bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical Analysis of a Window for Solar Receivers Using the Monte Carlo Ray Trace Method
Authors: Mecit Ahmet Murat , Miller Fletcher 
Published: December 2013

Concentrated solar power (CSP) systems use heliostats to concentrate solar radiation in order to produce heat, which drives a turbine to generate electricity. We, the Combustion and Solar Energy Laboratory at San Diego State University, are developing a new type of receiver for power tower CSP plants based on volumetric absorption by a gas-particle suspension. The radiation enters the pressurized receiver through a window, which must sustain the thermal loads from the concentrated solar flux and infrared reradiation from inside the receiver. The window is curved in a dome shape to withstand the pressure within the receiver and help minimize the stresses caused by thermal loading. It is highly important to estimate how much radiation goes through the window into the receiver and the spatial and directional distribution of the radiation. These factors play an important role in the efficiency of the receiver as well as window survivability.
Concentrated solar flux was calculated with a computer code called MIRVAL from Sandia National Laboratory which uses the Monte Carlo Ray Trace (MCRT) method. The computer code is capable of taking the day of the year and time of day into account, which causes a variation in the flux. Knowing the concentrated solar flux, it is possible to calculate the solar radiation through the window and the thermal loading on the window from the short wavelength solar radiation. The MIRVAL code as originally written did not account for spectral variations, but we have added that capability.
Optical properties of the window such as the transmissivity, absorptivity, and reflectivity need to be known in order to trace the rays at the window. A separate computer code was developed to calculate the optical properties depending on the incident angle and the wavelength of the incident radiation by using data for the absorptive index and index of refraction for the window (quartz) from other studies and vendor information. This method accounts for regions where the window is partially transparent and internal absorption can occur.
A third code was developed using the MCRT method and coupled with both codes mentioned above to calculate the thermal load on the window and the solar radiation that enters the receiver. Thermal load was calculated from energy absorbed at various points throughout the window. In our study, window shapes from flat to concave hemispherical, as well as a novel concave ellipsoidal window are considered, including the effect of day of the year and time of the day.
Analysis of Food Waste Resources Available for Sustainable Energy Production in the Finger Lakes Region of New York State
Authors: Chan Wai Hon , Ebner Jacqueline , Ramchandra Rajiv , Trabold Thomas 
Published: December 2013

Prior research conducted by our Institute has revealed the large quantities of food waste available in New York State, particularly in the Upstate corridor extending from Buffalo to Syracuse. The Finger Lakes region is heavily populated with agricultural operations, dairy farms and food processing plants, including those producing milk, yogurt, wine, and canned fruits and vegetables. The diverse supply of organic waste generated by these facilities offers the opportunity for sustainable energy production through one of three primary pathways:
• Anaerobic digestion to produce methane
• Fermentation to produce alcohols
• Transesterification to produce biodiesel.
Generally speaking, food wastes are better suited for biochemical conversion instead of thermo-chemical conversion (combustion, gasification, pyrolysis) due to their relatively high moisture content. The current paper provides an initial assessment of food wastes within the 9-County Finger Lakes region around Rochester, New York. Available databases were utilized to first identify all the relevant companies operating in one of four broad industry sectors: agriculture, food processing, food distribution and food services (including restaurants). Our analysis has demonstrated that anaerobic digestion can be a viable method for sustainable energy production from food waste in the Finger Lakes region, due to the dual economic benefits of effective disposal cost reduction and production of methane-rich biogas.
Dome Window Geometry for a Large Scale Solar Receiver
Authors: Saung E-Fann , Miller Fletcher 
Published: December 2013

Windows are being evaluated for use in some high temperature solar receivers to reduce radiative and convective losses. The design process of a 1.7 meter diameter quartz dome window is explained to arrive at a window geometry able to maintain acceptable stresses when exposed to pressure differentials. The dome must be able to withstand the operational differential pressures of 0.5 MPa where the efficiency of the solar receiver/power cycle is maximized, and maximum temperatures upwards to 800°C may be observed. Brittle materials like glass need the tensile stresses to be reduced or eliminated to maximize the reliability of the dome window. However, glass does not possess a consistent characteristic strength and it is dependent on the flaw size. The dome mount is critical to maintaining an environmental seal, but careful attention must be taken in the glass-metal interface to minimize tensile bending stresses that can cause a catastrophic or rapid failure.
A method to characterize the strength of the quartz dome is discussed and aides in determining the maximum design stresses allowable during operation of the solar receiver. To determine an accurate model of the dome stress, a statistical analysis based on strength data has been carried out using the Weibull failure probability method. Finite Element Analysis (FEA) analysis of the dome is discussed, and a design trade study of the dome window geometry (ranging from a shallow angle to a full hemisphere) is presented. The combination of these perspectives will give insight on the process to design a glass dome window for this challenging environment and to predict the reliability.
Carbon Dioxide Emission Reduction Potentials in West Virginia’s Power Generation Sector
Authors: Zabihian Farshid , Gartin Darrel C. , Fung Alan S. 
Published: December 2013

In this paper, research will be discussed on how to scientifically, systematically, and economically reduce greenhouse gas emissions within the state of West Virginia, USA. While fossil fuels such as coal and natural gas remain the top resources within this particular state, there are new technologies, different approaches and modifications to current power generation cycles, and different fuels that can be presented to gain further reduction of these harmful emissions.
To achieve this objective, eight different scenarios were introduced. In the first scenario, existing power stations’ fuel was switched to natural gas. Existing power plants were replaced by natural gas combined cycle (NGCC), integrated gasification combined cycle (IGCC), solid oxide fuel cell (SOFC), hybrid SOFC, and SOFC-IGCC hybrid power stations in scenarios number 2 to 6, respectively. The last two scenarios involved carbon capture systems. It has been found that the CO2 emissions can be significantly reduced by introducing changes and alternatives to the current cycles and methods that are in place today.
Simulation of a Concentrating Solar Power Plant With Molten-Salt Thermocline Storage for Optimized Annual Performance
Authors: Flueckiger Scott M. , Iverson Brian D. , Garimella Suresh V. 
Published: December 2013

A finite-volume-based model of a molten-salt thermocline tank is developed to achieve simulation at a sufficient level of detail but at low computational cost. Combination of this storage model with a system-level power tower plant model enables yearlong thermocline tank simulation in response to historical weather data and corresponding plant control. The current study simulates a 100 MWe molten-salt power tower plant to optimize annual plant performance as a function of the thermocline tank size and the plant solar multiple.
Thermocline storage performance is characterized by the effectiveness of the tank in storing and delivering utilizable heat for steam generation and power production. Additional system-level metrics include thermal energy discard due to saturation of storage capacity and annual plant capacity factor. Economic assessment of the power output is characterized with a simple levelized cost of electricity. Minimum cost is observed with a solar multiple of 3 and a thermocline tank storage capacity of 16 hours.
Phase Change Material Thermal Energy Storage System Design and Optimization
Authors: Qiu Songgang , Galbraith Ross , White Maurice 
Published: December 2013

Thermal energy storage (TES) system integrated with concentrated solar power provides the benefits of extending power production, eliminating intermittency issues, and reducing system LOCE. Infinia Corporation is under the contract with DOE in developing TES systems. The goal for one of the DOE sponsored TES projects is to design and build a TES system and integrate it with a 3 KWe free-piston Stirling power generator. The Phase Change Material (PCM) employed for the designed TES system is a eutectic blend of NaF and NaCl which has a melt temperature of 680° C and energy storage capacity of 12 KWh. This PCM was selected due to its low cost and desired melting temperature. This melt temperature ensures the Stirling being operated at designed operating hot end temperature. The latent heat of this eutectic PCM offers 5 to 10 times the energy density of a typical molten salt. The technical challenges associated with low cost molten salt TES systems are the low thermal conductivity of the salt and large thermal expansion. To address these challenges, an array of sodium filled Heat Pipes (HP) is embedded in the PCM to enhance the heat transfer from solar receiver to PCM and from PCM to Stirling engine. The oversized dish provides sufficient thermal energy to operate a 3KWe Stirling engine at full power and to charge up the TES. The HP arrays are optimally distributed so that the solar energy is transferred directly from receiver to Stirling engine heat receiver. During the charge phase, the Stirling engine absorbs and converts the transferred solar energy to electricity and the excess thermal energy is re-directed and stored to PCM. The stored energy is transferred via distributed HP from PCM to Stirling engine heat receiver during discharge phase.
The HP based PCM thermal energy storage system was designed, built, and performance tested in laboratory. The TES/engine assembly was tested in two different orientations representing the extremes of system operation when mounted on sun-tracking dish, horizontal and vertical. Horizontal represents the zero elevation at sun rise and the vertical represents the extreme of solar noon. The testing allows the examination of orientation effect on the heat pipe performance and the maximum charge and discharge rates. The total energy stored and extracted was also examined. The areas for further system refinements were identified and discussed.
Fabrication of Low Cost Metal-Based Micro-Capillary Channels for Thermal Scavenging and Heat Transfer
Authors: Ogbonnaya E. , Weiss L. 
Published: December 2013

In this work, we present a low cost method for the fabrication of a heat exchanger utilizing metal-based microchannels using the LiGA technique. Lithography is used to pattern dry film negative photoresist (Ordyl P-50100) on the substrate. The resist is laminated over the substrate and exposed with a UV source. The use of dry film resist allows for simple and inexpensive microchannel patterns without requiring advanced cleanroom equipment. Following the lithography process, electrodepostion of metals is used to fill the recesses patterned in the resist. In this work, nickel has been electroplated into the bounding resist structure. After electroplating, the remaining resist is dissolved leaving free standing metal structures. The fabricated exchanger is then evaluated based on thermal absorption of simulated waste heat sources and capillary action of the metal channels themselves.
Channels are fabricated to heights of 60, 70 and 90 μm respectively using these methods. Working fluid mass transfer rate from the heated MHE is utilized as a basic metric of operation. The mass transfer rate recorded from the nickel-based MHE is 3.35, 3.37 and 3.41 mg/s respectively for the different channel heights. This implies an effective thermal power consumption rate of 2.54, 2.56 and 2.59 kW/m2 respectively.
Model Based Analysis of an Integrated System of Vapor-Compression Chiller and Absorption Heat Pump
Authors: Kung Yi-Shu , Qu Ming , Peng Steve 
Published: December 2013

Subcooling of the refrigerant at the exit of the condenser in a vapor compression refrigeration system could be an effective method to improve the coefficient of performance (COP). This method allows the refrigerant entering the evaporator with a lower mass fraction of vapor and absorbs more heat in the evaporator. The effort in this paper investigates a solar based integrated system of an electricity-driven vapor-compression chiller (VC) and an absorption heat pump (ABS) to provide both heating and cooling to space. Thermodynamic and heat transfer models of the integrated system were developed to estimate the system performance. The modeling results showed the integrated system can achieve 40% of the reduction on electricity consumption and 66% of the improvement in cooling COP. Furthermore, the hot water supply temperature can reach 50.25°C.
The models have also been used to conduct parametric sensitivity analysis. The key parameters which affect the performance of the system were the heat source temperature, the hot water return temperature, and the outdoor air flow rate. Hot water flow rate only has significant influence on the hot water supply temperature. Increasing the temperature and flow rate of the heat source can have benefits on both heating and cooling performance. However, increasing the outdoor air flow rate can only benefit on energy saving and cooling performance.
Exergogravimetric Design for Increased SOFC System Power Density
Authors: Haynes Comas , Miller Ryan 
Published: December 2013

Compact subsystems are pivotal to aeronautical applications, inclusive of advanced energy concepts. Regarding size minimization, an “exergogravimetric” approach has recently begun that attempts an exergy-aided weight reduction of advanced energy systems (inclusive of fuel); and this is based upon the added design insights afforded by Second Law considerations. The chief rationale and objective are to leverage the advancements that exergoeconomics affords in the realm of cost-effective thermal system design to aid size-effective thermal system design. A conceptual solid oxide fuel cell (SOFC) system for long-duration unmanned aerial vehicle (UAV) applications has been initially modeled and simulated, inclusive of exergy analysis, and preliminary findings are discussed. Additionally, the concepts and methodologies can be extended to other advanced energy system technologies.
There are project-specific and general milestones and conclusions drawn from the initial investigation. Specific to the project, a conceptual SOFC system simulation was completed via physics-based and literature-verified models along with structured language (i.e., MATLAB) numerical implementation. Specific component-level contributions to lost power potential and added mass were preliminarily resolved. Thermal exergy destruction and loss are predominant sources of unutilized specific power potential. Operational and physical degrees-of-freedom were explored, with the aid of exergy analysis, to resolve better design pathways. This included a counterintuitive preliminary finding that larger cell interconnects may facilitate smaller and more efficient system operation.
Generally, exergy analyses allow a system design opportunity to gain higher resolution insights (i.e., to component- and spatial-extents) regarding inefficiencies throughout a thermal system, and this is afforded by the comprising blend of 1st Law and 2nd Law considerations. There is also an added means of accounting for 2nd Law effects. The traditional 2nd Law verification point of entropy generation being non-negative does not provide the same level of process analysis closure as does the related constraint that all processes have to account for exergy being stored, converted, destroyed or rejected through any defined control volume. This alternative 2nd Law perspective facilitates verification and validation of simulations.
Design and Balance-of-Plant of a Demonstration Plant With a Solid Oxide Fuel Cell Fed by Biogas From Waste-Water and Exhaust Carbon Recycling for Algae Growth
Authors: Gandiglio M. , Lanzini A. , Leone P. , Santarelli M. 
Published: December 2013

The design and balance-of-plant of an integrated anaerobic digestion (AD) biogas solid oxide fuel cell (SOFC) demonstration plant is presented. A notable feature of the plant is the CO2 capture from the SOFC anode exhaust via an oxy-combustion reactor. The captured CO2 is fed to a photobioreactor installation downstream of the SOFC where C is fixed in an algae bio-fuel.
The main plant sections are described in detail including the gas cleaning unit, fuel processing, SOFC ‘hot-box’, oxy-combustor, CO2/H2O condensation unit and finally algae bioreactor.
The demonstration plant is fed with biogas from AD of the by-product sludge of the greatest waste-water treatment plant in Italy, serving over 2 million population equivalents in the Torino metropolitan area.
In this work, the main BoP components and engineering issues concerning the design of the SOFC plant are detailed. The as-produced biogas is firstly treated to remove moisture and then filtered to remove sulfur, halogens and siloxanes. Dry clean biogas (roughly 60–65% CH4, 35–40% CO2) is sent to a steam-reformer. The reformate gas is thus used to feed a 2 kWe SOFC module (operated at ∼ 800 °C). The cathode off-gas is kept separated from the anode and is used to pre-heat inlet fresh air; the anode outlet stream is sent first to an oxy-combustor to yield an almost pure H2O-CO2 mixture that is eventually cooled down to 300–400 °C. Steam is condensed and separated in a dedicated condenser unit. The resulting pure CO2 is thus pressurized (8 bar) and available for sequestration or other uses. Due to the limited size of the demo plant, the choice was to feed it to bioreactors with algae, where the latter are grown with sunlight and CO2 indeed. A tubular photo-bioreactor has been chosen with a productivity of 20 g/day/m2 of dry algae. The outlet stream will be an algae purge that, due to its low mass flow, could be re-sent to the biogas digesters.
A system analysis of a scaled-up version of the biogas fed SOFC power plant, with heat integration included, is also carried out with a calculated overall electrical efficiency exceeding 55% (LHV basis).
Non-Isothermal Hydrodynamic Modelling of the Flowing Electrolyte Channel in a Flowing Electrolyte-Direct Methanol Fuel Cell
Authors: Duivesteyn Eric , Cruickshank Cynthia A. , Matida Edgar 
Published: December 2013

The performance of a direct methanol fuel cell (DMFC) can be significantly reduced by methanol crossover. One method to reduce methanol crossover is to utilize a flowing electrolyte channel. This is known as a flowing electrolyte-direct methanol fuel cell (FE-DMFC).
In this study, recommendations for the improvement of the flowing electrolyte channel design and operating conditions are made using previous modelling studies on the fluid dynamics in the porous domain of the flowing electrolyte channel, and on the performance of a 1D isothermal FE-DMFC incorporating multiphase flow, in addition to modelling of the non-isothermal effects on the fluid dynamics of the FE-DMFC flowing electrolyte channel.
The results of this study indicate that temperature difference between flowing electrolyte inflow and the fuel cell have negligible hydrodynamic implications, except that higher fuel cell temperatures reduce pressure drop. Reducing porosity and increasing permeability is recommended, with a porosity of around 0.4 and a porous material microstructure typical dimension around 60–70 μm being potentially suitable values for achieving these goals.
In Vitro
Photodynamic Inactivation of Plant-Pathogenic Fungi Colletotrichum acutatum and Colletotrichum gloeosporioides with Novel Phenothiazinium Photosensitizers
Authors: de Menezes Henrique D. , Rodrigues Gabriela B. , Teixeira Simone de Pádua , Massola Nelson S. , Bachmann Luciano , Wainwright Mark , Braga Gilberto U. L. 
Published: December 2013

ABSTRACT

The increasing tolerance to currently used fungicides in both clinical and agricultural areas is of great concern. The nonconventional light-based approach of antimicrobial photodynamic treatment (APDT) is a promising alternative to conventional fungicides. We evaluated the effects of APDT with four phenothiazinium derivatives (methylene blue [MB], new methylene blue N [NMBN], toluidine blue O [TBO], and the novel pentacyclic phenothiazinium photosensitizer [PS] S137) on conidia of three fungal species (
Colletotrichum acutatum
,
Colletotrichum gloeosporioides
, and
Aspergillus nidulans
). The efficacy of APDT with each PS was determined, initially, based on photosensitizer MICs. Additionally, the effects of APDT with two selected PSs (NMBN and S137) on survival of conidia were evaluated. The subcellular localization of the PS in
C. acutatum
conidia was determined. The effects of photodynamic treatments on leaves of the plant host
Citrus sinensis
were also investigated. APDT with S137 showed the lowest MIC. MICs for S137 were 5 μM for the three fungal species when a fluence of 25 J cm
−2
was used. APDT with NMBN (50 μM) and S137 (10 μM) resulted in a reduction in the survival of the conidia of all species of approximately 5 logs with fluences of ≥15 J cm
−2
. Washing of the conidia before light exposure did not prevent photodynamic inactivation. Both NMBN and S137 accumulated in cytoplasmic structures, such as lipid bodies, of
C. acutatum
conidia. No damage to orange tree leaves was observed after APDT.
Potentially Pathogenic Escherichia coli Can Form a Biofilm under Conditions Relevant to the Food Production Chain
Authors: Nesse Live L. , Sekse Camilla , Berg Kristin , Johannesen Karianne C. S. , Solheim Heidi , Vestby Lene K. , Urdahl Anne Margrete 
Published: December 2013

ABSTRACT

The biofilm-producing abilities of potentially human-pathogenic serotypes of
Escherichia coli
from the ovine reservoir were studied at different temperatures and on different surfaces. A possible influence of the hydrophobicity of the bacterial cells, as well as the presence of two virulence factors, the Shiga toxin-encoding (Stx) bacteriophage and the
eae
gene, was also studied. A total of 99
E. coli
isolates of serotypes O26:H11, O103:H2, and O103:H25 isolated from sheep feces were included. The results show that isolates of all three
E. coli
serotypes investigated can produce biofilm on stainless steel, glass, and polystyrene at 12, 20, and 37°C. There was a good general correlation between the results obtained on the different surfaces.
E. coli
O103:H2 isolates produced much more biofilm than those of the other two serotypes at all three temperatures. In addition, isolates of serotype O26:H11 produced more biofilm than those of O103:H25 at 37°C. The hydrophobicity of the isolates varied between serotypes and was also influenced by temperature. The results strongly indicated that hydrophobicity influenced the attachment of the bacteria rather than their ability to form biofilm once attached. Isolates with the
eae
gene produced less biofilm at 37°C than isolates without this gene. The presence of a Stx bacteriophage did not influence biofilm production. In conclusion, our results show that potentially human-pathogenic
E. coli
from the ovine reservoir can form biofilm on various surfaces and at several temperatures relevant for food production and handling.