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Arsenic remediation of drinking water using iron-oxide coated coal bottom ash

Description: We describe laboratory and field results of a novel arsenic removal adsorbent called 'Arsenic Removal Using Bottom Ash' (ARUBA). ARUBA is prepared by coating particles of coal bottom ash, a waste material from coal fired power plants, with iron (hydr)oxide. The coating process is simple and conducted at room temperature and atmospheric pressure. Material costs for ARUBA are estimated to be low (~;;$0.08 per kg) and arsenic remediation with ARUBA has the potential to be affordable to resource-constrained communities. ARUBA is used for removing arsenic via a dispersal-and-removal process, and we envision that ARUBA would be used in community-scale water treatment centers. We show that ARUBA is able to reduce arsenic concentrations in contaminated Bangladesh groundwater to below the Bangladesh standard of 50 ppb. Using the Langmuir isotherm (R2 = 0.77) ARUBA's adsorption capacity in treating real groundwater is 2.6x10-6 mol/g (0.20 mg/g). Time-to-90percent (defined as the time interval for ARUBA to remove 90percent of the total amount of arsenic that is removed at equilibrium) is less than one hour. Reaction rates (pseudo-second-order kinetic model, R2>_ 0.99) increase from 2.4x105 to 7.2x105 g mol-1 min-1 as the groundwater arsenic concentration decreases from 560 to 170 ppb. We show that ARUBA's arsenic adsorption density (AAD), defined as the milligrams of arsenic removed at equilibrium per gram of ARUBA added, is linearly dependent on the initial arsenic concentration of the groundwater sample, for initial arsenic concentrations of up to 1600 ppb and an ARUBA dose of 4.0 g/L. This makes it easy to determine the amount of ARUBA required to treat a groundwater source when its arsenic concentration is known and less than 1600 ppb. Storing contaminated groundwater for two to three days before treatment is seen to significantly increase ARUBA's AAD. ARUBA can be separated from treated water by coagulation and ...
Date: June 1, 2010
Creator: Mathieu, Johanna L.; Gadgil, Ashok J.; Addy, Susan E. A. & Kowolik, Kristin
Partner: UNT Libraries Government Documents Department

Plug-in Electric Vehicle Interactions with a Small Office Building: An Economic Analysis using DER-CAM

Description: It is generally believed that plug-in electric vehicles (PEVs) offer environmental and energy security advantages compared to conventional vehicles. Policies are stimulating electric transportation deployment, and PEV adoption may grow significantly. New technology and business models are being developed to organize the PEV interface and their interaction with the wider grid. This paper analyzes the PEVs' integration into a building's Energy Management System (EMS), differentiating between vehicle to macrogrid (V2M) and vehicle to microgrid (V2m) applications. This relationship is modeled by the Distributed Energy Resources Customer Adoption Model (DER-CAM), which finds optimal equipment combinations to meet microgrid requirements at minimum cost, carbon footprint, or other criteria. Results derive battery value to the building and the possibility of a contractual affiliation sharing the benefit. Under simple annual fixed payments and energy exchange agreements, vehicles are primarily used to avoid peak demand charges supplying cheaper off-peak electricity to the building during workdays.
Date: June 1, 2010
Creator: Momber, Ilan; Gomez, Tomás; Venkataramanan, Giri; Stadler, Michael; Beer, Sebastian; Lai, Judy et al.
Partner: UNT Libraries Government Documents Department

How to Estimate the Value of Service Reliability Improvements

Description: A robust methodology for estimating the value of service reliability improvements is presented. Although econometric models for estimating value of service (interruption costs) have been established and widely accepted, analysts often resort to applying relatively crude interruption cost estimation techniques in assessing the economic impacts of transmission and distribution investments. This paper first shows how the use of these techniques can substantially impact the estimated value of service improvements. A simple yet robust methodology that does not rely heavily on simplifying assumptions is presented. When a smart grid investment is proposed, reliability improvement is one of the most frequently cited benefits. Using the best methodology for estimating the value of this benefit is imperative. By providing directions on how to implement this methodology, this paper sends a practical, usable message to the industry.
Date: June 8, 2010
Creator: Sullivan, Michael J.; Mercurio, Matthew G.; Schellenberg, Josh A. & Eto, Joseph H.
Partner: UNT Libraries Government Documents Department

Advanced Benchmarking for Complex Building Types: Laboratories as an Exemplar

Description: Complex buildings such as laboratories, data centers and cleanrooms present particular challenges for energy benchmarking because it is difficult to normalize special requirements such as health and safety in laboratories and reliability (i.e., system redundancy to maintain uptime) in data centers which significantly impact energy use. For example, air change requirements vary widely based on the type of work being performed in each laboratory space. We present methods and tools for energy benchmarking in laboratories, as an exemplar of a complex building type. First, we address whole building energy metrics and normalization parameters. We present empirical methods based on simple data filtering as well as multivariate regression analysis on the Labs21 database. The regression analysis showed lab type, lab-area ratio and occupancy hours to be significant variables. Yet the dataset did not allow analysis of factors such as plug loads and air change rates, both of which are critical to lab energy use. The simulation-based method uses an EnergyPlus model to generate a benchmark energy intensity normalized for a wider range of parameters. We suggest that both these methods have complementary strengths and limitations. Second, we present"action-oriented" benchmarking, which extends whole-building benchmarking by utilizing system-level features and metrics such as airflow W/cfm to quickly identify a list of potential efficiency actions which can then be used as the basis for a more detailed audit. While action-oriented benchmarking is not an"audit in a box" and is not intended to provide the same degree of accuracy afforded by an energy audit, we demonstrate how it can be used to focus and prioritize audit activity and track performance at the system level. We conclude with key principles that are more broadly applicable to other complex building types.
Date: August 1, 2010
Creator: Mathew, Paul A.; Clear, Robert; Kircher, Kevin; Webster, Tom; Lee, Kwang Ho & Hoyt, Tyler
Partner: UNT Libraries Government Documents Department

A comparison of global optimization algorithms with standard benchmark functions and real-world applications using Energy Plus

Description: There is an increasing interest in the use of computer algorithms to identify combinations of parameters which optimise the energy performance of buildings. For such problems, the objective function can be multi-modal and needs to be approximated numerically using building energy simulation programs. As these programs contain iterative solution algorithms, they introduce discontinuities in the numerical approximation to the objective function. Metaheuristics often work well for such problems, but their convergence to a global optimum cannot be established formally. Moreover, different algorithms tend to be suited to particular classes of optimization problems. To shed light on this issue we compared the performance of two metaheuristics, the hybrid CMA-ES/HDE and the hybrid PSO/HJ, in minimizing standard benchmark functions and real-world building energy optimization problems of varying complexity. From this we find that the CMA-ES/HDE performs well on more complex objective functions, but that the PSO/HJ more consistently identifies the global minimum for simpler objective functions. Both identified similar values in the objective functions arising from energy simulations, but with different combinations of model parameters. This may suggest that the objective function is multi-modal. The algorithms also correctly identified some non-intuitive parameter combinations that were caused by a simplified control sequence of the building energy system that does not represent actual practice, further reinforcing their utility.
Date: September 1, 2009
Creator: Kamph, Jerome Henri; Robinson, Darren & Wetter, Michael
Partner: UNT Libraries Government Documents Department

Global Cooling: Policies to Cool the World and Offset Global Warming from CO2 Using Reflective Roofs and Pavements

Description: Increasing the solar reflectance of the urban surface reduce its solar heat gain, lowers its temperatures, and decreases its outflow of thermal infrared radiation into the atmosphere. This process of 'negative radiative forcing' can help counter the effects of global warming. In addition, cool roofs reduce cooling-energy use in air conditioned buildings and increase comfort in unconditioned buildings; and cool roofs and cool pavements mitigate summer urban heat islands, improving outdoor air quality and comfort. Installing cool roofs and cool pavements in cities worldwide is a compelling win-win-win activity that can be undertaken immediately, outside of international negotiations to cap CO{sub 2} emissions. We propose an international campaign to use solar reflective materials when roofs and pavements are built or resurfaced in temperate and tropical regions.
Date: August 28, 2009
Creator: Akbari, Hashem; Levinson, Ronnen; Rosenfeld, Arthur & Elliot, Matthew
Partner: UNT Libraries Government Documents Department

Toward the Holy Grail of Perfect Information: Lessons Learned Implementing an Energy Information System in a Commercial Building

Description: Energy information systems (real-time acquisition, analysis, and presentation of information from energy end-uses) in commercial buildings have demonstrated value as tools for improving energy efficiency and thermal comfort. These improvements include characterization through benchmarking, identification of retrofit opportunities, anomaly detection to inform retro-commissioning, and feedback to occupants to encourage shifts in behavior. Energy information systems can play a vital role in achieving a variety of ambitious sustainability goals for the existing stock of commercial buildings, but their implementation is often fraught with pitfalls. In this paper, we present a case study of an EIS and sub-metering project executed in a representative commercial office building. We describe the building, highlight a few of its problems, and detail the hardware and software technologies we employed to address them. We summarize the difficulties encountered and lessons learned, and suggest general guidelines for future EIS projects to improve performance and save energy in the commercial building fleet. These guidelines include measurement criteria, monitoring strategies, and analysis methods. In particular, we propose processes for: - Defining project goals, - Selecting end-use targets and depth of metering, - Selecting contractors and software vendors, - Installing and networking measurement devices, - Commissioning and using the energy information system.
Date: May 14, 2010
Creator: Kircher, Kevin; Ghatikar, Girish; Greenberg, Steve; Watson, Dave; Diamond, Rick; Sartor, Dale et al.
Partner: UNT Libraries Government Documents Department

A novel technique for the production of cool colored concrete tile and asphalt shingle roofing products

Description: The widespread use of solar-reflective roofing materials can save energy, mitigate urban heat islands and slow global warming by cooling the roughly 20% of the urban surface that is roofed. In this study we created prototype solar-reflective nonwhite concrete tile and asphalt shingle roofing materials using a two-layer spray coating process intended to maximize both solar reflectance and factory-line throughput. Each layer is a thin, quick-drying, pigmented latex paint based on either acrylic or a poly(vinylidene fluoride)/acrylic blend. The first layer is a titanium dioxide rutile white basecoat that increases the solar reflectance of a gray-cement concrete tile from 0.18 to 0.79, and that of a shingle surfaced with bare granules from 0.06 to 0.62. The second layer is a 'cool' color topcoat with weak near-infrared (NIR) absorption and/or strong NIR backscattering. Each layer dries within seconds, potentially allowing a factory line to pass first under the white spray, then under the color spray. We combined a white basecoat with monocolor topcoats in various shades of red, brown, green and blue to prepare 24 cool color prototype tiles and 24 cool color prototypes shingles. The solar reflectances of the tiles ranged from 0.26 (dark brown; CIELAB lightness value L* = 29) to 0.57 (light green; L* = 76); those of the shingles ranged from 0.18 (dark brown; L* = 26) to 0.34 (light green; L* = 68). Over half of the tiles had a solar reflectance of at least 0.40, and over half of the shingles had a solar reflectance of at least 0.25.
Date: November 20, 2009
Creator: Levinson, Ronnen; Akbari, Hashem; Berdahl, Paul; Wood, Kurt; Skilton, Wayne & Petersheim, Jerry
Partner: UNT Libraries Government Documents Department

An implementation of co-simulation for performance prediction of innovative integrated HVAC systems in buildings

Description: Integrated performance simulation of buildings and heating, ventilation and air-conditioning (HVAC) systems can help reducing energy consumption and increasing level of occupant comfort. However, no singe building performance simulation (BPS) tool offers sufficient capabilities and flexibilities to accommodate the ever-increasing complexity and rapid innovations in building and system technologies. One way to alleviate this problem is to use co-simulation. The co-simulation approach represents a particular case of simulation scenario where at least two simulators solve coupled differential-algebraic systems of equations and exchange data that couples these equations during the time integration. This paper elaborates on issues important for co-simulation realization and discusses multiple possibilities to justify the particular approach implemented in a co-simulation prototype. The prototype is verified and validated against the results obtained from the traditional simulation approach. It is further used in a case study for the proof-of-concept, to demonstrate the applicability of the method and to highlight its benefits. Stability and accuracy of different coupling strategies are analyzed to give a guideline for the required coupling frequency. The paper concludes by defining requirements and recommendations for generic cosimulation implementations.
Date: July 1, 2010
Creator: Trcka, Marija; Wetter, Michael & Hensen, Jan L.M.
Partner: UNT Libraries Government Documents Department

Aerosol indirect effects ? general circulation model intercomparison and evaluation with satellite data

Description: Aerosol indirect effects continue to constitute one of the most important uncertainties for anthropogenic climate perturbations. Within the international AEROCOM initiative, the representation of aerosol-cloud-radiation interactions in ten different general circulation models (GCMs) is evaluated using three satellite datasets. The focus is on stratiform liquid water clouds since most GCMs do not include ice nucleation effects, and none of the model explicitly parameterises aerosol effects on convective clouds. We compute statistical relationships between aerosol optical depth ({tau}{sub a}) and various cloud and radiation quantities in a manner that is consistent between the models and the satellite data. It is found that the model-simulated influence of aerosols on cloud droplet number concentration (N{sub d}) compares relatively well to the satellite data at least over the ocean. The relationship between {tau}{sub a} and liquid water path is simulated much too strongly by the models. This suggests that the implementation of the second aerosol indirect effect mainly in terms of an autoconversion parameterisation has to be revisited in the GCMs. A positive relationship between total cloud fraction (f{sub cld}) and {tau}{sub a} as found in the satellite data is simulated by the majority of the models, albeit less strongly than that in the satellite data in most of them. In a discussion of the hypotheses proposed in the literature to explain the satellite-derived strong f{sub cld} - {tau}{sub a} relationship, our results indicate that none can be identified as a unique explanation. Relationships similar to the ones found in satellite data between {tau}{sub a} and cloud top temperature or outgoing long-wave radiation (OLR) are simulated by only a few GCMs. The GCMs that simulate a negative OLR - {tau}{sub a} relationship show a strong positive correlation between {tau}{sub a} and f{sub cld} The short-wave total aerosol radiative forcing as simulated by the GCMs ...
Date: March 12, 2010
Creator: Quaas, Johannes; Ming, Yi; Menon, Surabi; Takemura, Toshihiko; Wang, Minghuai; Penner, Joyce E. et al.
Partner: UNT Libraries Government Documents Department

An Analysis of Energy Use on Community College Campuses

Description: This paper provides an analysis of energy use on community college campuses which justifies the introduction of a simple model for describing that energy use. The model is then applied to the data from 80 campuses to determine average values for the parameters of the model. The model can be used to measure the energy savings of conservation programs as well as the cost avoidance associated with those savings. Because the model explicitly takes into account variations in weather, it provides an essential tool for evaluating energy conservation programs.
Date: March 1, 1980
Creator: York, C. M.
Partner: UNT Libraries Government Documents Department

Comparison of Demand Response Performance with an EnergyPlus Model in a Low Energy Campus Building

Description: We have studied a low energy building on a campus of the University of California. It has efficient heating, ventilation, and air conditioning (HVAC) systems, consisting of a dual-fan/dual-duct variable air volume (VAV) system. As a major building on the campus, it was included in two demand response (DR) events in the summers of 2008 and 2009. With chilled water supplied by thermal energy storage in the central plant, cooling fans played a critical role during DR events. In this paper, an EnergyPlus model of the building was developed and calibrated. We compared both whole-building and HVAC fan energy consumption with model predictions to understand why demand savings in 2009 were much lower than in 2008. We also used model simulations of the study building to assess pre-cooling, a strategy that has been shown to improve demand saving and thermal comfort in many types of building. This study indicates a properly calibrated EnergyPlus model can reasonably predict demand savings from DR events and can be useful for designing or optimizing DR strategies.
Date: May 14, 2010
Creator: Dudley, Junqiao Han; Black, Doug; Apte, Mike; Piette, Mary Ann & Berkeley, Pam
Partner: UNT Libraries Government Documents Department

Open Automated Demand Response Technologies for Dynamic Pricing and Smart Grid

Description: We present an Open Automated Demand Response Communications Specifications (OpenADR) data model capable of communicating real-time prices to electricity customers. We also show how the same data model could be used to for other types of dynamic pricing tariffs (including peak pricing tariffs, which are common throughout the United States). Customers participating in automated demand response programs with building control systems can respond to dynamic prices by using the actual prices as inputs to their control systems. Alternatively, prices can be mapped into"building operation modes," which can act as inputs to control systems. We present several different strategies customers could use to map prices to operation modes. Our results show that OpenADR can be used to communicate dynamic pricing within the Smart Grid and that OpenADR allows for interoperability with existing and future systems, technologies, and electricity markets.
Date: June 2, 2010
Creator: Ghatikar, Girish; Mathieu, Johanna L.; Piette, Mary Ann & Kiliccote, Sila
Partner: UNT Libraries Government Documents Department

EFFECT OF COMBUSTOR INLET GEOMETRY ON ACOUSTIC SIGNATURE AND FLOW FIELD BEHAVIOUR OF THE LOW SWIRL INJECTOR

Description: Low Swirl Injector (LSI) technology is a lean premixed combustion method that is being developed for fuel-flexible gas turbines. The objective of this study is to characterize the fuel effects and influences of combustor geometry on the LSI's overall acoustic signatures and flowfields. The experiments consist of 24 flames at atmospheric condition with bulk flows ranging between 10 and 18 m/s. The flames burn CH{sub 4} (at {phi} = 0.6 & 0.7) and a blend of 90% H{sub 2} - 10% CH{sub 4} by volume (at {phi} = 0.35 & 0.4). Two combustor configurations are used, consisting of a cylindrical chamber with and without a divergent quarl at the dump plane. The data consist of pressure spectral distributions at five positions within the system and 2D flowfield information measured by Particle Imaging Velocimetry (PIV). The results show that acoustic oscillations increase with U{sub 0} and {phi}. However, the levels in the 90% H{sub 2} flames are significantly higher than in the CH{sub 4} flames. For both fuels, the use of the quarl reduces the fluctuating pressures in the combustion chamber by up to a factor of 7. The PIV results suggest this to be a consequence of the quarl restricting the formation of large vortices in the outer shear layer. A Generalized Instability Model (GIM) was applied to analyze the acoustic response of baseline flames for each of the two fuels. The measured frequencies and the stability trends for these two cases are predicted and the triggered acoustic mode shapes identified.
Date: November 30, 2009
Creator: Therkelsen, Peter L.; Littlejohn, David; Cheng, Robert K.; Portillo, J. Enrique & Martin, Scott M.
Partner: UNT Libraries Government Documents Department

ASSESSMENT OF COMBINED HEAT AND POWER SYSTEM"PREMIUM POWER" APPLICATIONS IN CALIFORNIA

Description: The effectiveness of combined heat and power (CHP) systems for power interruption intolerant,"premium power," facilities is the focus of this study. Through three real-world case studies and economic cost minimization modeling, the economic and environmental performance of"premium power" CHP is analyzed. The results of the analysis for a brewery, data center, and hospital lead to some interesting conclusions about CHP limited to the specific CHP technologies installed at those sites. Firstly, facilities with high heating loads prove to be the most appropriate for CHP installations from a purely economic standpoint. Secondly, waste heat driven thermal cooling systems are only economically attractive if the technology for these chillers can increase above the current best system efficiency. Thirdly, if the reliability of CHP systems proves to be as high as diesel generators they could replace these generators at little or no additional cost if the thermal to electric (relative) load of those facilities was already high enough to economically justify a CHP system. Lastly, in terms of greenhouse gas emissions, the modeled CHP systems provide some degree of decreased emissions, estimated at approximately 10percent for the hospital, the application with the highest relative thermal load in this case
Date: June 1, 2010
Creator: Norwood, Zack; Lipman, Timothy; Stadler, Michael & Marnay, Chris
Partner: UNT Libraries Government Documents Department

Building Energy Information Systems: User Case Studies

Description: Measured energy performance data are essential to national efforts to improve building efficiency, as evidenced in recent benchmarking mandates, and in a growing body of work that indicates the value of permanent monitoring and energy information feedback. This paper presents case studies of energy information systems (EIS) at four enterprises and university campuses, focusing on the attained energy savings, and successes and challenges in technology use and integration. EIS are broadly defined as performance monitoring software, data acquisition hardware, and communication systems to store, analyze and display building energy information. Case investigations showed that the most common energy savings and instances of waste concerned scheduling errors, measurement and verification, and inefficient operations. Data quality is critical to effective EIS use, and is most challenging at the subsystem or component level, and with non-electric energy sources. Sophisticated prediction algorithms may not be well understood but can be applied quite effectively, and sites with custom benchmark models or metrics are more likely to perform analyses external to the EIS. Finally, resources and staffing were identified as a universal challenge, indicating a need to identify additional models of EIS use that extend beyond exclusive in-house use, to analysis services.
Date: March 22, 2010
Creator: Granderson, Jessica; Piette, Mary Ann & Ghatikar, Girish
Partner: UNT Libraries Government Documents Department

A PRIORI PREDICTIVE METHODS OF ASSESSING HEALTH EFFECTS OF CHEICALS IN THE ENVIRONMENT

Description: Passage of the Toxic Substances Control Act (TSCA) last year emphasized the urgent need for the formulation of viable criteria and interim standards limiting the exposure of increasingly large segments of the U.S. population to environmental chemical toxicants. Unfortunately, current methods of developing these standards are both time-consuming and costly. The resulting need for a priori predictive techniques to assess the inherent potential of chemicals, such as the halocarbons found in chlorinated waters, for inducing adverse biological effects, has led to the use of a number of analytical methods designed primarily for screening large numbers of chemical compounds before they impose unacceptable environmental hazards, frequently of crisis proportions. Four of the techniques best adapted to dealing with the multifactorial environmental problems of chemical health effects will be briefly described: (1) quantitative structure/activity relationships (QSAR); (2) factor analysis (FA); (3) pattern recognition/artificial intelligence (PR/AI); and (4) molecular connectivity (MC). While it is clear that none provides easy answers, it would appear that the more recent areas of PR and MC both merit more intensive investigation as predictive tools. In particular, the relative simplicity of the MC approach and the possibility of substantially reducing the empirical component are attractive incentives for pursuing further work in this area.
Date: October 1, 1977
Creator: Kland, M.J.
Partner: UNT Libraries Government Documents Department

Analysis of Potential Energy Saving and CO2 Emission Reduction of Home Appliances and Commercial Equipments in China

Description: China is now the world's largest producer and consumer of household appliances and commercial equipment. To address the growth of electricity use of the appliances, China has implemented a series of minimum energy performance standards (MEPS) for 30 appliances, and voluntary energy efficiency label for 40 products. Further, in 2005, China started a mandatory energy information label that covers 19 products to date. However, the impact of these standard and labeling programs and their savings potential has not been evaluated on a consistent basis. This research involved modeling to estimate the energy saving and CO{sub 2} emission reduction potential of the appliances standard and labeling program for products for which standards are currently in place, or under development and those proposed for development in 2010. Two scenarios that have been developed differ primarily in the pace and stringency of MEPS development. The 'Continued Improvement Scenario' (CIS) reflects the likely pace of post-2009 MEPS revisions, and the likely improvement at each revision step considering the technical limitation of the technology. The 'Best Practice Scenario' (BPS) examined the potential of an achievement of international best practice MEPS in 2014. This paper concludes that under the 'CIS' of regularly scheduled MEPS revisions to 2030, cumulative electricity consumption could be reduced by 9503 TWh, and annual CO{sub 2} emissions would be 16% lower than in the frozen efficiency scenario. Under a 'BPS' scenario for a subset of products, cumulative electricity savings would be 5450 TWh and annual CO{sub 2} emissions reduction would be 35% lower than in the frozen scenario.
Date: June 7, 2010
Creator: Zhou, Nan; Fridley, David; McNeill, Michael; Zheng, Nina; Letschert, Virginie; Ke, Jing et al.
Partner: UNT Libraries Government Documents Department

Conceptual Studies of a Fuel-Flexible Low-Swirl Combustion System for the Gas Turbine in Clean Coal Power Plants

Description: This paper reports the results of preliminary analyses that show the feasibility of developing a fuel flexible (natural gas, syngas and high-hydrogen fuel) combustion system for IGCC gas turbines. Of particular interest is the use of Lawrence Berkeley National Laboratory's DLN low swirl combustion technology as the basis for the IGCC turbine combustor. Conceptual designs of the combustion system and the requirements for the fuel handling and delivery circuits are discussed. The analyses show the feasibility of a multi-fuel, utility-sized, LSI-based, gas turbine engine. A conceptual design of the fuel injection system shows that dual parallel fuel circuits can provide range of gas turbine operation in a configuration consistent with low pollutant emissions. Additionally, several issues and challenges associated with the development of such a system, such as flashback and auto-ignition of the high-hydrogen fuels, are outlined.
Date: November 30, 2009
Creator: Smith, K.O.; Littlejohn, David; Therkelsen, Peter; Cheng, Robert K. & Ali, S.
Partner: UNT Libraries Government Documents Department

The Coupling of ESP-R and Genopt: A Simple Case Study

Description: This paper describes and demonstrates how to use the optimization program GenOpt with the building energy simulation program ESP-r. GenOpt, a generic optimization program, minimises an objective function that is evaluated by an external simulation program. It has been developed for optimization problems that are computationally expensive and that may have nonsmooth objective functions. ESP-r is a research oriented building simulation program that is well validated and has been used to conduct various building energy analysis studies. In this paper, the necessary file preparations are described and a simple optimization example is presented.
Date: July 1, 2010
Creator: Peeters, Leen; D'haeseleer, William; Ferguson, Alex & Wetter, Michael
Partner: UNT Libraries Government Documents Department

Effect of Vinylene Carbonate on Graphite Anode Cycling Efficiency

Description: Vinylene Carbonate (VC) was added to the electrolyte in graphite-lithium half-cells. We report its effect on the coulombic efficiency (as capacity shift) of graphite electrodes under various formation cycling conditions. Cyclic voltammetry on glassy carbon showed that VC passivates the electrode against electrolyte reduction. The dQ/dV plots of the first lithiation of the graphite suggest that VC alters the SEI layer, and that by varying the cell formation rate, the initial ratio of ethylene carbonate to VC in the SEI layer can be controlled. VC was found to decrease first cycle efficiency and reversible capacity (in ongoing cycling) when used to excess. However, experiments with VC additive used with various formation rates did not show any decrease in capacity shift.
Date: May 5, 2009
Creator: Ridgway, Paul; Zheng, Honghe; Liu, Gao; Song, Xiangun; Ross, Philip & Battaglia, Vincent
Partner: UNT Libraries Government Documents Department

Transport Properties for Combustion Modeling

Description: This review examines current approximations and approaches that underlie the evaluation of transport properties for combustion modeling applications. Discussed in the review are: the intermolecular potential and its descriptive molecular parameters; various approaches to evaluating collision integrals; supporting data required for the evaluation of transport properties; commonly used computer programs for predicting transport properties; the quality of experimental measurements and their importance for validating or rejecting approximations to property estimation; the interpretation of corresponding states; combination rules that yield pair molecular potential parameters for unlike species from like species parameters; and mixture approximations. The insensitivity of transport properties to intermolecular forces is noted, especially the non-uniqueness of the supporting potential parameters. Viscosity experiments of pure substances and binary mixtures measured post 1970 are used to evaluate a number of approximations; the intermediate temperature range 1 < T* < 10, where T* is kT/{var_epsilon}, is emphasized since this is where rich data sets are available. When suitable potential parameters are used, errors in transport property predictions for pure substances and binary mixtures are less than 5 %, when they are calculated using the approaches of Kee et al.; Mason, Kestin, and Uribe; Paul and Warnatz; or Ern and Giovangigli. Recommendations stemming from the review include (1) revisiting the supporting data required by the various computational approaches, and updating the data sets with accurate potential parameters, dipole moments, and polarizabilities; (2) characterizing the range of parameter space over which the fit to experimental data is good, rather than the current practice of reporting only the parameter set that best fits the data; (3) looking for improved combining rules, since existing rules were found to under-predict the viscosity in most cases; (4) performing more transport property measurements for mixtures that include radical species, an important but neglected area; (5) using the TRANLIB approach ...
Date: February 19, 2010
Creator: Brown, N.J.; Bastein, L. & Price, P.N.
Partner: UNT Libraries Government Documents Department

CERTS Microgrid Laboratory Test Bed

Description: CERTS Microgrid concept captures the emerging potential of distributed generation using a system approach. CERTS views generation and associated loads as a subsystem or a 'microgrid'. The sources can operate in parallel to the grid or can operate in island, providing UPS services. The system can disconnect from the utility during large events (i.e. faults, voltage collapses), but may also intentionally disconnect when the quality of power from the grid falls below certain standards. CERTS Microgrid concepts were demonstrated at a full-scale test bed built near Columbus, Ohio and operated by American Electric Power. The testing fully confirmed earlier research that had been conducted initially through analytical simulations, then through laboratory emulations, and finally through factory acceptance testing of individual microgrid components. The islanding and resynchronization method met all Institute of Electrical and Electronics Engineers Standard 1547 and power quality requirements. The electrical protection system was able to distinguish between normal and faulted operation. The controls were found to be robust under all conditions, including difficult motor starts and high impedance faults.
Date: June 8, 2010
Creator: Lasseter, R. H.; Eto, J. H.; Schenkman, B.; Stevens, J.; Volkmmer, H.; Klapp, D. et al.
Partner: UNT Libraries Government Documents Department