bluuebunny/crossref_metadata_2025 huggingface dataset:
Design Requirements for Direct Supercritical Carbon Dioxide Receiver Development and Testing
Authors: Ortega Jesus D. , Khivsara Sagar D. , Christian Joshua M. , Ho Clifford K.
Published: October 2015

This paper establishes the design requirements for the development and testing of direct supercritical carbon dioxide (sCO2) solar receivers. Current design considerations are based on the ASME Boiler and Pressure Vessel Code (BPVC). Section I (BPVC) considers typical boilers/superheaters (i.e. fired pressure vessels) which work under a constant low heat flux. Section VIII (BPVC) considers pressure vessels with operating pressures above 15 psig [2 bar] (i.e. unfired pressure vessels). Section III, Division I – Subsection NH (BPVC) considers a more detailed stress calculation, compared to Section I and Section VIII, and requires a creep-fatigue analysis. The main drawback from using the BPVC exclusively is the large safety requirements developed for nuclear power applications. As a result, a new set of requirements is needed to perform detailed thermal-structural analyses of solar thermal receivers subjected to a spatially-varying, high-intensity heat flux. The last design requirements document of this kind was an interim Sandia report developed in 1979 (SAND79-8183), but it only addresses some of the technical challenges in early-stage steam and molten-salt solar receivers but not the use of sCO2 receivers. This paper presents a combination of the ASME BPVC and ASME B31.1 Code modified appropriately to achieve the reliability requirements in sCO2 solar power systems. There are five main categories in this requirements document: Operation and Safety, Materials and Manufacturing, Instrumentation, Maintenance and Environmental, and General requirements. This paper also includes the modeling guidelines and input parameters required in computational fluid dynamics and structural analyses utilizing ANSYS Fluent, ANSYS Mechanical, and nCode Design Life. The main purpose of this document is to serve as a reference and guideline for design and testing requirements, as well as to address the technical challenges and provide initial parameters for the computational models that will be employed for the development of sCO2 receivers.
Initial Assessment of Microbial Fuel Cells for the Treatment of Tofu Processing Waste
Authors: Barber Steven T. , Dranoff Josh M. , Trabold Thomas A.
Published: October 2015

Due to ever increasing industrial organic material wastewater regulations, there is growing interest in the food production industry for technologies to mitigate soluble waste discharges. Currently, food manufacturers in NYS with wastewaters that have high concentrations of soluble organic material, indicated by its chemical oxygen demand (COD), are charged substantial premiums by publicly owned treatment works (POTWs) to dispose of their high COD wastewaters. As a result, these producers are keen on pursuing more economical and sustainable alternatives. One novel option is a microbial fuel cell (MFC), a recently developed type of bioreactor that greatly reduces soluble COD by harnessing the electrochemical potential found in the chemical bonds of these organic materials through redox reactions under anaerobic conditions facilitated by exoelectrogenic microorganisms. MFC technology treating homogeneous substrates such as acetate at the laboratory scale has advanced to the point where COD removal efficiencies of over 90% are commonly achieved; however, efficiencies at treating less uniform, high COD level industrial scale food manufacturing wastewaters have only been investigated in a handful of studies. Since most real world wastewaters are non-uniform, MFC performance characterization of treating these actual discharges is crucial in determining their efficacy and cost effectiveness in large scale applications. To help fill this gap, this paper gives a relative efficacy comparison of five identical 3 L bench scale single chamber and three dual chamber MFC configurations (SCMFCs and DCMFCs, respectively) to a simulated POTW aeration process treating high COD whey effluent from a tofu manufacturing plant. Standard parametric EPA water quality tests of COD reduction were performed to assess the extent of the MFCs and POTW simulant effectiveness. COD levels in the MFC’s were reduced between 72% and 92%, while the POTW aeration process reduced levels 98%. This corroborates previously published studies showing that POTW systems are effective in reducing COD, but also that MFCs could be a more sustainable option due to their unique ability to directly produce, rather than consume, electric current. While these findings are promising, more studies are required to accurately determine the relative proportion of bioelectrochemical and methanogenic processes in the actual lowering of the COD levels.
Techno-Economic Assessment of Different Pathways for Utilizing Glycerol Derived From Waste Cooking Oil-Based Biodiesel
Authors: Win Shwe Sin , Hegde Swati , Trabold Thomas A.
Published: October 2015

Crude (i.e., unrefined) glycerol is the major by-product of biodiesel production, based on the homogeneous alkaline catalytic transesterification reaction. Currently, global biodiesel production capacity has been rising rapidly due to the overall growth of renewable energy demand. The amount of glycerol is increasing in parallel, and there is presently little market value for crude glycerol. In addition, disposing of this material via conventional methods becomes one of the major environmental issues and a burden for biodiesel manufacturers. Thus, utilization of purified glycerol in value-added applications such as food processing, cosmetics, soap and pharmaceuticals is critical to achieve economic scale of biodiesel production. In this paper, various pathways available to community-based biodiesel producers have been modeled to inform the decision-making process. A case study at Rochester Institute of Technology (RIT) was selected to evaluate the proposed system. Different pathways of utilizing crude glycerol were investigated, and economic feasibility of each pathway was analyzed. Purification of crude glycerol from waste cooking oil-based-biodiesel production was performed at small bench scale. Various recipes with different raw materials and purified glycerol as an ingredient were created for different kinds of saponification processes and applications. The resulting data from this preliminary assessment showed that producing biodiesel and high-quality soap is the most profitable option for RIT.
CFD Study on Supersonic Ejectors Used for Suction of Two Different Gases
Authors: Tavakol Mohsen , Shafaee Maziar
Published: October 2015

In ejector refrigeration cycles, ejector working fluids include various refrigerants with different properties. In some cases, ejector works with mixture of two different refrigerants; that each refrigerant have distinct properties. The purpose of this paper is to evaluate the performance of an ejector used for suction of a mixture of air and water vapor. In this regard, the ejector performance was numerically studied under the operating condition that a mixture of air and steam with variable mass fractions, were sucked into the ejector. With the help of numerical simulation, various conditions for two perfect gas streams of air and water vapor were investigated. Initially, the numerical simulation was carried out for the case that pure water vapor was considered as the working fluid of ejector. After validation of initial case with experimental data, numerical method was expanded for a specific case that, water vapor was considered as the working fluid of motive flow and a mixture of air and water vapor was considered for suction flow. Numerical simulations were done for different mass fraction of air and water vapor for suction flow mixture. Results indicated that, variations of the mass fraction of air in suction flow, leads to obvious changes in ejector performance. Also, it was observed that the increment of suction flow pressure, leads to increment of the ejector performance sensitivity to variations of suction flow mass fraction.
Energy Efficiency and Environmental Life Cycle Assessment of Jatropha for Energy in Nigeria: A “Well-to-Wheel” Perspective
Authors: Onabanjo Tosin , Di Lorenzo Giuseppina
Published: October 2015

There is a large imbalance between demand and supply of energy in Nigeria, with inefficient power supply being the country’s greatest economic bane. Aside energy crisis, fuel is a luxurious commodity and petroleum diesel is the predominant fuel for power generation, particularly in the industrial sector. As a result, the country suffers from forced power outages, and persistent black out while residents and industries are forced to depend on self-generated electricity. These have notably reduced industrialization and increased environmental pollution across the country. This paper proposes the use of Jatropha biodiesel as a substitute fuel to petroleum diesel. It examines the energy efficiency and environmental life cycle impact of the production and use of 1MJ of Jatropha biodiesel in a typical 126 MW (ISO rating) industrial gas turbine power plant with multi-fuel capability using life cycle assessment methodologies and principles. A net energy ratio of 2.37, 1.54, and 1.32 and fossil fuel savings of 58%, 36% and 27% were achievable under three farming system scenarios: a) base-case rain-fed, b) base-case irrigated and c) large scale farming system. Also, an environmental benefit with GHG savings of 19% was attainable under the three farming scenarios. The results demonstrate that the contribution of GHGs and effect on climate change is most significant with the end use of the fuel. It also highlights the importance of clear definition of the reference system which should be indicative of the local production system and comparative to the system under study. A favourable business and economic climate driven by demand is proposed for Independent Power Producer (IPP) to generate power for off-grid users instead of generating power for the national grid using a decentralized Jatropha biodiesel production system coupled to waste to energy technologies.

This could significantly improve the energy situation; diversify the energy generation mix and fuel supply in Nigeria, especially for small-scale businesses and the rural population.
Efficient Heat Transfer Methods in a Hybrid Solar Thermal Power System for the FSPOT-X Project
Authors: Lee David E. , Nesmith Bill , Hendricks Terry , Cepeda-Rizo Juan , Petach Michael , Tward Emanuel , Penera Cecilia , Pohner John , Whitney Scott , Grandidier Jonathan
Published: October 2015

The FSPOT-X Project, focused on maximizing exergy generated from AM1.5 sunlight, targets an overall system efficiency of >35%. The objective hybrid power system will deliver grid-ready AC power while simultaneously providing thermal energy storage for dispatchable electrical power generation in post sunset conditions. The challenging system-level requirements flow-down critical temperature differential and thermal transport requirements to multiple system components and their interfaces. By integrating and demonstrating multiple technologies, the FSPOT-X hybrid power system seeks to efficiently convert photons to electrons maximizing heat transfer efficiency across system element interfaces. These include: I1) capturing all incident sunlight from the solar concentrator in a receiver cavity to maximize energy generation from the CPV cells, I2) extracting PV thermalization heat from the receiver and into the reflux chamber, I3) moving heat from the reflux chamber through the thermal transfer interface, I4) using the thermal transfer interface to shift heat into the TAPC’s hot heat exchanger, I5) storing excess unused heat in phase change material, and I6) disposal of waste heat at the system level. For each of these thermal interfaces, effective and efficient technical means are being used and applied in order to maximize overall system efficiency for delivery of a next generation cost-effective and market-ready solar power system.
Active Air Flow Control to Reduce Cavity Receiver Heat Loss
Authors: Zhang J. Jack , Pye John D. , Hughes Graham O.
Published: October 2015

Convective air flows are a significant source of thermal loss from tubular cavity receivers in concentrating solar-thermal power (CSP) applications. Reduction in these losses is traditionally achieved by tailoring the cavity geometry, but the potential of this method is limited by the aperture size. The use of active airflow control, in the form of an air curtain, is an established practice to prevent infiltration of cold air through building doorways. Its application in reducing solar receiver convective heat loss is new. In this study, computational fluid dynamics (CFD) simulations are presented for the zero wind case, demonstrating that an optimised air curtain can readily reduce convective losses by more than 45%. A parametric investigation of jet direction and speed indicates that two distinct optimal air curtain flow structures exist. In the first, the jet reduces the size of the convective zone within the cavity by partially sealing the aperture. The optimum velocity range for this case occurs with a low strength jet. At higher jet speeds, the losses are generally set by the flow induced in the cavity and entrainment into the jet. However, a second optimal configuration is discovered for a narrow range of jet parameters, where the entrainment is reduced due to a shift in the stack neutral pressure level, allowing the jet to fully seal the cavity. A physical model is developed, based on the fluid physics of a jet and the ‘deflection modulus’ concept typically used to characterise air curtains in building heating and ventilation applications. The model has been applied to the solar thermal cavity case, and shows good agreement with the computational results.
Numerical Assessment of the Slagging Potential of Nigerian Coal for Possible Co-Firing
Authors: Degereji Mohammed U.
Published: October 2015

Co-firing coal and biomass offers a sustainable renewable energy option. However, slagging and fouling have been identified as some of the major operational challenges associated with co-firing. The chemistry of individual fuels can be used to determine the slagging potential of the blend. Previously, we have developed a numerical slagging index (NSI) based on the ash content in coal and the chemical properties of the coal ash. The NSI has been tested on a wide range of coals, and very good prediction results were obtained. In this paper, the slagging potential of Nigerian coal and other coals from Australia, Colombia and South Africa have been numerically evaluated. The predicted results using the NSI indicate that the Nigerian coal has relatively low slagging propensity when compared with other coals tested in this paper. One of the Australian coals seems to have lower slagging potential, and this may be attributed to the extraordinary low ash content for the coal, as reported. It has been observed that the silica-rich coal ash composition can be used to select suitable coals that could be co-fired with the alkali-rich biomass, with low operational risk. However, detail information on the chemical properties of blend and the particle-particle interaction can improve the performance of the assessment tool.
Pressure Retarded Osmosis: Laboratory Scale Design and Experiment
Authors: Berry Alexander , Weinand Dylan , Zenouzi Mansour , Hennessy Conor , Mathieu James , Kowalski Greg
Published: October 2015

Clean forms of renewable energy with low to no environmental impact are highly desirable. Pressure Retarded Osmosis (PRO) has been a growing form of “Blue Energy” [1], a renewable energy medium involving mixing bodies of salt and fresh water. PRO systems take advantage of the pressure difference seen between freshwater and seawater by forcing fresh water across a semipermeable membrane into a body of saltwater. This transfer, through the means of forward osmosis, yields an increase in pressure on the saltwater side of the membrane. This observable increase in pressure can be used for generating electricity. A popular thought proposed has involved taking a part of this newly created pressure and diverting it back into the system with the use of a pressure exchanger. Residual pressure would then be devoted to the generation of electricity. If done correctly, a net gain can be seen between the electricity gleaned from the output of the system, and the energy consumed to run the pumps necessary for operation. The group’s aim is to design and construct a variant of the traditional PRO system for the purpose of analysis in a laboratory setting. The design proposed consists of a compact, two-membrane system that allows for the testing and analysis of forward osmosis in a closed system. While the system is not intended for actual electrical generation, it provides a medium for future experimentation.
Effect of Steam on the Performance of an IT-SOFC/GT Hybrid System
Authors: Lv Xiaojing , Lu Chaohao , Weng Yiwu
Published: October 2015

The performance of an intermediate-temperature solid oxide fuel cell (IT-SOFC) and a gas turbine (GT) hybrid system fueled with gasified wood chips is analyzed. The effects of steam on the thermodynamic performances of reformer, fuel cell, gas turbine and hybrid system are studied. The results show that the system electrical efficiency can reach up to 59.24% at design condition, and it demonstrates excellent performance. As the steam increases, the reforming temperature decreases, which leads to CH4 reforming reaction equilibrium constant decreases, and the reaction will be suppressed. The water gas shift reaction equilibrium constant increases with the decrease of the temperature. But the total amount of H2 shows a decreasing trend. With the steam increases, the fuel cell electrode and ohmic polarization losses increase, Nernst potential decreases, the output power and electrical efficiency show a decreasing trend. And then the hybrid system output power and electrical efficiency decrease. The electrical efficiency decreases from 61% to 56.91%. In consideration of operation security of reformer, fuel cell stack and the hybrid system, maintaining a high value of the steam is very important.
Model Based Investigation of Liquid Water Injection Strategies for Evaporatively Cooled PEM Fuel Cells
Authors: Fly Ashley , Thring Rob H.
Published: October 2015

Evaporative cooling through liquid water injection directly into the fuel cell flow channels removes the requirement for external humidification and liquid cooling channels within the stack. However, the amount of liquid water injected must be accurately controlled, to prevent on one hand membrane drying due to lack of water vapor and on the other hand flooding due to excessive liquid water.

In this paper a one-dimensional, non-isothermal model of an evaporatively cooled proton exchange membrane fuel cell (PEMFC) is produced. The model accounts for changes in relative humidity and temperature along the anode and cathode flow channels, water transfer through the membrane and liquid accumulation within the gas diffusion layers. The model was used to study liquid water injection strategies at both cell and localized level. The influence of current density, operating pressure and inlet humidity were investigated. Results show that provided high humidity is maintained throughout the cell, exhaust gas temperature increase from low to high current densities (0.4–1.4A/cm2) is less than 4.0°C, without the need for active temperature control. Furthermore both temperature regulation and good membrane hydration can be managed by uniform injection of liquid water throughout the cell to maintain a target cathode exhaust humidity.
Needs and Approaches for Novel Characterization of Direct Hybrid Fuel Cell/Gas Turbines
Authors: Tucker David , Haynes Comas , Geoghegan Patrick
Published: October 2015

Solid oxide fuel cell (SOFC)/ gas turbine (GT) hybrid systems possess the capacity for unprecedented performances, such as electric efficiencies nearly twice that of conventional heat engines at variable scale power ratings inclusive of distributed generation. Additionally, these hybrids can have excellent operational flexibility with turndowns possibly as great as 85%. There are, however, developmental needs such as turbomachinery characterization and re-design. A leading example is that of greater propensity to have occurrences of stall-surge given the significantly different operating environment in contrast to conventional heat engines. Additionally, dynamic variation in power generation has to be done with significant a priori insight to avoid thermomechanical threats to cell stack and turbomachinery.

State-of-the-art approaches involving hardware-in-the-loop simulation and, ultimately, additive manufacturing are being pursued to enable such characterization and re-design considerations given variable and dynamic operability requirements. Compressor performance in hybrid systems has been characterized at the United States National Energy Technology Laboratory (NETL), inclusive of a capability of feed forward hardware-in-the-loop simulation of hybrid systems under dynamic conditions and a capability of replacing turbine and compressor components at a relatively low cost. This paper highlights some of the simulation results, and the net result is an approach that addresses hybrid system developmental needs for accommodating generation transients.
Flame-Assisted Fuel Cell Operating With Methane for Combined Heating and Micro Power
Authors: Milcarek Ryan , Wang Kang , Falkenstein-Smith Ryan , Ahn Jeongmin , Khalifa H. E.
Published: October 2015

Solid Oxide Fuel Cells (SOFCs) operating in a Flame-assisted Fuel Cell (FFC) setup have potential for Combined Heating and micro Power applications. The feasibility of a FFC furnace operating with natural gas is investigated by using methane/ air flames. The confrontation between the FFCs operating temperature and fuel concentration under various conditions was investigated which uncovered the complex performance behavior. Variations in the fuel/ air equivalence ratio, fuel flow rate and distance between the FFC anode and burner outlet were studied. A critical distance for FFC placement above the burner outlet was uncovered, which has a significant impact on the FFCs performance. A high power density of 791mW.cm−2 was achieved which is comparable to the dual chamber SOFC and single chamber SOFC. Carbon coking was observed on the anode surface, but was not detrimental to FFC performance during testing.
Advanced Modeling of the Dynamics of Vanadium Redox Flow Batteries
Authors: Wang Yun , Cho Sung Chan
Published: October 2015

In this paper, a multi-dimensional dynamic model of vanadium Redox Flow Batteries (RFB) is employed to predict battery performance and internal operating condition during charge and discharge. The model consists of a set of partial differential equations of mass, momentum, species, charges, and energy conservation, in conjunction with the electrode’s electrochemical reaction kinetics. After validated against experimental data for a vanadium RFB, flow field, temperature distribution, and reactant evolution are presented. The developed numerical tool is extremely useful in optimizing RFB design and control.
Integrated Anaerobic Digester and Fuel Cell Power Generation System for Community Use
Authors: Falkenstein-Smith Ryan , Wang Kang , Milcarek Ryan , Ahn Jeongmin
Published: October 2015

New York State is expected to experience future population growth that is increasingly concentrated in urban areas, where there is already a heavy burden on the existing energy, water and waste management infrastructure. To meet aggressive environmental standards (such as that established by the State’s “80x50” goal), future electrical power capacity must produce substantially fewer greenhouse gas emissions than currently generated by coal- or natural gas-fired power plants. Currently, biogas is combusted to produce heat and electricity via an internal combustion engine generator set. A conventional internal combustion engine generator set is 22–45 % efficient in converting methane to electricity, thus wasting 65–78 % of the biogas energy content unless the lower temperature heat can be recovered. Fuel cells, on the other hand, are 40–60 % efficient in converting methane to electrical energy, and 80–90 % efficient for cogeneration if heat (> 400 °C) is recovered and utilized for heating and cooling in the community power system. This current research studies the feasibility of a community biomass-to-electricity power system which offers significant environmental, economic and resilience improvements over centrally-generated energy, with the additional benefit of reducing or eliminating disposal costs associated with landfills and publicly-owned treatment works (POTWs). Flame Fuel Cell (FFC) performance was investigated while modifying biogas content and fuel flow rate. A maximum power density peak at 748 mWcm-2 and an OCV of 0.856 V was achieved. It should be noted that the performance obtained with the model biofuel is comparable to the performances of direct methane fueled DC-SOFC and SC-SOFC. The common trends also concluded an acceptable range for optimal performance. Although the methane to CO2 ratios of 3:7 and 2:8 produced power, they are not the strongest ratios to have optimal performance, meaning that operation should stay between the 6:4/4:6 ratio range. Lastly, the amount of air added to the biogas mixture is crucial to achieving the optimal performance of the cell. The data obtained confirmed the feasibility of a biofuel driven fuel cell CHP device capable of achieving higher efficiency than existing technologies. The significant power output produced from the sustainable biogas composition is competitive with current hydrocarbon fuel sources. This idea can be expanded for a community waste management infrastructure.
A Review on Non-PGM Cathode Catalysts for Polymer Electrolyte Membrane (PEM) Fuel Cell
Authors: Zhuang Shiqiang , Shi Xuan , Lee Eon Soo
Published: October 2015

In recent years, people attach high attention to the energy problem owing to the energy shortage of the world. Since the price of energy resources significantly increases, it is a necessary requirement to develop new alternative sources of energy to replace non-renewable energy resources. Polymer electrolyte membrane (PEM) fuel cell technology is one of the promising fields of clean and sustainable power, which is based on direct conversion of fuel into electricity. However, at the present moment PEM fuel cell is unable to be successful commercialization. The main factor is the high cost of materials in catalyst layer which is a core part of PEM fuel cell. In order to reduce the overall system cost, developing active, inexpensive non-platinum group metal (non-PGM) electrode catalysts to replace currently used Platinum (Pt)-based catalysts is a necessary and essential requirement. This paper reviews several important kinds of non-PGM electro-catalysts with different elements, such as nitrogen, transition metal, and metal organic frameworks (MOF). Among these catalysts, transition metal nitrogen-containing complexes supported on carbon materials (M-N/C) are considered the most potential oxidation reduction reaction (ORR) catalysts. The main synthetic methods are high temperature heat treating (800–1000°C). The mechanical and electrochemical properties of the final product will be analyzed by several characterization methods. For example, a RRDE test will be used to measure electron transfer number and ORR reactivity, which are the most important electrochemical properties of the new catalyst. And the morphology, particle size, crystal phase and specific surface area can be analyzed with SEM, TEM, XRD and BET methods. Although great improvement has been achieved in non-PGM catalyst area of research, there are still some challenges in both ORR activity and stability of non-PGM catalysts. Consequently, how to improve the ORR activity and stability are the major challenge of non-PGM catalyst research and development. Based on the results achieved in this area, our future research direction is also presented and discussed in this paper.
Control Oriented Discretized Cathode Control Volume Method for Improved PEM Fuel Cell Modeling
Authors: Headley Alexander J. , Chen Dongmei
Published: October 2015

The humidity levels in PEM fuel cells has a profound effect on the performance. However, in large fuel cell stacks the relative humidity (RH) changes significantly along the length of the stack. This paper presents a control-oriented model with spatial considerations of the distribution of water vapor that can be used to properly predict and control the humidity levels in a PEM fuel cell stack.

This model predicts the dynamic response of the stack in real-time by tracking energy and mass flows in four basic CVs. To provide spatial information of the stack conditions, the cathode CV was further subdivided into 6 sub-volumes. The model was validated with experiments conducted on a 28-cell, 2kW fuel cell stack. The validation results show that the multiple CV approach can accurately predict the stack RH and voltage, and is capable of predicting localized voltage losses. This new modeling methodology shows the importance of a distributed understanding of the RH profile, and provides a tool to create control algorithms for PEM fuel cells that consider the health of all the sections of the stack.
Exergy Analysis for Small Modular Reactor Hybrid Energy System
Authors: Boldon Lauren , Sabharwall Piyush , Liu Li (Emily)
Published: October 2015

Nuclear hybrid energy systems (NHES) with the capability to store energy will advance the development of renewable energy technologies by providing reliable, non-carbon emitting, and integrated base-load nuclear energy. Small modular reactors (SMRs) will be significant in establishing hybrid energy systems because of their inherent financial advantages over larger commercial reactors; flexible deployment and faster onsite assembly; and ability to closely match required energy needs for industrial process heat applications. An SMR is a thermal energy plant comprised of many complex systems that interact with each other and their surroundings. To study such a system and set appropriate prices for outputs, it is important to assess thermoeconomics or the effective utility and costs of all resources. At its core, thermoeconomics is based upon the quality of energy, or exergy, flowing into and out of each component within a system. Limited research into the thermoeconomics behind SMRs has been performed, leaving an important gap in understanding. This article presents relevant exergetic cost theory and details methods behind an exergy analysis for an SMR-wind-storage system. To perform this analysis, both the physical and economic environments are identified to provide information on how overall system efficiencies and costs may be analyzed. The physical environment incorporates the actual system components, necessary raw materials, and the surroundings or reference environment. The economic environment refers to the upfront installation and operational costs in addition to market prices. In a purely thermodynamic exergy analysis, the exergetic cost may be determined from the physical environment alone and describes the necessary exergy for production to occur. To improve or optimize a system, system efficiency must be balanced with economics to make NHES more competitive and further their development.
Fission Products Distribution in TRISO Coated Fuel Particles Irradiated to 3.22 X 1021 n/cm2 Fast Fluence at 1092°C
Authors: Wen Haiming , Van Rooyen Isabella J. , Hill Connie M. , Trowbridge Tammy L. , Coryell Ben D.
Published: October 2015

Mechanisms by which fission products (especially silver [Ag]) migrate across the coating layers of tristructural isotropic (TRISO) coated fuel particles designed for next generation nuclear reactors have been the subject of a variety of research activities due to the complex nature of the migration mechanisms. This paper presents results obtained from the electron microscopic examination of selected irradiated TRISO coated particles from fuel compact 1-3-1 irradiated in the first Advanced Gas Reactor experiment (AGR-1) that was performed as part of the Next Generation Nuclear Plant (NGNP) project. It is of specific interest to study particles of this compact as they were fabricated using a different carrier gas composition ratio for the SiC layer deposition compared with the baseline coated fuel particles reported on previously. Basic scanning electron microscopy (SEM) and SEM montage investigations of the particles indicate a correlation between the distribution of fission product precipitates and the proximity of the inner pyrolytic carbon (IPyC)-silicon carbide (SiC) interface to the fuel kernel. Transmission electron microscopy (TEM) samples were sectioned by focused ion beam (FIB) technique from the IPyC layer, the SiC layer and the IPyC-SiC interlayer of the coated fuel particle. Detailed TEM and scanning transmission electron microscopy (STEM) coupled with energy dispersive X-ray spectroscopy (EDS) were performed to identify fission products and characterize their distribution across the IPyC and SiC layers in the areas examined. Results indicate the presence of palladium-silicon-uranium (Pd-Si-U), Pd-Si, Pd-U, Pd, U, U-Si precipitates in the SiC layer and the presence of Pd-Si-U, Pd-Si, U-Si, U precipitates in the IPyC layer. No Ag-containing precipitates are evident in the IPyC or SiC layers. With increased distance from the IPyC-SiC interface, there are less U-containing precipitates, however, such precipitates are present across nearly the entire SiC layer.
Thermal and Mechanical Design Guidelines and General Considerations for the Proper Design, and Location, of Various Types of Service Connections on Steam Surface Condensers
Authors: Nightingale Darren M.
Published: October 2015

The incorrect design and/or poor location of service connections on steam surface condensers can cause serious, often catastrophic, failures due to the inadequate dispersion of drain fluid energies. These failures often occur during a number of different operational scenarios, which in turn can cause condenser tube and/or structural failures, both of which can lead to the de-rating of steam turbines, or even complete unit shut downs. This paper includes the latest thermal and mechanical design guidelines and general considerations for the proper design, and location, of various types of service connections on steam surface condensers. The paper also includes considerations for a number of special cases; such as steam bypass, deaerating drains, heater drains, etc. Furthermore, examples of common operational issues are included, together with recommended modifications and upgrades to address typical service connection failures on existing condensers. A Case Study and some examples are also referenced.
Impact of Internal Entrainment on High Intensity Distributed Combustion
Authors: Khalil Ahmed E. E. , Gupta Ashwani K.
Published: October 2015

Colorless Distributed Combustion (also referred to as CDC) has been shown to provide ultra-low emissions and enhanced performance of high intensity gas turbine combustors. To achieve distributed combustion, the flowfield needs to be tailored for adequate mixing between reactants and hot reactive species from within the combustor to result in high temperature low oxygen concentration environment prior to ignition. Such reaction distribution results in uniform thermal field and also eliminates any hot spots for mitigating NOx emission. Though CDC have been extensively studied using a variety of geometries, heat release intensities, and fuels, the role of internally recirculated hot reactive gases needs to be further investigated and quantified. In this paper, the impact of internal entrainment of reactive gases on flame structure and behavior is investigated with focus on fostering distributed combustion and providing guidelines for designing future gas turbine combustors operating in distributed combustion mode. To simulate the recirculated gases from within the combustor, a mixture of nitrogen and carbon dioxide is introduced to the air stream prior to mixing with fuel and subsequent combustion. Increase in the amounts of nitrogen and carbon dioxide (simulating increased entrainment), led to volume distributed reaction over a larger volume in the combustor with enhanced and uniform distribution of the OH* chemiluminescence intensity. At the same time, the bluish flame stabilized by the swirler is replaced with a more uniform almost invisible bluish flame. The increased recirculation also reflected on the pollutants emission, where NO emissions were significantly decreased for the same amount of fuel burned. Lowering oxygen concentration from 21% to 15% (due to increased recirculation) resulted in 80∼90% reduction in NO with no impact on CO emission with sub PPM NO emission achieved at an equivalence ratio of 0.7. Flame stabilization at excess recirculation can be achieved using preheated nitrogen and carbon dioxide, achieving true distributed conditions with oxygen concentration below 13%.
Investigation on Gaseous Product Distributions During Co-Pyrolysis of Platanus Wood and Different Rank Coals From Northwestern China in a Drop Tube Furnace
Authors: Meng Haiyu , Wang Shuzhong , Chen Lin , Zhiqiang Wu , Zhao Jun
Published: October 2015

Co-thermochemical conversion of municipal solid waste blends with coal has the advantage of diversifying energy resources and decreasing consumption of fossil fuels. As the initial and fundamental stage of co-thermochemical conversion, co-pyrolysis of municipal solid waste and coal has important influence on performance of the further co-combustion or co-gasification process. In this paper, gaseous product distributions during co-pyrolysis of platanus wood (wood waste from urban roadside trees platanus acerifolia) and two different rank coals (Shenmu bituminous and Pingzhuang lignite from northwestern China) were investigated through a semi-batch type drop tube furnace at different temperatures. The platanus wood/coal blends were fed into the furnace with five different mass ratios of 100/0, 70/30, 50/50, 30/70, and 0/100. The gaseous products (H2, CO, CO2, CH4 and light hydrocarbons) were continuously collected and then determined by gas chromatography. Experimental results indicated that the gaseous product distributions from pyrolysis of the platanus wood and coal blends were significantly affected by the temperature, the platanus wood/coal mass ratio and coal type. Compared the experimental results with the calculated values obtained from individual samples based on weighted average, some signs about positive or negative synergistic effect were observed on the formation of the major gas composition. The synergistic effect could probably be caused by the secondary reactions between volatiles and chars. In addition, the coal rank appeared to have different influence on the synergistic effect between platanus wood and coal during co-pyrolysis process.
Thermogalvanic Waste Heat Recovery System in Automobiles
Authors: Gunawan Andrey , Fette Nicholas W. , Phelan Patrick E.
Published: October 2015

Recovering waste heat from automobiles remains an inviting subject for research. Solid-state thermoelectric generators (TEGs) have been widely investigated for this purpose, but their practical application remains challenging. An alternative to TEGs are thermogalvanic cells. Temperature difference between hot and cold electrodes creates a potential difference. Once connected to a load, electrical current and power are delivered, converting heat into electricity. In this work, we investigate the feasibility of incorporating such systems into automobiles. We carry out the experiments under real-world conditions. A climate-controlled wind tunnel is built to provide equivalent conditions to the ambient air stream under the car. The demonstrated system achieved a power density on the order of mW m−2. We compare the power generated to those of TEGs currently tested by GM, Honda, BMW and Ford. Further, a simple economic estimation is calculated to assess the $ per Watt cost of future practical thermogalvanic waste heat recovery system.
Feasibility of Matching Wind and Wave Energy Conversion for an Integrated Design Concept
Authors: Beyene Asfaw , Anderson Michael
Published: October 2015

Wave and wind modeling software were used to evaluate a combined resource availability of wave and wind along the California coast. A potential for an integrated wave and wind platform was evaluated and found that the resource increases in the northern direction. An integrated platform for wave and wind was proposed and modelled with estimates of implementation cost. The constructed platform was rated at 584 kW producing over 4,500,000 kWh/yr. This would lead to a yearly income of $599,022 resulting in an 8.8 year simple payback at 2014 currency value. This cost can change depending on several aspects such as the design details of the wind turbines as well as the wave platform, and the rate at which electricity can be sold.
Assessment of Critical Equipment for Preventative Maintenance of Plastic Plant
Authors: Aremu Adebayo A. , Aremu Adeniyi O. , Adeaga Oyetunde A.
Published: October 2015

With the continual demand for effective manufacturing performance, proper maintenance of production facilities and systems has become the standard of good manufacturing practice. In response, industrial plants, machines, and equipment are becoming more technically advanced, thus more complex and difficult to control and maintained. This paper is focused on a methodology for assigning relative criticality to production equipment in order to optimise a preventative maintenance program. As a case study, the authors examine equipment used in plastic production plants. Generic factors deciding the criticality were considered using a scoring system. With the use of cumulative percentage of scores, an Always Better Control (ABC) analysis was carried out and the critical equipment identified. An effective maintenance programme for the case study shows a 23%reduction of down time and also a 12.7% of equipment durability and about 96% criticality equipment factor, with optimum output. The result of this study will be significant to manufacturing company in minimizing incidences and stoppages not only on critical equipment but production facilities.
Water Consumption of Cooling Towers in Different Climatic Zones of the U. S.
Authors: Ludovisi Daniele , Garza Ivo A.
Published: October 2015

Cooling towers are widely used across a range of industries and represent the largest reuse of water in industrial and commercial applications. While continually recycling water, cooling towers loose significant inventory through evaporation and blowdown.

The local climate strongly affects the efficiency of a cooling tower and its water consumption. This paper discusses the performance of cooling towers in different climatic zone of the U.S. considering the seasonal variations of outdoor air temperature, wind speed and solar radiation. The analyses are carried out with the Sargent & Lundy’s software suite UHS which simulates the transient heat and mass transfers occurring in cooling tower/basin systems.
Transitional Effect on Turbulence Model for Wind Turbine Blade
Authors: Sui Chao , Lee Kyoungsoo , Huque Ziaul , Kommalapati Raghava R.
Published: October 2015

This paper presents the computational predictions of NREL Phase VI rotor using SST Gamma Theta turbulence model. All models were performed using the commercial CFD software, ANSYS Workbench CFX. Exactly the same geometry as NREL blades was built. Around 14 million unstructured mesh elements and 3.7 million nodes have been applied during the simulation. To deal with the boundary effect, 18 inflation layers were constructed around the boundary wall. The comparison of torque and thrust between several turbulent models and the experimental data were performed. For the overall performance, a better agreement with the NREL Experimental data was obtained with SST Gamma Theta model. After these verifications, the first, second SST blending function and transition blending function for seven distinct wind speeds were performed. It has been observed that SST Gamma Theta method can simulate the transition effect appropriately.
Flow Characteristics of High-Efficient Axial Flow Pump System
Authors: Liu Chao , Yang Fan , Jin Yan , Yang Hua
Published: October 2015

Three-dimensional flow-fields in a high-efficient axial flow pump system were simulated by CFD to further study the internal flow characteristics. The internal flow patterns of the pump system were obtained at large, small and optimum operating conditions. The highest efficiency of pump system measured and calculated are 82.57% and 81% respectively at blade angle 0°. For the suction passage, the axial velocity distribution uniformity reach 97.51%, and the hydraulic loss is 0.039m, the pipe efficiency calculated is 98.5% at the optimum operating conditions. The maximum velocity is 1.429 m/s in the range of operating conditions, which meet the requirement of National standard. The performances predicted were compared with measurement results. It was found that the calculated results agree well with the measured results. The overall flow pattern of the pump system is uniform and smooth, and the hydraulic loss is very small which gives the excellent hydraulic performances of pump system.
Hydroelectric Generator-Motor Brake Dust Collection: Boundary Condition Selection for Flow Modeling of a Dilute-Phase Pneumatic Conveying System
Authors: Washington DeVon A. , Lewis James B. , Gilmore Robert T.
Published: October 2015

Due to a significantly large mass moment of inertia many large vertical pump-turbines, used at pumped storage plants, for hydroelectric power generation are equipped with mechanical braking systems. After shutdown, these systems allow the unit to be brought to rest in a relatively short period of time. Even units which take advantage of electrical braking use mechanical brakes. The brakes are applied when the unit’s angular velocity is sufficiently small; this reduces wear on the thrust bearing and other components. Additionally, mechanical brakes prevent slow rotation of the unit due to wicket gate leakage and are also used during routine maintenance.

The brake dust generated from the braking process can contaminate various sections of the generator-motor, adversely impacting unit performance. To prevent this and improve unit reliability and availability, many larger units are equipped with brake dust collection systems. Brake dust collection systems utilize air to convey brake dust to a filtering apparatus, where the dust is collected and transported safely away from sensitive components. Such a system can be described as a dilute-phase pneumatic conveying system. The most significant design parameters are: pressure drop, solids flow rate, and gas flow rate. These parameters are optimized to ensure the correct saltation and pickup velocities are achieved to convey the material over the required distance.

Some system designers employ equal flow as an inlet boundary condition (BC) for designing pneumatic conveying systems of this type. This study examines the validity of using equal flow versus equal pressure as an inlet BC; with the goal of demonstrating that equal pressure is more appropriate and results in a more robust system design.

This was accomplished by developing a steady state flow model of the brake dust collection system in PIPENET™. Model results show that the equal pressure inlet BC is not only a more conservative BC, but its application also revealed potential short comings in the system’s ability to attain adequate pickup velocities in various sections of the system. The selection of the appropriate BC is essential to the successful design of a robust pneumatic conveying system.