bluuebunny/crossref_metadata_2025 huggingface dataset:
Home Energy Conservation in the Las Vegas Valley
Authors: France Todd M. , Hurt Rick A. , Boehm Robert F. , Sadineni Suresh B.
Published: October 2010

Pulte Homes, a production home builder and community developer partnering with the U.S. Department of Energy’s Building America program, has collaborated with the Center for Energy Research at the University of Nevada, Las Vegas, and NV Energy, the local electric utility, on an energy conservation project in the Las Vegas Valley. This study entails four model homes at a new development named Villa Trieste, located in the Summerlin community of Las Vegas. The models, ranging in floor plan area from 1,487 to 1,777 square feet, have been constructed under the Environments for Living program and have been platinum certified by LEED (Leadership in Energy and Environmental Design) for Homes. According to the Home Energy Rating System Index, all four models are over 50% more efficient than homes of equal size built to 2006 International Energy Conservation Code standards. The study focuses on the cost benefit of installing additional efficiency upgrades in future homes at the development. Though all proposed upgrades offer reductions in energy use, many offer little improvement relative to their installation costs. Higher-efficiency windows, heat recovery ventilators, and R-36 spray foam attic insulation have been deemed appropriate measures for future homes. All homes are to be equipped with photovoltaic arrays; increasing the size of the arrays will cost-effectively reduce net energy consumption.
Comparative Assessment of Alternative Cycles for Waste Heat Recovery and Upgrade
Authors: Little Adrienne , Garimella Srinivas
Published: October 2010

Thermally activated systems based on sorption cycles, as well as mechanical systems based on vapor compression/expansion are assessed in this study for waste heat recovery applications. In particular, ammonia-water sorption cycles for cooling and mechanical work recovery, a heat transformer using lithium bromide-water as the working fluid pair to yield high temperature heat, and organic Rankine cycles using refrigerant R245fa for work recovery as well as versions coupled to a vapor compression cycle to yield cooling are analyzed with overall heat transfer conductances for heat exchangers that use similar approach temperatures for each cycle. Thermal-to-mechanical conversion efficiencies of ∼9%, upgraded heat delivered at 150°C, or cooling coefficients of performance of 0.5–0.7 are realized for source temperatures of 120°C, with a nominal 1 kW of heat extracted from the waste heat stream. Ambient sink temperatures of 35°C are used, as well as indoor return air temperatures of 27°C for cycles that produce cooling at 8°C. Comparative assessments of these cycles on the basis of efficiencies and system footprints will guide the selection of waste heat recovery and upgrade systems for different applications and waste heat availabilities. The increased implementation of such waste heat recovery systems in a variety of applications will lead to decreased primary source inputs and sustainable energy utilization.
Methodology for Calculating the Ability of Renewable Energy Systems to Manufacture Themselves
Authors: King Carey W. , Webber Michael E.
Published: October 2010

Renewable energy and storage technologies are often thought of as sustainable energy systems and several life cycle analyses point to the positive energy return on energy invested for individual renewable systems. However, in order to power the various life cycle processes such as manufacturing, refining, and installation, fossil fuels are used to generate the required heat and electricity. Thus, there remains a question as to how the whole suite of renewable technologies, as considered in isolation from fossil fuels, can power their own life cycles. Because most renewable technologies have intermittent outputs due to intermittent inputs such as the sun, wind, and waves, it is unclear how compatible those power outputs are for our constant and high-power industrial processes. Storage technologies can possibly play a key role in providing dispatchable power, and storage systems are often quoted as being necessary to promote widespread use of renewable energy. This paper presents a methodology to measure innovation in renewable and storage technologies by using a time-varying renewable energy only energy return on energy invested – rEROI(t). Innovative technologies will therefore be those that make rEROI(t) increase over time. The methodology assumes that the power outputs of existing renewable systems would be the only source of power for the life cycle processes of making the next set of renewable and storage technologies. Thus, renewable systems are required to manufacture themselves.
Systems Optimization of SOFC-Based BCHP System
Authors: Zhao Xiling , Wang Hailong , Fu Lin , Wang Yi , Zhang Yating , Liu Wanbo
Published: October 2010

Fuel cell technology based on natural gas is a kind of promising and cleaning energy conversion technology under development. The generation mechanism of fuel cell is different from the traditional power generation device, and the efficiency of fuel cell is not restricted to Carnot cycle, therefore, it has almost the highest efficiency in most of the power generation device. Fuel cell as the motor of building cogeneration system is the integration of high efficiency energy conversion type with high efficiency energy utilization method. In this paper, a Solid oxide fuel cell (SOFC)-based Building Combined Cooling, Heating and Power (BCHP) system is simulated, and it can meet the basically electrical and heating (cooling) load of the end users. The peak power load could be supplied by power grid, and the peak heating (cooling) load could be supplied by the backup equipments. In this paper, the restricted nonlinear optimization model is built in order to solve the economic load balancing problem of the system, and the sequential quadratic programming (SQP) is used to successfully solve the optimal equipment capacity for the production costs minimization on the equality constraint of customer’s heat and power requirement, and the other inequality constraint of equipment capacity. The computation results show that it is a good method to size SOFC power generation capacity meet the electrical base load of a building. The model can be used to provide guidance in the SOFC based BCHP system design and optimization.
Performance Study of the Engineering Practice of Urban Sewage Source Heat Pump System
Authors: Fu L. , Zhao X. L. , Zhu J. Z. , Huang B. M. , He T. , Jiang Y.
Published: October 2010

As an energy-saving and environmentally friendly technology, the urban sewage source heat pump (USSHP) had been widely applied in the field of heating and air conditioning. Chinese researchers recently designed an urban sewage source heat pump system composed of a filth block device, a wastewater heat exchanger, a heat pump, and other assistant facilities, such as pumps, fans, and end user devices. The system was built in 2008, and has been in operation since then. We tested the parameters of the system on the heating and cooling status from the wastewater source to the heat pump, including the temperature and flux of sewage, the inlet and outlet parameters of different facilities, and the performance of different facilities for a typical operation status. Based on the test results, the overall COP of the system in the heating and cooling mode was computed, and the energy efficiency level was analyzed. Then a method was proposed to improve the system’s performance. After the improvements, the characteristic curves of the typical operation status were investigated. The results indicated that the heating COP is about 4.3, and the cooling COP is about 3.5 in the actual operating conditions. These results could serve as a reference for designing or evaluating urban sewage source heat pump systems.
Evaluation Indexes and Methods of Energy-Efficient Buildings
Authors: Wang Jiang-Jiang , Jing You-Yin , Zhang Chun-Fa , Shi Guo-Hua
Published: October 2010

The energy consumption in the world and the environment protection impel more attention to the energy-efficient building. This paper briefly introduced the energy consumption of buildings and the endeavor to improve energy efficiency in buildings in China. The evaluation indexes for energy-efficient buildings are reviewed and they would be obtained in different ways in the lifecycle of buildings. Then the evaluation methods or systems for energy-efficient buildings are presented. It can be found that the evaluation systems are prosperously developed and the evaluations in all lifecycle of the buildings is helpful to establish the policy, encourage governments, producers and users active actions and decrease the energy consumption in buildings in the future.
Truncation of the Secondary Concentrator (CPC) as Means to Cost Effective Beam-Down System
Authors: Segal Akiba , Epstein Michael
Published: October 2010

A central solar plant based on beam-down optics is composed of a field of heliostats, a tower reflector (hyperboloid mirror) and a ground receiver interfaced at its aperture with one or a cluster of secondary concentrators (CPC). In previous publications a method was presented illustrating the correlation between the tower reflector position and its size on one hand and the geometry, dimensions and reflective area of the secondary concentrator on the other hand, both related to the heliostat field reflective area. Obviously, when one wishes to reduce the size of a tower reflector by locating it closer to the upper focal point, the image created at the lower focus will be broader, resulting in a larger secondary ground concentrator. The present paper describes a method for substantial decrease of the dimensions of the ground secondary concentrator cluster (and, implicitly, the concentrator’s area) via truncation and some geometrical corrections without significant sacrifice of the optical performance. This offers a method for cost effective design of future central solar plants utilizing the beam-down optics.
Analysis of a Combined Power and Ejector Refrigeration Cycle for Low Temperature Heat Sources
Authors: Zheng Bin , Weng Yiwu
Published: October 2010

This paper presents a combined power and ejector refrigeration cycle for low temperature heat sources. The proposed cycle combines the organic Rankine cycle and the ejector refrigeration cycle. It can be used as an independent cycle powered by the low temperature sources, such as solar energy, geothermal energy, or as a bottom cycle of the conventional power plant for the recovery of low temperature waste heat. A program was developed to calculate the performance of the combined cycle. Several substances were selected as the working fluids including R113, R123, R245fa, R141b and R600. Simulation results show that R141b has the highest cycle efficiency, followed by R123, R113, R600 and then R245fa. While the working fluids are calculated by per unit, R600 can produce more power and refrigeration outputs due to the large latent heat. Simulations at different generating temperatures, evaporating temperatures and condensing temperatures were also discussed.
A Low Temperature Solar Thermochemical Power Plant With CO2 Recovery Using Methanol-Fueled Chemical Looping Combustion
Authors: Hong Hui , Han Tao , Jin Hongguang
Published: October 2010

A novel solar-hybrid gas turbine combined cycle was proposed. The cycle integrates methanol-fueled chemical-looping combustion and solar thermal energy at around 200°C, and it was investigated with the aid of the Energy-Utilization Diagram (EUD). Solar thermal energy, at approximately 150°C–300°C, is utilized to drive the reduction of Fe2O3 with methanol in the reduction reactor, and is converted into chemical energy associated with the solid fuel FeO. Then it is released as high-temperature thermal energy during the oxidation of FeO in the oxidation reactor to generate electricity through the combined cycle. As a result, the exergy efficiency of the proposed solar thermal cycle may reach 58.4% at a turbine inlet temperature (TIT) of 1400°C, and the net solar-to-electric efficiency would be expected to be more than 30%. The promising results obtained here indicate that this solar-hybrid combined cycle not only offers a new approach for highly efficient use of middle-and-low temperature solar thermal energy to generate electricity, but also provides the possibility of simultaneously utilizing renewable energy and alternative fuel for CO2 capture with low energy penalty.
Using the Multi Criteria Analysis Method PROMENTHEE II to Select the Optimal CCHP System: A Case Study
Authors: Jing You-Yin , Zhao Jun-Hong , Wang Jiang-Jiang
Published: October 2010

The PROMENTHEE II method is employed to evaluate five combined cooling, heat and power (CCHP) system systems using four aspects such as technology, economy, environment, and society. The CCHP systems with dynamical sources respectively are gas engine, gas turbine, Stiring engine, solid oxide fuel cell (SOFC) and a separate plant. The prime of the multi criteria evaluation method is the selection of preference function and calculation of the net flow. The criterion with linear preference function is applied to compare the five systems. The result shows that the SOFC mode is the optimal scheme in terms of the net flow. To verify the robustness of the PROMENTHEE II, the sensitivity analysis is done by exchanging the criteria weight. The result shows that PROMENTHEE II method is practical and convenient and it can provide a reliable evaluation result for CCHP systems.
Modeling and Simulation of Syngas Produced From Biomass Gasification Enriched With Solar Hydrogen
Authors: Cujia Gabriel , Bula Antonio , Mercado Alberto , Mendoza Jorge
Published: October 2010

Biomass gasification process is simulated in order to determine the influence of the operating parameters on the quality of the gas produced. Furthermore, the hydrogen required to enrich the syngas is also established. The modeling and simulation showed that the gas obtained by gasification at atmospheric pressure is mainly composed of H2 and CO; however, the molar ratio H2/CO is not favorable for synthesizing fuels such as methanol. This shows the need to enrich the syngas with additional hydrogen. For the case study developed, for each 100 kg / hr of biomass waste gasified, the amount of additional hydrogen required ranges between 2 to 6 kg / hr in order to obtain a molar ratio H2/CO close to 2. Using palm fiber, the amount of hydrogen required would be 4 kg / hr. This additional hydrogen could be derived from solar energy using thermoelectric modules with an effective area of solar radiation close to 400 m2 per kg of biomass. The simulation was performed using ASPEN PLUS®.
Experimental Investigations and Comparison of Energy and Exergy Efficiencies of the Box Type and Parabolic Solar Cooker
Authors: Rathore Nitesh , Shukla S. K.
Published: October 2010

In this paper two different types of solar cookers namely a flat plate box type solar cooker (SBC) and a parabolic solar cooker (SPC) are investigated experimentally. Experiments were done at roof top of Renewable Energy Lab, Department of Mechanical Engineering, Institute of Technology, Banaras Hindu University (BHU), Varanasi, India during month of October and November 2008. For comparison, these two cookers were kept on a single platform to ensure the same solar conditions. The energy and exergy efficiencies of both the cookers were experimentally evaluated. The experimental time period was from 09:00 to 15:00 solar time. During this period, it was found that the daily average temperature of water in the SPC was 333 K and for SBC was 326 K and the daily average difference between the temperature of water in the cooking pot and the ambient air temperature was 31.6 K for SPC and 26.4 K for SBC. The energy output of the SPC varied between 0.65 to 39.3 W and 7.44 to 33.49 W for SBC, whereas its exergy output was in the range of 0.92 to 2.58 W for SPC and for SBC it varies from 0.65 to 1.45 W. The energy efficiency of the SPC varied from 0.42% to 5.27% and for the SBC it varies from 4.7% to 29.81%.
The Energy Efficiency and Economic Feasibility Analysis of the Distributed Absorption Cooling Combined With District Heating System
Authors: Zhang Qunli , Fu Lin , Li Lihua , Di Hongfa
Published: October 2010

The distributed absorption cooling based district heating system was investigated in order to utilizing the reject heat from the combined heat and power (CHP) plant in summer. Compared with the electric compressor cooling, the energy efficient and cost-effectiveness of the distributed absorption cooling were furthermore analyzed by the Fuel Energy Saving Ratio (FESR) method. The sensitivity of some variables, such as the average electric efficiency, heating and electric generation efficiency of the CHP system, and the coefficient of performance (COP) of the chiller, were analyzed. The marginal heating price of the distributed absorption cooling can be obtained. According to the evaluation results, the applicability of the distributed cooling with district heating system is limited by the lower energy efficiency and economical benefits. The approaches to increase the energy efficiency were suggested in this paper. The improved distributed absorption cooling combined with liquid desiccant dehumidification which has higher heating utilization efficiency was put forward and analyzed, and the energy efficiency evaluation results showed that the improved distributed cooling has higher energy efficiency and economical benefits, and great applicability.
Circulation Control Applied to Wind Turbines
Authors: McGrain David , Angle Gerald M. , Wilhelm Jay P. , Pertl Emily D. , Smith James E.
Published: October 2010

The recent rise in fuel costs and global warming concerns have re-invigorated the search for alternative energy sources. Harnessing energy from the wind is a logical alternative; however the cost and efficiency of current wind turbines is a limiting factor. The use of an augmented Vertical Axis Wind Turbines (VAWTs) may become the superior choice to the more common Horizontal Axis Wind Turbines (HAWTs) that are usually associated with the harvesting of wind energy. HAWTs operate on the same principles as large airplane propellers, while VAWTs operate on lift and/or drag principles like an airplane wing or a sail on a boat. VAWTs are currently being investigated for use with circulation control to increase their potential power output. In this paper, two topics will be presented, a comparison between VAWTs and HAWTs for rotor diameter versus key turbine aspects and the impact of VAWTs on environmental concerns, such as bat and bird populations. The Center for Industrial Research Applications (CIRA) at West Virginia University (WVU) is currently developing a concept utilizing circulation control to increase the lift to drag ratio, maximizing the beneficial forces on the VAWT blade, allowing for improved wind energy production. For the comparison between VAWTs and HAWTs, there are currently 14 companies with a total of 34 wind turbines variations representing VAWTs and 11 companies with a total of 40 wind turbines representing HAWTs. Trend studies of VAWT and HAWT diameters to cut-in-speed, rated velocity, max velocity, power output (<100 kW), and power output (≥100 kW) were created to show the potential of VAWTs. A growing concern with wind energy is the impact on bat and bird populations. It is currently believed that VAWTs reduce the impact of wind energy by altering the interaction with the wind. If these benefits can be proven, then not only are VAWTs potentially more economical, but even more eco-friendly.
Potential of Solar Thermal Energy for CCHP Systems
Authors: Fumo Nelson , Chamra Louay M. , Bortone Vicente
Published: October 2010

Integrated energy systems combine distributed power generation with thermally activated components to use waste heat, improving the overall energy efficiency, and making better use of fuels. Use of solar thermal energy is attractive to improve combined cooling, heating, and power (CCHP) systems performance, particularly during summer time since the cooling load coincides very well with solar energy availability. Limitation of the use of solar systems is mainly related to high first cost and large surface area for solar energy harvesting. Therefore, solar thermal CCHP systems seem to be an alternative to increase the use of solar thermal energy as a means to increase energy systems overall efficiency and reduce greenhouse gases (GHGs) emissions. This study focuses on the use of solar collectors in CCHP systems in order to reduce PEC and emission of CO2 in office buildings. By using a base CCHP system, the energy and economic analysis are presented as the contribution of the solar system from the baseline. For comparison purposes, the analysis is made for the cities of Minneapolis (MN), Chicago (IL), New York (NY), Atlanta (GA), and Fort Worth (TX). Results show that solar thermal CCHP systems can effectively reduce the fuel energy consumption from the boiler. The potential of solar collectors in CCHP systems to reduce PEC and CO2 emission increases with the cooling demand; while the effectiveness of solar collectors to reduce primary energy consumption and CO2 emission, and the ability of the system to pay by itself from fuel savings, decreases with the number of solar collectors.
Design of a Vertical-Axis Wind Turbine Test Facility
Authors: Kweder Jonathan , Wildfire Patrick , Yarborough Christina , Smith James E.
Published: October 2010

Physical simulations of fatigue and wear of a vertical axis wind turbine (VAWT) are extremely complex and difficult to evaluate both analytically and numerically. The primary difficulty is simulating the fatigue at the point that the airfoil attaches to the wind turbine structure. Physical testing of VAWT models would provide a simpler method of analyzing the dynamics of a prototype. However, accurate reproduction of the aerodynamic loading imposed on a VAWT body due to the rotational wake is difficult to replicate. To truly incorporate a real world environment, the test facility needs to be exposed to a random, but measurable environment. This leads to the design and development of an outdoor wind turbine test facility. This proposed test facility will consist of an outdoor structure equipped with a 350 horsepower electric motor to turn an 88 inch diameter propeller which will drive the wind turbine model at specific rotational speeds. The propeller will be able to simulate wind speeds over the entire spectrum of 0 to 75 feet per second. The aerodynamic control of the freestream velocity and in turn, the model, will provide an accurate representation of the aerodynamic loadings experienced by the wind turbines tested. In addition to structural testing, this facility will introduce measurable environmental effects, such as wind gusts, pressure variation, and temperature changes to the model in order to create an accurate setting under which the model can be studied.
Cost Effective Energy Improvements for an Existing Commercial Building: A Case Study
Authors: Hill Davion M. , James Joshua , Mastin Brian , Padgett Barbara N.
Published: October 2010

In the beginning months of 2008, the energy consumption and water use data of a 28 year old commercial building in central Ohio was compiled with approximately one and a half years of prior data. At the initiation of the analysis period, studies were performed to identify key improvement areas for the most effective energy improvements for the building. Lighting, heating and cooling, insulation, and water use were all evaluated. Tenant involvement was incorporated to address waste management and conservation efforts. Improvement areas were identified and a program was implemented to make stepwise progress toward a reduced environmental footprint. Progress was tracked by continuous monitoring of energy and water use. Capital improvements were treated as investments with best approximations of return on investment. As the program gained momentum, opportunities arose for both ISO 14001 and LEED certifications. The improvement process was and continues to be for the long term, and the initial efforts resulted in a zero nonconformance evaluation during the first ISO 14001 audit. Studies and improvements for LEED certification for the existing building are currently ongoing.
Multi Criteria Evaluation Model of Renewable Energy Power Plants Based on ELECTRE Method
Authors: Wang Jiang-Jiang , Jing You-Yin , Zhao Jun-Hong
Published: October 2010

The feasibility evaluation of renewable energy power plants from multi criteria is necessary to save energy, protect environment and develop technology. This paper employs the improved elimination et choice translating reality (ELECTRE) method to evaluate 10 kinds of energy power plants in five criteria. The plants includes the coal fired, solar-thermal, geothermal, biomass, nuclear, photovoltaic solar, wind, ocean, hydro and natural gas combined cycle power plants. The evaluation criteria reflects four aspects from the technology, economy, environment and society. The concrete criteria are efficiency, installation, electricity cost, CO2 emission, and land requirement. Finally, the multi criteria evaluations show that the hydro power plant in the renewable energy are the optimal schemes at present.
Modeling and Analysis of Solar PV Power System for Greenhouse Application With Electrolyser Fuel Cell Back Up
Authors: Ganguly A. , Ghosh S. , Misra D.
Published: October 2010

The application of greenhouse technology for cultivation of flowers, vegetables and horticultural plants is rapidly expanding worldwide. But at present the requirement of grid connectivity imposes a restriction on the emanation of this technology to areas which are remote. In a developing country like India, where a significant number of villages are yet to be connected to any national or regional grid, this restriction assumes considerable significance. Due to abundant availability of solar energy in the plains of Indian subcontinent, its use in powering a greenhouse provides for a viable option. But due to the intermittent availability of solar energy, the provision of some form of back up arrangement to power the greenhouse becomes necessary. In the present paper a model for the power system of a greenhouse powered by solar photovoltaic system is presented and the back up arrangement is provided through a combination of electrolyser fuel cell system. The presented model shows that this integrated system comprising of greenhouse-solar photovoltaic module-electrolyser & fuel cell will provide a viable option for the design of stand alone greenhouses.
Design of Solar Assisted Community Biogas Plant
Authors: Gupta Ankit
Published: October 2010

This study aims at providing a solution to the difficulty in the production of biogas in cold weather conditions especially during winters and in hilly regions where the temperature remains low throughout the year. As is well known biogas can be produced by anaerobic fermentation of organic materials with the help of bacteria [1]. Meynell [2] pointed out that the production of biogas becomes insignificant when the slurry temperature is less than 15°C. Such situations are usually faced in northern India, where the ambient temperature and, hence, the slurry temperature, in the winters drops below 15°C and hence improper digestion of slurry leads to poor biogas yield. This problem can be overcome by making the biogas plant solar assisted. The heat requirements of the digesters generally consist of three parts; (i) heat required for raising the temperature of incoming slurry for digestion; (ii) for compensating heat losses through the boundaries of the digester and (iii) for compensating losses that might occur in the piping between the heat source and the digester [3]. The required heat is provided from the collector which absorbs solar radiation and converts it into heat which is absorbed by a heat transfer fluid passing through the collector [4]. In this work, a biogas plant for a specified capacity has been designed. Based on the biogas plant dimensions and the average ambient conditions for a specified location, the rate of loss of energy was determined. A solar collector system has been designed to supply sufficient energy to maintain the slurry temperature of 35° C.
Progress in Thermal Energy Storage Modeling
Authors: Bharathan Desikan , Glatzmaier Greg C.
Published: October 2010

Economic analyses for concentrated solar power (CSP) systems indicate that the cost of electricity can be reduced through the use a molten-salt thermal energy storage system (TES). Use of a thermocline in the tanks to keep cold and hot fluids separate in the tank has been proposed to further reduce the cost for TES to about $30/kWh thermal. This paper studies the details for molten-salt storage where the tank is filled with nominally 1-inch-size quartzite rocks and 1/4-inch sand particles. These filler materials are envisioned to occupy 75% of the tank’s volume. Experiments at Sandia National Laboratories indicate that these filler materials are compatible with the molten salt, and a well-established thermocline can be maintained in these tanks. The National Renewable Energy Laboratory attempts to look into the next level for the tank design, modeling heat transfer between solid filler and molten salt. Loose filler materials exert added hoop stresses in the tank that are likely to be unmanageable in the long run because of thermal cycling. Structured brick-like stacked shapes are needed that can maintain their structure without requiring sidewall support for the fill material. Large tanks with a volumetric capacity of 100,000 kL maintain a reasonable thermocline during charge and discharge. We report on progress in computational fluid dynamics (CFD) modeling of such tanks. However, for operational convenience for the plant, we suggest the use of multiple tanks.
Modelling of Pulsating Loads on Wind Turbine Blades
Authors: Gomez Alejandro , Seume Joerg R.
Published: October 2010

Measurements of the electric output of wind turbines have shown power oscillations with a 3p frequency which are caused by the interaction of the rotor with the supporting structure (tower). Potentially more troublesome than the power variations are the load pulses acting on the blades, the main shaft, the support bearings, the power transmission system, and the tower. These pulses are one factor among many causing the complex state of loading to which a wind energy converter is subjected. Simple aerodynamic modelling of this interaction is not capable of capturing all the effects present such as tower wake meandering, stall delay on the blades, lateral tower loads, and break-up of the rotor wake and trailing tip vorticity. This paper shows a method for estimating the magnitude of these effects based on fully turbulent CFD computations and discusses their importance for the design of structural components. Several turbulence models are used and their advantages and drawbacks are discussed. A better understanding of the aerodynamic and aeroelastic interaction between the rotor and the tower influences design parameters such as the tilt and overhang of the main shaft and should also be considered in the selection of the gear box and in possible modelling of blade damage. It is also shown that the near wake aerodynamics of the rotor has an influence on the far wake behavior making this an important factor for wind park simulations.
Influence of Operating Parameters on Energy Consumption of Electrohydrodynamic Drying
Authors: Bai Ya-xiang , Sun Bing
Published: October 2010

In order to improve the drying technique and the drying efficiency, reducing the energy consumption of Electrohydrodynamic (EHD) drying, the influence of operating parameters on the drying rate and energy consumption were investigated. Tofu contained in the petri dish was put in EHD system which was made up of a wire pole and a plate pole. By changing the voltage, electrode spacing and the distance between the two neighboring wires, the factors related to the drying rate and energy consumption were quantitatively studied. The results indicate that when the distance between the wire electrodes and the surface of the plate pole is constant, the drying rate increases linearly while the drying energy consumption increases nonlinearly with the supplied voltage. When the supplied voltage is not changed, the tofu drying rate and energy consumption are changed with the distance between the two neighboring wires. When the distance between the two neighboring wires is not changed, the tofu drying rate and energy consumption are changed with electrode spacing. When electrode spacing is 9 cm and the distance between the two neighboring wires is 9 cm, the drying rate is the highest while the energy consumption is relative least, 45 kV is the optimum value for drying voltage.
Integrated Wind, Sun, Fossil, Biomass and Nuclear for Energy Sustainability
Authors: Hobbs Raymond , Sun Xiaolei
Published: October 2010

The Advanced Hydrogasification Process (AHP) is being developed at Arizona Public Service (APS) to utilize the America’s abundant western coal supply to address concerns of diminishing domestic oil and natural gas resources as energy providers, while also incorporating a renewable energy and reducing greenhouse gas emissions. The AHP utilizes coal as a source for carbon, and hydrogen produced by renewable energy in the hydrogasification process to produce substitute natural gas (SNG) that can be fed to existing natural gas pipeline. The hydrogen will be produced through water electrolysis using wind firmed with off peak nuclear/coal electricity. The CO2 produced from the process will be recycled through biological approach — algae farming. With water and sun, algae will convert CO2 into starch, protein and lipids by photosynthesis.
Optimizing Comfort and Energy Use in Reheat Systems
Authors: Hutzel William J. , Odukomaiya Oluwaseun Seun
Published: October 2010

This project investigated the relationship between energy use and human thermal comfort in a small commercial single zone VAV system with reheat. The reheat configuration is not optimal in terms of energy efficiency, but there are a large number of these systems installed; thus there is a need for improved operating strategies to reduce waste. This project was conducted in the Midwest U.S.; where cooling and dehumidification are needed during the summer. Data on electricity use by the reheat system was collected on days that met or exceeded the 2% summer design condition. Additional data on environmental conditions inside the building zone was also collected and put into a model for predicting occupant comfort. To extend the range of the project, a building energy simulation for the reheat system was developed and calibrated. The calibrated model was used to estimate energy/comfort trends over a broader range of indoor operating conditions. This experiment shows that electricity consumption for a single zone VAV system with reheat can be significantly reduced while satisfying the thermal comfort needs of over 90% of the building’s occupants by offsetting a lower dry-bulb temperature set point with correspondingly higher zone humidity. In other words, reheat systems can optimize energy and occupant comfort by operating at set points in the upper middle segment of the comfort zone from ASHRAE Standard 55.
A Novel Approach to Extract Power From Free-Flowing Water and High Altitude Jet Streams
Authors: Platzer Max , Sarigul-Klijn Nesrin
Published: October 2010

It is well known to aeronautical engineers that oscillating wings may extract power from an air stream. The bending and torsion flexure of airplane wings exposed to an air flow may extract sufficient energy to result in structural damage or even catastrophic failure. Fortunately, this phenomenon can also be used to extract energy from a wind or water stream and convert it into electric power.
Studies on the Effects of Particle Size and Substrate Surface Properties on the Deposition Dynamics of Inkjet-Printed Colloidal Drops for Printable Photovoltaics Fabrication
Authors: Biswas Somnath , Gawande Sailee , Bromberg Vadim , Sun Ying
Published: October 2010

Using fluorescence microscopy, the inkjet deposition dynamics of monodispersed polystyrene particles in the size range of 0.02 to 1.1 μm have been studied on glass, Ar plasma cleaned glass, and PDMS coated glass substrates. The results show that the substrate properties play an important role in determining the final dried patterns formed by the colloidal particles. Our observations also reveal that particle size and contact angle formed by the solvent in the dispersion determine how close to the contact line the particles can be deposited. It is found that smaller particles can move closer to the deposited contact line than particles with bigger sizes. This study can serve as a realistic experimental model system for a number of fundamental queries on how the final deposition microstructure depends on the ink formulation and substrate properties. The knowledge obtained here can be explored further to optimize process parameters for the fabrication of hybrid solar cells with improved morphology and device properties.
The SkyTrakker™ Parabolic Trough Control System
Authors: Moore Coleman , LeSuer David
Published: October 2010

The SkyTrakker™ is a highly accurate and highly efficient parabolic trough control system. The system includes the microprocessor control board, separate motor controller, and sensors (temperature, position, hydraulic pressure). The SkyTrakker™ has several distinct advantages and design features that provide better manufacturability, shorten installation time, and reduce O&M cost. Some of the advantages and features are: 1. Maximum control and performance with reduced parasitic power consumption. 2. Lower motor input power consumption during deploy, tracking and stow (the SkyTrakker™ uses 52% of the power consumed at NSO). 3. Simple 110v AC single-phase motor requirements with digital motor interface to reduce parasitic power consumption at motor start-up and during tracking. 4. Local or remote monitoring and control. 5. Separate motor control providing a high level of motor power isolation from the electronics. 6. Microprocessor based control board offering fast response, monitoring of HTF temperature, SCA position, hydraulic pressures, and control of the motor. 7. Enhanced field diagnostics to isolate position sensor and motor control problems and provide run-time status of operation. 8. Accurate tracking using virtual tracking algorithms, eliminating the use and maintenance of sun sensors. The SkyTrakker™ control system is modular and designed for quick assembly and installation at the SCA pylon. The major sub-system parts (control board and motor controller) are pre-assembled and are mounted on a pre-wired mounting panel. The NEMA 4 electrical enclosure can be mounted to the pylon with or without the internal pre-wired panel, providing installation flexibility when building the field. All control system components (control board, motor controller and sensors) can be easily replaced in the field. And motor life is greatly extended due to reduced overall power and reduced parasitic power consumption.
Finite Element Modeling of a Dual Axis Resonant Test System for Wind Turbine Blades
Authors: Desmond Michael , White Darris , Barott William
Published: October 2010

Structural testing of wind turbine blades is required for designing reliable, structurally efficient blades. Full-scale blade fatigue testing conducted at the National Renewable Energy Laboratory’s (NREL) National Wind Technology Center (NWTC) provides blade manufacturers quantitative information on design details including design assessment, manufacturing quality, and design durability. Blade tests can be conducted as a single axis test (flapwise or lead-lag) or a dual-axis test (flapwise and lead-lag simultaneously). Dual-axis testing is generally the preferred full-scale test method as it simulates to a greater extent the characteristic loading the blade is subjected to in the field. Historically, wind turbine blade fatigue testing has been performed through forced displacement methods using hydraulic systems which directly apply load to the blade. More efficient methods of fatigue testing are being developed at the NWTC that employ resonant excitation systems to reduce hydraulic supply requirements, increase the test speed, and improve distributed load matching. In the case of a dual-axis resonant test, the blade is excited through multiple actuators at two distinct frequencies corresponding to the flapwise and lead-lag frequencies. A primary objective of a dual-axis test is to test the blade to equivalent damage moments in multiple axes. A code was developed to simulate the performance of the dual-axis resonant test system, comparing the predictions to actual test results. Modeling of this test system was performed using a MATLAB script that integrates the NREL FAST code with a commercial dynamic simulator package ADAMS. This code has the advantage over existing methods to more accurately simulate the coupled response between the flapwise and lead-lag directions. In summary, this paper will provide information on the modeling of wind turbine blade dual-axis resonant test systems.
A Study on the Effects of Reburning in Secondary Combustor on Efficiencies and Emission Reduction in Diesel Engine Boiler System
Authors: Lee Dae Hee , Lee Jun Sik
Published: October 2010

An experimental study on the effects of secondary combustion on efficiencies and emission reduction in the Diesel engine boiler system has been undertaken. The co-generation concept is utilized in that the electric power is produced by the generator connected to the Diesel engine, and heat is recovered from both combustion exhaust gases and the engine by the fin-and-tube and shell-and-tube heat exchangers, respectively. A specially designed secondary combustor is installed at the engine outlet in order to reburn the unburned fuel from the Diesel engine, thereby improving the system’s efficiency as well as reducing air pollution caused by exhaust gases. The main components of the secondary combustor are coiled Nichrome wires heated by the electric current and Diesel Oxidation Catalyst (DOC) housed inside a well insulated stainless steel shell. The performance tests were conducted at four water flow rates of 5, 10, 15 and 20 L/min and five electric power outputs of 3, 5, 7, 9 and 11 kW. The results show that at a water flow of 20 L/min and a power output of 9 kW, the total efficiency (thermal efficiency plus electric power generation efficiency) of this system reaches a maximum 94.4% which is approximately 20% higher than that of the typical Diesel engine boiler system. Besides, the use of the secondary combustor and heat exchangers results in 80%, 35%, and 90% reduction of carbon monoxide (CO), nitrogen oxide (NOx) and particulate matter (PM), respectively.
High Hydrogen Yield by Fermentation Using Clostridium Saccharoperbutylacetonicum N1-4
Authors: Alalayah Walid M. , Kalil Mohd Sahaid , Kadhum Abdul Amir H. , Jahim Jamaliah Md. , Alauj Najeeb M.
Published: October 2010

High hydrogen yield was carried out using Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564). The ability of this Clostridium on hydrogen production was studied in 250 mL batch culture with glucose as the sole organic carbon source. The effect of initial substrate concentration, initial medium pH, addition of Fe2+ and temperature were investigated. Results show that the highest yield (Yp/s) of hydrogen produced was about 3.10 mol (mol glucose)−1 when the initial glucose concentration was 10 gL−1, initial pH of 6.0 ± 0.2 and temperature 37°C. The yield of hydrogen produced decreased when higher initial glucose concentration was applied. The yield of hydrogen was increased when 25 mg L−1 Fe2+ was added to the medium.
Exergoeconomic Analyses of a Combined Water and Power Plant (CWPP)
Authors: Mahbub Fazle , Hawlader M. N. A. , Mujumdar A. S.
Published: October 2010

In this study, exergy and thermoeconomic analyses of MSF/MED and Reverse Osmosis (RO) processes are presented. Exergy analyses of every streams, both incoming and outgoing, for each plant configurations have been performed to quantify the exergy losses. The evaluation of cost depends upon the chosen methodology of accruing fuel cost. The exergy equations coupled with appropriate cost provide a valuable insight into areas of potential improvement of the Combined Water and Power Plant (CWPP). Various combinations (Combined cycle power plant (CCPP) with stand alone MSF, MED and RO; CCPP with MSF-RO hybrid or MED-RO hybrid) have been considered. This study reveals that major exergy losses occur in the evaporators (about 34%) especially in the first and last few stages, in case of MSF, and, hence, improvements in the evaporator design will have significant impact on the whole plant performance. Similar trend is also observed for MED. It exhibits low exergetic efficiency for the first stage as well the last few stages. All these results suggest that more focus on these design aspects have potential for further improvement. Moreover, among the three top brine temperatures 65 °C, 70 °C and 75°C, 65 °C show better exergetic efficiency. Comparison between MSF, MED shows that unit product cost decreases by about 30% in favor of MED.
Investigation on the Performance Characteristic of a Solar-Driven Braysson Heat Engine With Multi-Irreversibilities
Authors: Wu Lan Mei , Lin Guo Xing
Published: October 2010

An irreversible solar-driven Braysson heat engine system is put forward, in which finite rate heat transfer with the radiation-convection mode from the solar collector to the heat engine and the convection mode from the heat engine to the heat sink, the radiation-convection heat loss from the solar collector to the ambience, the internal irreversibility due to nonisentropic processes in the expander and compressor devices are taken into account. On the basis of thermodynamic analysis method, the analytic expression between the overall efficiency of the solar-driven Braysson heat engine system and the operating temperature of the solar collector is derived and the influences of different heat transfer mechanism, the internal irreversibility parameter, the isobaric temperature ratio, the ratio of heat-transfer coefficients on the optimal performance of the solar-driven Braysson heat engine system are evaluated and depicted quantificationally. The results obtained in the present paper are helpful to deeply reveal the effect of heat transfer mechanism and multi-irreversibilities on the performance of solar driven heat engines.