bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Atomistic and Continuum Methods for Calculating Ballistic Phonon Transmission in Nanoscale Waveguides
Authors: Cheney Drew A. , Lukes Jennifer R.
Published: July 2013

We compare two methods for the calculation of mode dependent ballistic phonon transmission in nanoscale waveguides. The first method is based on continuum acoustic waveguide theory and uses an eigenmode expansion to solve for phonon transmission coefficients. The second method is an atomistic, lattice dynamics (LD)-molecular dynamics (MD) hybrid that uses LD computed mode shapes to excite guided phonon wavepackets in a nonequilibrium MD simulation and calculates phonon transmission from the final distribution of system energy. The two methods are compared for a planar waveguide with a t-stub irregularity, a geometry which has been proposed for the tuning of phonon transmission and nanostructure thermal conductance. Our comparison highlights advantages and disadvantages of the two methods and illustrates regimes when atomistic effects are prominent and continuum approaches are not appropriate.
Convection, Evaporation, and Condensation of Simple and Binary Fluids in Confined Geometries
Authors: Qin Tongran , Grigoriev Roman O.
Published: July 2013

Rayleigh-Bénard and Marangoni convection in a layer of a homogeneous fluid with a free surface in the absence of phase change is a classic (and extensively studied) problem of fluid mechanics. Phase change has a major effect on the convection problem. Most notably, significant latent heat generated at the free surface as a result of phase change can dramatically alter the interfacial temperature, and hence, the thermocapillary stresses. Furthermore, differential evaporation in binary fluids can lead to considerable variation in the concentration field, producing solutocapillarity stresses, which can compete with thermocapillarity and buoyancy.

This talk describes numerical studies of convection in alcohol and alcohol-water mixtures due to a horizontal temperature gradient in the presence of phase change. We illustrate how the composition of the liquid and the presence of non-condensable gases (e.g., air) can be used to alter the balance of the dominant forces. In particular, by adding or removing air from the test cell, the direction of the flow can be reversed by emphasizing either the thermocapillary or the solutocapillary stresses.
Temperature Sensitivity of Nanohole Array Sensors
Authors: Sen Mehmet , Kowalski Gregory , Fiering Jason , Larson Dale
Published: July 2013

Small, sensitive temperature sensors are required to develop chip-scale calorimeters for pharmaceutical and related industries. Laser illuminated nanohole array apertures (NHA) that produce extraordinary optical transmission (EOT) perform as temperature sensors and may be suitable for micro-calorimetry. We investigated NHA sensors by an experimental parametric study to determine the most sensitive configuration. Temperature sensitivity of EOT is discussed, and the results suggest that nanohole arrays enable thermal measurements with microscale spatial resolution. The sensing chip is a glass substrate with 105nm thick gold surface, illuminated with a helium–neon laser. 15 different designs were milled in a formation of 3×5 matrix. Each row has a different array size (3×3, 5×5 and 10×10) and each column has a different pitch size varying from 250nm to 450nm in 50nm increments. The aperture size was fixed at 150 nm, thus the overall size of the array varies from 0.65μm×0.65μm to 4.20μm×4.20μm. The highest sensitivity was achieved with 350nm and 400nm pitch sensors and a 10×10 array (up to8% intensity gain per 0.10°C). These conditions correspond to a predicted peak wavelength region with high transmission gradients, due to the transmission maxima, causing higher sensitivity. This behavior was consistent in all array sizes. Results also showed that even the smallest sensors are sensitive to temperature changes, and they suggest a means for designing future NHA sensors to accommodate different light sources and fluids.
Conjugated Heat Transfer in Micro-Channels With a Single Domain Formulation and Integral Transforms
Authors: Knupp Diego C. , Naveira Cotta Carolina P. , Cotta Renato M.
Published: July 2013

The present work is an extension of a novel methodology recently proposed by the authors for the analytical solution of conjugated heat transfer problems in channel flow, here taking into account the axial diffusion effects which are often of relevance in micro-channels. This methodology is based on a single domain formulation, which is proposed for modeling the heat transfer phenomena at both the fluid stream and the channel walls regions. By making use of coefficients represented as space variable functions, with abrupt transitions occurring at the fluid-wall interface, the mathematical model is fed with the information concerning the transition of the two domains, unifying the model into a single domain formulation with space variable coefficients. The Generalized Integral Transform Technique (GITT) is then employed in the hybrid numerical-analytical solution of the resulting convection-diffusion problem with variable coefficients. When the axial conduction term is included into the formulation, a non-classical eigenvalue problem must be employed in the solution procedure, which is itself handled with the GITT. In order to covalidate the results obtained by means of this solution path, we have also proposed an alternative solution, including a pseudo-transient term, with the aid of a classical Sturm-Liouville eigenvalue problem. The remarkable results demonstrate the feasibility of this single domain approach in handling conjugated heat transfer problems in micro-channels, as well as when fluid axial conduction cannot be neglected.
Thermal Radiative Properties of Vertical Graphitic Petal Arrays
Authors: Duvvuri Bhagirath , Kumar Anurag , Bao Hua , Huang Haoxiang , Fisher Timothy , Ruan Xiulin
Published: July 2013

In this work, thermal radiative properties of vertical graphene petal arrays are theoretically and experimentally investigated to show that they are superior absorbers of radiation. Finite difference time domain (FDTD) simulations are first performed to calculate optical properties of vertical graphitic arrays of different configurations, namely, graphitic gratings, periodic graphitic cavities, and random graphitic cavities. The effect of polarization of incident radiation on optical properties of such structures is systematically evaluated. When the incident electric field is parallel to the graphitic plane (S polarization) in graphitic gratings, the absorptance is very high, but the reflectance low but still significant when compared to reflectance from a MWCNT array. On the other hand, when the electric field is polarized perpendicular to the graphitic plane (P polarization), the absorptance is significantly lower, as well as the reflectance. This contrast is due to the stronger optical response for the S polarization. Ordered graphitic petal cavity arrays show optical properties falling between the above two cases because of the presence of both polarizations. The random graphitic petal cavity arrays with various angles of orientation show similar properties with ordered petal arrays, and the simulated reflectance agrees very well with experimental data measured on a fabricated thin graphite petal sample.
Quantum-Well Si/SiC Self-Cooling for Thermal Management of High Heat Flux GaN HEMT Semiconductor Devices
Authors: Wang Peng , Manno Michael , Bar-Cohen Avram
Published: July 2013

Wide bandgap semiconductor technology is expected to have a dramatic impact on radar and communications systems. To take full advantage of the power capabilities and small device sizes of wide bandgap semiconductors, new and novel thermal management solutions, especially for high power density, monolithic microwave integrated circuits (MMICs) are in high demand. In this paper, a quantum-well Si/SiC self-cooling concept for hot spot thermal management at the multi-fingered GaN high electron mobility transistor (HEMTs) in the GaN-on-SiC package is proposed and investigated using a three dimensional (3-D) thermal-electric coupling simulation. The impact of electric current, cooler size, Si/SiC substrate thickness, Si/SiC thermal conductivity, and interfacial parasitic effect on the hot spot cooling is examined and discussed. The preliminary modeling results strongly suggest that self-cooling phenomenon inherent in the quantum-well Si/SiC substrate can be used to remove local high heat flux hot spot on the semiconductor devices.
Heat Transfer and Pressure Drop Through Nano-Fin Arrays in the Free-Molecular Flow Regime
Authors: Martin Michael James
Published: July 2013

Gas flow through arrays of rectangular nano-fins is modeled using the linearized free-molecular drag and heat transfer equations. These are combined with the one-dimensional equations for conservation of mass, momentum, and energy, and the ideal gas law, to find the governing equations for flow through the array. The results show that the pressure gradient, temperature, and local velocity of the gas are governed by coupled ordinary differential equations. The system of equations is solved for representative arrays of nano-fins to find the total heat transfer and pressure drop across a 1 cm chip.
Simulation of Particle Property Effects in Energy Transport in Brownian Motion
Authors: Martin Michael James
Published: July 2013

The change in particle concentration and heat transfer in a slot filled with a nano-fluid is computed using a 2-fluid model. The slot has a width L of 5000 micron slot with a 30 K temperature differential. The working fluid is glycerine. The nano-particle materials used are aluminum oxide, copper, silicon oxide, and titanium oxide. The particle diameter is 5 nm, and a volumetric particle concentrations ϕ of 0, 0.005, 0.01, 0.015, and 0.02 are used. Simulation of the transport equations shows that the change in volumetric concentration across the slot is approximately 5% of the total volumetric concentration, and does not change based on the particle material for the four materials selected. The calculated heat transfer in the slot changes by up to 35%, and is dependent on the nano-particle material and concentration. These results show that the significance of nano-particle material in nano-fluid effectiveness is a result of the varying specific heat of the particles.
Water Infiltration in ZSM-5 Zeolites: Effect of Pore Volume and Water Structure
Authors: Maroo Shalabh C. , Humplik Tom , Laoui Tahar , Wang Evelyn N.
Published: July 2013

This study investigates the infiltration of water in ZSM-5 zeolite crystals via molecular dynamics simulations and experiments. A zeolite nano-crystal is constructed in the simulations and is surrounded by water molecules which enter and saturate the pores. The average number of water molecules per unit cell of the zeolite is determined along with the radial distribution function of water inside the zeolites. A geometric approximation of the zeolite pores and intersections is proposed and verified. Partial charge on the zeolite atoms is found to be a crucial parameter which governs the water infiltration behavior. ZSM-5 zeolite crystals were also synthesized and water infiltration experiments were conducted using an Instron. The simulation and experimental findings are compared and discussed. The understanding gained from these studies will be important for the development of zeolite based reverse osmosis membranes for water desalination.
The Effects of Diameter and Chirality in the Thermal Transport in Free-Standing and Supported Carbon-Nanotubes
Authors: Qiu Bo , Wang Yan , Zhao Qing , Ruan Xiulin
Published: July 2013

We use molecular dynamics (MD) simulations to explore the lattice thermal transport in freestanding and supported single-wall carbon-nanotube (SWCNT) in comparison to that in graphene nanoribbon (GNR) and graphene sheet. We find the lattice thermal conductivity of freestanding SWCNT and GNR increases with diameter/width and approaches that of graphene. This is partly attributed to the curvature that shortens phonon lifetime in SWCNT. In contrast to GNR, there is only weak chirality dependence in the thermal conductivity of freestanding SWCNT. When SWCNT is put on substrate, an effective boundary along the SWCNT axial direction at the SWCNT-substrate interface is created, rendering resemblance between the phonon transport in supported SWCNT and that in freestanding GNR. As a result, the thermal conductivity of supported SWCNTs differ by around 10%, depending on chirality. The thermal conductivity of SWCNT decreases by about 34–41% when supported, which is less than that of the reduction seen in supported graphene.
Solar Energy Harvesting Using Nanofluids-Based Concentrating Solar Collector
Authors: Khullar Vikrant , Tyagi Himanshu , Phelan Patrick E. , Otanicar Todd P. , Singh Harjit , Taylor Robert A.
Published: July 2013

Dispersing trace amounts of nanoparticles into the base-fluid has significant impact on the optical as well as thermo-physical properties of the base-fluid. This characteristic can be utilized in effectively capturing as well as transporting the solar radiant energy. Enhancement of the solar irradiance absorption capacity of the base fluid scales up the heat transfer rate resulting in higher & more efficient heat transfer. This paper attempts to introduce the idea of harvesting the solar radiant energy through usage of nanofluid-based concentrating parabolic solar collectors. In order to theoretically analyze the nanofluid-based concentrating parabolic solar collector (NCPSC) it has been mathematically modeled, and the governing equations have been numerically solved using finite difference technique. The results of the model were compared with the experimental results of conventional concentrating parabolic solar collectors under similar conditions. It was observed that while maintaining the same external conditions (such as ambient/inlet temperatures, wind speed, solar insolation, flow rate, concentration ratio etc.) the NCPSC has about 5–10% higher efficiency as compared to the conventional parabolic solar collector. Furthermore, some parametric studies were carried out which reflected the effect of various parameters such as solar insolation, incident angle, convective heat transfer coefficient etc. on the performance indicators such as thermal efficiency etc.
Nanosecond Time-Resolved Measurements of Hole Opening During Laser Micromachining of Aluminum Films
Authors: Willis David A. , Hendijanifard Mohammad
Published: July 2013

Laser micromachining of aluminum films on glass substrates is investigated using a time-resolved transmission imaging technique with nanosecond resolution. Micromachining is performed using a 7 ns pulse-width Nd:YAG laser operating at the 1064 nm wavelength for fluences ranging from 2.2 to 14.5 J/cm2. Transmission imaging uses a nitrogen laser-pumped dye laser with a 3 ns pulse-width and 500 nm wavelength. Images are taken from the back of the sample at various time delays with respect to the beginning of the ablation process, allowing the transient hole opening process to be observed and measured. Results show that for high fluences the holes begin opening during the laser pulse and that the major portion of the holes have opened within the first 50 ns of the process. The second stage of the process is slower and lasts between 100–200 ns. The rapid hole opening process can be attributed to melt expulsion due to recoil pressure on the surface of the melt pool rather than Marangoni flow. Recoil pressure may be due to vaporization at the free surface at low fluences and phase explosion (explosive liquid-vapor phase change) at higher fluences. Measurements of the transient shock wave position are used to estimate the pressure behind the shock wave and indicate pressures at high as 89 atm during ablation. The high pressure above the laser spot results in pressure on the molten surface, leading to expulsion of the molten pool in the radial direction.
Experimental Study of Tube Row Effects on Evaporation Heat Transfer Using a Micro-Scale, Porous-Layer Coating on a Horizontal-Tube, Falling-Film Heat Exchanger
Authors: Köroğlu Batikan , Bogan Nicholas , Park Chanwoo
Published: July 2013

An experimental study was conducted to investigate the effects of tube row and a micro-scale porous-layer coating on solution fluid wetting and heat transfer of a horizontal-tube, falling-film heat exchanger using an inline tube arrangement. A uniform layer of micro-scale copper particles was directly bonded onto plain copper tubes by sintering to create a porous-layer coating on the tubes. Distilled water was used as solution and heating fluids. The visual observation performed in open ambient condition revealed that when the solution was dripped onto horizontal tubes from a solution dispenser, the conventional plain tubes were always partially wetted while the porous-layer coated tubes were completely wetted due to capillary action, even at low solution flow rates. It was shown from the comparison of the evaporation heat transfer results of the plain and porous-layer coated tubes tested in a closed chamber under saturated conditions that the porous-layer coated tubes exhibited a superior evaporation heat transfer rate (around 70% overall improvement at low solution flow rates) due to the complete solution wetting and thin solution liquid film on the evaporator tubes. It was also observed that the heat transfer and surface wetting of the horizontal-tube, falling-film heat exchanger are greatly affected by both the flow mode of the solution fluid between the tubes and tube wall superheats. The effect of the tube row of the falling-film heat exchanger on the solution wetting and heat transfer was significant.
Micro/Nanoscale Heat Transfer: Interfacial Effects Dominate the Heat Transfer
Authors: Zhang X. , Guo Z. Y.
Published: July 2013

This paper describes the effects of size on heat conduction in nanofilms, convective heat transfer in micro/nanochannels, and near-field radiation in nanogaps. As the size is reduced, the ratio of the surface area to the volume increases; therefore, the relative importance of the interfacial effects also increases. The physical mechanisms for these size effects have been classified into two classes. When the scale is reduced to the order of micrometers (except for gases), the interfaces only affect the macro parameters and the continuum assumption still holds, but the relative importance of the various forces (inertia force, viscous force, buoyancy, etc.) and effects (interfacial effect, axial heat conduction in the tube wall, etc.) changes, resulting in changes in the heat transfer characteristics from normal conditions. As the size is further reduced to the order of submicrometers or nanometers, the interface affects not only the macro parameters but also the micro parameters (mean free path, relaxation time, etc.) so the continuum assumption breaks down and Newton’s viscosity law and Fourier’s heat conduction law are no longer applicable. Thus, the major characteristic of micro/nanoscale heat transfer is that the interfacial effects dominate the heat transfer.
Carbon Monoxide Emission Improvements From Combustion System Upgrades at the Wheelabrator Portsmouth Refuse Derived Fuel Plant
Authors: Pethe Samit J. , Britt Michael L. , Morrison Scott A.
Published: July 2013

Wheelabrator Technologies Inc. (WTI) operates a waste-to-energy facility in Portsmouth, Virginia. At full capacity, a total of 2,000 tons/day of refuse derived fuel (RDF) can be fired in four identical boilers to generate a total of 600,000 lb/hr of steam and 60 MW of electricity. The boilers were originally designed to co-fire RDF and coal; however, coal burning capability was removed a few years after commissioning. The plant provides all of the process/heating steam and the majority of the electrical power to the nearby Norfolk Naval Shipyard.

Historically, the boilers had not been able to reliably achieve carbon monoxide (CO) emissions compliance. CO emissions experienced during normal boiler operation would be more than twice the mandated emission limit. WTI’s goal was to improve the boilers’ CO emissions performance while achieving sustained boiler operation at higher steam generation and RDF firing rates.

WTI contracted Jansen Combustion and Boiler Technologies, Inc. (JANSEN) to evaluate the operation of the boilers, to assess the overall feasibility of meeting WTI’s goals, and to develop design concepts to overcome boiler limitations. The project was initiated by an engineering site visit where boiler operating data was collected and evaluated to develop a baseline of boiler operation.

Current and new combustion system arrangements were evaluated with Computational Fluid Dynamics (CFD) modeling. The results confirmed that the root cause of the poor CO emissions performance was the inadequate penetration and mixing of the original overfire air (OFA) system (comprised of multiple rows of small ports on the front and rear furnace walls). CFD modeling also showed increased CO emissions to result from non-uniform RDF delivery profiles generated by the original fuel distributors that were installed at a high elevation over the grate. Modeling of the furnace with larger and fewer OFA nozzles placed on the side walls in an interlaced pattern, and the installation of “new-style” RDF distributors at a lower elevation where the boiler’s original coal distributors formerly were located was shown to significantly improve CO burnout.

From December 2010 to May 2011, the new combustion systems were installed on all four boilers. Subsequent testing has shown that CO levels have been lowered by more than 70% and boiler availability has been significantly improved. Nitrogen oxides (NOx) emissions, although slightly higher following the upgrade, are still within the NOx compliance limit.

This paper describes the process that led to a successful project, including: data collection and analyses, CFD modeling, equipment design and supply, operator training, and start-up assistance.
Air Permitting of New WTE Projects
Authors: Henderson Thomas M. , Hanisch John L. , Scott Kevin R. , Cohn Joel S.
Published: July 2013

Two major new Waste-To-Energy (WTE) Projects have received Air Construction Permits under the Prevention of Significant Deterioration (PSD) program during the past two years and a third is scheduled to receive its permit prior to NAWTEC 20. These new facilities are being required to operate with significantly lower emissions of nitrogen oxides (NOx) and other major air pollutants than similar existing US facilities. This paper will explore the permitting process on these three projects and the divergent approaches being taken by the applicants to meet the stringent emission requirements imposed by the PSD permits.

The Palm Beach County (Florida) Renewable Energy Facility No. 2 (PBREF No. 2) will be a three unit, 3,000 ton per day (tpd) mass burn facility which will utilize Selective Catalytic Reduction (SCR) systems similar to that used in many recent European WTE facilities for NOx control. The Fairfield (Maryland) Renewable Energy (Fairfield) and Aercibo (Puerto Rico) Renewable Energy (Aercibo) Projects are each two unit, 2,106 tpd Refuse Derived Fuel (RDF) facilities which will utilize regenerative SCR (RSCR®) systems. This will be the first time RSCR® has been used in a WTE application. All three permits require achievement of a NOx emission rate of 45 parts per million by volume at 7% O2 dry basis (ppmvd).

PBREF No. 2 and Fairfield received PSD permits from delegated state programs prior to the new Greenhouse Gas (GHG) and condensable PM2.5 permitting rules going into effect at the beginning of 2011. Aercibo is being permitted by United States Environmental Protection Agency (EPA) Region II and will reflect new GHG and condensable PM2.5 permitting rules. This paper discusses the approach to the Best Available Control Technology (BACT) and Lowest Achievement Emission Rate (LAER) determinations and differences in final permit requirements.
Modeling and Design of a High Temperature Chamber Fed by a Plasma Torch for Removal of Tars
Authors: Demarthon Romain , Marias Frédéric , Fourcault Alice , Robert-Arnouil Jean Paul
Published: July 2013

One way of biomass and/or waste recycling is its thermochemical conversion into combustible gas. Mainly composed of CO,H2 and CH4, the gas may also contain varying amounts of impurities (dust, polluting products, tar or soot). Specifically, there is a tar problem: their high condensation temperature is incompatible with an industrial utilization. They can cause rapid fouling, corrosion and abrasion into turbines or engines.

Proposed by EUROPLASMA, the CHO-Power process aims to generate electricity from a mixture of municipal waste and biomass using a fixed bed gasifier with conventional gas treatment. Its specificity consists of an unit called Turboplasma. This stage allows to reach very high temperature in order to obtain temperature around 1600K, and so to degrade all tars present, even heavier.

Indeed, EUROPLASMA built a gasification pilot unit based on fluidized bed technology, (called KIWI) to qualify the synthesis gas produced. TURBOPLASMA pilot scale will be installed there. The objective of this work is the design of this high temperature stage thanks to numerical modeling.

Reaction scheme used previously [4] to modelize tar degradation in the Turboplasma of CHO-Power, has been improved: a discrete phase modeling has been added providing a better view of the TURBOPLASMA internal behavior. Indeed, char particles from syngas can significantly change the reactor performance. This study shows that char particles react primarily with the H2O and CO2. Char gasification takes place in areas of high velocity and temperature gradient. Increased understanding of aerodynamics inside the reactor allows a better estimate of the overall performance of the reactor. Performance evaluation of the reactor is based on a set of parameters such as levels of heat loss, velocity gradient, mixing quality, residence time.
Comparison of Environmental Performance Expectations: Gasification Versus Mass-Burn WTE Facilities Currently Under Construction in North America
Authors: Rice Elizabeth A.
Published: July 2013

In recent years, factors including limited landfill capacity, increasing costs of fossil fuels, and increased pressure to actively recover value from waste in the form of materials and energy have encouraged municipalities throughout North America to advance waste management strategies that utilize waste-to-energy (WTE) technologies as an alternative to landfilling. Currently, utilization of alternative conversion technologies, including gasification, is limited to small-scale or pilot municipal solid waste (MSW) to energy facilities in North America. Though limited history of environmental performance when using MSW as a primary feedstock has delayed public acceptance of facility proposals, municipalities are now moving forward with alternative conversion technology applications.

In Florida, two entities have received permits from the Department of Environmental Protection to proceed with construction of gasification facilities — Geoplasma, Inc. in St. Lucie County, and INEOS New Planet BioEnergy in Vero Beach. In Edmonton, Alberta, Canada, Enerkem GreenField Alberta Biofuels has received a permit from Alberta Environment to begin construction of a gasification facility that will produce bioethanol from post-recycled MSW.

Since 1996, no new greenfield MSW-processing mass burn facility has been constructed in the U.S., though facilities in Hillsborough County, FL; Lee County, FL; and Olmstead County, MN have undergone expansions, and in Honolulu, FL, a 900 TPD unit is currently under construction. In recent years, two municipalities have received permits to proceed with construction of mass burn WTE facilities and have made significant progress toward implementation: The municipalities of Durham and York, Ontario, Canada and The Solid Waste Authority of Palm Beach County, Florida.

This paper will provide a direct comparison of the expected environmental performance of the recently permitted gasification facilities to the expected environmental performance of the recently permitted mass burn WTE facilities, as established by permit applications and emissions modeling studies. Comparison of emissions of particulate matter, sulfur dioxide, nitrogen oxides, carbon monoxide, volatile organic compounds, and hydrogen chloride will be performed on the basis of one ton of feedstock processed. Emission of these pollutants at the recently permitted facilities discussed above will be contrasted with emissions experienced at currently operating WTE facilities within North America.
A Comparison of Air Emissions of Conversion Technology Processes Using Materials Recovery Facility Residues
Authors: Raibley Timothy J.
Published: July 2013

In order to maximize the beneficial use of waste materials within its jurisdiction, the Western Placer Waste Management Authority (Authority) is exploring the economic, technical, and regulatory feasibility of recovering energy from waste residues delivered to its waste management facility. The purpose of the Study is to support the results of the Authority’s analysis of the emissions associated with converting municipal solid waste (MSW) residuals currently being landfilled into energy as compared to current waste disposal practices.
Deactivation and Energy Analysis of Char Catalysts in Biomass Gasification Systems
Authors: Klinghoffer Naomi , Castaldi Marco J.
Published: July 2013

One of the major barriers to gasification is the need for elimination of tars that are generated in thermochemical conversion processes. While metal catalysts can be used for tar decomposition, and cheaper alternative is char. Deactivation of char catalysts has been studied and these deactivation rates have been applied to a model for a gasification system. The calculations and experimental data presented here show that if the char from a gasifier is recycled to a tar reformer then some char deactivation will take place, but the activity will not fall below 40% of its initial activity. The energy penalty for diverting char, a potential heat source, to a catalytic reactor has been accounted for. This was done by comparing the heating value of char to the heating value of syngas generated from reforming tar using the char as a catalyst. At high gasification temperatures, when tar production in the gasifier was low, the char had a higher heating value than the syngas that was produced from tar reforming. At low temperatures, the heating value of the syngas exceeded that of the char combustion, which implies an overall energy benefit.
Breaking Ground for a New 3,000 Ton Per Day Waste to Energy Facility
Authors: Schauer Raymond H. , Richter Leah K.
Published: July 2013

Created in 1978, the Solid Waste Authority of Palm Beach County (Authority) has developed an “award winning” solid waste management system that includes the following facilities to service the residents and businesses in Palm Beach County, Florida:

• North County Resource Recovery Facility (NCRRF);

• Residential and Commercial Recovered Materials Processing Facility;

• Six Transfer Stations;

• Class I Landfill;

• Class III Landfill;

• Biosolids Processing Facility;

• Ferrous Processing Facility;

• Woody Waste Recycling Facility;

• Composting Facility; and

• Two Household Hazardous Waste Facilities.

The Authority has proactively planned and implemented an integrated program to provide for the long term, reliable, economically sound and environmentally sustainable management of solid waste in Palm Beach County.

The County’s anticipated growth necessitated that the Authority evaluate several options for long-term processing and disposal capacity. This resulted in a decision to expand its WTE capacity with a new mass burn facility, the first facility of its kind to be constructed in the US in almost two decades, reaffirming its commitment to waste-to-energy. The planned 3,000 TPD facility will provide the Authority with a total disposal capacity of 5,000 TPD generating approximately 150MW of renewable energy. The decision to proceed with the expansion was approved by the Authority’s Board in October 2008. The Authority, with its Consulting Engineer, Malcolm Pirnie/ARCADIS, has since made significant progress in the implementation of this landmark project including the completion of the preliminary design, securing environmental permits, procuring a full service vendor, issuance of nearly $600 million revenue bonds for signing an electrical sales contract, and ongoing extensive public outreach efforts.

This presentation will focus on the ongoing development of the new mass burn facility and an update of the status of activities conducted to date such as:

• Environmental Permitting – Issuance of the PPSA Conditions of Certification and submittal of the Post Certification/Pre Construction requirements;

• Vendor Procurement – Iterative procurement process designed to obtain vendor input through final selection and contract award of a full service vendor (Design, Build and Operate);

• Preliminary Design – Innovative design features such as the utilization of SCR technology for control of NOx emission and incorporation of rainwater harvesting and water reuse;

• Public Outreach – the Authority’s efforts to keep the public informed through mass mailings, community meetings, television commercials and educational materials for all audiences; and

• Financing – Approach designed to preserve alternative minimum tax benefits.
The Effect of Food Waste Diversion on Waste Heating Value and WTE Capacity
Authors: LoRe Anthony M. , Harder Susana
Published: July 2013

Most communities use curbside recycling and yard waste composting programs to reduce the amount of solid waste that needs to be disposed in a waste-to-energy (WTE) facility or landfill. Communities with well established programs have come to realize that there is a practical limit to the amount of solid waste that can be diverted using these methods. To increase waste diversion rates further, some communities have begun to target other materials. One material that is receiving increased attention is food waste.

Food waste represents a significant portion of the remaining waste stream and several alternative options are available to manage this material, including composting and anaerobic digestion. In some cases, communities have already begun to implement separate residential food waste collection programs—commonly referred to as the “green bin.” In addition, several jurisdictions have already enacted regulations to promote the diversion of food waste from commercial generators such as food processors, restaurants and supermarkets.

Since food waste has a relatively high moisture content, removal of this high-volume component can significantly affect the composition and characteristics of the remaining waste, most notably the heat content. It is important that current and future WTE facility owners understand the potential impacts to their WTE project should they implement a food waste diversion program.

This paper evaluates the potential outcome of food waste diversion on the heating value of the remaining waste based on recent waste characterization data collected by Metro Vancouver. Metro Vancouver represents a good case study since they currently own a WTE facility and are considering constructing a second one. Metro Vancouver’s long-term solid waste management plan also includes implementing a food waste diversion program in order to increase their overall waste diversion rate from 55 to 70 percent by 2015. The potential effect of food waste diversion on the capacity of Metro Vancouver’s existing WTE facility as well as the capacity and cost of a new WTE facility is also examined.
Effect of Methyl Chloride on Landfill Gas Dry Reforming
Authors: Kohn McKenzie P. , Castaldi Marco J. , Farrauto Robert J.
Published: July 2013

Landfills are the second-largest source of anthropogenic methane emissions in the U.S., accounting for 22% of CH4 emissions. Landfill gas (LFG) is primarily composed of CH4 and CO2, and currently only 18% of this is used for energy. Because landfills will continue to be used for the foreseeable future, complete utilization of LFG is becoming more important as the demand for energy increases. Catalytically reforming LFG produces syngas (H2 and CO) that can be converted to liquid fuels or mixed into the LFG stream to produce a more reactive, cleaner burning fuel. It has been demonstrated that injecting 5% syngas into a simulated LFG mixture prior to engine combustion decreases CO, UHC, and NOx emissions by 73%, 89%, and 38%, respectively. One barrier to using LFG in a catalytic system is the contaminant content of the LFG, including chlorine and sulfur compounds, higher order hydrocarbons, and siloxanes that have the potential to poison a catalyst. Chlorinated compounds are present in LFG at 10–100ppm levels and are often found as chlorocarbons. This research explores the effect of methyl chloride on the activity of a Rh/γ-Al2O3 catalyst while dry reforming LFG to syngas. It has been found that methyl chloride acts as a reversible poison on the dry reforming reaction, causing a loss in dry reforming activity, decrease in syngas production, and increase in H2/CO ratio while CH3Cl is present in the feed. CH3Cl exposure also decreases the acidity of the catalyst which decreases carbon formation and deactivation due to coking.
CFD Analysis of NOx Formation in Waste-to-Energy Systems Using Detailed Chemical Kinetic Modeling
Authors: Frank Alex , Castaldi Marco J.
Published: July 2013

This study was undertaken to better understand the governing processes and reaction conditions under which NOx is produced in Waste to Energy (WtE) boilers. A three dimensional CFD model was created and calculated using the GRI 3.0, 50 species, 309 step detailed chemical kinetic model (DCKM) for methane/ethane combustion. Model results for primary NOx emissions and other pollutants agree well with collected data, proving the fidelity of the model. NO was the primary pollutant accounting for approximately 99% of the total NOx emissions. Fuel bound nitrogen was found to be the main source of NO produced in the boiler with thermal and prompt mechanisms having lesser impacts. Three principal intermediates were identified in the formation of NO; NH, HNO, and NCO. The assumption of fuel nitrogen conversion to either NH3 or HCN is an unknown parameter that was shown to have a small impact on NO emissions, indicating that this is an area that should not be explored further in this continuing study. Furthermore, varying the boiler pressure had a small impact on final NO emissions, indicating that this is not a condition that should be considered for plant operation. The next phase of this research will include the development of a reduced DCKM in order to expedite the running of new scenarios for future studies as well as optimization of boiler geometry and combustion mixing to achieve the lowest possible NOx emissions.
Developmental Control of the Melanocortin-4 Receptor by MRAP2 Proteins in Zebrafish
Authors: Sebag Julien A. , Zhang Chao , Hinkle Patricia M. , Bradshaw Amanda M. , Cone Roger D.
Published: July 2013

Accessory to Obesity?

Melanocortin receptors are a family of cell membrane receptors that control diverse physiological functions. Mutations in the gene encoding melanocortin 4 receptor (MC4R) are a cause of familial early-onset obesity.

Asai
et al.

(p.
275
) studied the function of an accessory protein for MC4R signaling, MRAP2, and found that mice genetically deficient in MRAP2 develop severe obesity. Sequencing of
MRAP2
in unrelated, severely obese humans revealed one individual with a clearly disruptive genetic variant, suggesting that
MRAP2
mutations might also be a rare cause of human obesity. In a zebrafish model,

Sebag
et al.

(p.
278
) studied two paralogs of the MRAP2 accessory protein, one of which enhanced MC4R responsiveness to α–melanocyte-stimulating hormone, which regulates feeding and growth.
Switchable Static and Dynamic Self-Assembly of Magnetic Droplets on Superhydrophobic Surfaces
Authors: Timonen Jaakko V. I. , Latikka Mika , Leibler Ludwik , Ras Robin H. A. , Ikkala Olli
Published: July 2013

Magnetic Self-Assembly

During self-assembly, objects spontaneously assemble into larger ordered patterns as observed, for example, in the phase segregation of block copolymers or the assembly of micrometer-sized objects and components in electronics. In dynamic self-assembly, the ordered patterns require an external energy source, but still form because of intrinsic interactions within the system.

Timonen
et al.

(p.
253
; see the Perspective by

Hermans
et al.

) studied the organization of magnetic droplets, in the form of a ferrofluid, placed on a low-friction surface. A time-varying magnetic field transformed the statically arranged droplets into a dynamic pattern.
Crowdsourcing and Curating Online Education Resources
Authors: Porcello Darrell , Hsi Sherry
Published: July 2013

The diverse wealth of crowdsourced online tools can benefit from professional coordination and quality control.
Droplets Out of Equilibrium
Authors: Hermans Thomas M. , Frauenrath Holger , Stellacci Francesco
Published: July 2013

Magnetic droplets can be switched between static and dynamic structures.

[Also see Report by

Timonen
et al.

]
Latest Skirmish Over Ancestral Violence Strikes Blow for Peace
Authors: Culotta Elizabeth
Published: July 2013

Are hunter-gatherer societies warlike? That question has sparked a war of its own among scientists. Now in this issue of
Science
, a study fires a salvo in support of peace among mobile foraging cultures.
Germany Debates How to Strengthen Universities
Authors: Vogel Gretchen
Published: July 2013

Germany's recent push to boost a handful of its universities to the world's top ranks got a yellow light this week as an advisory council recommended taking a break from the national competition to find, and fund, Germany's top schools.
Mars Rover Plans Roll While Asteroid Acrimony Continues
Authors: Bhattacharjee Yudhijit
Published: July 2013

As NASA's plan for a Mars rover advances, its asteroid capture effort faces skepticism.
Human Antibody Neutralizes Severe Fever with Thrombocytopenia Syndrome Virus, an Emerging Hemorrhagic Fever Virus
Authors: Guo Xiling , Zhang Li , Zhang Wenshuai , Chi Ying , Zeng Xiaoyan , Li Xian , Qi Xian , Jin Qiu , Zhang Xiao , Huang Mingming , Wang Hua , Chen Yin , Bao Changjun , Hu Jianli , Liang Shuyi , Bao Lin , Wu Tao , Zhou Minghao , Jiao Yongjun
Published: July 2013

Severe fever with thrombocytopenia syndrome virus (SFTSV), a newly discovered member of the
Bunyaviridae
family, is the causative agent of an emerging hemorrhagic fever, SFTS, in China. Currently, there are no vaccines or effective therapies against SFTS. In this study, a combinatorial human antibody library was constructed from the peripheral lymphocytes of 5 patients who had recovered from SFTS. The library was screened against purified virions for the production of single-chain variable-region fragments (ScFv). Of the 6 positive clones, one clone (monoclonal antibody [MAb] 4-5) showed neutralizing activity against SFTSV infection in Vero cells. MAb 4-5 was found to effectively neutralize all of the clinical isolates of SFTSV tested, which were isolated from patients in China from 2010 to 2012. MAb 4-5 was found to bind a linear epitope in the ectodomain of glycoprotein Gn. Its neutralizing activity is attributed to blockage of the interactions between the Gn protein and the cellular receptor, indicating that inhibition of virus-cell attachment is its main mechanism. These data suggest that MAb 4-5 can be used as a promising candidate molecule for immunotherapy against SFTSV infection.
Immunogenicity of Recombinant Proteins Consisting of Plasmodium vivax Circumsporozoite Protein Allelic Variant-Derived Epitopes Fused with Salmonella enterica Serovar Typhimurium Flagellin
Authors: Leal Monica Teixeira Andrade , Camacho Ariane Guglielmi Ariza , Teixeira Laís Helena , Bargieri Daniel Youssef , Soares Irene Silva , Tararam Cibele Aparecida , Rodrigues Mauricio M.
Published: July 2013

A
Plasmodium falciparum
circumsporozoite protein (CSP)-based recombinant fusion vaccine is the first malaria vaccine to reach phase III clinical trials. Resistance to infection correlated with the production of antibodies to the immunodominant central repeat region of the CSP. In contrast to
P. falciparum
, vaccine development against the CSP of
Plasmodium vivax
malaria is far behind. Based on this gap in our knowledge, we generated a recombinant chimeric protein containing the immunodominant central repeat regions of the
P. vivax
CSP fused to
Salmonella enterica
serovar Typhimurium-derived flagellin (FliC) to activate the innate immune system. The recombinant proteins that were generated contained repeat regions derived from each of the 3 different allelic variants of the
P. vivax
CSP or a fusion of regions derived from each of the 3 allelic forms. Mice were subcutaneously immunized with the fusion proteins alone or in combination with the Toll-like receptor 3 (TLR-3) agonist poly(I·C), and the anti-CSP serum IgG response was measured. Immunization with a mixture of the 3 recombinant proteins, each containing immunodominant epitopes derived from a single allelic variant, rather than a single recombinant protein carrying a fusion of regions derived from each of 3 allelic forms elicited a stronger immune response. This response was independent of TLR-4 but required TLR-5/MyD88 activation. Antibody titers significantly increased when poly(I·C) was used as an adjuvant with a mixture of the 3 recombinant proteins. These recombinant fusion proteins are novel candidates for the development of an effective malaria vaccine against
P. vivax
.
Magnetic Fractionation and Proteomic Dissection of Cellular Organelles Occupied by the Late Replication Complexes of Semliki Forest Virus
Authors: Varjak Margus , Saul Sirle , Arike Liisa , Lulla Aleksei , Peil Lauri , Merits Andres
Published: July 2013

Alphavirus replicase complexes are initially formed at the plasma membrane and are subsequently internalized by endocytosis. During the late stages of infection, viral replication organelles are represented by large cytopathic vacuoles, where replicase complexes bind to membranes of endolysosomal origin. In addition to viral components, these organelles harbor an unknown number of host proteins. In this study, a fraction of modified lysosomes carrying functionally intact replicase complexes was obtained by feeding Semliki Forest virus (SFV)-infected HeLa cells with dextran-covered magnetic nanoparticles and later magnetically isolating the nanoparticle-containing lysosomes. Stable isotope labeling with amino acids in cell culture combined with quantitative proteomics was used to reveal 78 distinct cellular proteins that were at least 2.5-fold more abundant in replicase complex-carrying vesicles than in vesicles obtained from noninfected cells. These host components included the RNA-binding proteins PCBP1, hnRNP M, hnRNP C, and hnRNP K, which were shown to colocalize with the viral replicase. Silencing of hnRNP M and hnRNP C expression enhanced the replication of SFV, Chikungunya virus (CHIKV), and Sindbis virus (SINV). PCBP1 silencing decreased SFV-mediated protein synthesis, whereas hnRNP K silencing increased this synthesis. Notably, the effect of hnRNP K silencing on CHIKV- and SINV-mediated protein synthesis was opposite to that observed for SFV. This study provides a new approach for analyzing the proteome of the virus replication organelle of positive-strand RNA viruses and helps to elucidate how host RNA-binding proteins exert important but diverse functions during positive-strand RNA viral infection.