old C57BL/6 mice were colonized with
C. difficile
strain 630. After
C. difficile
colonization was established, mice (
n
= 10 per group) were treated with either a 5-day course of tigecycline (6.25 mg/kg every 12 h subcutaneously) or a 5-day course of vancomycin (0.4 mg/ml in drinking water) and compared to infected, untreated control mice. Mice were evaluated for clinical signs of CDI throughout treatment and at 1 week posttreatment to assess potential for disease development. Immediately following a treatment course,
C. difficile
was not detectable in the feces of vancomycin-treated mice but remained detectable in feces from tigecycline-treated and untreated control mice. Toxin activity and histopathological inflammation and edema were observed in the ceca and colons of untreated mice; tigecycline- and vancomycin-treated mice did not show such changes directly after treatment. One week after the conclusion of either antibiotic treatment,
C. difficile
load, toxin activity, and histopathology scores increased in the cecum and colon, indicating that
C. difficile
-associated disease occurred.
In vitro
growth studies confirmed that subinhibitory concentrations of tigecycline were able to suppress toxin activity and spore formation of
C. difficile
, whereas vancomycin did not. Taken together, these data show how tigecycline is able to alter
C. difficile
pathogenesis in a mouse model of CDI.
A Novel CO-Responsive Transcriptional Regulator and Enhanced H
2
Production by an Engineered Thermococcus onnurineus NA1 Strain
Authors: Kim Min-Sik , Choi Ae Ran , Lee Seong Hyuk , Jung Hae-Chang , Bae Seung Seob , Yang Tae-Jun , Jeon Jeong Ho , Lim Jae Kyu , Youn Hwan , Kim Tae Wan , Lee Hyun Sook , Kang Sung Gyun
Published: December 2014

Genome analysis revealed the existence of a putative transcriptional regulatory system governing CO metabolism in
Thermococcus onnurineus
NA1, a carboxydotrophic hydrogenogenic archaeon. The regulatory system is composed of CorQ with a 4-vinyl reductase domain and CorR with a DNA-binding domain of the LysR-type transcriptional regulator family in close proximity to the CO dehydrogenase (CODH) gene cluster. Homologous genes of the CorQR pair were also found in the genomes of
Thermococcus
species and “
Candidatus
Korarchaeum cryptofilum” OPF8. In-frame deletion of either
corQ
or
corR
caused a severe impairment in CO-dependent growth and H
2
production. When
corQ
and
corR
deletion mutants were complemented by introducing the
corQR
genes under the control of a strong promoter, the mRNA and protein levels of the CODH gene were significantly increased in a ΔCorR strain complemented with integrated
corQR
(ΔCorR/
corQR
↑
) compared with those in the wild-type strain. In addition, the ΔCorR/
corQR
↑
strain exhibited a much higher H
2
production rate (5.8-fold) than the wild-type strain in a bioreactor culture. The H
2
production rate (191.9 mmol liter
−1
h
−1
) and the specific H
2
production rate (249.6 mmol g
−1
h
−1
) of this strain were extremely high compared with those of CO-dependent H
2
-producing prokaryotes reported so far. These results suggest that the
corQR
genes encode a positive regulatory protein pair for the expression of a CODH gene cluster. The study also illustrates that manipulation of the transcriptional regulatory system can improve biological H
2
production.
Genotypic and Phenotypic Characterization of Escherichia coli Isolates from Feces, Hands, and Soils in Rural Bangladesh via the Colilert Quanti-Tray System
Authors: Julian Timothy R. , Islam M. Aminul , Pickering Amy J. , Roy Subarna , Fuhrmeister Erica R. , Ercumen Ayse , Harris Angela , Bishai Jason , Schwab Kellogg J.
Published: December 2014

The increased awareness of the role of environmental matrices in enteric disease transmission has resulted in the need for rapid, field-based methods for fecal indicator bacteria and pathogen detection. Evidence of the specificity of β-glucuronidase-based assays for detection of
Escherichia coli
from environmental matrices relevant to enteric pathogen transmission in developing countries, such as hands, soils, and surfaces, is limited. In this study, we quantify the false-positive rate of a β-glucuronidase-based
E. coli
detection assay (Colilert) for two environmental reservoirs in Bangladeshi households (hands and soils) and three fecal composite sources (cattle, chicken, and humans). We investigate whether or not the isolation source of
E. coli
influences phenotypic and genotypic characteristics. Phenotypic characteristics include results of biochemical assays provided by the API-20E test; genotypic characteristics include the Clermont phylogroup and the presence of enteric and/or environmental indicator genes
sfmH
,
rfaI
, and
fucK
. Our findings demonstrate no statistically significant difference in the false-positive rate of Colilert for environmental compared to enteric samples.
E. coli
isolates from all source types are genetically diverse, representing six of the seven phylogroups, and there is no difference in relative frequency of phylogroups between enteric and environmental samples. We conclude that Colilert, and likely other β-glucuronidase-based assays, is appropriate for detection of
E. coli
on hands and in soils with low false-positive rates. Furthermore,
E. coli
isolated from hands and soils in Bangladeshi households are diverse and indistinguishable from cattle, chicken, and human fecal isolates, using traditional biochemical assays and phylogrouping.