bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on a Newly Absorption Heat Pump District Heating System
Authors: Hu Peng , Fu Lin , Zhang Shigang , Luo Yong , Xiao Changlei
Published: October 2010

Combined heat and power (CHP) has higher efficiency than other heating supply methods. However, the total heating supply capacity from CHP plants will soon be lower than the total heating demand in Beijing by 2010. Investigation showed that 10% to 20% of total energy consumption was rejected to the surroundings through cooling water in CHP plants. The cooling water temperature leaving the condenser is normally in the range of 20–35°C during the heating season. This temperature is too low to be used for heating purpose. The total quantity of rejected heat is roughly equivalent to the energy to condition (heating) 25 million m2 building areas. Although circulating water in power plants has many advantages compared with other HP heat sources commonly used, it’s nearly impossible to operate a pipe network with such a small ΔT (10∼15°C) economically. A newly solution based on absorption heat pump (HP) was investigated and a smallscale demonstration project was built in Chifeng, a city of Inner Mongolia in North China. In such a newly district heating (DH) System, the primary pipe network will operate in ΔT of ≈100°C without any change in both outlet temperature of CHP sources and operating temperature of secondary pipe network. Inlet temperature of primary pipe network decreased to 20∼25°C, which makes possibility for waste heat recovery of circulating cooling water in most CHP plants. Comprehensive efficiency in CHP plants will improve 10% ∼ 20% theoretically. Operation effect during whole heating season of the demonstration project was also introduced.
Impact of Size and Scattering Mode on the Optimal Solar Absorbing Nanofluid
Authors: Otanicar Todd , Taylor Robert A. , Phelan Patrick E. , Prasher Ravi
Published: October 2010

The concept of using a direct absorbing nanofluid, a liquid-nanoparticle suspension, has recently been shown numerically and experimentally to be an efficient method for harvesting solar thermal energy. Studies show that the size and shape of the nanoparticles as well as the scattering mode (e.g. dependent, independent, and multiple) all impact the amount of energy absorbed and emitted by the nanofluid. In order to optimize the efficiency of a direct absorption solar thermal system the optimum nanoparticle-liquid combination needs to be developed. The optimum nanofluid for a direct absorption solar thermal collector is investigated numerically through the variation of particle size, including the impact of size on optical properties, and scattering mode. The study addresses both the absorption of solar energy within the fluid as well as the emission of the fluid.
An Energy and Exergy Analysis of Economizer-Based Data Centers
Authors: Meakins Michael E. , Okamoto Nicole C. , Bash Cullen E.
Published: October 2010

Electrical consumption for data centers is on the rise as more and more of them are being built. Data center owners and operators are looking for methods to reduce energy consumption and electrical costs. One method of reducing facility costs for a chilled water plant is by adding an economizer. Most studies concerning economizer systems are largely conducted by looking at energy alone since the primary focus has reducing electrical costs. However, little research has been published that examines exergy destruction for these types of systems based on varying outdoor air conditions by locale. The purpose of this study has been to develop energy and exergy-based models of each of the most common economizer systems. In this paper, a normal chiller plant without an economizer and a chiller plant with an indirect wet-side economizer (the most common type of economizer system) are compared. A method for simulating a mechanical cooling system is provided and results show outdoor conditions influence facility energy consumption and exergy destruction.
A Framework to Report the Production of Biodiesel From Algae
Authors: Beal Colin M. , Smith Colin H. , Webber Michael E. , Ruoff Rodney S.
Published: October 2010

Recently, algae have received a significant amount of attention as a potential feedstock for alternative fuels. Although multiple fuels have been proposed that would use algae as a feedstock, the most commonly explored algae-based alternative fuel is biodiesel. There are several coarse estimates that quantify the potential of algae as a feedstock for biodiesel. Some of these analyses have not incorporated specific values of algal lipid content and did not include processing inefficiencies. For example, in some analyses, specificity to the algal species and growth conditions is not provided, thereby introducing the opportunity for error. In addition, all necessary processing steps required for biodiesel production and their associated energy, materials, and costs might not be included. The accuracy associated with these estimates can be improved by using data that are more specific, including all relevant information for biodiesel production, and by presenting information with more relevant metrics. In order to determine whether algae are a viable source for biodiesel, two questions must be answered: 1) how much biodiesel can be produced from algae, and 2) what is the cost of production? To accurately answer these questions, we propose a framework for characterizing biodiesel production from algae. The framework focuses on three main principles. The first principle is the need for results to be presented in strong metrics. The strength of a metric is dependent upon the amount of information that it represents. The second principle in the proposed framework is that we suggest that researchers leave unknown information in symbolic form in order to present results in strong metrics. Presenting results in this manner ensures that results are not taken out of context; enables primary research results to be incorporated in systems-level analyses; and specifically identifies the areas where additional research is needed. The third principle is that results should be specific (to algal species, growth conditions, and product composition) and include as much information relevant to the entire biodiesel production pathway as possible, particularly including information for the energy, materials, and cost balances. To illustrate the application of the proposed framework, several examples of strong reporting metrics are presented. In addition, the presentation of unknowns in symbolic notation, and the associated benefit, is demonstrated. Finally, the limitations of several non-specific and non-inclusive reporting metrics are presented to highlight the necessity for consistent results regarding the potential for algae as a biodiesel feedstock.
Structural Design Considerations of a Circulation Controlled Vertical Axis Wind Turbine
Authors: Williams Kenneth A. , Yarborough Christina N. , Smith James E.
Published: October 2010

In the latter half of the twentieth century extensive research had been performed to improve the efficiency and operational life of Vertical axis wind turbines (VAWTs) in order to make them competitive with the more common horizontal axis wind turbines (HAWTs). Due to the completely random wind conditions and a continuously changing angle of attack of the rotating airfoil, fatigue of the system components was a major contributor to the short operational life of these traditional VAWTs. The fluctuating aerodynamic forces generated by the airfoil during rotation subject the support shaft to a substantial amount of torque ripple. In addition to the varying torque produced by the turbine, the centripetal forces generated by the airfoil’s rotation proved to be extremely large and create problems with deflection and fatigue in the airfoil’s internal support structure and especially at the attachment point of the airfoil to the support arm. One method for improving the efficiency of an aerodynamic system is to reduce the weight of the system. However, because of the forces generated during turbine operation, this proved to be a nontrivial task. West Virginia University’s (WVU) Center for Industrial Research Applications (CIRA) is exploring the implementation of circulation control on a vertical axis wind turbine to increase the lift to drag ratio of the turbine’s airfoils in order to produce a greater turning force and improve the efficiency of the system. While the common structural challenges of vertical axis wind turbines still apply, those implementing circulation control introduce additional design hurdles which must be overcome. These additional design problems concern mainly with the airfoil construction and support shaft in that they must be capable of accommodating the circulation control system components. This paper introduces the geometrical design constraints imposed on a vertical axis wind turbine through the operational requirements and serviceability of the circulation control system in addition to the traditional aerodynamic and centripetal forces generated and how they are resolved onto the individual turbine components.
Device to Transfer Heat From the Oxidation of Organic Waste Utilizing Activated Carbon
Authors: Cressey Marc W. , Labrecque Justin R. , Zenouzi Mansour , Chedid Loutfallah G. , Dow Douglas E. , McLaughlin Hugh
Published: October 2010

A device was developed for laboratory testing of a heat generating process that can use commercial organic by-products as fuel. This process, Activated Carbon Facilitated Oxidation (AC FOX), enables less refined organic compounds to be used as fuel sources, including glycerin, animal fats, and forms of brown grease. AC FOX oxidizes these compounds on the carbon surface in an exothermic reaction that does not involve combustion via flame. Although AC FOX has been demonstrated and patented, further development is required for industrial application. The device developed in this project forms a packed column vessel measuring three inches in diameter by five inches in height. Multiple ports have been drilled for temperature sensors and fluid flow. A thermosyphon design is being tested for heat transfer, and consists of a steel tube that will be partially filled with a working fluid. The bottom of the tube, evaporator, sits centrally in the packed column of activated carbon while the top section, condenser, is submerged in water. This device will enable the establishment of optimal conditions for AC FOX heat generation.
A Green Hybrid Solar Cell and Fuel Cell Power Plant Generating Electricity and Water
Authors: Moghbelli Hassan , Vartanian Robert
Published: October 2010

One major problem in the world is global warming that is now in the concern of some countries. Most countries are working on the usage of renewable energy sources such as solar energy, clean fuels like hydrogen and also increasing the efficiency of fossil fuel plant to help the global warming effect. Countries having high potential of solar energy and also natural gas as a source of hydrogen can use the finding of this research by developing usage of the solar energy converters and natural gas fuel cells for electric power plants. This paper discusses hybridization of renewable solar energy source with high efficient and clean usage of natural gas fossil fuel. Other aspects of this hybrid power plant is using the renewable energy sources as a reliable power supply with stand alone and grid connected capability which can increase network power quality. This paper also discusses the hybridization of solar energy as a renewable energy source and natural gas fuel cells as a fossil fuel and also improvement of power plant efficiency by using power electronics technology and electric energy storages.
The SkyTrough™ Parabolic Trough Solar Collector
Authors: Farr Adrian , Gee Randy
Published: October 2010

The SkyTrough™ is a new high-efficiency parabolic trough solar collector that has been designed with features to reduce capital cost, shorten installation time, and reduce O&M cost. This collector builds on the excellent success of prior generation utility-scale parabolic trough designs, but incorporates several engineering and material innovations, listed below. 1. Lightweight, low cost, unbreakable non-glass reflectors using ReflecTech® Mirror Film with reflectance equal to silvered glass mirrors — and easy to install and replace, 2. Large aperture area parabolic trough module with more than double the aperture area of the Nevada Solar One (NSO) module, 3. Longer linear receiver (SCHOTT PTR™80) utilized to match the larger aperture width SkyTrough, 4. Aluminum space frame structure that is considerably lighter per unit of aperture area compared to NSO, 5. Total component “part count” that is considerably reduced per unit of aperture area, yielding a shorter assembly time per unit of aperture than the NSO modules, 6. Hydraulic-based rotary actuation system that provides built-in “stow” locking capability and higher torque capability compared to NSO, 7. SkyTrakker™ control system reduces inrush currents and reduces parasitic power consumption associated with collector sun tracking.
Reactive Structures for Two-Step Thermochemical Cycles Based on Non-Volatile Metal Oxides
Authors: Siegel Nathan , Diver Richard , Miller James E. , Garino Terry , Livers Stephanie
Published: October 2010

Metal-oxide based thermochemical cycles, such as those including a class of iron containing materials commonly known as ferrites, involve two reaction steps: a thermal reduction at temperatures up to 1600 °C driven by a solar energy input, and a lower temperature exothermic oxidation in the presence of either carbon dioxide or water. In order to maximize performance, the reactive materials must be arranged into structures that provide an effective interface for the direct absorption of concentrated solar energy and also have relatively high surface area to support rapid chemical reactions. In this paper we discuss the attributes of reactive structures for solar thermochemical processes as well as some of the fabrication techniques currently under development at Sandia National Labs. One of these structures has been demonstrated on-sun in a two step carbon dioxide splitting cycle. The results, given in this paper, indicate that performance may be improved as the fraction of the total directly illuminated surface area is increased, reducing the need to rely on conduction or convection to distribute heat throughout the material.
Assessment of CHP System Performance With Commercial Building Benchmark Models in Different U.S. Climate Zones
Authors: Cho Heejin , Luck Rogelio , Mago Pedro J. , Chamra Louay M.
Published: October 2010

Combined Cooling, Heating, and Power (CHP) systems have been widely recognized as an alternative for electric and thermal energy generation because of their outstanding energy efficiency, reduced environmental emissions, and relative independence from centralized power grids. The performance of CHP systems depends on the type of buildings and climate conditions. Recently the U.S. Department of Energy (DOE) has developed a set of standard benchmark building models. According to the DOE [1], these models cover approximately 70% of the commercial building energy use. This paper evaluates and discusses the simulations of the performance of CHP systems for several commercial building benchmark models in 16 locations representing the U.S. climate zones described in the DOE report. The evaluation has been carried out using an optimal energy dispatch algorithm. The performance index for the optimization process is varied in order to investigate the impact of optimizing operational cost, primary energy consumption, and carbon dioxide emission. The results of this simulation can be used as a guideline to end-users when deciding on energy alternatives for their buildings or by policy makers deciding on regulations for cost, primary energy, or carbon dioxide emissions.
A Techno-Economic Analysis of a Proposed 1.5 MW Wind Turbine With a Hydrostatic Drive Train
Authors: Browning James R. , McGowan Jon G. , Manwell James F.
Published: October 2010

Although decreases in the cost of energy from utility scale wind turbine generators has made them competitive with conventional forms of utility power generation, further reductions can increase the presence of wind energy in the global energy mix. The cost of energy from a wind turbine can be reduced by increasing the annual energy production, reducing the initial capital cost of the turbine, or doing both. In this study, the cost of energy is estimated for a theoretical 1.5 MW wind turbine utilizing a continuously variable ratio hydrostatic drive train between the rotor and the generator. The estimated cost of energy is then compared to that of a conventional wind turbine of equivalent rated power. The annual energy production is estimated for the theoretical hydrostatic turbine using an assumed wind speed distribution and a turbine power curve resulting from a steady state performance model of the turbine. The initial capital cost of the turbine is estimated using cost models developed for various components unique to the hydrostatic turbine as well as economic parameters and models developed by the National Renewable Energy Lab (NREL) for their 2004 WindPACT advanced wind turbine drive train study. The resulting cost of energy, along with various performance characteristics of interest, are presented and compared to those of the WindPACT baseline turbine intended to represent a conventional utility scale wind turbine.
Effect of Solar Brightness Profiles on the Performance of Parabolic Concentrating Collectors
Authors: Chapman Daniel J. , Arias Diego A.
Published: October 2010

Solar brightness profiles were used to model the optical performance of a parabolic linear solar concentrator. A sensitivity analysis of the sun size on collector performance was completed using analytical methods. Ray traces were created for solar brightness profiles having circumsolar ratios from 0–40%, slope errors of the optical surface from 2–5 mrads, and angles of incidence varying from 0–60 degrees. Using typical meteorological data for two locations, the optical performance was calculated and averaged over a year. Intercept factors of these simulations were compared to simpler analytical models that cast the sun shape as a Gaussian function. Results showed that collector performance is relatively insensitive to solar profile, and that using a representative Gaussian solar profile will tend to underestimate collector performance compared to using exact weighted solar profiles by about 1%. This difference is within the uncertainty propagation of the intercept factor calculated with analytical methods.
Field Test of a Cooper LSVB-20GDT Engine Operating on Biodiesel
Authors: Beshouri Greg , Lam Henry
Published: October 2010

NRG Energy Center Paxton LLC (NRG-ECP) operates two Cooper LSVB-20GDT gas-diesel engines at a combined heat and power facility in Harrisburg, PA. NRG-ECP commissioned Advanced Engine Technologies Corporation (AETC) to conduct a literature review on the impacts of operating these engines on Biodiesel. Based on the somewhat favorable results of the review, NRG-ECP with support from AETC performed single cylinder and then full engine testing on one engine to assess the impact of Biodiesel operation on engine performance, emissions and operability as an alternative to full diesel operation. The results showed the engine exhibited no major differences in combustion performance or engine operability when running on Biodiesel in comparison to standard diesel fuel. During single cylinder testing the switch between diesel and Biodiesel was virtually undetectable. In the full engine Biodiesel test the unit started, idled, synchronized and loaded identical to diesel fuel. From a combustion perspective, the differences in Biodiesel vs. diesel operation are primarily attributable to the difference in air/fuel ratio due to the different fuel compositions. Fuel injection performance did not appear to change significantly or impact engine emissions.
Aggregation Method of Multi-Criteria Evaluations in New and Renewable Energy Power Plants: A Case Study
Authors: Wang Jiang-Jiang , Zhang Chun-Fa , Jing You-Yin
Published: October 2010

The multi-criteria evaluation methods of complex systems such as the new and renewable technologies gradually spring up. The feasibility of energy power plants is evaluated and considered from many aspects, such as technology, economic cost and environment protection. However, the energy power plants’ ranking results in different methods or different weighs can be different. Accordingly, the sequencing results should be aggregated and analyzed, and then an integrated result should be given out. Aiming to get the specific evaluation result, 10 kinds of energy power plants, such as hydro, nuclear, wind, geothermal and biomass plants are considered and evaluated. The singular value decomposition method is employed to aggregate the evaluation results in grey relational method, PROMENTHEE II method, and other results from literature. The integrated evaluation result shows that the hydro and nuclear power plants are located on the first place and the renewable energy power plants have great potential development in the future.
Retrograde Condensation as a Future Technology Base
Authors: Labinov Mark
Published: October 2010

The goal of the paper is to present an analytical description of the retrograde condensation (RC) phenomenon in the pure substances and the perspective of its utilization in the sustainable energy systems. Modern power storage and extraction technologies are based on equilibrium thermodynamic processes, not on the physicochemical nature of the working substances subjected to those processes. Practice and ingenuity guide the complex of the thermophysical and transport properties per application. The development of the JP7 fuel for a special aircraft in the US presents a perfect example [1]. Sustainable energy requires an environment-based approach such as targeting fluids as operational environments with certain optimal points or loci coveting to specific ways of power extraction or transmission. Usage of such intrinsic locations in the fluids would constitute a fundamentally new technology. Retrograde condensation presents such an opportunity. It manifests itself in a pure fluid as a reverse behavior of the vapor quality at a constant specific volume to the left of the critical value. For every specific volume there is only one unique point where the rate of the quality variation with temperature dx/dT changes its sign (from positive to negative). The formula for the locus connecting those points defines the retrograde condensation line. Around each point on this line a limit cycle of evaporation/condensation takes place with the frequency of oscillations depending solely on the properties of substance. These oscillations lead to the associated pressure waves with significant amplitudes depending on the location of the point on the locus. The phenomenon can lead to several energy-related applications with a strikingly different design approach-the adjustment of the device to the substance, its specifics. Here both primary power-generating parameters (pressure amplitude and oscillation frequency) become substance-dependent commensurate to the new requirements of sustainable energy-related designs.
Telescopic Wind Turbines to Capture Energy at Low Wind Speeds
Authors: Imraan Mustahib , Sharma Rajnish N. , Flay Richard G. J.
Published: October 2010

The reduction in cost of energy of wind turbines requires many technical contributions from all areas of the Wind Energy Conversion System. The variations in the wind (e.g. Diurnal, Monthly, Seasonal and Long term) as normally shown on probability density distributions directly affect the wind turbine performance. The turbine power output is also dependent upon a number of other variables, and a lot of research has been carried out to increase the power coefficient that has an upper limit of 0.593 called the Betz Limit. A possible way for improving the power output of a turbine is to control the swept area by controlling the diameter of the rotor. Ideally the wind turbine designer will use the long term mean wind speed to design and establish the rated power output of the wind energy conversion system. The stochastic nature of wind will fluctuate the power output of the turbine. Therefore to maintain the design rated power of the turbine, the telescopic wind turbine concept can be used. When the wind speed drops, the telescopic blades extend in order to maintain the power output, and when the wind speed increases, the telescopic blades retract in order to reduce the loads on the system. By telescoping the blades, the capacity factor of the wind energy conversion system is thus enhanced. The wind energy characteristic of a region in New Zealand was studied and the results show an 18% increase in annual energy production of a 10 kW wind turbine with telescopic blades.
High Quality Solid Biofuel Briquette Production From Palm Oil Milling Solid Wastes
Authors: Shamsuddin Abd Halim , Liew Mohd Shahir
Published: October 2010

Malaysia has about 4.2 million hectares of oil palm plantation. The palm oil milling industry has over 400 mills throughout the country with total milling capacity of 82 million tonnes fresh fruit bunches, FFB, per year. In 2003, the amount of FFB processed was 67 million tonnes, which generated solid wastes in the forms of empty fruit bunches, EFB (19.43 million tonnes), mesocarp fibres (12.07 million tonnes) and palm kernel shell (4.89 million tonnes). These wastes has moisture content of 60–70% for EFB and mesocarp fibre, and 34–40% for palm kernel shell, and calorific value of 5.0 – 18.0 Mj/kg. A processing technology was developed to process these low quality biomass fuels into high quality solid biofuel briquettes with moisture content in the range 8–12%. Depending on the formulations and the sources of the raw biomass, the final solid biofuel briquettes can have calorific values in the range of 18–25 Mj/kg. The production of the solid biofuel briquettes would be an attractive financial advantage for full exploitation of biomass fuels. Logistic problems due to the disperse nature of the biomass resources would significantly be addressed.
Recycling Biomass Co-Combustion Fly-Ash Products for an Integrated Solar-Assisted Ventilation System
Authors: Kwong C. W. , Chao C. Y. H. , Hui K. S.
Published: October 2010

The potential use of biomass co-combustion derived fly-ash products and zeolite 13X for the elimination of volatile organic compounds (VOCs) using ozone was investigated for an integrated solar-assisted air purification and desiccant cooling system. Fly-ash products from rice husk-coal co-combustion at different biomass blending ratios were used as the adsorbent/catalyst materials. The material characteristics of the adsorbent/catalyst materials such as metal content and surface area were compared and correlated with the catalytic activities. It was found that the surface area and the metal constitutes have made the catalytic activities over the fly-ash products from biomass co-combustion superior to that from coal-only combustion. The elevated reaction temperatures from 25°C to 75°C also have significant effects on the removal of VOCs. The apparent activation energies of the reaction path over the fly-ash products with the addition of ozone to the air were reduced, when compared with the use of air as an oxidant. On the other hand, the potential synergy to Zeolite 13X was explored. The combined catalytic ozonation and adsorption enhanced the VOCs removal and at the same time reduced the intermediates emission. Furthermore, the hydrophilic properties of zeolite 13X could be utilized to handle the latent load of the solar-assisted ventilation system for energy conservations.
Analyzing Tradeoffs in Electricity Choices Using the Texas Interactive Power Simulator (TIPS)
Authors: Lott Melissa C. , King Carey W. , Webber Michael E.
Published: October 2010

The Texas Interactive Power Simulator (TIPS) is an interactive analytical tool developed at the University of Texas at Austin for quantitatively comparing the first-order economic and environmental tradeoffs of different electricity production methods in Texas. The tool is designed for analysis of different power choices and is presented in an online format for use by students, the general public, and government decision-makers. The core electricity industry data are Texas-specific, but the flexibility of the framework, when combined with user supplied content, extends its applicability to the United States and world electricity markets. TIPS provides a method for assessing the tradeoffs of electricity generation technologies in terms of economic costs and environmental impacts. Economic costs include major factors such as the cost of capacity, fuel, operation and maintenance (O&M), as well as the costs of conservation programs and environmental impact mitigation technology. Environmental impacts include market externalities such as the environmental impacts on air, land, and water, and are normalized per kWh generated (for example, pounds of CO2 or NOx, acres of land, or gallons of cooling water consumed per kWh of generated electricity). Environmental impacts can further be associated with a cost, which is included in the overall levelized cost of electricity. Users can supply their own data for interactive experimentation, though peer-reviewed data are provided as default values. TIPS’ outputs include text, graphs, and pictograms showing the electricity output and environmental impact of the user’s selections, which allow the user to interpret the overall impact for different fuel mixes. Source data are incorporated from government sources and peer reviewed technical literature. The TIPS interactive interface allows the user to analyze a desired electricity mix according to the percentage breakdown of electricity production for each generation technology. The user input determines the overall direct and indirect costs of a unit of electricity according to the particular cost parameters associated with each generation technology. This manuscript discusses the methodology used in TIPS calculation and shares the results of using TIPS to analyze the cost and environmental impacts for a variety of illustrative and possible generation scenarios in Texas, including the following: high carbon prices, nuclear renaissance, and continuing wind market growth.
Comparison of U.S. and Swiss Homes and Lifestyles
Authors: Hutzel William J. , Koch Daphene C. , Kutch Jason M. , Furter Rudolf
Published: October 2010

This case study compared U.S. and Swiss homes with the goal of identifying construction practices that are most beneficial in terms of energy efficiency and life cycle costs. The research was a collaboration between the Departments of Mechanical Engineering Technology (MET) and Building Construction Management (BCM) at Purdue University and The Lucerne University of Applied Arts and Sciences (HTA Lucerne) in Switzerland. The first phase of this project compared U.S. and Swiss approaches to low energy residential buildings. Construction costs and annual energy consumption were estimated using homes with a similar size and layout, but with specific changes to one or more features that affect overall energy use. The results show that a Swiss-style low-energy home is not cost-effective for Indiana in the short term, but could become attractive after a relatively long (40+ year) period of home ownership. Recognizing that technology by itself will not minimize energy consumption, a second part of the project explored cultural norms that influence energy use. A survey of U.S. and Swiss college students was used to compare lifestyles and energy habits. It was found with a high level of confidence that Swiss students are more energy conscious than their U.S. counterparts.
Thirty Years of Performance of an Active Solar Space Heating/DHW System
Authors: Reid Robert L.
Published: October 2010

A solar house in Knoxville, Tennessee has been operating for thirty years providing space heating and domestic hot water. The active system with air collectors and rock storage and heat pump back up has required minimal maintenance. Using data from sub-meters, the auxiliary and operating energy have been compared for the first three years of operation and the last eight years. There appears to be little or no degradation in performance during the thirty-year period.
Modeling and Optimal Control of Distributed Generation Systems for Demand and Energy Management
Authors: Yosten Andrew J. , Henze Gregor P.
Published: October 2010

A procedure for the simplified modeling of distributed generation (DG) systems and finding optimal control and dispatch schedules is presented. Mixed integer linear programming can be used to develop optimized equipment dispatch schedules for a wide range of constraints and objective functions. For the monetary objective function considered in this study, optimal control of distributed generation equipment can reduce operating costs by reducing the amount of energy purchased from the grid, reducing demand charges, and reducing the heating energy cost through the implementation of a CHP plant. The procedure can easily be modified for alternative objective functions considering site energy, primary energy, or emissions and the resultant dispatch schedules used to derive operational guidelines. Moreover, a wide range of operational constraints can be modeled. Results are presented for a healthcare outpatient care center in Richmond, Indiana for the cases of single-day and multi-day demand management using on/off control of emergency generation equipment, continuous control of the emergency generation equipment between a nonzero minimum and a maximum part-load ratio, and combined heat and power systems with thermal storage. Nonlinearities in the objective function due to demand charges or nonzero lower bounds on the part-load operation of the DG equipment have been avoided by properly formulating substitute problems. The emphasis of this article is on the model development process rather than the specific dispatch schedules generated.
Adaptive Neuro Fuzzy Control Design of a Solar Power Plant’s Complete Oil Cycle
Authors: Shahmaleki P. , Amiri M. , Mahzoon M.
Published: October 2010

To enhance the performance and achieve a controlled condition with an optimized system a more precise modeling for power plant dynamics is needed. In this paper, a complete oil cycle of Shiraz solar power plant is modeled and controlled. Also, adaptive network-based fuzzy inference system (ANFIS) was employed to control collectors’ field. Furthermore, fuzzy switching control is utilized In order to prevent chattering phenomena of this multi-loop plant. Simulation results of the oil cycle solar power plant and the controller system show that the applied controller system can manage the oil cycle in different situations within safe operating conditions and with better performances.
New Electric Transmission Technologies for Renewable Integration
Authors: Brown Merwin , Cibulka Lloyd , Cole Jim , Miller Larry
Published: October 2010

California has established aggressive Renewables Portfolio Standard (RPS) goals to increase the fraction of electricity generated from renewable energy resources and to decrease greenhouse gas emissions. Legislation AB 32 requires 20% of California’s electricity to come from renewables by 2010. More recently, an executive order has set a goal of 33% by 2020. Most of this new renewable generation will require the electric grid for delivering its electricity to customers. Renewable generators will be integrated into the grid at both transmission and distribution levels, but most of this capacity is expected to connect to the transmission system in locations remote from load centers and existing transmission infrastructure. Consequently, new transmission extensions must be built. But permitting and constructing new transmission are taking considerably longer than they do for the power plants the new transmission will serve, creating a significant challenge for meeting the RPS goals. Once connected to the grid, some of this renewable generation will exhibit properties, such as intermittency, quite different from traditional generation and loads, which pose special challenges for providing timely grid delivery capacity, maintaining reliability, and avoiding economic inefficiencies. Finally, power flow constraints through existing transmission “gateways” into population centers must be relieved before the electricity from renewables can reach customers. Meeting these challenges will require new or expanded capabilities for the grid. At higher RPS levels, the conventional “build” solutions, namely new extension lines, expanding the capacity of existing transmission gateways to load centers, and building conventional power plants for support, will prove inadequate by themselves, either because they are not the most cost effective or can’t be permitted. New transmission technologies offer the prospect of providing a substantial portion of these new or expanded capabilities to supplement these build solutions. This paper provides a technology development survey for achieving an electric transmission infrastructure functionally capable of performing its role in meeting the Renewables Portfolio Standard goals. These new technologies were examined in the context of providing three new or expanded broad capabilities: (1) Provide physical access for each new power plant, (2) Reliably accommodate any unique renewable generator behaviors, and (3) Increase the grid’s power carrying capacity to handle the additional electric power flows. Many of these new capabilities will foster a more intelligent, robust and flexible transmission system as part of the Smart Grid. This intelligence also opens the prospects for an expanded role for distributed renewable generation to help meet the RPS goals and reduce some of the burden on transmission. Finally new physical capabilities must be added to turn the intelligence into actions.
Submicron Superhydrophobic Surface Treatment Suitable for High Performance Condensers: A Modeling
Authors: Kim Sunwoo , Kim Kwang J. , Kennedy John M. , Liu Jiong , Skandan Ganesh
Published: October 2010

The effect of the drop-contact angle on dropwise condensation heat transfer of saturated steam on a single horizontal copper tube with the superhydrophobic coating was investigated theoretically. The theoretical model is established by combining heat transfer through a single droplet with a well-known drop size distribution theory. The analysis of single droplet heat transfer incorporates resistances due to vapor-liquid interface, drop curvature, conduction through the drop, and conduction through the superhydrophobic coating layer. Each resistance is expressed as a function of the contact angle. The total resistance for a drop with a fixed radius increases as the contact angle increases. A population balance model is used to develop a drop distribution function for the small drops that grow by direct condensation. Drop size distribution for large drops that grow mainly by coalescence is obtained from the empirical equation proposed by Le Fevre and Rose (1966). The results indicate that the contact angle has a strong correlation with the maximum drop radius, which plays a pivotal role in determining drop size distribution. A high contact angle leads to a significant reduction in the radius of the largest drop that is about to fall down due to gravity and sweep away drops in its path. Thus, there are more areas on the condensing surface for small drops, allowing for greater heat transfer. Also, it is shown that surface wettability affects the performance of dropwise condensation heat transfer and our theoretical model successfully predicts this phenomenon.
Ferrite-Loaded Ceramic Foam Devices Prepared by Spin-Coating Method for a Solar Two-Step Thermochemical Cycle
Authors: Gokon Nobuyuki , Kodama Tatsuya , Nagasaki Ayumi , Sakai Ko-ichi , Hatamachi Tsuyoshi
Published: October 2010

A two-step water-splitting thermochemical cycle using redox working material of iron-based oxide (ferrite) particles has been developed for converting solar energy into hydrogen. The two-step thermochemical cycle for producing a solar hydrogen from water requires a development of a high temperature solar-specific receiver-reactor operating at 1000–1500°C. In the present work, ferrite-loaded ceramic foams with a high porosity (7 cells per linear inch) were prepared as a water splitting device by applying ferrite/zirconia particles on a MgO-partially stabilized Zirconia (MPSZ) ceramic foam. The water splitting foam device was prepared using a new method of spin coating. A spin coating method we newly employed that has advantages of shortening preparation period and reducing of the coating process in comparison to previous preparation method reported. The water-splitting foam devices, thus prepared, were examined on hydrogen productivity and reactivity through a two-step thermochemical cycle. NiFe2O4/m-ZrO2/MPSZ and Fe3O4/c-YSZ/MPSZ foam devices were firstly tested for thermal reduction of ferrite using the laboratory scale receiver-reactor by a sun-simulator to simulate concentrated solar radiation. Subsequently, with another quartz reactor the light-irradiated device was reacted with steam by infrared furnace. As a result, it was possible to perform cyclic reactions over several times and to produce hydrogen through thermal-reduction at 1500°C and water-decomposition at 1100–1200°C. In further experiments, the NiFe2O4/m-ZrO2/MPSZ foam device was successfully demonstrated in a windowed single reactor for cyclic hydrogen production by solar-simulated Xebeam irradiation with input power of 1 kW. The NiFe2O4/m-ZrO2/MPSZ foam device produced hydrogen of 70–190μmol per gram of device through 6 cycles and reached ferrite conversion of 60% at a maximum.
Case Study for Integrated Regional Energy Planning in Sino-Singapore Tianjin Eco-City
Authors: Li Yonghong , Fu Lin , Jie Chen
Published: October 2010

Regional integrated energy plan is considered for urban energy infrastructure utilization. Heating mode such as heating technology of central heating by waste heat recovery in power plant, geothermal heat, sewage water heat pump, ground source heat pump will be developed in Tianjin Eco-city. Electricity supplying mode such as urban power distribution network, solar power generation system, wind power generation system, biogas CHP and natural gas fired BCHP will be developed in eco-city. A medium pressure natural gas network will be developed with two gas pressure-regulating station in north and southern part of eco-city. Low energy consumption buildings have a low heating and air-conditioning energy consumption and electricity consumption. Based on the building energy simulation analysis, we put forward the indicator system of energy planning closely focus on the suitable energy demand. In this paper, the integrated energy planning with space and time characteristics is also presented and analyzed briefly.
Passive Structural Health Monitoring Applied to a Wind Turbine Model
Authors: Bassett Kyle , Carriveau Rupp , Ting David S.-K.
Published: October 2010

Structural health monitoring is a technique devised to monitor the structural conditions of a system in an attempt to take corrective measures before the system fails. A passive structural health monitoring technique is presented, which serves to leverage historic time series data in order to both detect and localize damage on a wind turbine blade aerodynamic model. First, vibration signals from the healthy system are recorded for various input conditions. The data is normalized and auto-regressive (AR) coefficients are determined in order to uniquely identify the normal behavior of the system for each input condition. This data is then stored in a healthy state database. When the structural condition of the system is unknown the vibration signals are acquired, normalized and identified by their AR coefficients. Damage is detected through the residual error which is calculated as the difference between the AR coefficients of the unknown and healthy structural conditions. This technique is tailored for wind turbines and the application of this approach is demonstrated in a wind tunnel using a small turbine blade held with four springs to create a dual degree-of-freedom system. The vibration signals from this system are characterized by free-stream speed. Damage is replicated through mass addition on each of the blades ends and is located by an increase in residual error from the accelerometer mounted closest to the damaged area. The outlined procedure and demonstration illustrate a single stage structural health monitoring technique that, when applied on a large scale, can avoid catastrophic turbine disasters and work to effectively reduce the maintenance costs and downtime of wind farm operations.
The Impacts of Vehicle-to-Grid Technology on Mitigating High-Energy Demand Day Emissions in New York City
Authors: Ferdon Charles , Foster Earl , Acquaviva Jonathan , Rawat Shashank , Zhang K. Max
Published: October 2010

In this report, a theoretical implementation of vehicle-to-grid power in the New York Metropolitan Area was evaluated with the goal of reducing peaking unit NOx emissions to comply with upcoming emissions limits on high energy demand days. In addition, the net cost of implementing this program was estimated using cost and revenue models based on available electricity rates and approximate battery cost. Finally, the improvement of air quality in some of the most populated areas of the NYMA was evaluated using the AERMOD air quality model from the EPA. By selectively offsetting the peaking units with the highest emissions rates, the average daily reduction was .25 tons at 1% penetration, 1.2 tons at 5% penetration, and 2.13 tons at 10% penetration. The implementation cost ranged from $315,000 to $9.5 million with different electricity rate structures and different penetration scenarios. Reduction of ambient particulate matter concentration was highly variable: the average reduction of all five population centers was negligible at 1% penetration, .83% at 5% penetration, and 1.42% at 10% penetration.
Passive Energy Harvesting From Human Activities
Authors: Romero Edwar , Neuman Michael R. , Warrington Robert O.
Published: October 2010

Energy harvesting from environmental sources such as motion, light, and temperature changes, has been demonstrated with commercially viable products (such as human-powered flashlights, solar-powered calculators, and thermal-powered wristwatches). Vibration or motion is an attractive environmental energy source due to its abundance and availability. A new electromagnetic energy harvester presented here is found to be capable for scavenging energy from human motion. The electrical power output of an inertial energy scavenger is proportional to the acceleration-squared-to-frequency (ASTF) and the quality (Q) factor. Human motion is associated with large ASTF values and low Q factors while machine vibrations are usually related with the opposite. Thus, passive energy harvesting from human activities could generate as much power as the one available from machine harvesters. The limit for such inertial generator is estimated to be on the order of 1mW/cm3. This paper reviews the energy harvesting limits, the energy generation from human activities, and the development of a new oscillating electromagnetic generator. This energy harvester is built with a permanent magnet (PM) ring with multiple poles and a gear-shaped planar coil. The PM ring has attached an eccentric proof mass for converting external movement into oscillations or rotations, these oscillations induce an electrical potential on the planar coil. As much as 3.45μW of power have been generated with a prototype at a frequency of 2.7Hz on a laboratory shaker and 2.35μW had been obtained when positioned laterally on the hip while walking.