bluuebunny/crossref_metadata_2025 huggingface dataset:
Feasibility Assessment of Medium-Scale Anaerobic Digesters for Conversion of Brewery and Dairy Farm Waste Streams
Authors: Hegde Swati , Ebner Jacqueline H. , Williamson Anahita A. , Trabold Thomas A.
Published: October 2015

Anaerobic digestion (AD) involves the conversion of organic matter in the absence of oxygen to produce methane (CH4)-rich bio-gas that can be used for heating, vehicle fuel, or for generating electricity. The evolution of AD systems has historically followed two distinct paths: small residential-scale systems in the developing world to provide modest bio-gas resources for heating and cooking, and multi-million dollar facilities in the developed world for grid electricity production. However, there is a strong need to explore the possibility of applying AD technology in the medium-scale range (on the order of 100s of kW to 1 MW), which would be relevant to many farm installations and food processing plants that have significant organic waste resources. In this paper, technical and economic feasibility assessments have been conducted of two specific applications important to New York State: treatment of dairy farm resources in the Upstate region, and treatment of brewery and distillery waste in the New York City region where significant waste disposal barriers exist. In each case, a comprehensive analysis was first conducted of the available waste resources. Then, using data available in the open literature, an estimate of the total amount of renewable bio-gas that can be produced (bio-methane potential, BMP) was developed and used to compute the achievable size of a centralized AD system. For both the farm and brewery applications, it was determined that energy systems based on anaerobic digestion can be economically and environmentally viable, provided that ample organic resources are available, as well as incentives to offset the initial capital investment.
On the Environmental Sensible/Latent Heat Fluxes From A/C Systems in Urban Dense Environments: A New Modeling Approach and Case Study
Authors: González Jorge E. , Gutierrez Estatio
Published: October 2015

Recent trends for denser cities and associated levels of human activity reflected in energy demands are requiring new ways for quantifying human environmental impacts in cities. There is little information on human-induced environmental heat fluxes from very dense urban environments, and far less information on the anthropogenic sensible/latent heat flux partition. To address this, a surface energy model that takes into account evaporation from impervious surfaces and from cooling towers from buildings was implemented in the multilayer urban canopy model (BEP+BEM) of the Weather Forecasting Research (WRF) model to estimate the overall sensible/latent heat fluxes from urban surfaces and from air condition (A/C) systems from buildings in complex urban environments. The scenario used as case study was New York City (NYC) during summers (2010 & 2013). Urban canopy parameters from the Department of City Planning of NYC were assimilated into WRF with BEP+BEM at 250 meters horizontal resolution to have an accurate representation of the city topology. The modeling approach was calibrated with surface weather stations in NYC showing general good agreement with slight tendency to overestimate maximum temperatures and underestimate moisture content at nighttime. The A/C component was estimated in 150W/m2 latent heat due to cooling towers, and close to 40 W/m2 in sensible. Evaporative cooling technology diminishes between 80 and 90% the amount of sensible heat which is transformed into latent heat. Impacts of anthropogenic in the Planetary Boundary Layer (PBL) reflect warm season increases in the PBL height, and significant increases of atmospheric instability.
Achieving Sustainable Urban Energy Planning: With Specific Focus on Transportation
Authors: El-Sherif Doaa M.
Published: October 2015

The global population is expected to reach over 9 billion by 2050. The ‘second wave of urbanization’ indicates that developing world cities are growing much faster than their developed world counterparts, and most of these people will live in African and Asian cities where city growth rates are the highest.

This, ‘second wave of urbanization’ is a core driver of change in the 21st century and follows the first wave of urbanization that took place in developed countries from 1750, lasted 200 years and resulted in the urbanization of 400 million people. By contrast, the second wave of urbanization is projected to see over 3 billion additional people living in cities in a time-span of just 80 years, bringing unprecedented challenges to city doorsteps.

In the current era of development, urban sustainability is threatened by heightened global uncertainty and change. In broad terms, these changes consist of the following global factors: economic change, scarcity of resources, rapid technological and social change, environmental and climate change effects. These drivers of change have broad reach, and threaten multiple sectors — such as food, water, energy, transport and waste — that are critical for urban sustainability.

In response, this paper discusses cities’ transition to urban energy sustainability and the role of infrastructures, with focus on transportation planning. The paper highlights the case of Egypt as an example of developing countries.

The objectives of the paper are; firstly to identify the different factors affecting Egyptian cities’ transition to sustainability, and secondly to analyze the strategic urban planning process in Egypt which is a bottom-up participatory approach leading to urban sustainability.

The paper presents a case study from Egypt, illustrating the preparation of a future urban strategic plan for a small Egyptian city. The case study shows how participatory approach can result in innovative solutions leading to sustainable urban energy planning with focus on transportation.
Solar-Powered Absorption Chillers for Air-Conditioning Applications: Simulation and Techno-Economic Evaluation
Authors: Shirazi Ali , Pintaldi Sergio , Taylor Robert A. , White Stephen D. , Morrison Graham L. , Rosengarten Gary
Published: October 2015

This study investigates the techno-economic feasibility of solar-powered absorption cooling and heating systems for a large-sized hotel building in Sydney, Australia. The proposed plant primarily consists of evacuated tube solar collectors, a hot water storage tank, a single-effect absorption chiller, and a backup gas burner. Dynamic simulation of the system has been carried out using the TRNSYS environment. Several control strategies have been implemented in the model to increase the overall efficiency of the system. Solar fraction and levelized total cost of the system have been considered as energetic and economic indicators, respectively. The parametric study results reveal that the optimal values of the storage tank volume and specific collector area are 70 L/m2 and 4 m2 per kW cooling capacity of the chiller, corresponding to the solar fraction of ∼72% and levelized total cost of ∼874,000 AUD/year. Finally, the payback period of the solar equipment is calculated to be 30.8 years, reiterating this technology still needs a great deal of subsidy in order to be economically competitive with conventional air-conditioning systems.
Solar Concentrator Shape Characterisation Using Composite Light-Field Imaging
Authors: Garbrecht Oliver , Zapata José , Kneer Reinhold
Published: October 2015

The shape of an installed solar concentrator (e.g. a heliostat) may differ from its original design due to manufacturing defects, structural/wind loads and thermal expansion. By measuring the shape of a solar concentrator, it is possible to account for the deviation in optical performance from its original design point. A method to measure concentrator shape needs to be fast, accurate, and not involve contact or interference with the reflective surface of the concentrator. State-of-the-art techniques include flux mapping, photogrammetry, and deflectometry using conventional cameras.

This paper presents a study to characterise solar concentrator shapes using light-field imaging. Conventional cameras capture the light intensity of a point in a scene at a single point in the sensor, creating a two-dimensional image. A light field camera features multiple micro-lenses placed between the main lens and the sensor, providing many small images from slightly different angles in a single shot. This information is used to reconstruct the position of a light source in space. The advantage of this new technique to the ones mentioned above is that the light field camera is robust and self-contained, which allows easy-to-use application in heliostat fields.

In this study, light-field camera measurements were performed with flat mirrors and a curved mirror under laboratory conditions. In order to resolve the surface of the mirror surfaces, several methods to impose contours of the mirror surface have been studied, including dirt, small water droplets, scattering of low-power laser light, and paper-marks. A wide range of camera-to-mirror distances between 43 cm and 5 m have been studied. Greater distances allow the capture of the entire surface, but decrease the precision of depth measurements. In order to obtain high precision measurements while being able to capture the entire surface, a compositing strategy has been developed, combining several light-field image measurements. The overall accuracy of the system was improved further by averaging measurements over several image frames. Subsequently, the reconstructed surface points have been fed to a ray-tracing algorithm realized in Matlab/Python.

Results in this study are able to resolve the shape of small concentrators to sub-millimetre precision when taking pictures at a distance of 0.4 m.
The Application of a Microgrid Considering Wind Generation
Authors: Katooli Javad , Ameri Mohammad , Katooli Mohammad Hadi
Published: October 2015

Conventional power networks have experienced a gradual evolution from a centralized nature to distributed and localized structures. The upgrading of power system toward a smart grid is being developed to improve reliability and facilitate the integration of different types of renewable energies and improve load management. Due to different uncertainties linked to electricity supply in renewable MGs, probabilistic energy management techniques are going to be necessary to analyze the system. In this study, the short-term operation planning of a typical microgrid (MG) with diverse units for achieving the maximum profit, considering technical and economical constraints, for the next 24 hours, using gravitational search algorithm (GSA) with SPSS software is presented and the effect of wind generation in the planning is investigated. The MG consists of a diverse variety of power system components such as wind turbine, microturbine, photovoltaic, fuel cell, Hydrogen storage tank, reformer, a boiler, and electrical and thermal loads. Moreover, MG is connected to an electrical grid for exchange of power. The MG is managed and controlled through a central controller. The system costs include the operational cost, thermal recovery, power trade with the local grid, and hydrogen production costs. The system costs include the operational cost, thermal recovery, power trade with the local grid, and hydrogen production costs. Total obtained profit from the MG, considering with US electricity and natural gas prices is $5.312902×103.
Methanol From Electricity, Water and Carbon Dioxide: Operational Results
Authors: Morgan Eric R. , Acker Tom
Published: October 2015

A chemical reactor has been developed that takes only carbon dioxide, water and electricity as inputs and produces a mixture of methanol and water. The system includes an electrolyzer that splits water into oxygen and hydrogen; and data logging capabilities for four temperatures probes, two pressure probes and three flow rates. The methanol synthesis unit was run under a number of flow conditions to help characterize its operation. One day of continuous temperature, pressure and flow rate data from the reactor will be presented to illustrate the system robustness. Finally, synchronized flow, temperature, and pressure data will be presented for the system as it undergoes step changes in the synloop flow rate. The results show that the flow rate through the reactor strongly influences the reactor temperature, which, in turn, influences the rate of methanol production.
Design of a Cogeneration Hybrid Propulsion System for Commuter Aircrafts With Thermal Recovery
Authors: Trancossi Michele
Published: October 2015

This paper approaches the argument of cogeneration in aircraft propulsion. It presents an effective design of a cogeneration system with thrust augmentation by heat recovery for aeronautic propulsion which can be installed inside an electrical ducted fan unit. The system optimization is based on constructal law. Energy comparison against potential competitors is produced together with an analysis in terms of GHG emissions.
Heat and Mass Transfer Model for Cooling Tower and LiBr Regenerator in Turbine Inlet Chilling System
Authors: Chen Qin
Published: October 2015

A gas turbine normally suffers significant penalties in power output and heat rate during hot days. Turbine inlet chilling is an effective approach to reduce these penalties. Reducing the inlet air temperature increases the density of turbine inlet air and as a result, more air mass flow enters the compressor, resulting in more power produced. Cooling towers and liquid desiccant (Lithium Bromide, LiBr) regenerators are important components in a turbine inlet chilling system. Understanding of their heat and mass transfer performance, particularly the performance of LiBr regenerators, is of importance for system design and integration. 1-dimensional finite difference heat and mass transfer models were developed in this study to simulate the cooling capability of cooling towers and the efficiency of water removal of LiBr regenerators. The models were used to perform sensitivity analysis on the performance of the regenerator to understand the effects of major parameters such as Lewis factor (Lef), the ratio of the air to solution mass flow and the temperature of the LiBr solution at the inlet. The simulation results show that the performance is insensitive to Le. Reducing the ratio of the air to solution mass flow or increasing the temperature of the solution at the inlet increases the thermal efficiency of the regenerator.
Numerical Simulation Study for the Performance of a Large Solar Hot Water System With Horizontal Storage Tank
Authors: Yang Ru , Lin Geng-Yi
Published: October 2015

A large solar hot water system can be utilized to provide driving energy for heating system, heat-driven cooling system, as well as to provide hot water. This research addresses the effects of the storage tank design parameters on the performance of a large-scale solar hot water system with a horizontal storage tank. Most literatures only considered the stratification performance of the thermal storage tank itself instead of considering the overall system performance. Also, there is lack of experimental research data available for the design purpose. Therefore, this study employs a numerical simulation technique to study the design parameters effect of a horizontal thermal storage tank on the performance of a large-scale solar hot water system. In this study, the ANSYS-CFX program is employed to calculate the flow and temperature distributions inside horizontal thermal storage tank. Then the inlets and outlets of the tank are combined with the TRNSYS program to simulate the entire system performance under the weather of three representative cities of Taiwan, (Taipei, Taichung and, Kaohsiung). The results of the present study indicate that the vertical stratification baffles in the tank have important effects on system performance improvement. Quantitative increase of solar fraction of the total load is obtained. The comparison with the system with vertical storage tank is provided. The results of the present study can provide important reference for the large solar hot water system design in improving system efficiency.
Response Surface Based Optimization of Solar Collector Integrated With an Ammonia-Water Combined Power/Cooling Cycle Supported by Exergy Analysis
Authors: García Jesús M. , Sanjuan M. Marco E. , Padilla Ricardo Vasquez
Published: October 2015

Finding optimal operating conditions of solar-based power and cooling systems is always a challenge. Performance of these systems is highly dependent on several important parameters, which not only impact the long-term efficiency but also its technical and economic feasibility. This paper studies the operation/configuration problem of an ammonia-water power and cooling cycle using an exergetic analysis. Thermodynamic performance of the combined cycle was addressed by using analysis of variance and multiple linear regression analysis. Modeling was done in Matlab®, using Refprop 9.0 to calculate the thermodynamic properties of the ammonia-water mixture. Convergence issues were observed on the thermodynamic properties estimation carried out by Refprop when the stream had high ammonia mass fraction. To solve this issue an averaging algorithm was implemented online to estimate such properties using pure ammonia data and high, but stable, ammonia concentration data. After this implementation, small differences between current and reference model were seen.

Optimum operating conditions were obtained using response surface technique. The response variable used was the ratio between exergetic efficiency and exergy destruction. Results showed that the response variable is mainly influenced by the ammonia concentration, pressure ratio, turbine efficiency and temperature gradient in the heat exchanger. Finally integration of the power/cooling cycle with a solar field was performed using two types of concentrated solar collectors: Linear Fresnel Collector (LFC) and Parabolic Trough Collector (PTC). The analysis showed that LFC technology can be a viable alternative for small scale applications combined with power/cooling systems.
Optimization of a Solid Oxide Fuel Cell and Gas Turbine Hybrid System
Authors: Kanarit Setthawut , Karunkeyoon Wirinya , Al-Alili Ali , Eveloy Valerie , Rodgers Peter
Published: October 2015

The low efficiency and high environmental impact of conventional power cycles are a major concern. The integration of solid oxide fuel cells (SOFCs) and gas turbines (GTs) has been proposed in the literature to increase fuel to power conversion. Parametric studies are usually conducted to identify suitable operating conditions for such integrated systems. However, parametric studies only consider the main effects of the design variables and do not provide information on the interactive effect of the design variables. In this study, a multi-objective optimization is performed to optimize the performance of a SOFC-GT hybrid system. The objective functions are system efficiency and total cost rate, including capital, operating, and environmental penalty costs. The design variables are selected based on sensitivity analysis to assess the effect of the variables on the objective functions. The performance of the SOFC-GT hybrid system is modeled in Aspen Plus, while MATLAB is used for multi-objective optimization. The multi-objective optimization solution is presented in terms of a Pareto frontier.
Analysis of Li-Air Battery: Voltage Loss due to Insoluble Discharge Formation
Authors: Yuan Hao , Wang Yun
Published: October 2015

In this paper, we present analysis of air cathode performance, taking into account both electrode passivation and transport resistance raised by insoluble products. Both effects are theoretically evaluated and compared. Validation is carried out against experimental data under low currents. The effects of electrode pore structure, such as porosity and tortuosity, on both the influence of insoluble precipitates and discharge capability are investigated.
Model-Based Analysis of Electrode Design in a Direct Methanol Microscale Fuel Cell
Authors: Hollinger Adam S. , Willis Michael G. , Doleiden Daniel G.
Published: October 2015

The performance of microscale fuel cells with high-aspect-ratio electrodes, defined as the ratio of electrode length to width, is often limited by the depletion of fuel along the length of the anode. Here we present a mathematical model to study electrode aspect ratio in a direct methanol microscale fuel cell. The model is supported with experimental data to show that low-aspect-ratio electrodes achieve higher power densities via improved mass transport to electrodes. The influence of electrode width on overall cell performance was investigated by varying the catalyst deposition region in low-aspect-ratio electrodes. The performance of our experimental fuel cell is consistent with our modeling studies, achieving a maximum power density of 25.3 mW/cm2 at room temperature with 1 M methanol. The model presented here can be used to further improve the geometric design of electrodes in a microscale fuel cell.
Assessment of Cooling Tower Discharge Recirculation and Dispersion Using CFD Techniques
Authors: Pal S. , Peltier L. J. , Rizhakov A. , Kinzel M. P. , Elbert M. H. , Knight Kelly J. , Rao S.
Published: October 2015

The performance of cooling towers, whether operating by themselves, or in close vicinity of other cooling towers can be adversely affected by the re-ingestion of the cooling tower discharge into the tower intakes. The recirculation of the discharge from a wet cooling tower raises the wet bulb temperature of the air entering a wet cooling tower. Current design strategies, often account for this discharge re-ingestion issue, through a conservative adjustment to the far field ambient wet bulb temperature to calculate the actual intake wet bulb temperature. Critical applications, such as those related to nuclear safety applications where there is concern about cooling tower performance, may require more accurate and comprehensive assessment of the recirculation and dispersion of cooling tower discharge. Gaussian plume models alone are of limited use when dealing with discharges in the vicinity of large structures. This paper discusses the use of a computational fluid dynamics approach to evaluate worst case discharge recirculation effects in cooling towers. The bounding design values of tower intake wet bulb temperature increase due to recirculation (ingestion of tower’s own discharge), and interference (ingestion of another interfering tower’s discharge), are calculated considering the various conditions of cooling tower operation, ambient temperature, humidity and wind conditions. The RANS CFD model used in the study is evaluated against published experimental data for flow over bluff bodies at high Reynolds numbers, and experimental data on buoyant jets in cross flow.
Impact of Oxygen Enriched Air on High Intensity Combustion and Emission
Authors: Said Ahmed O. , Khalil Ahmed E. E. , Dalgo Daniel , Gupta Ashwani K.
Published: October 2015

The influence of oxygen enriched air-methane flame under non-premixed and premixed fuel-lean combustion conditions is examined with focus on the emission of NO and CO, combustor exit temperature (Texit), and distribution of OH* chemiluminescence intensity. A cylindrical combustor was used at combustion intensity of 36MW/m3.atm and heat load of 6.25 kW. Results are also reported with normal air (21% oxygen). Oxygen enrichment provided stable combustion operation at lower equivalence ratios than normal air and also reduced CO emission. Increase in oxygen concentration from 21% to 25% and 30% increased the NO and decreased CO emissions at all equivalence ratios examined. Using 30% O2 enriched air in premixed case showed NO emissions of 11.4 ppm and 4.6 ppm at equivalence ratios of 0.5 and 0.4, respectively. Oxygen enrichment also reduced CO emission to 38 ppm at equivalence ratio of 0.5. Operating the combustor with normal air at these equivalence ratios resulted in unstable combustion. OH* Chemiluminescence revealed increased chemiluminescence intensity with the reaction zone to shift upstream at increased oxygen concentration. The exhaust temperature of the combustor increased with oxygen enrichment leading to lower CO concentration and increased combustion efficiency. The oxidizer injected at higher velocities mitigated the impact of reaction zone to move upstream that helped to reduce significantly both the NO and CO emission specifically under non-premixed combustion.
Wave-Powered Desalination
Authors: Stiber Brian , Beyene Asfaw
Published: October 2015

Climate change, drought, population growth and increased energy and water costs are all forces driving exploration into alternative, sustainable resources. The abundance of untapped wave energy often presents an opportunity for research into exploiting this resource to meet the energy and water needs of populated coastal regions. This paper investigates the potential and impact of harnessing wave energy for the purpose of seawater desalination. First the SWAN wave modeling software was used to evaluate the size and character of the wave resource. These data are used to estimate the cost of water for wave-powered desalination taking a specific region as a case example. The results indicate that, although the cost of water from this technology is not economically competitive at this time, the large available resource confirms the viability of significantly supplementing current freshwater supplies. The results also confirm that research into the feasibility of wave power as a source of energy and water in the area is warranted, particularly as water and energy become more scarce and expensive coinciding with the maturity of commercial wave energy conversion.
Impact of Startup Purge Credit on Combined Cycle Plant Operation
Authors: Fabricius Andreas , Taylor Mark , Moelling David
Published: October 2015

Normal boiler and Heat Recovery Steam Generator Operation have required a complete purge of the boiler by fresh air before startup firing to remove potentially explosive fuels and other substances from the boiler/HRSG. For power plants in daily two-shift cycling (or more frequent starts) this not only adds time to the startup sequence but can impose significant thermal stresses on hot components exposed to cooler purge air. Since the approval of a purge credit mode in NFPA 85 (2011) where the flow of air through the HRSG during shutdown can be credited as a purge, plants can operating without a startup purge with enhanced fuel systems and operating procedures. This paper will look at the impact of purge (and purge credit) on the thermal stress and fatigue lifetimes of HRSG operating with and without purge credit. Data and simulation results will demonstrate the range of fatigue life changes from implementation of purge credits as well as other operational impacts as seen in operating data.
Reconciling Compressor Performance Differences for Varying Ambient Inlet Conditions
Authors: Smith Natalie R. , Berdanier Reid A. , Fabian John C. , Key Nicole L.
Published: October 2015

Careful experimental measurements can capture small changes in compressor total pressure ratio that arise with subtle changes in an experiment’s configuration. Research facilities that use unconditioned atmospheric air must account for changes in ambient compressor inlet conditions to establish repeatable performance maps. A unique dataset from a threestage axial compressor has been acquired over the duration of 12 months in the Midwest United States where ambient conditions change significantly. The trends show a difference in compressor total pressure ratio measured on a cold day versus a warm day despite correcting inlet conditions to sea level standard day. To reconcile these differences, this paper explores correcting the compressor exit thermodynamic state, Reynolds number effects, and variations in rotor tip clearance as a result of differences in thermal growth.
Experimental Investigations of the Effect of Scheme Exit Height and Double Row Injection on the Film Cooling Performance of a Micro Tangential Jet Scheme: Part I — Pressure Side
Authors: Hassan O. , Hassan I.
Published: October 2015

This paper presents experimental investigations of the effect of scheme exit height and double jet injection on the film cooling performance of a Micro-Tangential-Jet (MTJ) scheme. The investigations were conducted over a gas turbine vane pressure side using the transient Thermochromic Liquid Crystal technique. The suction side investigations are presented in Part II of the present paper. The MTJ scheme is a micro-shaped scheme designed so that the micro-sized secondary jet is supplied tangentially to the vane surface. The scheme combines the benefits of micro jets and tangential injection. In order to investigate the effect of scheme exit height, one row of the MTJ scheme with 1.0 hole diameter exit height and another row with 1.5 hole diameter exit height were investigated. Meanwhile, to investigate the effect of double injection, one row of the MTJ scheme in staggered arrangement with one row of fan-shaped scheme was investigated. The investigations were conducted at various blowing ratios, calculated based on the scheme exit area. The average density ratio, turbulence intensity and Reynolds number were 0.93, 8.5, and 1.4E+5, respectively. The investigations showed that the smaller the exit height, the better the film cooling performance. Meanwhile, double injecting the secondary stream from MTJ and shaped schemes did not result in significant film cooling enhancement due to the enhanced turbulence over the vane surface.
Experimental Investigations of the Effect of Scheme Exit Height and Double Row Injection on the Film Cooling Performance of a Micro Tangential Jet Scheme: Part II — Suction Side
Authors: Hassan O. , Hassan I.
Published: October 2015

This paper presents experimental investigations of the effect of scheme exit height and double jet injection on the film cooling performance of a Micro-Tangential-Jet (MTJ) scheme on the suction side of a gas turbine vane using the transient Thermochromic Liquid Crystal (TLC) technique. In part I of the present paper the investigations over the pressure side are presented. The MTJ scheme is a micro-shaped scheme designed so that the micro-sized secondary jet is supplied tangentially to the vane surface. In order to investigate the effect of scheme exit height, one row of the MTJ scheme with exit height of 1.5 hole diameters was investigated and compared with the case of 1.0 hole diameter scheme exit height. Meanwhile, to investigate the effect of double injection, one row of the MTJ scheme in staggered arrangement with one row of fan-shaped scheme was investigated. The investigations were conducted at a blowing ratio, calculated based on the scheme exit area, ranging from 0.25 to 0.625. The average density ratio during the investigations was 0.93, and the Reynolds Number was 1.4E+5, based on the free stream velocity and the main duct hydraulic diameter. The pitch to diameter ratio of the cooling holes is 6.5, and the turbulence intensity during all investigations was 8.5%. The increase in the MTJ scheme exit height did not result in significant change in the Mach number distribution. Moreover, increasing the scheme exit height resulted in enhanced effectiveness performance. The enhanced effectiveness was accompanied with Heat Transfer Coefficient (HTC) ratio augmentation as well. As a result, a reduction in the Net Heat Flux Reduction (NHFR) accompanied increasing the scheme exit height from 1.0 to 1.5 hole diameters. Besides, adding a row of shaped schemes in front of the MTJ scheme result in significant effectiveness reduction, compared to the case of single row injection. The latter was attributed to the presence of the shaped scheme inclination angle that result in enhanced secondary stream loss due to the perpendicular momentum component to the vane surface accompanying the shaped scheme secondary jet.
Gainesville Regional Utilities Kelly Plant Asset Management With Cycling Operation
Authors: Hilleman Douglas , Lindsay John M. , Hinson Tim
Published: October 2015

Gainesville Regional Utilities (GRU) is a fully vertically-integrated utility with electric power generation, transmission, and distribution system owned by the City of Gainesville, FL. We have two primary generating plant sites: Deerhaven with two conventional coal-fired steam units (DH1 and DH2) and John R. Kelly (JCC1) combined-cycle Unit 1. Kelly Station (the focus of this study) is located in southeast Gainesville near the downtown business district. It has one - 120 MW combined-cycle unit (JCC1) in 1 × 1 configuration, consisting of: one GE Frame 7E combustion turbine (dual fuel), one Applied Thermal Systems two pressure HRSG, one 50-year old Westinghouse steam turbine unit with cooling tower, fuel storage, pumping equipment, transmission, and distribution equipment.

In 2013, GRU with a seasonal peak load of approximately 500 MWs was to start receiving the output of a new 100 MW bio-fuel plant under a purchase power agreement. It was apparent that the operation of the GRU units would drastically change. It was predicted by GRU that DH2 a 255 MW coal unit would move to a cycling duty unit and the Kelly combined-cycle unit would be relegated to “peaking” operation. To better understand and predict future operational impacts, GRU contracted with Intertek AIM (APTECH) to conduct a Cost of Cycling study.

This paper is our presentation of the results of the study and the changes that were indicated by the cycling analysis to manage the GRU system at the lowest cost and to incorporate the new modes of cycling operation. The expected modes of operation based on the results of the study were reversed to use the lowest cost unit for frequent cycling of JCC1 and changed the previously base loaded coal unit DH2 into a seasonal unit with long seasonal shut downs. This paper further shows the actions implemented by GRU at Kelly station to improve the cycling response and reduce the damage impact of each cycle by managing the startup ramp rates of the limiting equipment. The plant had limited budget for capital improvements and focused principally on managing the cost by modifying the startup procedures using real time operating data.

Our conclusion was that by following the report recommendations, a new “Start Model” produced repeatable and acceptable results that minimized possible damage to the unit while meeting the need to use the renewable energy and support the customer by providing power at the lowest cost. The paper will demonstrate the improvement areas, the actual changes, and the results of those changes to the cycling data and the savings due to reduced damage.
Analysis of Radial Turbine of ORC Power Generation System for Low Temperature Heat Sources
Authors: Bo Zemin , Sang Zhenkun , Zhang Qianqian , Weng Yiwu
Published: October 2015

The radial turbine is a key component of the Organic Rankine Cycle (ORC) power generation system. In order to improve the performance of ORC system for low temperature heat sources, a 150kW radial turbine using R600a has been designed and analyzed. First, the aerodynamic calculation of the radial turbine was conducted and one-dimensional aerodynamic parameters were obtained. Then three-dimensional CFD numerical analysis has been conducted to optimize the geometric design of the radial turbine. The results show the distribution of the flow field around the blades at different height and streamline distribution from leading edge to the trailing edge. At last, the effect of rotation speed on the performance of radial turbine was analyzed. The results can provide basic data for the design of radial turbine of ORC power generation system for low temperature heat sources.
Experimental Study on the Natural Circulation System for Single-Phase Water
Authors: Nie Zesen , Bi Qincheng , Wu Di , Wu Jiangbo
Published: October 2015

The investigation on a natural circulation system for single-phase water is of value for engineering application, which has been researched by various methods. In the present study, a natural circulation experiment for single-phase water in a rectangular loop was conducted, in which water was electrical heated in a tank at the bottom of the loop and cooled by pool boiling outside of the tube bundles at the top of the loop. The system pressure was 2–6 MPa and heating power was 10–30 kW. Results show that natural circulation flow increases with heating power as a straight line for the same pressure, while no obvious influence of pressure on circulation flow for the same heating power can be found. In addition, a contrast experiment was carried out with different system resistance for further study, and it was found that the system resistance could significantly decrease heat exchange efficiency of the natural circulation system, which mainly resulted from distinctly reductive circulation flow. Emphasis was also put on extending the correlation proposed by Vijayan to the present experiment.
Preventive Maintenance and Spare Parts Management Optimization in Natural Gas Pipelines Operating Under Variable Conditions Across the Year
Authors: Carlucci Elisa , Tognarelli Leonardo
Published: October 2015

Pipeline architecture consists in several stations in series configuration; hence the unavailability of one station impacts the availability of the whole pipeline. This lead to the need of optimizing the availability of each station in terms of configuration and number of units required in order to be able of satisfying the demand at any time. The loss of production cost in gas supply application is very high.

Aero-derivatives gas Turbines are typically used as drivers in pipeline applications since they maximize train efficiency, minimizing gas consumption.

PGT25+ aero-derivative Gas Turbines are among the most popular units applied in pipeline services. They merge demonstrated reliability performances together with a very limited outage duration impact that leads to very high Availability. Outage duration is optimized through modular replacement of both GG and HSPT that is facilitated by light weight of the machine.

A Reliability Block Diagram has been built with the aim to optimize the Pipeline PGT25+ Gas Generator scheduled maintenance. Each block represents a Gas Generator while each station is realized taking into account the actual k-out-of-N configuration of each station units.

Once the model has been created, a sensitivity analysis has been performed in order to estimate the impact of the Gas Generator cycle time (Gas Generator refurbishment time),that is what if larger or shorter than the baseline 6 months. Further, even a sensitivity study has been carried on to estimate the impact of the number of available spare parts on the delay that some units will suffer due to un-sufficient number of GG spare with consequent higher risk.
Application of CFD in Optimizing Rapid Filling of Natural Gas
Authors: Kishor Shyam
Published: October 2015

A new approach for natural gas rapid fill is presented. In this approach, filling (loading) rate and gas inlet conditions are optimized to ensure optimum fill while ensuring safety and regulatory compliance.

Computational Fluid Dynamics (CFD) is used to predict loading behavior under different conditions. CFD analysis includes transient simulations of turbulent compressible flow to predict complex heat and mass transfer during filling, involving turbulence, buoyancy, compressibility and Joule-Thomson effects.

Rapid fill under various conditions are investigated. Temperature change during loading and percentage fill with the new approach are compared with the results from the conventional approach. The new approach ensures 100 percent fill at a fill rate several times faster than the conventional approach.
Numerical Investigation of Perfectly Premixed Combustion and the Effect of NOx Emission for Syngas in a Gas Turbine Combustor
Authors: Hossain Sarzina , Hossain Mohammad A.
Published: October 2015

Integrated Gasification Combined Cycle (IGCC) is a gasification process that is used to produce syngas from variety of fossil fuels, including coal, biomass, organic waste, and refinery residual. It contains variable composition of CO and H2. Because of its wide fuel flexibility, the syngas is considered as most effective fuel particularly for power generation purposes. These types of high hydrogen content fuel faces a great difficulty to lower the NOx emission due to its high flame speed, low ignition energy can cause flashback. This paper is focused on the syngas combustion along with the NOx emissions for different equivalence ratios for a multi-tube injector inside a gas turbine combustion chamber. This paper describes the numerical study of the emissions of nitrogen oxides (NOx) for perfectly premixed combustion using CFD combustion modeling. In this study CO+H2 is mixed with air in lean equivalence ratio. The CFD Eddy Dissipation model is used to study the perfectly premixed combustion. Commercial software ANSYS Fluent has been used for CFD analysis. The Eddy Dissipation model is best for turbulent flows when the chemical reaction rate is fast relative to the transport processes in the flow. There is no kinetic control of the reaction process. The Eddy Dissipation model is sufficient enough for the combustion process if air and fuel is available in a control volume.
Operability and Performance of Central (Pilot) Stage of an Industrial Prototype Burner
Authors: Kundu Atanu , Klingmann Jens , Whiddon Ronald , Subash Arman Ahamed , Collin Robert
Published: October 2015

An investigation on the central-pilot stage of a Siemens Industrial Turbomachinery 4th Generation DLE prototype test burner has been performed to understand the emission performance and operability. The core section, which is defined as RPL (Rich premixed lean) plays an important role for full burner combustion operation by stabilizing the main and pilot flames at different operating condition. Optimal fuel-air flow through the RPL is critical for multiple stages mixing and main flame anchoring. Heat and radical production from the central stage provides the ignition source and required heat for burning the main flame downstream of the RPL section. Surrounding the RPL outside wall cooling air has been blown through an annular passage. The cooling air protects the RPL wall from overheating and provides the oxygen source for the secondary combustion downstream of the RPL. At rich operation unburned hydrocarbon/radicals can pass the RPL and burns by the co-flow air entrainment. To determine the flame stabilization and operability, an atmospheric pressure test has been accomplished using methane as a fuel. Primary flame zone can be identified by a thermocouple placed outside the RPL wall and secondary combustion zone at the exit has been examined by chemiluminescence imaging. Emission measurement and LBO (Lean blow out) limits have been determined for different equivalence ratios from 1.8 to LBO limit. Co-flow air temperature was changed from 303 K to 573 K to evaluate the secondary combustion and RPL wall heat transfer effect on flame stability/emission. It is found that equivalence ratio has strong effect on the RPL flame stabilization (primary/secondary flame). Emissions/radical generation were also influenced by the chemical reaction inside the RPL. It can be noticed that co-flow air temperature has a significant role on emission, LBO and flame stabilization for the central-pilot stage burner due to the heat loss from the flame zone and RPL wall. A chemical kinetic network (Chemkin™) and CFD modelling approaches (Fluent) are employed to understand in detail the chemical kinetics, heat transfer effect and flow field inside the RPL (combustion and heat loss inside and emission capability). Experiment shows that the low CO and NOx levels can be achieved at lean and rich condition due to lower flame temperature. Present experimental results by changing equivalence ratio, residence time and co-flow temperature, creates a complete map for the RPL combustion, which is key input for full 4th Generation DLE burner design.
Numerical Simulation of Low Grade Heat and Water Recovery Using Nanoporous Transport Membrane Condensers Bundle Tubes
Authors: Soleimanikutanaei Soheil , Lin Cheng-Xian , Wang Dexin
Published: October 2015

Low grade waste heat and water recovery using ceramic membrane, is an emerging technology which helps to increase the efficiency of boilers and gas or coal combustors in various industrial processes and conventional power plants. The tube wall of a Transport Membrane Condenser (TMC) based heat exchanger is made of a nano-porous material with high membrane selectivity which is able to extract condensate water from the flue gas in the presence of other non-condensable gases (i.e. CO2, O2 and N2). In this work, a numerical study has been carried out to investigate the effects of transversal pitches of the TMC bundle tubes on the performance of a TMC based cross flow heat exchanger. A simplified multi-species transport model is used to investigate the heat and mass transfer characteristics of a condensing combustion flue gas in a crossflow transport membrane tube bundle. Various transversal (0.4”–0.6”) and longitudinal (0.4”–0.8”) pitches were used. The numerical results revealed that the effect of transversal pitches on the outlet parameters are more pronounced.
Numerical Simulation of Heavy Fuel Oil Combustion Characteristics and NOx Emissions in Calciner in Cement Industry
Authors: Aboelsaod Hisham , Khalil Essam E.
Published: October 2015

The aim of the present study is to numerically investigate the combustion characteristics of Heavy Fuel Oil (HFO) and NOx emissions inside a calciner used in cement industry. The calciner is a furnace placed before the rotary Kiln its main objectives are the reduction of CO2 emissions and air pollutions while enhancing the cement quality through separating the calcination and clinkering processes. In order to conduct the present investigations the calciner at CEMEX Egypt Cement Company was considered and real dimensions and operating conditions were applied. The combustion model was based on the conserved scalar (mixture fraction) and prescribed Probability Density Function (PDF) approach. The (RNG) k-ε turbulence model has been used. The HFO droplet trajectories were predicted by solving the momentum equations for the droplets using Lagrangian treatment. The radiation heat transfer equation was solved using P1 method. The formation of thermal NOx from molecular nitrogen was modeled according to the extended Zeldovich mechanism. The effects of varying the burner’s swirl number and viscosity grade on the combustion performance of HFO and the resulting NOx emissions were considered. The burner’s swirl number influences the mixing rate of air and fuel. A small swirl number ≤ 0.6 is not desired as it elongates the flame; increases flue gases temperatures and increases the NOx emissions inside the calciner. A swirl number ≥ 0.6 is found optimal for good combustion characteristics and NOx emissions concentration. Meanwhile, it was found that the HFO viscosity has a significant effect on the injection velocity and must be considered as a function of temperature during the analysis as this will significantly affects the combustion characteristics.
Add-On Performance Tests Based Upon PTC 46
Authors: Le Galudec Olivier
Published: October 2015

In the area of Combined Cycle Power Plant ASME PTC 46 Committee so far focussed on the performance tests of overall Plant and by doing so closed a gap since before 1996 no other test code delivered such guidelines. In present paper author addresses a smaller field, ie the Add-On Plant topic (ie Combined Cycle Plants where gas turbine(s) are not part of the scope) and suggests a methodology derived from ASME PTC 46 key principles, with the support of gas turbine and HRSG respective Codes too.