bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Solar PV System Simulation Using PVsyst to Minimize Power Outage During Dry Season in Padang, Indonesia
Authors: Asikin Rizki , Kowalski Gregory , Faizal Ricky
Published: October 2015

Padang, the capital city of West Sumatra in Indonesia, has experienced major power outage repeatedly every year since 2006, typically causing people to experience 4–12 hours without electricity per day. The area is mainly supported by three lake-based hydro power plants, Maninjau, Singkarak, and Batang Agam. The electrical supply problems appear during the dry season when water availability is limited. Power outage during dry season in Padang area also becomes inevitable because the Sumatra island electricity system is a 150 kV interconnection power grid and due to the limitation of the transmission power transfer capacity lines from the Southern part of Sumatra (max for 250 MW) the demand cannot be satisfied. This paper presents the 2012 data of power outage and power production in Padang area. Using PVsyst software, a simulation of 200 MW solar PV systems in the Padang location is studied. Three scenarios are described, the current conditions without solar PV, with solar PV, and with solar PV-hydro collaboration. The results show that solar PV-hydro collaboration reduces the power outages significantly and distributes it more uniformly for the 2012 data.
Chloride Salt Systems for High Temperature Thermal Energy Storage: Properties and Applications
Authors: Myers Philip D. , Bhardwaj Abhinav , Goswami D. Yogi , Stefanakos Elias
Published: October 2015

There is substantial potential to increase the operating temperatures of concentrating solar power (CSP) plants, thereby increasing the Carnot efficiency. Coupled with viable thermal energy storage (TES) strategies, this would bring us closer to achieving the goals of the U.S. Department of Energy Sunshot Initiative. Current TES media employ molten inorganic salts (namely, nitrate salts) for thermal storage, but they are limited in application to lower temperatures: generally, below 600°C. While sufficient for parabolic trough power plants, these materials are inadequate for use with the higher operating temperatures achievable in solar power tower-type CSP plants. For these higher temperatures, chloride salts are more ideal candidate storage media, either for sensible heat storage in the molten salt (e.g, a dual-tank storage arrangement) or for sensible and latent heat thermal energy storage (LHTES) as phase change materials (PCMs). Their melting points and those of their eutectic mixtures cover a broad range of potential operating temperatures, up to and including 800.7°C, the melting point of pure NaCl.

This paper examines these salt systems and presents relevant properties and potential applications in high temperature (>400°C) utility scale solar thermal power generation. A preliminary screening of pure chloride salts based on available literature yields a list of promising candidate salts. Eutectic mixtures of these salts are also considered; the eutectic systems were modeled using the thermodynamic database software, FactSage. Thermophysical properties (melting point, latent heat) are summarized for each salt system. Radiative properties are also addressed, since at these temperatures, thermal radiation can become a significant mode of heat transfer. Candidate containment materials and strategies are discussed, along with the attendant potential for corrosion. Finally, cost data for these systems are presented, allowing for meaningful comparison among these systems and other materials in the context of utility scale thermal energy storage units.
Heat and Mass Transfer Analysis of a Water and Solute Separation System: Using Solar Thermal Energy for Water Desalination
Authors: Li Peiwen , Peri Aditya , Ma Hongzhang , Chen Yingwen
Published: October 2015

A concept and the associated device of thermal-driven water treatment to fully separate water and solute have been proposed. The device is integrated to a conventional multi-effect-distillation water treatment system to achieve high energy efficiency and 100% water extraction using high temperature thermal energy. In the water treatment system, water for reclamation is sprayed into droplets which fall into hot, dry air and creates very effective convective heat transfer between water droplets and hot airflow. During the heat transfer process, water is vaporized for pure water collection while the crystallized solute from the reclamation water settles down to the bottom for collection. The current study investigates the energy consumption versus water treatment in the system, the correlation of the size of droplets and the temperature of hot air, and the mass heat distribution in subsystems or devices. Results from the study provide important guidance to the design of such a water treatment system.
Design of a Solar Thermochemical Reactor for Calcium Oxide Based Carbon Dioxide Capture
Authors: Reich Leanne , Melmoth Luke , Gresham Robert , Simon Terrence , Lipiński Wojciech
Published: October 2015

An engineering design for a 1-kW dual-cavity solar-driven reactor to capture carbon dioxide via the calcium oxide based two-step carbonation-calcination cycle is presented. In the low temperature carbonation step, gas containing up to 15% carbon dioxide flows through a gas manifold and plenum into an annular reaction zone filled with calcium oxide particles. The carbon dioxide reacts with the calcium oxide, forming calcium carbonate. Carbon dioxide-depleted gas flows out of the reactor through a second gas manifold. In the high temperature calcination step, concentrated solar radiation enters the beam-up oriented, windowless reactor and is absorbed by the diathermal cavity wall, which transfers heat via conduction to the calcium carbonate particles formed in the previous step. The calcium carbonate dissociates into calcium oxide and carbon dioxide. Additional carbon dioxide is used as a sweep gas to ensure high purity carbon dioxide at the outlet. Mechanical and thermal analyses are conducted to refine an initial reactor design and identify potential design shortcomings. Numerically predicted temperature profiles in the reactor are presented and the final reactor design is established.
Performance of a Multi-Cell MgCl2/NH3 Thermo-Chemical Battery During Recharge and Operation
Authors: Udell Kent S. , Kekelia Bidzina , Fan Peng , Zhou Chengshang , Fang Zhigang
Published: October 2015

The development of thermal energy storage technologies to match sustainable energy production is of interest. A prototype of a multi-cell thermochemical battery consisting of connected cells containing MgCl2 salt, and additional air-cooled or air-heated cells containing liquid ammonia of varying quality, was constructed and tested. Each of the 17 cells contained thermocouple probes at three different axial locations within the cylindrical cells. Heat transfer rates, pressures, and ammonia condensation and vaporization rates were measured.

Three tests were run. In the first test, the hot bed containing 10 cells was heated using cartridge heaters, driving vaporous ammonia from the salt phase once sufficient salt temperatures were reached. The evolved gaseous ammonia was condensed in an additional 7 empty air-cooled cells. Once the recharging cycle was complete, a valve in the ammonia vapor line connecting the cold and hot beds was closed, allowing indefinite storage of cooling or heating capacity. The second operational test involved the opening of the valve while simultaneous air-cooling the hot bed cells and air-heating the cold bed cells. Heating rates and cooling rates to/from air forced through the hot bed and cold bed, respectively, were monitored to gauge HVAC performance. The second recharge was performed by using a air/air heat exchanger that captured waste heat from an automobile engine exhaust manifold and transferred it to air that was re-circulated through the hot bed array. Temperatures, pressures, heating rates, cooling rates, and cell array heat transfer specifications are reported.
Measurement of Particulate Flow in Discrete Structure Particle Heating Receivers
Authors: Khayyat A. W. , Knott R. C. , Nguyen C. L. , Golob M. C. , Abdel-Khalik S. I. , Jeter S. M. , Al-Ansary H. A.
Published: October 2015

Conventional central receiver power tower plants typically use steam or molten salts as the heat collection medium. Recently, attention has returned to using solid particulates in a particle-heating receiver (PHR). In this project we are interested in discrete structure PHR that includes structures, such as an array of wire mesh protrusions in our current design, to increase the residence time of particles falling through the receiver. The meshes should be sized to accommodate the falling particles without exposing too much mesh to concentrated radiation, which might degrade collection efficiency and expose the mesh material to high temperature thermal degradation. The experiment described in this paper was implemented to measure the appropriate exposed length of such discrete porous structures for a PHR.

Particulates are introduced to the model PHR from a perforated plate distributor. As detailed in the body of the paper, a laser and photosensor (responding in units of lux) are used at positions 546 mm and then 1111 mm downstream from the perforated plate to measure the transparency of the flow in a vertical plane across the receiver. The laser light forms a vertical sheet, and its intensity is measured by the photosensor on the opposite side of the receiver. By comparing the lux data with and without particles flowing, the transparency of the particulate curtain can be determined. Different mesh counts have been tested and compared, and plotted for comparison. This research is useful for designers to use when planning a PHR and will inform the proper length of wire meshes to use. This paper reports the results obtained so far including a standard error propagation analysis.
From Passive to Active Pitch Regulation of Wind Turbines: Optimization Method With Numerical Validation
Authors: Al-Abadi Ali , Kim YouJin , Park Jin-young , Kang Hyunjin , Ertunc Özgür , Delgado Antonio
Published: October 2015

An optimization method that changes the control strategy of the Horizontal Axis Wind Turbine (HAWT) from passive- to active-pitch has been developed. The method aims to keep the rated power constant by adjusting the blade pitch angle while matching the rotor and the drive torques. The method is applied to an optimized wind turbine model. Further, numerical simulations were performed to validate the developed method and for further investigations of the flow behavior over the blades.
Economical Optimization of Microgrids: A Non-Causal Model
Authors: Milis Kevin , Peremans Herbert
Published: October 2015

In this paper we present an economical optimization model for a microgrid connected to the general electricity grid by minimizing the total operating cost over a given period in the presence of uncertain future grid electricity prices. The microgrid is modeled to consist of five distinct blocks, four of which make up the microgrid and the fifth one being the connection to the general electricity grid. Each of these components has various adjustable attributes, allowing for the simulation of different kinds of consumers as well as different storage and generation technologies. Consumption and intermittent generation are exogenous variables derived from existing datasets. Under uncertain future grid electricity prices, the storage component introduces a non-causal dependency into the model, to cope with this non-causality, we present various storage use strategies and analyze the resulting cost patterns using real electricity price data and Monte Carlo simulations.
Irreversibility and Second Law Analysis in a Solar Cooker Box-Type
Authors: Terres Hilario , Chavez Sandra , Lopez Raymundo , Lizardi Arturo , Lara Araceli , Morales Juan R.
Published: October 2015

In this work, four different arrangements of solar cooker box-type with internal reflectors results, for irreversibility and second law efficiency are presented. The solar cooker has two glasses in its cover to diminish the losses of heat radiation and convection, which in turn creates the hot house effect inside the cooker. The interior of the cooker has flat mirrors placed at different angles to reflect the solar radiation toward recipient with water. The obtained results are based on the heated water temperatures. These are obtained by means of numerical simulation, which in turn allows the comparison under identical conditions for the cookers. The results reveal that the energy reaching the cookers, less than 5%, is used in the water heating process. Most of the available energy is “stored” into the cooker glass cover, which shows the need for further work on improving cover materials in order to diminish such a situation.
Optimisation of Paraboloidal Dish Fields for Direct-Steam Generation
Authors: Cumpston J. , Pye John D.
Published: October 2015

We investigate losses and costs associated with direct steam generation via parabolidal dish concentrators and steam transport to a central steam Rankine power cycle for electricity generation. This study presents a power plant model that accounts for the effects of shading, steam transport, energy conversion at the power block, and capital costs of land and pipework. The pipe network topology used was optimised using a genetic algorithm based on evolution of minimal spanning trees connecting all dishes to a central power block. Optimal pipe sizing of the network is determined by considering the trade-off of frictional losses against thermal losses and material costs. Weather data provides input for the solar resource, and shading is calculated using an established numerical model. The plant model is used to determine the collector layout for which the effective annual revenue is maximised. Results show that the optimal rectangular layout is closely spaced in the North-south direction, along which most of the pipe links run, while East-west spacing is less important. The annual thermal performance of the optimised dish field on a per-unit-area basis is then compared to simulation of a parabolic trough employed for the same purpose. A detailed breakdown of the thermal analysis used forms the basis of comparison between the collector types, giving the overall advantage and a comparison of various sources of loss. We demonstrate that dish fields can collect approximately 49% more thermal energy annually per unit collector area than a trough system employed for the same purpose.
Study on Performance Improvement of a Compressive Thermoelastic Cooling System Using Single Objective Optimization
Authors: Qian Suxin , Alabdulkarem Abdullah , Ling Jiazhen , Hwang Yunho , Radermacher Reinhard
Published: October 2015

Thermoelastic cooling, also known as elastocaloric cooling, is one alternative cooling technology aiming to reduce the use of global warming potential refrigerants in vapor compression cycles. The cooling is based on the latent heat associated with the martensitic phase change induced by stress in shape memory alloys, driven by either compression or tension. A few past studies have explored and proposed the cycle options and system setup of a compressive thermoelastic cooling system using nitinol tubes as working material. The system coefficient of performance (COP) and cooling capacity were predicted by a dynamic model based on the physics of the integrated complicated heat transfer process and martensitic phase change. This study aims to start the performance improvement studies via optimization using the model. The objective function of the optimization problem is COP. Design variables include a few important operating parameters, such as flow rates and cycle frequency. The previously developed dynamic model is used to evaluate the system performance for this study. It is estimated that the COP enhancement can be as large as 51% from the baseline design candidate. Finally, an updated performance improvement potential is presented to guide future studies.
Acoustic Emission Minimization in a Wind Turbine Using Trip-Wires and Owl-Wing-Serrations
Authors: Madadnia Jafar , Nurdin Muhammad Fauzan
Published: October 2015

Acoustic noises emitted from wind turbine blades should be reduced to an acceptable level for the uptake of wind energy in buildings and in the urban environment. This paper reports on effectiveness of, Owl-wing-serrations (OWS), two-dimensional trip-wires, and Active-noise-cancellation (ANC) in minimization of aerodynamic noises in a micro model turbine. The OWS and trip wires were attached to the blade leading edges and trailing edges in the wind turbine. The model was operated in the fan mode as a single row. Combined effects of OWS and ANC were also tested in a counter rotating double-row Fan. Air velocity (m/s), shaft-revolution (rpm); electric-power (W), amplitude of acoustic noise (dB) and its Centre frequency (CF in Hz) were measured at a reference location, for a number of spacing. Experimental results were plotted in the forms of dB vs. Tip Speed Ratio (TSR), dB vs. CF, and Efficiency or Coefficients of Performance COP vs. TSR.

It was noticed that

• In the single row operations, 3mm trip wires and OWS attached to blades have influenced on the emitted aerodynamic noises. OWS reduced dB and increased Cf more than the trip-wires. For example, at a fixed TSR, amplitude of noise (dB) decreased with trip wires or OWS with the lowest dB occurring with the OWS alone. At a fixed dB, Centre frequency (Cf) increased with the highest frequency Cf occurring with OWS alone. Minor changes in efficiency (COP) were noticed with the trip wires or Owl-wing serrations. It may suggest that larger eddies are converted into small turbulences with lower amplitudes and higher frequencies.

• Active-noise-cancellation (ANC) in the double row operation affected acoustic noises as spacing/gap between the counter-rotating rows changed. At a fixed TSR, dB decreased in the double row operations in comparison with the single-row operations, the reduction in dB increased at higher TSR. At a fixed dB, Centre frequency (Cf) increased by 100% with the highest frequency Cf occurring at the spacing of 50mm. Efficiency or COP decreased by 50% when ANC was implemented with a minor change due to spacing between rows.

• Combined effects of OWS and ANC were moderate comparing to ANC alone, reducing both dB and COP by around 35% while doubling Cf as compared to the single raw fan conditions. The minimum dB and maximum Cf occurred at the gap/spacing of 50mm. No significant change was noticed at COP with combined OWS and ANC.
Performance Characteristics of 20kW Ocean Thermal Energy Conversion Pilot Plant
Authors: Lee Ho-Saeng , Lee Seung-Won , Kim Hyeon-Ju , Jung Young-Kwon
Published: October 2015

To experiment 20kW OTEC, the closed-cycle type of OTEC (Ocean Thermal Energy Conversion) was designed and manufactured. R32 (Difluoromethane, CH2F2) was used as the working fluid and a temperature of heat source and heat sink is 26°C, 5°C, respectively. The semi-welded type heat exchanger is applied for the evaporator and condenser and the cycle was designed for the gross power of 20kW. In the plate arrangement of the semi-welded type heat exchanger, one channel for working fluid is welded, and another channel for seawater is sealed by gasket. In this paper, various performance evaluations and experiments were carried out as constructing subminiature pilot plant of the OTEC and compared with the results of cycle analysis. In results, gross power of the turbine shows 20.1kW and cycle efficiency is 1.91% when heat source and heat sink is 26°C, 5°C. For the variation of temperature difference between the heat source and heat sink, when the temperature difference was 21°C, the gross power increased by about 33.3% from that when the temperature difference was 19 °C.
Latent Heat of Fusion and Melting Temperature of Molten Salt Based Carbon Nanotube Suspensions Used as Phase Change Materials
Authors: Gimenez-Gavarrell Pau , Romanin Vincent D. , Fereres Sonia
Published: October 2015

Thermal Energy Storage (TES) can improve the efficient and economical use of available resources associated with renewable energies. The choice of Phase Change Materials (PCM) for TES applications is particularly attractive, since PCMs provide high energy storage densities, low costs, and allow energy storage at constant temperatures during the melting/solidification process. However, most commonly used PCMs have low thermal conductivity values, typically less than 1 W/mK. This leads to insufficient heat exchange rates in many applications, where power is as important as the amount of energy stored. Previous studies have shown that adding nanoparticles to molten salts can enhance the thermal conductivity and heat capacity, thus improving performance in TES systems. This study analyzes how adding nanoparticles to ionic liquids/solids affects the latent heat of fusion and melting temperature, critical characteristics of many thermal management systems. An important aspect of nanoparticle suspension preparation is the synthesis method, both from the point of view of scalability and effect on thermophysical properties. Several nanoparticle suspensions are synthesized with carbon nanotubes (CNT) and salt or ionic liquid base materials, using different synthesis methods and sonication times. The melting point and latent heat of fusion are measured for the base materials and nanoparticle suspensions using a Differential Scanning Calorimeter (DSC). The change in latent heat and melting temperature of the nanofluid with respect to the base fluid is shown to be present but not substantial. Possible explanations for the modification of thermal properties with respect to the base fluid are discussed.
Investigation of Gas Diffusion Layer Properties Using X-Ray Microtomography
Authors: Hasanpour Sadegh , Phillion Andre , Hoorfar Mina
Published: October 2015

An essential part of proton exchange membrane fuel cells (PEMFCs) is the gas diffusion layer (GDL), which provides pathways for by-products to be removed from PEMFCs. One of the main properties of GDLs is porosity. The two widely used experimental methods for finding the porosity of GDLs are mercury intrusion porosimetry (MIP) and method of standard porosimetry (MSP). In addition to these methods, the porosity of GDLs can be calculated based on the high resolution 3D images that are acquired using X-ray microtomography (μXCT) as shown in recent studies (e.g., [7,12]). Despite the general success of using μXCT to measure GDL porosity, different porosity values have been reported for similar GDLs.

These variations are due to different assumptions made for determining the surface of the sample, and hence, its external dimensions. In this research, current methods used for calculating porosity of GDLs from μXCT images are discussed, and a new surface identification method based on a rolling ball algorithm is introduced. The main advantage of this new method is that variations in surface topology or roughness are taken into account when calculating porosity. The new method is not only applicable to GDLs, but can be applied to characterize a wide range of highly porous media.
GDC Electrolytes With Patchwork Type Morphology and Their Microtubular SOFC Applications
Authors: Zahir Md. Hasan , Bahaidarah Haitham
Published: October 2015

A patchwork type morphology was formed due to an accidental addition of excess polyvinyl butyral (PVB) polymer powder into the Gadolinia doped Ceria (GDC) slurries during the preparation of homogeneous slurries by a wet atomization process. GDC thin layer has been fabricated on the top of porous tubular anode (GDC-NiO) support at 1400 °C. The results of this study show that polymer can be used not only to fabricate a dense electrolyte but also to generate a nanoporous grain boundary. The fabricated electrolytes have been tested for SOFC (Solid Oxide Fuel Cell) applications in the intermediate-temperature region. The single-cell with dense electrolytes performance test showed a high power density at 550 °C with wet H2 fuel. The effect of different polymers, such as polyvinyl pyrrolidinone (PVP) and polytetrafluoroethylene (PTFE), into the electrolyte slurry was also tested. The polymer binder used in preparing GDC slurry is preferably neither PVP nor PTFE, and/or contains no amounts of these polymers.
Comparisons of Performances and Liquid Water Distributions Within Bio-Inspired and Single-Serpentine PEM Fuel Cell Channels
Authors: Saripella Bhaskar P. , Koylu Umit O. , Leu Ming C.
Published: October 2015

Flow field design in Proton Exchange Membrane (PEM) fuel cells is a major area of research for performance improvement. Bio-inspired flow field designs are a relatively recent development in fuel cell technology evolution. These novel designs have potential for performance improvements by effective distribution of reactant gases with better water management capabilities. This work investigates the performance and water distribution in a bio-inspired flow field design, formulated using Murray’s law and mimicking a typical leaf venation pattern, in comparison to a conventional single serpentine design. Experiments were conducted using a transparent fuel cell with copper as the conductive channel and current collector. The results indicated the superior performance of the bio-inspired design with a 30% increase in peak power density in comparison to the single serpentine design. Additionally, the flow regimes based on two-phase flows in micro channels were identified and their effects on fuel cell stability were determined.
High Throughput and High Resolution In-Line Monitoring of PEMFC Materials by Means of Visible Light Diffuse Reflectance Imaging and Computer Vision
Authors: Rupnowski Peter , Ulsh Michael , Sopori Bhushan
Published: October 2015

In this paper we present results from our recent work in which polymer electrolyte membrane fuel cell electrodes with intentionally introduced known defects were imaged and analyzed using a fuel cell scanner recently developed at the National Renewable Energy Laboratory. The defect types considered included particle debris, scuffs, scores, slits, and laser perforated pinholes. The debris defects were analyzed on samples from three different production stages, whereas the other defect types were introduced in a membrane tacked on a catalyst-coated diffusion media. We are showing that the fuel cell scanner can generate good quality, high resolution images of both baseline and defect-containing material. Based on the scanned images, an automatic, computer vision algorithm is developed that identifies presence and location of debris particles. The presented results clearly indicate that the in-line visible-light-diffuse-reflectance-based system can be successfully employed to monitor quality and to detect critical defects in fuel cell electrodes that are transported with high speed in a high volume manufacturing facility.
Thermal Contact Resistance Measurements of Gas Diffusion Layers in Polymer Electrolyte Fuel Cells
Authors: Hollinger Adam S. , Thynell Stefan T.
Published: October 2015

Localized temperature gradients in a polymer electrolyte fuel cell are known to decrease the durability of the polymer membrane. The most important factor in controlling these temperature gradients is the thermal contact resistance at the interface of the gas diffusion layer and the bipolar plate. Here we present thermal contact resistance measurements of carbon paper and carbon cloth gas diffusion layers over a pressure range of 0.7–14.5 MPa. Contact resistances are highly dependent upon the clamping pressure applied to a fuel cell, and in the present work, contact resistances vary from 3.5E−4 to 2.0E−5 m2K/W, decreasing non-linearly over the pressure range for each material tested. The data presented here also shows that the thermal resistance of the sample is negligible in comparison to the thermal contact resistance. Thermal uniformity in a fuel cell is desirable, and the measurements presented here can be used to more accurately predict temperature distribution in a polymer electrolyte fuel cell.
Molten Carbonate Fuel Cells as Means for Post-Combustion CO2 Capture: Retrofitting Coal-Fired Steam Plants and Natural Gas-Fired Combined Cycles
Authors: Spinelli Maurizio , Campanari Stefano , Romano Matteo C. , Consonni Stefano , Kreutz Thomas G. , Ghezel-Ayagh Hossein , Jolly Stephen , Di Nitto Matthew
Published: October 2015

The state-of-the-art conventional technology for post combustion capture of CO2 from fossil-fuelled power plants is based on chemical solvents, which requires substantial energy consumption for regeneration. Apromising alternative, available in the near future, is the application of Molten Carbonate Fuel Cells (MCFC) for CO2 separation from post-combustion flue gases. Previous studies related to this technology showed both high efficiency and high carbon capture rates, especially when the fuel cell is thermally integrated in the flue gas path of a natural gas-fired combined cycle or an integrated gasification combined cycle plant. This work compares the application of MCFC based CO2 separation process to pulverized coal fired steam cycles (PCC) and natural gas combined cycles (NGCC) as a ‘retrofit’ to the original power plant.

Mass and energy balances are calculated through detailed models for both power plants, with fuel cell behaviour simulated using a 0D model calibrated against manufacturers’ specifications and based on experimental measurements, specifically carried out to support this study. The resulting analysis includes a comparison of the energy efficiency and CO2 separation efficiency as well as an economic comparison of the cost of CO2 avoided under several economic scenarios. The proposed configurations reveal promising performance, exhibiting very competitive efficiency and economic metrics in comparison with conventional CO2 capture technologies. Application as a MCFC retrofit yields a very limited (<3%) decrease in efficiency for both power plants (PCC and NGCC), a strong reduction (>80%) in CO2 emission and a competitive cost for CO2 avoided (25–40 €/ton).
A One-Dimensional Modelling Approach for Planar Cylindrical Solid Oxide Fuel Cell
Authors: Marra Dario , Sorrentino Marco , Pianese Cesare , Mennella Antonio
Published: October 2015

In this paper a 1-D steady-state model of a planar cylindrical Solid Oxide Fuel Cell (SOFC) is described. The SOFC 1-D model developed has been applied for both co-flow and counter-flow configurations. The computational domain selected is a symmetrical single cell slice with an angle of twenty degrees (i.e. one eighteen of the entire cell). The cell has been divided into computational units in the radial direction, for each of them energy, mass and electrochemical conservation equations have been solved. The cell is considered non-adiabatic with heat conduction inside the solid material and convective-radiative heat transfer mechanism between the outer section and the surrounding gases. Moreover, at the cell outlet the residual fuel mixes with the surrounding gases and is completely burnt (afterburning).

The 1-D model has been verified making use of literature data generated from 3-D model of a planar cylindrical SOFC. The results obtained confirmed the good performance of the model developed and its applicability in a computational framework for the development of either control or diagnosis algorithm.
Fuel-Cell and Electrolysis By-Product D2O Improves Third Way to Mitigate CO2
Authors: Schenewerk William Ernest
Published: October 2015

Rapid atomic power deployment may be possible without using fast breeder reactors or making undue demands on uranium resource. Using by-product D2O and thorium-U233 in CANDU and RBMK piles may circumvent need for either fast breeder reactors or seawater uranium.

Atmospheric CO2 is presently increasing 2.25%/a (2.25 percent per year) in proportion to 2.25%/a exponential fossil fuel consumption increase. Roughly 1/3 anthropologic CO2 is removed by various CO2 sinks. CO2 removal is modeled as being proportional to 50-year-earlier CO2 amount above 280 ppm-C.

Water electrolysis produces roughly 0.1 kg-D20/kWa. Material balance assumes each electrolysis stage increases D2O bottoms concentration times 3. Except for first electrolysis stage, all water from hydrogen consumption is returned to electrolysis. D2O enrichment from water electrolysis is augmented by using the resulting Hydrogen and Oxygen in fuel cells. Condensate from hydrogen consumption returns to the appropriate electrolysis stage. Fuel cell condensate originally from reformed natural gas may augment second-stage feed.

Previously, recycling only hydrogen from combustion back to upper electrolysis stages allowed a 5%/a atomic power expansion. Using fuel-cells to augment upper-stage electrolysis enrichment increases atomic power expansion from 5%/a to 6%/a. Implementation of this process should start by 2020 to minimize peak atmospheric CO2 concentration to 850 ppm-C.

Atomic power expansion is 6%/a, giving 45000 GW by 2100. World primary energy increases at the historic rate of 2.25%/a, exceeding 4000 EJ-thermal/a by 2100. J-electric ∼ 3J-thermal. CO2 maximum is roughly 850 ppm-C around year 2100. CO2 declines back below 350 ppm-C by 2250 if the 50-year-delay seawater sink remains effective. The 15-year global temperature rise hiatus is apparently caused by convective heat transfer into seawater. Presumably convective CO2 transfer into seawater also occurs by the same mechanism. Each decade rapid atomic power expansion is delayed results in a 100 ppm increase in maximum atmospheric CO2 concentration. 50 TW dispatchable CSP (concentrated solar power), including 2 TWa storage, costs 1600 trillion USD and covers two Australias.
Effects of the Shape of the Foil Corners on the Irradiation Performance of U10Mo Alloy Based Monolithic Mini-Plates
Authors: Ozaltun Hakan , Medvedev Pavel
Published: October 2015

Monolithic plate-type fuel is a fuel form being developed for high performance research and test reactors to minimize the use of enriched material. These fuel elements are comprised of a high density, low enrichment, U-Mo alloy based fuel foil, sandwiched between Zirconium liners and encapsulated in Aluminum cladding. The use of a high density fuel in a foil form presents a number of fabrication and operational concerns, such as: foil centering, flatness of the foil, fuel thickness variation, geometrical tilting, foil corner shape etc. To benchmark this new design, effects of various geometrical and operational variables on irradiation performance have been evaluated. As a part of these series of sensitivity studies, the shape of the foil corners were studied. To understand the effects of the corner shapes of the foil on thermo-mechanical performance of the plates, a behavioral model was developed for a selected plate from RERTR-12 experiments (Plate L1P785). Both fabrication and irradiation processes were simulated. Once the thermo-mechanical behavior the plate is understood for the nominal case, the simulations were repeated for two additional corner shapes to observe the changes in temperature, displacement and stress-strain fields. The results from the fabrication simulations indicated that the foil corners do not alter the post-fabrication stress-strain magnitudes. Furthermore, the irradiation simulations revealed that post-fabrication stresses of the foil would be relieved very quickly in operation. While, foils with chamfered and filleted corners yielded stresses with comparable magnitudes, they are slightly lower in magnitudes, and provided a more favorable mechanical response compared with the foil with sharp corners.
The Effects of Subcooling on Quenching of a Vertical Brass Cylinder With Heating Power
Authors: Ho Yuan-Hong , Ho Ming-Xi , Pan Chin
Published: October 2015

Film boiling is usually induced while a very hot object contacts with a coolant. Such phenomena will deteriorate the heat transfer and degrade the cooling process. Film boiling is of significant concern for the design of an emergency core cooling system after a hypothetical loss of coolant accident happens in a nuclear power plant. Furthermore, after a nuclear power plant is shut down, the fuel rods will continue to release heat due to the decay of fission products. Moreover, the subcooling of coolant might be changed dramatically during the reflood process. Therefore, it is of significant importance and interest to understand the effect of decay heat and subcooling of coolant on the quenching process of a hot object. This study demonstrates the quenching of a vertical brass cylinder without and with heating power of 105W in deionized water with different subcoolings. The diameter and length of the cylinder is 24 mm and 112 mm, respectively. Six K-Type thermocouples are embedded 2mm below the cylinder surface at different axial locations. The experimental results reveal that, with heating power of 105W, the duration of film boiling becomes much larger than the case without heating power under the same subcooling condition. Besides, the duration of film boiling decreases with increasing subcooling. This study also reveals that the Leidenfrost temperature increases significantly with increasing the subcooling with or without heating power. Significantly, a stable film boiling with approximately constant wall temperature can be sustained in saturated water. This is of significant concern for nuclear safety.
High Temperature Intrinsically Safe Nuclear Reactor
Authors: McDaniel Robin J.
Published: October 2015

Small Modular Reactor (SMR) technologies have been recently included by the DOE as clean energy, a low carbondioxide emitting “alternative energy” source. The objective of this paper is to further the discussion of intrinsically safe nuclear reactors in the context of passive safety design principles and introduction of a novel conceptual reactor design. After a multiple year research study of past fast neutron reactor designs and recent reactor proposals, the following design is the result of analysis of the best concepts discovered.

An improved fast reactor of the liquid metal cooled type including a core configuration allowing for only two operational states, “Power” or “Rest”. The flow of the primary cooling fluid suspends the core in the “Power” state, with sufficient flow to remove the heat to an intermediate heat exchanger during normal operation. This design utilizes the force of gravity to shut down the reactor after any loss of coolant flow, either a controlled reactor shut down or a Loss of Coolant Accident (LOCA) event, as the core is controlled via dispersion of fuel elements. Electromagnetic pumps incorporating automatic safety electrical cut-offs are employed to shutdown the primary cooling system to disassemble the core to the “Rest” configuration due to a loss of secondary coolant or loss of ultimate heat sink. This design is a hybrid pool-loop pressurized high-temperature reactor unique in its use of a minimum number of components, utilizing no moving mechanical parts, no rotating seals, and no control rods.

This defines an elegantly simple Gen IV intrinsically safe nuclear reactor. [Advanced Small Modular Reactor (aSMR)]
Effects of the Foil Centering on the Irradiation Performance of U10Mo Alloy Based Monolithic Mini-Plates
Authors: Wright Jill , Ozaltun Hakan
Published: October 2015

Monolithic plate-type fuel is a fuel form being developed for high performance research and test reactors to minimize the use of enriched material. These plate-type fuels consist of a high uranium density LEU foil contained within diffusion barriers and encapsulated within a cladding material. To benchmark this new design, effects of various geometrical and operational variables on irradiation performance have been evaluated. For this work, the effects of fuel foil centering on the thermo-mechanical performance of the mini-plates were studied. To evaluate these effects, a selected plate from RERTR-12 experiments, the Plate L1P756, was considered. The fuel foil was moved within the fuel plate to study the effects of the fuel centering on stress, strain and overall shape of the fuel elements. The thickness of the fuel foil, thickness of the Zr-liners and total thickness of the plate were held constant, except the centerline alignment of the fuel foil. For this, the position of the fuel foil was varied from the center position to a maximum offset corresponding to the minimum allowable aluminum cladding thickness of 0.1524 mm. Results for various offset cases were then compared to each other and to the ideal case of a centered fuel foil. Fabrication simulations indicated that the thermal expansion mismatch results in warping of the fuel plate during fabrication as the fuel plate is cooled from the HIP temperature when the fuel is not centered. Even if the model is constrained during cooling to simulate the rigid HIP can surrounding the fuel plate during cooling, warping is observed when the constraint is removed. Similarly, irradiation simulations revealed that the fuel offset causes virtually all irradiation-induced swelling to occur on the thin-cladding side of the plate. This is observed even for the smallest offset that was considered. The total magnitude of the swelling is approximately same for all offsets values.
Acid Gas Simulation for Recovering Syngas and Sulfur
Authors: Groisil Melanie , Ibrahim Salisu , AlShoaibi Ahmed S. , Gupta Ashwani K.
Published: October 2015

Numerical examination of acid gas pyrolysis is presented with a focus to determine optimum condition for producing both sulfur and syngas that can be used in industry at high conversion efficiency of acid gas. Detailed simulation of acid gas to produce sulfur and syngas is presented that provides the feasibility of establishing plausible reactor conditions for such a recovery. This is a much different approach of producing thermal energy and sulfur. The results revealed that only pyrolysis of specific acid gas composition leads to the production of syngas and that temperature plays an important role in the conversion process. The simulation results provided here reveal the role of acid gas composition on high sulfur and syngas recovery under different operational conditions of the reactor with minimal adverse effect on the environment. The produced syngas can be utilized to enhance energy generation or produce valuable chemicals. The operational conditions provide means to seek different composition of the syngas. The syngas can then be used to produce value added products or liquid fuels. Detailed results under various input and operational conditions of the reactor are presented in the paper.
A Study of the ASME B&PV Code for Pipe Support and Restraint Design Rules From 1974 to 2013
Authors: Wiseman Phillip E. , Goel Gaurav S.
Published: October 2015

The pipe support and restraint design rules are based on the linear elastic analysis outlined in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Subsection NF. The subarticle NF-3300, primarily introduced by replicating the Allowable Stress Design (ASD) rules from the AISC Steel Construction Manual, differs from most of the ASME B&PV Code. Additionally, the Code must fulfill the Nuclear Regulatory Guide requirements, i.e. Regulatory Guide 1.124, which mandates the criteria for pipe support design in nuclear applications. The Code has been edited on multiple occasions to refine the rules for pipe support engineering since the inaugural publication of Subsection NF in the 1973 Winter Addenda. The changes in the design rules in the Code have been incorporated to meet the nuclear rules and regulations along with the general needs of the industry. A review of some of these modifications in the design rules provides a better insight on the subarticle since the institution of the first publication of Subsection NF. The changes in the design rules are essential to highlight since the first generation of commercial nuclear power plants constructed 40 years ago are approaching the end of their design life.
Stator Cooling Water System Instrumentation
Authors: Bauer Thomas , Svoboda Mat , Chetwynd Russell J.
Published: October 2015

Large turbo- and hydro-generators are directly cooled with high purity water for efficient heat transfer from the coils. Plant operators, engineers and chemists don’t get a lot of experience with troubleshooting, as operation can be trouble free for decades. However, when a problem arises, it can happen rapidly. The reason is often plugging of the stator cooling water system (SCWS) copper hollow conductors. This can result in forced outages or major generator failures and can occur within weeks — or years — after first indication. Thus, proper instrumentation will support plants to early detect a malfunctioning cooling water system and can provide sufficient time to take effective corrective actions.

The focus is on how both the SCWS and its internal instrumentation, along with enhanced monitoring techniques, can help facilitate a more proactive approach to manage corrosion effects such as hollow conductor plugging. Different basic OEM supplied instrumentation for both high- and low-oxygen systems are discussed and benefits thereof are outlined as well as “state-of-the-art” instrumentation is presented. Industry examples are demonstrating the benefit of proper instrumentation as early detection of copper oxide plugging prevented power plants from forced outages and costly rewinds. Subsequently, full cooling capacity was restored by online removal of the copper oxides.
Numerical Prediction of a Multistage Centrifugal Pump Performance With Stationary and Moving Mesh
Authors: Nocente Alessandro , Arslan Tufan , Nielsen Torbjørn K.
Published: October 2015

The present work reviews a comparison between calculations of a steady and unsteady three dimensional (3D) flow past the diffuser channels of a centrifugal pump. The commercial software ANSYS Fluent has been used. The considered domain is one of the three stages, since each has exactly the same design.

In the first part, simulations are carried out at the best efficiency point (BEP) both steady and transient state, single phase flow and four different turbulence models. Results are compared with the performance report from the manufacturer. In the second part, only the realizable k-ε turbulence model has been taken into account. The simulations have been repeated for different mass flows and the results were again compared with the data from the manufacturer.

The comparison performed in the first part shows that integral quantities results are not sensibly influenced by the turbulence model. The comparison at different mass flow shows that the steady state simulations demonstrated to be a good approximation of the transient state, always containing the error within an acceptable limit. The minor computational effort needed makes it attractive to be used for further investigations which will involve two-phase flow studies on the same pump.
Performance Investigation of a Small Horizontal Axis Wind Turbine Equipped With Flexible Blades
Authors: MacPhee David W. , Beyene Asfaw
Published: October 2015

Wind turbine technology has improved dramatically over the past decade, to the extent where wind turbine diameters are expected to soon exceed 160m and top 10MW in rated power output. While the development of these larger turbines has become immensely sophisticated, relatively little effort is being put forth to improve performance of smaller wind turbines, typically used in applications otherwise unsuitable for large installations. In this paper we investigate both computationally and experimentally the feasibility of a morphing turbine rotor, wherein blades are constructed of a flexible material and permitted to bend passively in response to external loading. The results indicate that the flexible blades can act as a passive pitch control device, resulting in significant improvements in efficiency when compared to a traditional rigid-blade design.