bluuebunny/crossref_metadata_2025 huggingface dataset:
A Multiobjective Approach to Locate Emergency Shelters and Identify Evacuation Routes in Urban Areas
Authors: Alçada‐Almeida Luís , Tralhão Lino , Santos Luís , Coutinho‐Rodrigues João
Published: January 2009

Evacuation planning is an important component of emergency preparedness in urban areas. The number and location of rescue facilities is an important aspect of this planning, as is the identification of primary and secondary evacuation routes for residents to take. This article introduces a multiobjective approach to identify these aspects of evacuation planning. The approach incorporates a multiobjective model into a geographical information systems–based decision support system that planners can access via the Internet. The proposed approach is demonstrated with a case study for the City of Coimbra, Portugal, for evacuation during major fires. Although presented in this context, this approach is applicable to other emergency situations such as earthquakes, floods, and acts of terrorism.
Breastfeeding protects against adverse respiratory outcomes at 15 months of age
Authors: Silvers Karen M. , Frampton Chris M. , Wickens Kristin , Epton Michael J. , Pattemore Philip K. , Ingham Tristram , Fishwick David , Crane Julian , Town G. Ian ,   the New Zealand Asthma and Allergy Cohort Study Group
Published: January 2009

The relationship between breastfeeding, respiratory and other allergic disorders has been controversial. Our aim was to investigate the relationships between breastfeeding, respiratory outcomes, eczema and atopy at 15 months of age in a prospective birth cohort in New Zealand.

A total of 1105 children were enrolled at birth, and 1011 (91.2%) were followed up at 15 months. Logistic regression was used to model associations between breastfeeding duration and respiratory outcomes, eczema and atopy after adjusting for relevant confounding variables: ethnicity, socio‐economic status, parity, body mass index, smoking in pregnancy, gender and respiratory infections in the first 3 months of life.

Breastfeeding was associated with a significant reduction in the risk of adverse respiratory outcomes at 15 months. After adjustment for confounders, each month of exclusive breastfeeding reduced the risk of doctor‐diagnosed asthma by 20% (odds ratio 0.80, 95% confidence interval 0.71 to 0.90), wheezing by 12% (0.88, 0.82 to 0.94) and inhaler use by 14% (0.86, 0.78 to 0.93). Associations for both exclusive and additional breastfeeding durations, and respiratory outcomes remained independently significant when modelled simultaneously. Although independently associated with all respiratory outcomes, adjusting for parental history of allergic disease or maternal history of asthma did not alter our findings. Breastfeeding was not associated with eczema or atopy at 15 months.

In conclusion, there was a significant protective effect of breastfeeding on infant wheezing and other adverse respiratory outcomes that may be early indicators of asthma in New Zealand children.
Evaluation of a diabetes specialist–guided primary care diabetes treatment program
Authors: King Allen B. , Wolfe Gary S.
Published: January 2009

Purpose: An initial pilot program demonstrated promising results in improvements in glycosylated hemoglobin (HbA1c), low‐density lipoprotein cholesterol (LDL‐C), and systolic blood pressure (SBP) and prompted us to test these findings in a controlled trial. The purpose of the Diabetes‐focused, Algorithm‐directed care, Midlevel practitioner–administered, Electronically coached, Treatment (DAMET‐2) program clinical trial was to investigate the benefits of a novel program for disseminating guidance in the treatment of diabetes from a central specialist clinic to primary care centers with access to midlevel provider services.

Data sources: DAMET‐2 included standardized treatment algorithms and education disseminated through computer‐assisted and traditional methods associated with distance medicine. Two primary care practices were selected and subjects with diagnosed type 2 diabetes ≥6 months, ≥18 years of age with one or more cardiovascular risk factors (identified by chart review) were eligible for inclusion. Midlevel practitioners for subjects in the experimental group (N = 34) received training in American Diabetes Association treatment algorithms, had telephone consultations at 2‐ to 4‐week intervals and bimonthly visits with diabetes specialists, and received treatment guidance within 24 h from remote diabetes specialists. Weekly diabetes clinics were made available to subjects in the experimental group. After 12 months, the last available subject data were extracted from the subjects’ charts and compared to 12‐month chart data from a control group (N = 101) that did not receive additional study services.

Conclusions: Mean HbA1c values decreased from baseline by 0.46% in the active treatment group versus 0.06% in the control group; however, reductions in HbA1c did not achieve statistical significance potentially because of the small sample size of the experimental group. Mean SBP values were significantly reduced in both groups; however, LDL‐C was only significantly reduced in the control group, where more aggressive use of statins may have had an effect.

Implications for practice: Despite the inconsistencies in risk factor reduction from the pilot program, the DAMET‐2 program provided insights regarding the importance of electronic records and provider notifications, patient adherence, prioritization of provider resources by risk factor level among patients, and access to self‐management education.
Healthcare experiences of the homeless
Authors: Nickasch Bonnie , Marnocha Suzanne K.
Published: January 2009

Purpose: To explore the healthcare experiences of homeless individuals and inform providers of the barriers created by the situation of homelessness.

Data sources: This was a qualitative research study using a grounded theory approach. The sample included homeless individuals older than 18 years living in northeastern Wisconsin.

Conclusions: This research provided rich insight into the healthcare experiences of the homeless. Five key conclusions were made: (a) the great majority of homeless people have an external locus of control; (b) most homeless individuals lack the necessary resources to meet their physical needs of shelter, air, water, and food; (c) most homeless individuals lack the financial resources to seek adequate health care; (d) access to resources is limited because of poor transportation, telephones, and mail; and (e) all those interviewed felt that healthcare providers lack compassion for the homeless.

Implications for practice: Healthcare providers can use the concepts discovered in this study to help improve their skills and comfort level when working with homeless individuals. A decrease in acute illnesses and an increase in the effective management of chronic disease resulting in fewer long‐term complications and medical costs because of these unnecessary complications could be seen. Healthcare professionals may also volunteer to become more involved with the care of the homeless if they are confident in their skills. Improving the health of the homeless in the community will result in improvements in the overall health of the community.
The Use of a Single‐Pill Calcium Channel Blocker/Statin Combination in the Management of Hypertension and Dyslipidemia: A Randomized, Placebo‐Controlled, Multicenter Study
Authors: Neutel Joel M. , Bestermann William H. , Dyess Eric M. , Graff Alan , Kursun Attila , Sutradhar Santosh , Yunis Carla
Published: January 2009

Poor control of hypertension or dyslipidemia may at least in part be due to these risk factors being treated in isolation. The Caduet in Untreated Subjects Population (CUSP) trial was an 8‐week, randomized, double‐blind, placebo‐controlled trial evaluating the efficacy/safety of the combination of a calcium channel blocker (amlodipine besylate) and a statin (atorvastatin calcium) in a single‐pill form (5/20 mg) plus therapeutic lifestyle changes (TLC) compared with placebo plus TLC in patients with comorbid hypertension and dyslipidemia without evidence of cardiovascular disease. At week 4, additional antihypertensive/lipid‐lowering medication was permitted. The primary end point was the proportion of patients in whom the dual goal of blood pressure (<140/90 mm Hg) and low‐density lipoprotein cholesterol control (<100 mg/dL) was met at week 4. This dual goal attainment was significantly greater with amlodipine/atorvastatin plus TLC compared with placebo plus TLC at week 4 (47.6% vs 1.7%; P<.001), with further improvements at week 8. Most adverse events were mild to moderate. Therapy with single‐pill amlodipine/atorvastatin plus TLC in these patients significantly increased dual blood pressure/low‐density lipoprotein cholesterol goal attainment compared with placebo plus TLC.
Pulse Wave Velocity as a Marker of Severity of Coronary Artery Disease
Authors: Alarhabi Ahmed Yahya , Mohamed Mohd Sapawi , Ibrahim Suhairi , Hun Tee Meng , Musa Kamarul Imran , Yusof Zurkurnai
Published: January 2009

To determine whether pulse wave velocity (PWV) as a measure of arterial stiffness is a marker of coronary artery diseases (CAD), the authors did a cross‐sectional study in 92 patients undergoing coronary angiography for suspected CAD. Arterial stiffness was assessed through recording PWV from the left carotid–right femoral arteries using an automated machine. The mean PWV was higher in patients with CAD than in those without CAD (11.13±0.91 vs 8.14±1.25 m/sec; P<.001). When the severity of CAD was expressed as 1‐, 2‐, and multiple‐vessel disease, there was a significant association between the severity of CAD and PWV. PWV differed significantly with different categorical severity of CAD even when age and total cholesterol were controlled for. In a univariable analysis, PWV was higher with higher systolic blood pressure (P<.004). The authors conclude that arterial stiffness measured through PWV is an independent and complementary cardiovascular risk marker.
In-Situ Capture of CO2 in a Fluidized Bed Combustor
Authors: Abanades J. Carlos , Alvarez Diego , Anthony Edward J. , Lu Dennis
Published: January 2009

Increasing atmospheric concentration of CO2 and concern over its effect on climate is a powerful driving force for the development of new advanced energy cycles incorporating CO2 capture. This paper investigates the feasibility of CO2 capture using the carbonation reaction of CaO “in situ” in a fluidised bed combustor, where natural gas or petroleum coke (or any other fuel with low ash content) is being burned. The sorbent can be partially regenerated for CO2 capture by combustion of part of the fuel with O2/CO2 in a separate FBC. The thermodynamic limits in the proposed cycles, in terms of CO2 capture efficiencies, are examined along with the limits imposed by the rapid decay in the sorbent activity during repeated carbonation/calcination cycles, which will be exacerbated by the presence of S. Despite these limitations, it is shown that operating windows exist where it is possible to integrate fuel combustion, CO2 and SO2 capture in a single dual reactor facility. The decay in activity in the sorbent appears to be the major practical limitation to this concept, but this can be compensated for by using a relatively large supply of fresh sorbent, which appears to be acceptable considering the low cost of limestone. Also, a novel concept to reactivate the spent sorbent using sonic energy is outlined here as an alternative to reduce the use of fresh limestone.
The Performance of a Scaled-Down Fluidized Loop Seal
Authors: Johansson Andreas , Johnsson Filip , Andersson Bengt-A˚ke
Published: January 2009

This work investigates the solids cross flow in a super-heater tube bundle immersed in the loop seal of a cold CFB unit. The loop seal and the tube bundle are scaled to a 1/3rd of the size of a loop seal and a super-heater located in a 30 MWth CFB boiler. The simplified scaling laws proposed by Glicksman et al. [1] are applied to the flow in the seal. The loop seal was built into an existing CFB unit with riser dimensions 0.7 m × 0.12 m × 8.5 m. The riser is not scaled but the pressure distribution in the CFB loop is similar to that in the boiler. The solids flow through the tube bundle was studied by means of visual observations, pressure drop and tube-temperatures, corresponding to the overall heat transfer rate to each tube. The loop seal was operated under various conditions, including those typical for the boiler. Thus, the recirculation flux of solids through the loop seal, as well as the fluidization velocity in the seal, were varied. In addition, the fraction of the bottom area that is fluidized was varied. The overall flow behavior of the CFB loop with the scaled loop seal was found to be similar to that of the boiler. The temperature measurements showed that the heat transfer rate to the tubes in the bundle differed depending on operating conditions and on the position of the tube, both laterally and vertically. The recirculation flux could be maintained with a substantial decrease of the fluidization flow in the seal compared to the conditions corresponding to full load in the boiler. In addition, it was possible to significantly decrease the fraction of the bottom of the seal that was fluidized. However, if the area beneath the tube bundle is not fluidized, the heat transfer rate to the tubes decreased.
Gasification of Biomass: The Consequences of Equilibrium
Authors: Scott S. A. , Harris A. T. , Dennis J. S. , Hayhurst A. N. , Davidson J. F.
Published: January 2009

A model minimising Gibbs Free Energy is used to examine the thermodynamic limits of performance of a gasifier for biomass and other alternative fuels. The minimisation of free energy is highly flexible in that it allows a large number of species to be examined. Such an equilibrium model gives insight into the differences in the behaviour of coal and biomass in gasifiers. Biomass differs from coal in terms of heating value, ash, volatile and carbon contents and the amount of elemental oxygen. The model has been used to explore, entirely from a thermodynamic viewpoint: (i) the off-gas compositions, (ii) the impact of process variables on the heat balance and when gasification is complete, (iii) the effect of different gasification agents on process performance and (iv) optimisation of the calorific value of the hot and cold gas produced. Dried sewage sludge was used as a typical biomass fuel for these simulations. For biomass fuels with a low calorific value, it is shown that co-gasification with a support-fuel of higher calorific value, for example coal, is more practicable than gasification of the biomass alone.
A New Method to Inhibit Bed Agglomeration Problems in Fluidized Bed Boilers
Authors: Silvennoinen Jaani
Published: January 2009

Fluidized bed combustion (FBC) technology was commercialized in the 70s. Both bubbling fluidized bed (BFB) and circulating fluidized bed (CFB) technology are capable of handling a wide variety of solid fuels. Natural sand is typically used as the fluidizing material. However, the properties and behavior of some solid fuel ash may limit the use of these fuels due to bed agglomeration problems. Natural sand contains several minerals, typically mainly consisting of 20–50 wt.-% of plagioclase (NaAlSi3O8 + CaAlSi3O8), 10–30 wt.-% of potash feldspar (KAlSi3O8), and 25–100 wt.-% of quartz (SiO2). Biomass based fuels contain high amounts of alkali. Ash high in alkali may react with the free quartz of the natural sand, producing an alkali silicate mixture with low melting point. This mixture may act as an adhesive between fluidized bed particles and may, in the worst-case, result in serious fluidization problems. This problem can be avoided by using AGGLOSTOP™ quartz-free bed material. Four different bed materials were tested in a 15 kW laboratory-scale FBC test rig with plywood residue, which is known to cause severe fluidization problems in FB boilers. Two of the tested bed materials were quartz-free. When quartz-free bed materials were used, no signs of bed agglomeration were observed. The other two bed materials containing free quartz caused total defluidization at a temperature of around 750°C after about half an hour of operation. The concept of using AGGLOSTOP™ quartz-free bed material with high alkali fuels has been successfully applied in two industrial scale BFB boilers (15 and 74 MWth). The use of AGGLOSTOP™ fluidized bed material enables energy production in FB boilers based on high alkali fuels, which were earlier impossible to utilize due severe bed agglomeration problems. This paper focuses on the bed agglomeration phenomenon by discussing the results from laboratory and industrial-scale boilers and presents a new solution to extend the use of high alkali fuels in FB boilers.
Co-Firing in FBC: A Challenge for Fuel Characterization and Modeling
Authors: Zevenhoven Maria , Skrifvars Bengt-Johan , Yrjas Patrik , Backman Rainer , Mueller Christian , Hupa Mikko
Published: January 2009

Co-combustion of coal with biomass or firing biomass alone is used more and more in a first step in meeting the Finnish commitments under the Kyoto protocol. A frequently used technique for firing mixtures of fuels is fluidized bed combustion (FBC). Firing coal, co-combustion with biomass or firing biomass alone may, however, lead to unwanted ash-related problems. Prediction of ash formation behavior can help to avoid these problems before taking new fuels into use. Standard fuel analyses have shown to provide insufficient information for proper prediction especially when considering fuel mixtures. In an attempt to minimize the number of lab scale and pilot scale combustion experiments an extensive database is under development. This database contains data used as input for prediction models such as standard fuel analyses, results from stepwise leaching experiments, SEM/EDS analyses of original and partly burned-out fuels and thermodynamic estimations of the melting behavior of the fuels. Today the database contains 51 fuels, i.e. 8 bark fuels, 10 wood fuels, 3 annual biomasses, 8 peats, 6 coals and 16 miscellaneous fuels, such as RDF, sludge, hulls and husks, bagasse and other residues. Standardized fuel analysis is available for all fuels; melting calculations have been carried out for some 33 fuels. SEM/EDS analysis has been carried out for 20 fuels. The extended utilization of these data with computational fluid dynamic modeling (CFD) has proven to be a useful tool in prediction of deposits in FBC boilers. An example of the prediction tool shows the ability of deposit formation prediction.
Co-Combustion of Pulp- and Paper Sludge With Wood: Emissions of Nitrogen, Sulphur and Chlorine Compounds
Authors: A˚mand Lars-Erik , Leckner Bo , Sva¨rd Solvie Herstad , Gyllenhammar Marianne , Eskilsson David , Tullin Claes
Published: January 2009

Sludge from wastewater treatment plants in five Swedish pulp and paper mills has been burned together with wood in a circulating fluidised bed (CFB) boiler. The sludge was either mechanically dewatered or pre-dried. The mechanically dewatered sludge had to be fed with a pump, but the pre-dried sludge could be fed by the fuel feed system normally used for coal, wood chips or wood pellets. In parallel to the combustion tests in the CFB boiler the sludges were also investigated as single fuels in a small laboratory FB. The Swedish pulp and paper industry produces three major fractions of sludge: pure fibre sludge, sludge produced by employing a precipitation species like ironaluminiumsulphate, and finally, sludge subjected to biological cleaning. The way of production of the sludge influences its content of, for example, nitrogen, sulphur and chlorine, but the composition of the sludge is also influenced by the pulp and paper process. The present measurements show that the concentrations of nitrogen, sulphur and chlorine in the sludge have a great impact on the corresponding gaseous emissions from combustion. Actions to prevent these emissions could be necessary, depending on the origin of the sludge and treatment process used. In the present project all sludges were burned with wood-pellets as the main fuel under identical operating conditions, typical for a CFB boiler. Wood pellets were chosen as a well defined, low-polluting fuel that makes comparison of emissions from the sludges clear. Co-combustion with wood-pellets has the advantage of enabling operation also with wet sludges that cannot be used as single fuels without pre-drying. No actions were taken to improve sulphur and chlorine retention, by for example adding limestone. From a combustion point of view the co-combustion works well with low levels of carbon monoxide present in the flue gas and no light hydrocarbons.
Characterization of Ash Deposition During Co-Combustion of Coal With Refuse-Derived Fuels in a Pilot FBC Facility
Authors: Zhang Jun , Liu Kunlei , Pan Wei-Ping , Riley John T. , Xu Yiqian
Published: January 2009

This paper presents data from a recent investigation of the character of ash deposition in the convective zone (547°C to 338°C) in a 0.1 MWth bench-scale FBC system at Western Kentucky University. The ash deposit samples were collected during co-firing experiments using two coals with various blends of a refuse-derived fuel (RDF). A low sulfur coal, a high sulfur coal, and commercially available RDF sample were selected to investigate the influence of sulfur and chlorine in the fuels on the formation of ash deposits. Limestone was added to the combustor as the bed material and desulfurization sorbent. The results showed that the formation of ash deposits had a close relationship to the active fine lime particles produced from the limestone. An increase in the concentration of SOx in the flue gas restricts the formation of the ash deposits because of the reaction between SOx and the fine lime particles, which drops the adhesive force of the fine lime particles by reducing the contact area among the particles. With an increase in the content of the RDF in the fuels, the rate of deposit of ash decreased because of the higher content of chlorine and aluminum, which also decreased the contact area among the particles, leading to a low deposition rate of the fly ash.
Emission Control of Gaseous Pollutants From Co-Firing of Petroleum Coke and Coal in CFB
Authors: Zhao Changsui , Wang Wenxuan , Wang Fengjun , Chen Chuanmin , Han Song
Published: January 2009

Petroleum cokes including delayed coke, fluid coke, etc. are byproducts of solid residuals from the crude refining process. Using high sulfur petroleum coke as alternative fuel is feasible owing to its high fixed carbon and low ash content, but petroleum cokes are difficult to ignite due to their low volatile content and containing substantial concentrations of vanadium, nickel, nitrogen and sulfur, which can be sources of pollution emission and fireside fouling or corrosion problem. Co-firing petroleum coke and coal in circulating fluidized bed (CFB) is an ideal solution for those problems. Emission characteristic of gaseous pollutants from co-firing petroleum coke and coal is investigated in the paper. Experiments were carried out in a 0.6 MWt pilot-scale CFB combustor with the total height of 12m from the air distributor to the exit of combustor. The concentrations of SO2, NO, N2O, O2, CO2 and CO were measured on line by the gas analyzer. The effect of several parameters, in term of the primary air percentage, air excess coefficient, bed temperature, Ca/S molar ratio and percentage of petroleum coke in mixed fuel on the emission of SO2, NO, N2O is verified in experiments. Experimental results show that SO2 concentration in flue gas reduces with increase in the primary air percentage, excess air coefficient and Ca/S ratio for all kinds of fuel mixtures, whereas NO, N2O concentration rises with increase in the primary air percentage and excess air. When the bed temperature changes, the NO concentration varying trend is opposite to N2O. There is an optimal temperature for sulfur retention. Co-firing of petroleum coke and coal with different mixing ratio in CFB can be stable, efficient and environment friendly.
Experience on Combustion and Co-Combustion of Greek Brown Coal in Fluidized Bed Facilities
Authors: Kakaras Emmanuel , Grammelis Panagiotis , Skodras George , Vourliotis Panagiotis
Published: January 2009

The paper aims to present the experience gained from the combustion trials of Greek brown coal in different installations, both in semi-industrial and laboratory scale. Specifically, these research activities are separated in two parts, i.e. combustion tests using only brown coal and co-combustion tests with brown coal and biomass. Combustion tests with Greek lignite were realised in three different Circulating Fluidized Bed Combustion (CFBC) facilities. Low rank lignite was burned in a pilot scale facility of approx. 100kW thermal capacity, located in Athens (NTUA) and a semi-industrial scale of 1.2 MW thermal capacity, located at RWE’s power station Niederaussem in Germany. The results include the determination of operating conditions to achieve proper fuel burnout, the examination of the influence of air staging on the temperature distribution inside the reactor and the investigation of the combustion behaviour of the particular fuel type and emitted pollutants. Several conclusions are drawn concerning the necessary modifications and requirements of the plant layout when a large scale CFBC installation is designed to utilize low grade brown coal. Co-combustion tests with Greek xylitic lignite and waste wood were carried out in the 1 MWth CFBC installation of AE&E, in Austria. During the tests, oxygen concentration and CO, SO2, N2O and NOX emissions were continuously monitored. Ash samples were collected and analysed for heavy metals content in ICP-AES spectrophotometer. The improved combustion behaviour of this lignite type was more than evident, since it has lower moisture content and increased calorific value. In all co-combustion tests, low emissions of gaseous pollutants were obtained and metal element emissions were lower than the corresponding values anticipated by the guidelines. In addition, lab-scale co-combustion tests of Greek pre-dried lignite with biomass were accomplished in a bubbling fluidised bed. The main purpose of these experiments was to examine ash melting problems and differentiation to the emitted pollutants due to biomass addition. The obtained results of all aforementioned activities showed that fluidised bed is the appropriate combustion technology to efficiently exploit the low quality Greek brown coal either alone or in conjunction with other biomass materials.
ALSTOM’s Large CFBs and Results
Authors: Marchetti M. M. , Czarnecki T. S. , Semedard J. C. , Devroe Sebastien , Lemasle Jean-Michael
Published: January 2009

This paper describes various designs of large CFBs that ALSTOM has undertaken in the last several years. We discuss available operational results of Red Hills (2 × 250 MW) and AES Puerto Rico Total Energy Project (2 × 255 MW). Also included is a description and overview of three projects that are nearing completion: Reliant Energy – Seward Repowering Project (2 × 294 MW); East Kentucky Power Cooperative – E. A. Gilbert (1 × 294 MW); and ENEL – Sulcis Repowering Project (1 × 340 MW gross). Each of these projects had individual technical challenges and solutions, which will be reviewed.
Revamping of 4 x 58 MWth Pulverized Coal-Fired Boilers With Circulating Fluidized Bed Firing
Authors: Sen A. N. , Miller L. , Basu P. , Dutta A.
Published: January 2009

A techno-economic feasibility study has been conducted to investigate revamping four 58 MWth (15 MWe) pulverized-coal (PC) boilers with circulating fluidized bed (CFB) firing. The steam generators at Amarkantak Thermal Power Station in Chachai, Madhya Pradesh, are owned by Madhya Pradesh State Electricity Board (MPSEB), supplied by Simmering-Graz-Pauker AG of Vienna, Austria, and commissioned in mid-1965. The study reveals that: (i) CFB revamping of the boilers is technically feasible and economically sound; (ii) Performance improvement of the plant is significant in terms of such indices as plant load factor, forced outage and auxiliary oil consumption, among others. The expected performance improvement is due in large part to the elimination of key outage-prone components such as pulverizers (mills) and burners. (iii) There is significant improvement in emissions performance due to the reduction in emissions of NOx and fly ash; (iv) The financial analysis indicates that the CFB revamping option gives the highest return on investment compared to alternatives.
Fabrication and Performance Evaluation of Miniaturized Proton Exchange Membrane (PEM) Fuel Cells
Authors: Zhang Tao , Li Pei-Wen , Wang Qing-Ming , Schaefer Laura , Chyu Minking K.
Published: January 2009

Two types of miniaturized PEM fuel cells are designed and characterized in comparison with a compact commercial fuel cell device in this paper. One has Nafion® membrane electrolyte sandwiched by two brass bipolar plates with micromachined meander-like gas channels. The cross-sectional area of the gas flow channel is approximately 250 by 250 (μm). The other uses the same Nafion® membrane and anode structure, but in stead of the brass plate, a thin stainless steel plate with perforated round holes is used at cathode side. The new cathode structure is expected to allow oxygen (air) being supplied by free-convection mass transfer. The characteristic curves of the fuel cell devices are measured. The activation loss and ohmic loss of the fuel cells have been estimated using empirical equations. Critical issues such as flow arrangement, water removing and air feeding modes concerning the fuel cell performance are investigated in this research. The experimental results demonstrate that the miniaturized fuel cell with free air convection mode is a simple and reliable way for fuel cell operation that could be employed in potential applications although the maximum achievable current density is less favorable due to limited mass transfer of oxygen (air). The relation between the fuel cell dimensions and the maximum achievable current density is also discussed with respect to free-convection mode of air feeding.
Development of Natural Gas Reformer in ITRI
Authors: Lee C. H. , Huang C. H. , Lin C. T. , Liu Y. C. , Shyu R. J.
Published: January 2009

Recently, research of the polymer electrolyte fuel cell with the aim of applying to stationary power source appears to be progressively activated. The residential polymer electrolyte fuel cell system needs a natural gas reformer to transform methane into the hydrogen-rich reformate gas with CO concentration less than 20 ppm. Except the catalyst for low temperature water gas shift reaction, ITRI has developed several catalysts for autothermal reforming, high temperature water-gas shift reaction, and CO preferential oxidation reaction. In addition, we have integrated these catalysts to assemble a 2 kW natural gas reformer operated at steady state with hydrogen flow rate of 30 L/min., H2 concentration of 40% above, CO concentration less than 40 ppm, and the cold startup time less than 60 minute.
Structured Catalysts for Autothermal Reforming of Hydrocarbon Fuels
Authors: Bae J.-M. , Ahmed S. , Kumar R. , Doss E.
Published: January 2009

Argonne national laboratory has been developing fuel processing technologies for fuel cell based electric power. We have reported the development of novel catalysts that are active and selective for hydrocarbon reforming reactions. It has been realized, however, that with pellet or conventional honeycomb catalysts, the reforming process is mass transport limited. This paper reports the development of catalyst structures with microchannels that are able to reduce the diffusion resistance and thereby achieve the same production rate within a smaller reactor bed. These microchannel reforming catalysts were prepared and tested with natural gas and gasoline-type fuels in a microreactor (1-cm dia.) at space velocities of up to 250,000 per hour. These catalysts have also been used in engineering-scale reactors (10 kWe, 7-cm dia.) with similar product qualities. Compared to pellet catalysts, the microchannel catalysts enable a nearly 5-fold reduction in catalyst weight and volume.
3D Modeling of Polymer Electrolyte Membrane Fuel Cells
Authors: Eldrid Sacheverel , Shahnam Mehrdad , Prinkey Michael T. , Dong Zhirui
Published: January 2009

Polymer Electrolyte Membrane (PEM) fuel cell performance can be optimized and improved by modeling the complex processes that take place in the various components of a fuel cell. Operability over a range of conditions can be assessed using a robust design methodology. Sensitivity analysis can identify critical characteristics in order to guide hardware and softgoods development. A computational model is necessary which captures the critical physical processes taking place within the cell. Such a model must be validated against experimental data before it can be used for product development. A computational model of an experimental PEM fuel cell has been developed. The model is based on the FLUENT CFD solver with the addition of user-defined functions supplied by FLUENT. These functions account for local electrochemical reactions, electrical conduction within diffusion layers and current collectors, mass and heat transfer in the diffusion layers and the flow channels along with binary gas diffusion. The results of this model are compared to experimental data. A PEM fuel cell consists of an ion conducting membrane, anode and cathode catalyst layers, anode and cathode gas diffusion layers, flow channels, and two bipolar plates. Hydrogen and oxygen are supplied to the anode and cathode respectively. As a result of hydrogen oxidation at the anode catalyst layer, hydrogen ions and electrons are produced. The hydrogen ions are conducted through the membrane to the cathode catalyst layer where they combine with oxygen and electrons to produce water and heat. Therefore, a PEM fuel cell model has to take into account: • Fluid flow, heat transfer, and mass transfer in porous anode and cathode diffusion layers; • Electrochemical reactions; • Current transport and potential field in porous anode, cathode, and solid conducting regions. FLUENT Inc. has developed such a model based on their commercially available FLUENT CFD code. This model was exercised on an experimental Plug Power fuel cell. The voltage characteristic of the model was compared to the experimentally measured values. The preliminary comparison between the predicted polarization curve and the experimental results are very favorable.
PEM Fuel Cell Bipolar Plate Reliability and Material Selection
Authors: Ajersch Michael J. , Fowler Michael W. , Karan Kunal , Peppley Brant A.
Published: January 2009

The majority of the research on PEM fuel cells to date has been focused on assessing fuel cell behavior in the early stages of its life cycle. However, as widespread commercialization approaches, PEM fuel cells will be required to operate reliably for increasingly longer periods of time. It therefore also becomes equally important to characterize fuel cell performance at the end of its lifecycle. The reliability of a PEM fuel cell is dependent on the material properties, the manufacturing methods, and the design of its individual components. Among these components, the bipolar plates have received the least attention as a factor that may limit a fuel cell’s life cycle performance. Driven by the need for cost and weight reduction of fuel cell stacks, a significant amount of development work has been directed towards the development of new materials and designs for bipolar plates. Selection of an appropriate design and/or material for bipolar plates requires that reliability and durability data must be available, and that testing protocols appropriate and indicative of fuel cell operation be established. This paper provides a review fuel cell bipolar plate reliability and durability. Topics that will be addressed include bipolar plate functionality and design requirements, plate materials selection, plate failure modes. This is followed by a description of new bipolar plate reliability/durability test methods being developed at the CAMM Fuel Cell Research Group.
A Silicon Microfabricated Direct Formic Acid Fuel Cell
Authors: Yeom J. , Mozsgai G. Z. , Asthana A. , Flachsbart B. R. , Waszczuk P. , Choban E. R. , Kenis P. J. A. , Shannon M. A.
Published: January 2009

A silicon-based microfabricated fuel cell running on formic acid has been developed to provide a high energy and power density power source on the millimeter size scale. A polymer electrolyte membrane fuel cell was fabricated utilizing the Nafion™112 membrane bonded between electrodes on silicon substrates. The cell was fueled by a concentrated formic acid-water solution and the catalyst used was Pt. The preliminary result shows that the microfabricated formic acid fuel cell may be a promising alternative for very small portable fuel cell applications.
Theoretical Analysis of a Water Desalination System Using Low Grade Solar Heat
Authors: Al-Kharabsheh S. , Goswami D. Yogi
Published: January 2009

Theoretical analysis of a solar desalination system utilizing an innovative new concept, which uses low-grade solar heat, is presented. The system utilizes natural means of gravity and atmospheric pressure to create a vacuum, under which liquid can be evaporated at much lower temperatures and with less energy than conventional techniques. The uniqueness of the system is in the way natural forces are used to create vacuum conditions and its incorporation in a single system design where evaporation and condensation take place at appropriate locations without any energy input other than low grade heat. The system consists of solar heating system, an evaporator, a condenser, and injection, withdrawal, and discharge pipes. The effect of various operating conditions, namely, withdrawal rate, depth of water body, temperature of the heat source, and condenser temperature were studied. Numerical simulations show that the proposed system may have distillation efficiencies as high as 90% or more. Vacuum equivalent to 3.7 kPa (abs) or less can be created depending on the ambient temperature at which condensation will take place.
Improving Energy Performance and Indoor Air Quality in Laboratory Buildings Using an Innovative Air Handling Unit System
Authors: Cui Y. , Liu M.
Published: January 2009

The Laboratory Air Handling Unit (LAHU) system is developed to improve building energy performance and indoor air quality (IAQ) in laboratory buildings. The LAHU system sends more (up to 100%) outside air to the office section first and re-circulates the office section air to the laboratory section. The theoretical model analysis shows that the LAHU system improves office section indoor air quality, uses less outside air during hot and cold weathers, and consumes significantly less thermal energy. The optimal control of outside air intake to office section maximizes IAQ improvement and thermal energy savings.
Convective Heat Transfer Analysis of Open Cell Metal Foam for Solar Air Heaters
Authors: Dukhan Nihad , Quinones Pablo D.
Published: January 2009

A one-dimensional heat transfer model for open-cell metal foam is presented. Three aluminum foams having different areas, relative densities, ligament diameters, and number of pores per inch were analyzed. The effective thermal conductivity and the heat transfer increased with the number of pores per inch. The effective thermal conductivity of the foams can be up to four times higher than that of solid aluminum. The resulting improvement in heat transfer can be as high as 50 percent. The maximum heat transfer for the aluminum foams occurs at a pore Reynolds number of 52. The heat transfer, in addition, becomes insensitive to the flow regime for pore Reynolds numbers beyond 200.
Yaw Control of Small Wind Turbines With a New Passive Tail Device: Part 1 — Steady-State Case
Authors: Meji´a Eduardo Rinco´n , Salazar Jesu´s Tovar , Filipek Jo´zef Wo´jcik
Published: January 2009

This paper describes the behavior of a new tail device to yaw smoothly small wind turbine rotors out of the wind during strong wind or gusts. The passive tail device consists of a rigid short tail, an aerodynamic rotating vane, a tail bumper, and a spring. This passive tail device reduces gyroscopic loads, is easy to adjust, can be manufactured in smaller sizes, and is much stronger than conventional vanes used in small wind machines. Besides, the energy collected with it is greater. Field test results indicate that its behavior agrees very well with simulations, and that the regulator can be advantageously utilized, as compared with conventional vanes and other mechanical or electromechanical means, in horizontal-axis wind turbines with diameters of 12 m or smaller. Here the steady-state case (quasi-steady wind velocity is assumed) is analyzed, showing the technical viability of the regulator proposed.
Meeting Military Energy Demands
Authors: Bailey Margaret B. , Sanders David , Arnas A. O¨zer
Published: January 2009

The United States Army’s Soldier Tactical Mission System is capable of providing a dramatic change in small-unit warfare with its enhanced communications, situational awareness, and navigation capabilities. A significant drawback to this system, however, is that the very systems that provide these advantages to the soldier also demand high quantities of energy. In order to design an adequate energy delivery system to support the operation of the soldier’s enhanced equipment, the problem is broken down and analyzed into three general areas: energy demand, energy management, and energy source design. The aim of this paper is to introduce the reader to each of these three general areas, thereby providing a potential catalyst for future research and exploration into the design solution of adequate energy delivery systems.
Operation of 350 kW of Amonix High Concentration PV Systems at Arizona Public Service
Authors: Stone Kenneth W. , Garboushian Vahan , Dutra David , Hayden Herb
Published: January 2009

Amonix has manufactured and installed over 350 kW of their 5th generation high concentration PV systems for Arizona Public Service (APS). This paper describes the power and energy performance of the system since the start of installation in May 2000 and describes the operating characteristics that make this system attractive for both on-grid and off-grid use. The performance of a unit with the latest design revisions is compared to the performance of one of the first manufactured units, and the reasons for the improvements are discussed. Data are also presented that show the Amonix system will produce more annual energy per installed kW than will a conventional fixed-flat plate system. The current construction status of the largest concentrating PV plant in the world is also discussed.
Thermochemical Hydrogen Production Using Ni-Ferrite and CH4
Authors: Kim Jong Won , Sim Kyu Sung , Son Hyun Myung , Jung Kwang Deog
Published: January 2009

Hydrogen production by a 2-step water-splitting thermochemical cycle using metal oxides (ferrites) redox pairs and CH4 have been studied in this experiment. Reactions were performed in a two-step redox cycle in which the ferrites were reacted with CH4 at 700°C–800°C to produce CO, H2, and various reduced phases (reduction step); these were then reoxidized with water vapor to generate H2 in water-splitting step (oxidation step) at 600°C–700°C. The reduced forms of Ni-Fe2O3, Ni-FeO and Ni-Fe alloy from XRD, showed respectively different reactivity for H2 formation from H2O. These were oxidized to the ferrite phase to produce H2 in the water-splitting step at 600°C–700°C. In reduction reaction at 800°C, carbon deposition arise on surface of Ni-ferrite due to CH4 decomposition. This reduced phase containing carbon, which reacts with H2O at 600°C, produce H2, CO, and CO2. The amount of H2 evolved using reduced phase containing carbon was much than that of other phase.
Design Review and Approval of Grid-Tied Photovoltaic Systems
Authors: Farhi Brian N. , Dunlop James P. , Ventre Jerry , Atmaram Gobind , Lynn Kevin W.
Published: January 2009

The Florida Solar Energy Center has been accredited by both the American Association for Laboratory Accreditation and PowerMark Corporation to certify grid-tied photovoltaic systems. The certification process involves both the testing of photovoltaic modules for performance ratings and the review and approval of system designs to provide photovoltaic system design certification. This paper focuses on the design review and approval process, which consists of a documentation review and focuses on the completeness and accuracy of instructions, schematics, and accompanying materials. System designers have received substantive critiques and assistance through the third-party technical reviews used in this process. As a result, photovoltaic system manuals that accompany reviewed systems lead to a greater likelihood of code-compliant and high-performing installations.
Development and Characterization of a Color 2F Alignment Method for the Advanced Dish Development System
Authors: Steffen Bridgette J. , Andraka Charles E. , Diver Richard B.
Published: January 2009

Dish/Stirling systems rely on accurate mirrors and alignment. Inaccuracies in alignment can lead to flux “hotspots” that can reduce performance and even damage the solar receiver. To improve the alignment process a procedure that can be used to align solar dish concentrator facets was developed on the second-generation (Mod 2) Advanced Dish Development System (ADDS) at Sandia National Laboratories in Albuquerque, NM. The previously used facet alignment method was based on the distant light source technique and required the dish to be pointed near the horizon while an observer located approximately 100 meters away views the image of a target and calls in adjustments to an aligner. At high sun elevation angles structural deflections inherent in any dish concentrator result in facet misalignments. To address these issues while allowing improved access to facet adjustments, an alignment technique that permits alignment at any elevation angle was developed and evaluated. This technique utilized a video camera and color target affixed on a lightweight tower at a distance near twice the dish focal length (2f) from the vertex of the dish, hence the name “color 2f”. The camera and target are centered on the optical axis of the concentrator. During the initial evaluation of the color 2f facet alignment procedure on the ADDS Mod 2 concentrator, no facet adjustments were made. Instead concentrator facet deflections were measured by taking and evaluating images of the dish reflecting the target while the dish was pointed at the horizon, 45 degrees elevation, and vertical. These images were compared to each other, to determine gravity induced pointing errors as the dish changes in elevation. Future implementations of the color 2f system could be used to align the system rather than simply diagnose it. The proposed approach has the potential to accurately align concentrators without large open land spaces, and to account for elevation-induced structural deflections. In this paper, the color 2f alignment technique is described along with the results from the gravity induced structural deflection study. Issues and recommendations for improvement of the 2f alignment system are also presented.
Waste-to-Energy Facilities: A National Strategic Asset
Authors: Rosania Sam M.
Published: January 2009

The importance of the topics illustrated to the audience and industry in this presentation will become self evident as to the industry’s future. In light of the events of September 11, 2001; the volatility of the middle eastern oil interests; and initiatives regarding national security and homeland defense, it would appear that any energy technology that can reduce America’s dependence on foreign oil should be considered a national strategic asset. As such, one could assert that today’s municipal waste combustors that provide electrical capacity and/or steam capacity (i.e. waste-to-energy facilities) are a strategic asset since they reduce our dependence on foreign oil and convert “garbage” into a resource.