bluuebunny/crossref_metadata_2025_split huggingface dataset:
Waste Heat Recovery in LNG Liquefaction Plants
Authors: Pillai P. , Meher-Homji C. , Meher-Homji F. 
Published: August 2015

High thermal efficiency of LNG liquefaction plants is of importance in order to minimize feed usage and to reduce CO2 emissions. The need for high efficiency becomes important in gas constrained situations where savings in fuel auto consumption of the plant for liquefaction chilling and power generation can be converted into LNG production and also from the standpoint of CO2 reduction. This paper will provide a comprehensive overview of waste heat recovery approaches in LNG Liquefaction facilities as a measure to boost thermal efficiency and reduce fuel auto-consumption. The paper will cover types of heating media, the need and use of heat for process applications, the use of hot oil, steam and water for process applications and direct recovery of waste heat. Cogeneration and combined cycle approaches for LNG liquefaction will also be presented along with thermal designs. Parametric studies and cycle studies relating to waste heat recovery from gas turbines used in LNG liquefaction plants will be provided.
The economic viability of waste heat recovery and the extent to which heat integration is deployed will depend on the magnitude of the accrual of operating cost savings, and their ability to counteract the initial capital outlay. Savings can be in the form of reduced fuel gas costs and reduced carbon dioxide taxes. Ultimately the impact of these savings will depend on the owner’s measurement of the value of fuel gas; whether fuel usage is accounted for as lost feed or lost product. The negative impacts include the reduction in nitrogen rejection that occurs with reduced fuel gas usage and the power restrictions imposed on gas turbine drivers due to the increased exhaust system back-pressure caused by the presence of the WHRU. When steam systems are acceptable, a cogeneration type liquefaction facility can be attractive. In addition to steam generation and hot oil heating, newer concepts such as the use of ORCs or supercritical CO2 cycles will also be addressed.
An Introduction to Combustion, Fuels, Emissions, Fuel Contamination and Storage for Industrial Gas Turbines
Authors: Welch Michael , Igoe Brian 
Published: August 2015

It is important that gas turbines used in Oil & Gas applications can burn a wide variety of fuels with the minimum impact on the environment or project economics. This paper is an introduction for those unfamiliar with gas turbine combustion in any detail into how emissions such as NOx are formed, and how the two most common types of gas turbine combustion system — the ‘conventional’ diffusion flame combustor and the Dry Low Emissions (DLE) combustor operate.
There are many types of gaseous and liquid fuels that can be used in Gas Turbines, which can come from a wide range of natural and industrial sources. These different potential fuels are discussed, along with the flexibility of the two different combustion systems to accept different types of fuel.
Some of the common contaminants found in these fuels are also discussed, along with the impact these have on the operability and maintenance of industrial and aero-derivative gas turbines, and methods to minimize the impact of these contaminants identified. Finally the paper looks at recommendations on liquid fuel storage to minimize operational issues on liquid fuels.
Performance Potential Analysis of Heavy-Duty Gas Turbines in Combined Cycle Power Plants
Authors: Seydel Carl Georg 
Published: August 2015

Within the last decades heavy-duty gas turbines have become more relevant for the energy sector, especially due to the changing requirements on fossil power plants. In combination with high fluctuating renewables, such as wind and solar energy, combined cycle power plants provide the needed operational flexibility along with high thermal efficiency. In order to meet the ambitious reduction targets for future CO2 emissions, the extension of renewable power solutions is mandatory. Meanwhile further development of fossil power plants is important, to ensure a secure energy supply at all conditions and to back up the worldwide increasing power demand. Enhancements for heavy-duty gas turbines focus on higher thermal efficiency and increasing power output, whilst providing a high operational flexibility.
This study analyzes the future performance potential for heavy-duty gas turbines in combined cycle power plants, by further development of the main gas turbine components: compressor, combustion chamber and turbine, including the cooling system. The performance potential will be evaluated separately for each component and in combination for on- and off-design operation. The thermodynamic power plant design will be calculated with the performance software GTlab of the German Aerospace Center. Furthermore the fuel and CO2 savings for different levels of component technology development will be quantified. Concluding a potential evolution timeline for combined cycle power plants until the year 2050 will be given.
The results show that there is a high potential regarding to thermal efficiency and power output, by conventional component improvements of heavy-duty gas turbines. Also the improved components lead to a significant reduction of fuel consumption and CO2 emissions.
Aerodynamic Gas Turbine Compressor Design for an Oxy-Fuel Combined Cycle
Authors: Dahlquist Adrian , Genrup Magnus 
Published: August 2015

A number of different CCS-technologies are currently being developed to reduce CO2 emissions from thermal power stations. One of these technologies is based on the oxy-fuel combined cycle process, the basics of which have been described in several publications. The key difference in this cycle is the working fluid, which requires further investigation. The working fluid in the topping gas turbine cycle of an OCC mainly consists of CO2 (80–95 wt%) and steam (5–15 wt%), with a few percentage of enriched N2 and Ar. The gas properties of this working fluid differ significantly from those of a conventional air-breathing gas turbine; hence, the gas turbine has to be designed accordingly.
The isentropic exponent is lower, for example, with the result that a higher pressure ratio is required in an oxy-fuel combined cycle gas turbine than in a conventional combined cycle to achieve exhaust gas conditions that fit the design of a conventional bottoming steam cycle. This higher pressure ratio results in additional challenges in the design of the aerodynamic compressor.
The amount of information in the public domain about designing an oxy-fuel gas turbine is sparse and is mainly limited to the cycle design. The main objective of this work is therefore to demonstrate the feasibility of achieving the aerodynamic compression in a single-spool compressor design, suitable for an oxy-fuel combined cycle application, with the aim of bringing the technology closer to commercialization.
The aerodynamic compressor design includes 1D mid-span and 2D through-flow design calculations, and a steady-state 3D analysis calculation for validation.
The compressor’s design suits an oxy-fuel combined cycle with a net plant power of 115 MWel.
Influencing Parameters of a Tip Blowing Interacting With Rotor Tip Flow
Authors: Guinet Cyril , Inzenhofer André , Gümmer Volker 
Published: August 2015

The design space of axial-flow compressors is restricted by stability issues. Different axial-type casing treatments have shown their ability to enhance compressor stability and to influence efficiency. Casing treatments have proven to be effective, but there still is need for more detailed investigations and gain of understanding for the underlying flow mechanism. Casing treatments are known to have a multitude of effects on the near-casing 3D flow field. For transonic compressor rotors these are more complex, as super- and subsonic flow regions alternate while interacting with the casing treatment. To derive design rules it is important to quantify the influence of the casing treatment on the different tip flow phenomena. Designing a casing treatment in a way that it antagonizes only the deteriorating secondary flow effects can be seen as a method to enhance stability while increasing efficiency.
The numerical studies are carried out on a tip-critical rotor of a 1.5 stage transonic axial compressor. The examined recirculating tip blowing casing treatment, which consists of a recirculating channel with an air off-take above the rotor and an injection nozzle in front of the rotor. The design and functioning of the casing treatment is influenced by various parameters. A variation of the geometry of the tip blowing, more specifically the nozzle aspect ratio, the axial position or the tangential orientation of the injection port, was carried out to identify key levers.
The tip blowing casing treatment is defined as a parameterized geometric model and is automatically meshed. A sensitivity analysis of the respective design parameters of the tip blowing is carried out on a single rotor row. Their impact on overall efficiency and their ability to improve stall margin is evaluated. The study is carried out using URANS simulations.
A Method for Efficient Performance Prediction for Fan and Compressor Stages With Degraded Blades
Authors: Giebmanns A. , Schnell R. , Werner-Spatz C. 
Published: August 2015

Over service time fan and compressor blades vary in their geometry. Due to the geometric irregularities it is difficult to reliably assess the fan or compressor performance. Therefore, in the present study, a method that allows an efficient and accurate estimation of the performance for fan and compressors with degraded blades is established.
In a first step, the blade regions mainly exposed to geometry variations are identified. Then, a simple parameterization that enables to easily describe the blade geometry as well as to independently represent the variations of all relevant geometric parameters is defined. For each geometric parameter (e.g. leading edge shape, rotor clearance gap height), the shifts of the operating points in the performance map due to the geometric variations are calculated. This is done with an adjoint flow solver which simultaneously provides the shifts for all extents of geometric parameter variations. As the geometric parameters are assumed to be independent of each other, the combination of variations in several geometric parameters is estimated by simply adding the shift vectors determined for the individual parameters.
The results for a subsonic compressor stage show a significant influence of the variations in the geometric parameters on the compressor performance. As validation with few nonlinear simulations demonstrates, this influence is well predicted by the method presented in this study. The relative deviation of the performance map parameters in the operating points around peak efficiency is less than 0.5 %. Compared to the nonlinear simulations, the numeric effort to determine the influence of seven geometric parameters on the performance map with the method based on adjoint simulations is considerably reduced by a factor of 35. In summary, the results demonstrate the feasibility of the method and encourage its application in an industrial context.
Characterization of Emissions From the Use of Alternative Aviation Fuels
Authors: Chan Tak W. , Chishty Wajid A. , Canteenwalla Pervez , Buote David , Davison Craig R. 
Published: August 2015

Alternative fuels for aviation are now a reality. These fuels not only reduce reliance on conventional petroleum-based fuels as the primary propulsion source, but also offer promise for environmental sustainability. While these alternative fuels meet the aviation fuels standards and their overall properties resemble those of the conventional fuel, they are expected to demonstrate different exhaust emissions characteristics because of the inherent variations in their chemical composition resulting from the variations involved in the processing of these fuels.
This paper presents the results of back-to-back comparison of emissions characterization tests that were performed using three alternative aviation fuels in a GE CF-700-2D-2 engine core. The fuels used were an unblended synthetic kerosene fuel with aromatics (SKA), an unblended Fischer Tropsch synthetic paraffinic kerosene (SPK) and a semi-synthetic 50-50 blend of Jet A-1 and hydroprocessed SPK.
Results indicate that while there is little dissimilarity in the gaseous emissions profiles from these alternative fuels, there is however a significant difference in the particulate matter emissions from these fuels. These differences are primarily attributed to the variations in the aromatic and hydrogen contents in the fuels with some contributions from the hydrogen-to-carbon ratio of the fuels.
Axial Flow Fan Design Experience for a Project Based Turbomachinery Class
Authors: Cardillo Lucio , Corsini Alessandro , Delibra Giovanni , Sheard Anthony G. , Volponi David 
Published: August 2015

In consideration of the extremely rapid progress in turbomachinery technology after the WWII, when the first gas engine was run, modern turbomachinery could be considered a young subject. Developments in computational power and numerical techniques since the 1940s, totally changed designer’s perspectives, giving them the possibilities to increase power and sophistication of design tools consolidated by years of laboratory and field tests from the 1940’s and 1950’s. A huge database from which, we believe, “there is still so much to be learned” (Cumpsty, 1986) [1].
On the other hand turbomachinery performance correlations, or even design procedures, have tended to be developed in individualistic ways. A reason for this has been the use of different approaches within engineering companies and the development of customized design tools and correlation of previous experience or performance optimization.
These circumstances reflected in an extraordinary knowledge, hided by confidentiality and intellectual property issues. In this respect, proprietary design techniques acts as a barrier to the dissemination of concepts at the early stages such as the university.
This paper illustrates the design process of an industrial fan as taught at Sapienza, University of Rome, during lectures of Turbomachinery Design. Objective of the class was to help students learn to develop their own design tools from the available suggested literature Horlock (1958, 1962, 1966) [2] [3] [4], Dixon (1975) [5], Lakshminarayana (1995) [6], Cumpsty (1989) [1] and Lewis (1996) [8]. Moreover, the activities were oriented to the use of open source software, specifically Scilab, used to code preliminary design and optimization routines as well as OpenFoam for the CFD verification step.
Performance Testing of the 100 kW Shell-and-Tube Heat Exchanger Using Low-Finned Tubes With Supercritical Carbon Dioxide on the Shell Side and Water on the Tube Side
Authors: Fourspring Patrick M. , Nehrbauer Joseph P. 
Published: August 2015

BMPC completed thermal-hydraulic testing of a shell-and-tube heat exchanger with low-finned tubes for transferring heat from supercritical carbon dioxide (S-CO2) on the shell side to water on the tube side.
The measured performance of the shell-and-tube heat exchanger using low-finned tubes on the shell side showed that it achieved the specified thermal-hydraulic performance.
The analytical approach to determine the performance of a shell-and-tube heat exchanger with low-finned tubes and S-CO2 on the shell side compares well with the measured performance of the heat exchanger.
The additional heat transfer area provided by the low-finned tubes remained fully effective — even with reduced flow velocity and the supercritical fluid near its critical point or a pseudo-critical temperature1. Over a range of limiting flow conditions of the supercritical fluid, the thickness of the thermal boundary layer remained sufficiently thin to allow the low-finned tubes to remain fully effective. This result supports (but is not sufficient to prove) the general guidance to limit the estimated thickness of the thermal boundary layer to the fin height and twice the fin spacing to ensure the additional heat transfer area provided by the low-finned tubes remains effective.
Aerodynamic Characterization of Conical Diffusers for Radial Turboexpanders Under Realistic Inlet Conditions
Authors: Insinna Massimiliano , Salvadori Simone , Cagnarini Claudia , Mariotti Gabriele 
Published: August 2015

Radial inflow expander units are increasingly employed in both oil and gas upstream and downstream markets for energy saving purposes. While prominent attention is given to the performance of the expansion wheel, the downstream diffuser is scarcely covered in literature. In modern expanders, the gas entering the diffuser is typically high-speed, non-uniformly distributed from hub to shroud. Recovery factor and pressure loss coefficient are then affected by both the inlet gas conditions and the geometry of the system, including shaft end and divergence angle of the diffuser.
In the present work, the application of computational methodologies to expander diffusers is initially assessed. A sensitivity analysis is then performed with respect to the inlet flow conditions and the diffuser shape. Trends of variation of recovery factor and loss coefficient are provided as a function of selected geometrical parameters and boundary conditions. It is shown that, starting from a non-optimized diffuser, an overall machine efficiency gain can be achieved. That performance improvement can be appreciated by the current market of expanders as a non-negligible competitive advantage.
Process Integration for Large Front-Stage Blades Mechanical Integrity Design
Authors: Hecker Philipp , Cerutti Stefano , Lötzerich Michael 
Published: August 2015

The mechanical integrity design of front stages for heavy duty gas turbines is by definition a challenging task. Several design criteria need to be fulfilled, reaching from static stress requirements over sufficient cyclic lifetime to a defined dynamic behavior of the component. This design task becomes even more challenging in case the size of the engine increases.
To satisfy the need for designing larger front stage blades, an automated and integrated design tool suite for Mechanical Integrity analysis tasks has been developed. This paper introduces the specific steps of the mechanical assessment in the early concept phase of new designs. The overall process relies on advanced numerical methods, namely Design of Experiments, numerical optimization and probabilistic techniques, which are combined into a single package. The delineated procedure represents an incremental approach, which contrasts to the integrated and partially multi-disciplinary optimization processes which are typically described in literature.
The benefits of the incremental method can be identified with regard to computational time, enhancement of interfaces and feedback loops with neighboring disciplines. By applying the process outlined in this paper, a new generation of frontstage blades could be developed with further improved mechanical properties and reduced development efforts.
An Experimental and Numerical Assessment of Airfoil Polars for Use in Darrieus Wind Turbines: Part 1 — Flow Curvature Effects
Authors: Bianchini Alessandro , Balduzzi Francesco , Rainbird John M. , Peiro Joaquim , Graham J. Michael R. , Ferrara Giovanni , Ferrari Lorenzo 
Published: August 2015

A better comprehension of the aerodynamic behavior of rotating airfoils in Darrieus Vertical-axis wind turbines (VAWTs) is crucial both for the further development of these machines and for improvement of conventional design tools based on zero or one-dimensional models (e.g. BEM models).
When smaller rotors are designed with high chord-to-radius (c/R) ratios so as not to limit the blade Reynolds number, the performance of turbine blades has been suggested to be heavily impacted by a virtual camber effect imparted on the blades by the curvilinear flow they experience.
To assess the impact of this virtual camber effect on blade and turbine performance, a standard NACA0018 airfoil and a NACA0018 conformally transformed such that the airfoil’s chord line follows the arc of a circle, where the ratio of the airfoil’s chord to the circle’s radius is 0.25 were considered. For both airfoils, wind tunnel tests were carried out to assess their aerodynamic lift and drag coefficients for Reynolds numbers of interest for Darrieus VAWTs.
Unsteady CFD calculations have been then carried out to obtain curvilinear flow performance data for the same airfoils mounted on a Darrieus rotor with a c/R of 0.25. The blade incidence and lift and drag forces were extracted from the CFD output using a novel incidence angle deduction technique.
According to virtual camber theory, the transformed airfoil in this curvilinear flow should be equivalent to the NACA0018 in rectilinear flow, while the NACA0018 should be equivalent to the inverted transformed airfoil in rectilinear flow.
Comparisons were made between these airfoil pairings using the CFD output and the rectilinear performance data obtained from the wind tunnel tests and XFoil output in the form of pressure distributions and lift and drag polars.
Blade torque coefficients and turbine power coefficient are also presented for the CFD VAWT using both blade profiles.
An Experimental Investigation of the Performance Impact of Swirl on a Turbine Exhaust Diffuser/Collector for a Series of Diffuser Strut Geometries
Authors: Xue Song , Guillot Stephen , Ng Wing F. , Fleming Jon , Lowe K. Todd , Samal Nihar , Stang Ulrich E. 
Published: August 2015

A comprehensive experimental investigation was initiated to evaluate the aerodynamic performance of a gas turbine exhaust diffuser/collector for various strut geometries over a range of inlet angle. The test was conducted on a 1/12th scale rig developed for rapid and accurate evaluation of multiple test configurations. The facility was designed to run continuously at an inlet Mach number of 0.40 and an inlet hydraulic diameter-based Reynolds number of 3.4×105. Multi-hole pneumatic pressure probes and surface oil flow visualization were deployed to ascertain the effects of inlet flow angle and strut geometry. Initial baseline diffuser-only tests with struts omitted showed a weakly increasing trend in pressure recovery with increasing swirl, peaking at 14° before rapidly dropping. Tests on profiled struts showed a similar trend with reduced recovery across the range of swirl and increased recovery drop beyond the peak.
Subsequent tests for a full diffuser/collector configuration with profiled struts revealed a rising trend at lower swirl when compared to diffuser-only results, albeit with a reduction in recovery. When tested without struts, the addition of the collector to the diffuser not only reduced the pressure recovery at all angles but also resulted in a shift of the overall characteristic to a peak recovery at a lower value of swirl. The increased operation range associated with the implementation of struts in the full configuration is attributed to the de-swirling effects of the profiled struts. In this case the decreased swirl reduces the flow asymmetry responsible for the reduction in pressure recovery attributed to the formation of a localized reverse-flow vortex near the bottom of the collector. This research indicates that strut setting angle and, to a lesser extent, strut shape can be optimized to provide peak engine performance over a wide range of operation.