bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Passive Polymeric Micromixer Using 3D Porous Structure
Authors: Wang Hai , Li Wei
Published: February 2009

In microfluidic related chemical and biological applications, mixing on the micro scale is important and has been considered as one of the most challenging tasks. With a trend for polymeric microfluidic systems, a simple yet efficient passive micromixer is highly preferred [1–4]. We developed a novel passive micromixer with 3D porous microstructure on a polymer chip. The fabrication process uses high-intensity focused ultrasound to selectively foam gas-impregnated polymers. The selective ultrasonic foaming technique is simple, low-cost, and biocompatible. The porous microstructure is easily controlled by adjusting the parameters of the ultrasonic foaming process. The 3D porous microstructure can split, stretch, fold and break the mixing flows in microfluidic channels and thus dramatically improve the mixing efficiency.
Development of a Novel Fluid Management System for Accurate Continuous Hemofiltration in Extracorporeal Membrane Oxygenation
Authors: Dasi Lakshmi P. , Sucosky Philippe , Goldman Stephen , Paden Mathew , Fortenberry James , Yoganathan Ajit P.
Published: February 2009

Failure of the cardiac or respiratory system is a common problem in the pediatric and neonatal intensive care unit. When conventional management fails to improve the child’s condition, extracorporeal life support such as extracorporeal membrane oxygenation (ECMO) can serve to provide life-saving temporary heart and lung support [1]. Renal failure often complicates care of these critically ill children on ECMO, leading to accumulation of fluid and volume overload that can worsen their heart and lung disease. Restrictive fluid management has been demonstrated to improve patient outcomes in acute lung injury.
Measuring the Cell-Induced Deformation of Collagen Matrix Detected With Digital Holographic Microscopy
Authors: Azartash Kaveh , Gratton Enrico
Published: February 2009

A modified Mach-Zender set-up in reflection is applied to record and reconstruct holographic amplitude and phase images. A charged couple device (CCD) is used to record a hologram and numerical reconstruction algorithms are then applied to rebuild the hologram for obtaining both phase and amplitude information. One could also focus on multiple focal planes from a single hologram, similar to the focusing control of a conventional microscope. The morphology and behavior of mammalian cells is determined by an interaction between signals from the intracellular matrix and the cellular responses. It is important to note that the physical aspect of the extracellular matrix is as significant as the chemical nature of it. Specifically the stresses, mechanical forces, and the profile of the external environment have major effects on cell behavior. The mechanical and physical characteristics of a tissue are greatly dependent on a hierarchical spatial arrangement of its extra-cellular matrix components. A key player in the ECM is collagen which exhibits significant tensile strength on the cellular scale. Digital holographic microscopy (DHM) is applied to study the deformation of collage matrix in response to cell migration.
Percutaneous Electro-Chemo-Mechanical Reshaping of Cartilage Tissue
Authors: Manuel Cyrus , Protosenko Dimitry , Sepehr Ali , Wong Brian J. F.
Published: February 2009

For centuries, surgeons have heavily relied on scalpels and sutures to reshape cartilage. Reshaping the cartilaginous frameworks of the head and neck requires open surgery to counteract the intrinsic elastic forces that resist deformation. Recently, non-surgical techniques that use radio frequency or laser sources to reshape cartilage have been developed, but they rely on heat generation and may produce thermal injury [1,3]. We recently developed new techniques to reshape cartilage called Electro-Mechanical Reshaping (EMR) that combines mechanical deformation with the application of low-level DC electric fields. Shape change is driven by electrochemical reactions that occur between electrodes placed in contact with the mechanically deformed specimen. Previous studies have shown that EMR of cartilage can be accomplished using graphite and aluminum surface electrodes [2,4]. In this study, EMR was further investigated with the use of needle electrodes that can be inserted into the mechanically deformed specimen rather than on the surface. Needle electrodes offer several advantages to surface electrodes because they can be incorporated into percutaneous surgical devices and instrumentation, deliver electric energy precisely to the site of desired shape change, and by design limit the spatial extent of tissue injury.
An Implantable Microbolus Pump With Contactless Rechargeable Battery Power Source Triggered by Remote Activation
Authors: Givrad Tina K. , Holschneider Daniel P. , Moore William H. , Yang Jun , Maarek Jean-Michel I.
Published: February 2009

We describe the design and testing of an implantable miniature infusion pump that uses a rechargeable battery as a power source. This design includes a receiver printed coil that allows inductive power transfer from a transmitter coil wound around a 20 cm diameter charging unit and a frequency-gated optical sensor that allows activation of the pump at a distance using pulses of infrared light. This mini pump can be charged in the home cage by inductive power transfer, and then operates independently from its power link in freely moving animals.
Measuring Neck Nerve Strain: An Experimental Investigation
Authors: Johnson Tara L. , LaPointe Vanessa , Shoukas Artin A. , Gurewitsch Edith D. , Allen Robert H.
Published: February 2009

We sought to determine the effects of head rotation, lateral neck flexion, and traction force on brachial plexus (BP) nerve strain, specifically at C5-C6 (Erb’s point), and C7, C8, and T1 roots in a multi-“filament” 3D model of the fetal BP. Using our constructed simulator and a tailored data acquisition system, strain readings were recorded and accurate to within <2%. Using our model and a position-sensing system, controlled loads and deformations were applied to a fetal head attached to a flexible spine. For each simulation, we measured BP strain at Erb’s point, and C7, C8, and T1 roots. Increasing total traction force increases strain in the upper and middle nerves (Erb’s point, C7, and C8). Lateral neck flexion produces the most strain (up to 25.4±6.6% in Erb’s point with 4.5 kg (10 lbs) of traction), with concomitant head rotation magnifying strain levels by up to a factor of 1.7. Increasing head rotation and lateral neck flexion increases the strain in the lower nerve roots more than in the upper roots. in general, upper nerves undergo double the strain of lower nerves. Direct axial traction has the least effect, with 4.5 kg of traction producing a peak strain of 3.6±2.5% at Erb’s point. BP strain can be reduced at Erb’s point, C7, and C8 by maintaining neutral alignment between the head and trunk prior to applying traction, which should be minimized.
In Vivo Monitoring of Osseointegration
Authors: VanSchoiack Lindsey R. , Shubayev Veronica I. , Myers Robert R. , Earthman James C.
Published: February 2009

The process of osseointegration is the firm anchoring of a surgical implant by the growth of bone around it without fibrous tissue formation at the interface. This process is critical for long-term implant success. The ability to monitor this process in vivo would allow for personalization of loading protocols to increase the rate of implant success overall by ensuring that implants are not over or under loaded during recovery. Accordingly, there is a strong need for an instrument that has the sensitivity to noninvasively measure osseointegration in vivo. One of the objectives of the present study was to assess the performance of an instrumented percussion probe for quantitatively monitoring the osseointegration process.
A Novel Technique to Achieve Fusion Using Local Autograft Bone: The Button Fusion
Authors: Pfeiffer Ferris M. , Abernathie Dennis L.
Published: February 2009

Back pain is one of the most widespread sources of chronic pain in the human population. The etiology of back pain is nearly as diverse as the treatment measures used to alleviate the discomfort. However, when conservative options have been exhausted, without achieving adequate relief, the patient and physician often turn to surgical options to eliminate the source of pain.
Polymer-Based Cardiovascular Shear Stress Sensors
Authors: Yu Hongyu , Ai Lisong , Rouhanizadeh Mahsa , Hamilton Ryan , Hwang Juliana , Meng Ellis , Kim Eun Sok , Hsiai Tzung K.
Published: February 2009

This paper describes a polymer-based cardiovascular shear stress sensor built on catheter for atherosis diagnosis. This flexible sensor detects small temperature perturbation as fluid past the sensing elements leading to changes in the resistance, from which shear stress is inferred. MicroElectroMechanical System (MEMS) surface manufacture technology is utilized for fabrication of the devices with biocompatible materials, such as parylene C, Titanium (Ti) and Platinum (Pt). The temperature coefficient of resistance (TCR) of the sensor is 0.11%/°C. When a catheter-based sensor is positioned near the wall of the rabbit aorta, our 3-D computational fluid dynamic model demonstrates that flow disturbance is negligible under steady state in a straight segment. The sensor has been packaged with a catheter and will be deployed into the aorta of NZW rabbits for realtime shear stress measurement.
Development of a Temperature-Controllable Heat-Acupuncture System Using PWM Current Control
Authors: Kim Ki-Hong , Oh Sang-Rok , Rhim Sungsoo , Lee Soon-Geul , Kim Sun Kwang , Park Jung Hyuk , Min Byung-Il
Published: February 2009

In this paper, a new temperature-controllable heat-acupuncture system is developed to replace the conventional heat-stimulating therapy practiced with moxibustion and heat acupuncture. The improved heat-stimulating characteristics of the developed system are experimentally verified.
Electric Field Directed Fabrication of Biosensor Devices From Biomolecule Derivatized Nanoparticles
Authors: Heller Michael J. , Dehlinger Dieter , Esener Sadik , Sullivan Benjamin
Published: February 2009

An electronic microarray has been used to carry out directed self-assembly of higher order 3D structures from Biotin/Streptavidin and DNA derivatized nanoparticles. Structures with more than forty layers of alternating biotin and streptavidin and DNA nanoparticles were fabricated using a 400 site CMOS microarray system. In this process, reconfigurable electric fields produced by the microarray device have been used to rapidly transport, concentrate and accelerate the binding of 40 and 200 nanometer biotin, streptavidin, DNA and peroxidase derivatized nanoparticles to selected sites on the microarray. The nanoparticle layering process takes less than one minute per layer (10–20 seconds for addressing and binding nanoparticles, 40 seconds for washing). The nanoparticle addressing/binding process can be monitored by changes in fluorescence intensity as each nanoparticle layer is deposited. The final multilayered 3-D structures are about two microns in thickness and 50 microns in diameter. Work is now focused on assembling “micron size” biosensor devices from bio-molecule derivatized luminescent and fluorescent nanoparticles. The proposed structure for a nanolayered glucose sensor device includes a base layer of biotin/streptavidin nanoparticles, a layer of glucose oxidase derivatized nanoparticles, a layer of peroxidase derivatized nanoparticles, a layer of quantum dots, and a final layer of biotin/streptavidin nanoparticles. Such a device will serve as a prototype for a wide variety of applications which includes other biosensor devices, lab-on a-chip devices, in-vivo drug delivery systems and “micron size” dispersible bio/chem sensors for environmental, military and homeland security applications.
Effects of Surface Roughness on Flows Through Nano/Micro Channel Based Biomedical Devices: A Study by Lattice Boltzmann Method
Authors: Mayeed Mohammed S. , Newaz Golam M.
Published: February 2009

The objective of this research is to study the effects of surface roughness on flows through nano/micro channels with a focus on designing better biomedical devices. A two dimensional computational model for fluid flow based on Lattice Boltzmann (LB) method has been applied first to a 10 μm width channel with flat boundary conditions and the flow profiles have been found to have an excellent comparison with analytical results. Rough boundary conditions using rectangular tooth-shaped corrugations giving about 0.25 μm average roughness have then been applied to the same 10 μm channel flow. We have observed significant differences in the velocity profiles between the flows with rough and flat boundary conditions. Boundary slips have also been observed in case of flows with rough boundary conditions. Surface roughness effects have increased or the differences between the flows with rough and flat boundary conditions have increased with decreased channel widths.
A Frequency Counter Based Analog-to-Digital Converter for a Low-Power RFID Biomedical Telemetry System
Authors: McCoy Michael , Isert Christopher , Jackson Douglas , Naber John
Published: February 2009

This paper describes a method for determining a digital representation of a remote sensing element using a novel and lower power method of analog to digital conversion [1]. This conversion process is most effective for low-frequency and very low current Radio Frequency Identification (RFID) sensing systems where the sensing element tags are powered by an inductively coupled carrier signal of fixed frequency. This method eliminates the need for a traditional, large and power-hungry Analog-to-Digital Converter (ADC). This approach is being developed for an orthopedic application that measures the invivo strain on titanium rods to help surgeons better understand the progress of fusion in spinal fusion surgery [2]. Previous work has been shown using the difference of two clocks for sending digital data from the reader to the tag [3], whereas this approach is optimized for sending digital data in the other direction, from tag to the reader. The sensor element may be a resistive or capacitive device integrated into an oscillator of variable frequency. This variable oscillation signal is then divided down and used as the time base to a frequency counter clocked by the recovered carrier signal. In recovering and using the carrier signal as an internal clock, an additional on chip oscillator is not necessary. The resultant value then undergoes additional post processing to add a unique identification string, a CRC check word, Manchester encoding, and Frequency-Shift Key (FSK) encoding for load modulation transmission [3,4].
A Thermodynamic Analysis of Compressing Hydrogen for Storage
Authors: Lingel Clinten D.
Published: February 2009

Storing hydrogen gas under pressure to provide an energy source for fuel cells or internal combustion engines is a real issue that must be addressed. Diatomic hydrogen does not occur naturally and therefore, must be made through electrolysis, methane reforming or some other process. From the production of pure hydrogen to the final end user, the entire cycle must be considered. Once formed, hydrogen will need to be compressed to a storage container. A hydrogen based transportation system will be both an economic and engineering challenge.
Sustainable Energy @ Puerto Rico
Authors: Colucci Jose´ A. , Irizarry-Rivera Agusti´n , O’Neill-Carrilo Efrain
Published: February 2009

During the last 15 years a renewed interest and growth in renewable energy (RE) processes emerged. It was driven by strong environmental movements, oil dependence/depletion concerns and lately national security concerns. Several RE technologies such as wind, niche photovoltaic and biodiesel are presently very competitive in certain applications versus their oil counterparts especially in Europe and certain locations in the mainland United States. Others are slowly penetrating certain markets such as fuel cells. In the discussion section an overview of the most mature RE technologies will be given focusing on their potential implementation in Puerto Rico. The discussion section will also include findings from an ongoing study at the municipality of Caguas who is becoming the sustainable model for Puerto Rico including energy. The overall analysis includes some elements of social, technical, cultural, political and economic criteria. In the latter capital, operating costs and foot print will be considered. Also sensitivity analyses will be performed regarding the energy generation potential of these processes. The technologies included are photovoltaic, wind energy, fuel cells, concentrated solar power and solar thermal water heating. These are referred to as near term implementation technologies. Other medium/long term ocean energy technologies will be discussed including tide, waves and ocean thermal. The last discussion subsection will briefly consider the area of transportation fuels (gasoline and diesel). In the last section an implementation plan will be presented for these processes including the University of Puerto Rico @ Mayagu¨ez (UPRM) capabilities and potential role in this puertorrican SAGA (Sol, Aire, Gente and Agua).
Analysis of Thermal Energy Collection From Precast Concrete Roof Assemblies
Authors: Abbott Ashley B. , Ellis Michael W.
Published: February 2009

The development of precast concrete housing systems provides an opportunity to easily and inexpensively incorporate solar energy collection by casting collector tubes into the roof structure. A design is presented for a precast solar water heating system used to aid in meeting the space and domestic water heating loads of a single-family residence. A three-dimensional transient collector model is developed to characterize the precast solar collector’s performance throughout the day. The model describes the collector as a series of segments in the axial direction connected by a fluid flowing through an embedded tube. Each segment is represented by a two-dimensional solid model with top boundary conditions determined using a traditional flat plate solar collector model. The precast collector is coupled to a series solar assisted heat pump system and used to meet the heating needs of the residence. The performance of the proposed system is compared to the performance of a typical air-to-air heat pump. Using the system model, various designs and operating parameters were analyzed to determine a set of near optimal design values. The annual performance of the near optimal system was evaluated to determine the energy and cost savings for applications in Atlanta, GA and Chicago, IL. In addition, a life cycle cost was completed to determine the economic feasibility of the proposed system. The results of the annual study show that capturing solar energy using the precast collector and applying the energy through a solar assisted heat pump can reduce the electricity required for heating by more than 50 percent in regions with long heating seasons such as Chicago. The life cycle cost analysis shows that the energy savings justifies the increase in initial cost in locations with long heating seasons but that the system is not economically attractive in locations with shorter heating seasons.
Development of a Pump Water Flow Station for HVAC Systems
Authors: Liu Guopeng , Liu Mingsheng
Published: February 2009

It is important to find an effective way to accurately and inexpensively measure the water flow rates for building energy monitoring and simulation. A pump water flow station (PWS) was developed that measures the water flow rate using pump head, pump speed, and pump performance curve. The pump water flow station includes a differential pressure transducer and pump speed transducer. The pump speed transducer can be replaced by the calibrated control system’s command to the variable frequency drive (VFD). This method has been experimentally proved in a real building’s chilled water system in this paper. The case study shows that the PWS can measure water flow rate and monitor the energy consumption continuously and accurately. Therefore the PWS can be used as a cost-effective control monitoring method in heating, ventilating and air-conditioning (HVAC) systems.
Analysis of the Performance of Earthship Housing in Various Global Climates
Authors: Kruis Nathanael J. , Heun Matthew K.
Published: February 2009

Earthships are houses that use walls of recycled automobile tires packed with soil to retain a berm on three sides of the home while glazing on the sunny side (south in the Northern Hemisphere, north in the Southern Hemisphere) allows solar heat into the home’s interior. This paper discusses the design and application of earthships and assesses the feasibility of earthships as sustainable and healthy places of residence. The paper begins by describing the aspects of earthship design which contribute to sustainability, including the construction of the thermal envelope and its effect on the thermal comfort of the occupants; the building’s ability to harness renewable energy; and the catchwater and water reuse system. Each of these aspects is analyzed with computer models that simulate homes in four distinct climate zones to determine (a) whether the design meets the comfort, electrical, and water demand for each location, and (b) the financial implications for construction and operation of an earthship in each location in comparison with a standard wood-frame house. The study shows that earthships are a financially feasible design alternative for dry/arid, humid continental, and continental sub-arctic climates; but are not feasible for tropical wet/dry climates.
Energy Security and Independence for Military Installations: Candidate Mission-Focused Vision and Policy Measures
Authors: Hartranft Thomas J.
Published: February 2009

Army installations are essential for the development and sustainment of operational capabilities and readiness to serve and protect the nation and its interests. Installations are small cities with a full spectrum of facility types and utility requirements that use large amounts of energy. This paper describes the process and activities underway to establish operational requirements and investment policy for Army installation energy security. The military environment is described in which the installation mission requirements and the future investment policy are being crafted. Military mission must be mapped to power requirements such that mission readiness impacts are quantifiable for a multitude of power outage or power quality anomaly scenarios. The paper draws from real-time discussions that the author’s organization sponsored December 2006 on Army Installation Energy Security & Independence to carry out the mission of Army installations. These insights are applicable to any campus-like entity.
Design and Analysis of a Large Solar Industrial Heat Plant for Frito Lay in Modesto California
Authors: Walker Andy , Kutscher Chuck , Halvorsen Al , McKenna Chris , Chambers Dave , May Ken
Published: February 2009

Industry-specific technology demonstration projects are key to facilitating deployment of solar industrial process heat technologies. Frito Lay North America (FLNA) is pursuing installation of a solar industrial process heat plant at the manufacturing plant in Modesto CA. FLNA contracted with Industrial Solar Technology Corp. for design and installation of the system and with National Renewable Energy Lab for technical assistance. The US Department of Energy and California Energy Commission both facilitate private companies implementation of technology demonstration projects with incentives, tax policy, and technical assistance. The solar plant would include: 5,387 m2 (57,969 sf) of parabolic trough solar collectors; pipe from solar array to unfired steam generator; unfired steam generator (USG); hot water heat exchanger (HWHX); pipe from hot water heat exchanger back to array field; and associated pumps, bypass piping, and controls. Performance of each component of the solar heating system varies with changing conditions of intensity of the sunlight, position of the sun, and ambient temperature. Since each of these parameters change throughout the day and throughout the seasons an hourly simulation of one year’s performance is performed. The simulation is used to estimate annual energy delivery as well as to inform design recommendations. The solar array inlet temperature is solved for iteratively for each hour of the year based on an energy balance of the entire loop including all components. Nested within this iteration are iterations for the operating temperature of each of the 16 modules in series. Hourly direct beam solar radiation (W/m2) data for Modesto CA for 8 years from 1998–2005 was provided by the National Renewable Energy Laboratory Renewable Resource Data Center and the minimum year, average year, and maximum year were used in the analysis. Results indicate that the system would deliver between 3,898 MWh and 4,308 MWh per year (13.3 and 14.7 billion Btu/year) with an average of 4,044 MWh/year (13.8 billion Btu/year). This average estimate of 13.8 billion Btu/year agrees with the contractors proposal and also with methods described in the Industrial Process Heat Handbook published by NREL. The simulation is able to model more detail and inform design recommendations, such as bypassing the steam generator and only making hot water on winter days.
Performance Modeling of a Solar Thermal System for Cooling and Heating in Carnegie Mellon University’s Intelligent Workplace
Authors: Masson Sophie V. , Qu Ming , Archer David H.
Published: February 2009

The Robert L. Preger Intelligent Workplace (IW) is a 650 m2 living laboratory of office space at Carnegie Mellon University (Pittsburgh, PA). The IW has received the first commercially available solar absorption system for air-conditioning with integrated controls as a donation from BROAD in August 2006. The IW is now testing this solar thermal system. A TRNSYS model has been developed and used to assist the design of the system, evaluate its performance throughout an entire year, and optimize its initial configuration. The components of the system are a 52 m2 parabolic trough high temperature solar array, a 16 kW hot water and gas fired absorption chiller, and an overall control system. This model predicts the energy required to cool and heat the south part of the IW (around 10 MWh in winter, 15 MWh in summer) and the fraction of that energy that can be provided by solar energy. The effects of significant system parameters — orientation of the receivers, volume of hot/chilled water thermal storage and insulation thicknesses on the piping and tank — on the fraction of solar provided energy have been calculated by the model. This study emphasizes on two significant aspects: - the impact of system integration during the preliminary building design on the energy performance, - the importance of the energy modeling to assist and optimize the design of the system and its operation but also to reduce the investment and operation costs.
Economic Analysis of a Vertical Sheet Algal Photobioreactor for Biodiesel Production
Authors: Zemke Peter E. , Wood Byard D. , Dye Daniel J. , Bayless David J. , Muhs Jeff D.
Published: February 2009

The combination of a 100% increase in diesel fuel prices since 2002 and a new photobioreactor technology has renewed interest in producing biodiesel, a direct petroleum diesel fuel substitute, from microalgae. A new photobioreactor technology in which the microalgae are grown on vertically suspended membranes promises to increase algal productivity per acre ten-fold compared to microalgae ponds, and 400-fold compared to soybeans. This paper describes the general photobioreactor concept and assesses the economic viability of such technology given the current crude oil prospects. The majority of the data necessary for assessment are obtained from published articles, with experimental results providing the remaining necessary information. Analysis results indicate that the photobioreactor would need to be constructed and operate on the order of dollars per square foot per year.
Energy Sustainability Study of a Rural ICT Telecenter at the Bario Highland
Authors: Abdullah Mohammad Omar , Yung Voon Chun , Jom Audra Anak , Wee Alvin Yeo , Anyi Martin , Hamid Khairuddin B. Ab. , Tarawe John , Tarawe James
Published: February 2009

The eBario project has won the eAsia Award and the Mondialogo Engineering Award in 2004 and 2005 respectively for it’s successful implementation of an Information and Telecommunications Technology Center (ICT) and solar renewable energy-incentive rural community project at the Bario Highland of Sarawak, East Malaysia, Borneo (http://www.unimas.my/ebario/). Although solar photovoltaic (PV) energy has been opted for power generation at the ICT Telecenter for the past five years, there is still a need to investigate the cost-effectiveness of the current energy setup as well as to conduct sustainability study taking into account factors such as system efficiency, weather, costs of fuel, operating costs, as well as to explore the feasibility of implementing alternative energy resources for the rural ICT Telecenter. Recent theoretical study conducted has shown that renewable combined power systems are more sustainable in terms of supplying electricity to the ICT Telecenter, and in a more cost-effective way compared to a standalone PV system which is subject to the cloud and the recent dense haze problems. For that purpose, two combined power systems are being put into consideration namely PV-Hydro and PV-Hydro-Fuel Cell, where the total simulated annualized cost for these two system configurations are US$10,847 and US$76,010 respectively as far as the present location is concerned. The PVHydro-Fuel Cell produces electrical energy at the amount of 3,577 kWh/yr while the annual energy consumption is 3,203 kWhr/yr. On the other hand, PV-Hydro produces 3,789 kWhr/yr of electricity annually load which consumes energy at 3,209 kWhr/yr. Results thus obtained has shown that the PVHydro scheme is expected to have advantages over the existing PV standalone system. Firstly, it is more cost-effective. Secondly, it provides the best outcomes for the local indigenous community and the natural highland environments both for now and the future. Thirdly, it also able to relate the continuity of both economic and social aspects of the local society as a whole. As the combined PV-Hydro system had been chosen, plus for completeness purposes, the present paper also discussed the custom design and construction of a small waterwheel breast-shot hydro-generator, suited to the local location and existing water energy resources. Energy saving design calculations and Sankey diagram showing the energy flows for the new combined system are also given herein. Finally, the energy system performance equations and the performance curves introduced in this study provide a new simple method of evaluating renewable energy systems.
New Solar Water-Splitting Reactor With Ferrite Particles in an Internally Circulating Fluidized Bed
Authors: Gokon Nobuyuki , Takahashi Shingo , Yamamoto Hiroki , Kodama Tatsuya
Published: February 2009

The thermal reduction of metal oxides as part of a thermochemical two-step water splitting cycle requires the development of a high temperature solar reactor operating at 1000–1500°C. Direct solar energy absorption by metal-oxide particles provides efficient heat transfer directly to the reaction site. This paper describes experimental results of a windowed thermochemical water-splitting reactor using an internally circulating fluidized bed of the reacting metal-oxide particles under direct solar irradiation. The reactor has a transparent quartz window on the top as aperture. The concentrated solar radiation passes downward through the window and directly heats the internally circulating fluidized bed of metal-oxide particles. Therefore, this reactor needs to be combined with a solar tower or beam down optics. NiFe2O4/m-ZrO2 (Ni-ferrite supported on zirconia) particles is loaded as the working redox material in the laboratory scale reactors, and thermally reduced by concentrated Xe-beam irradiation. In a separate step, the thermally-reduced sample is oxidized back to Ni-ferrite with steam at 1000°C. As the results, the conversion of ferrite reached about 44% of maximum value in the reactor by 1kW of incident solar power. The effects of preheating temperature and particle size of NiFe2O4/m-ZrO2 were tested for thermal reduction of internally circulating fluidized bed in this paper.
Solar Thermochemical Generation of Hydrogen: Development of a Receiver Reactor for the Decomposition of Sulfuric Acid
Authors: Noglik Adam , Roeb Martin , Rzepczyk Thomas , Sattler Christian , Pitz-Paal Robert
Published: February 2009

A key step in the sulfur based thermochemical cycles for hydrogen production is the highly endothermic decomposition of sulfuric acid at temperatures between 800 °C and 1200 °C. This reaction can be carried out in a receiver-reactor which is irradiated with concentrated solar radiation from a heliostat field. To investigate this process a test reactor was developed and built. The reaction takes place on the surface of a catalytically coated porous absorber irradiated through a quartz pane of the receiver-reactor. This concept has the advantage of a minimum number of heat transferring steps. Experiments with the test reactor were performed in the DLR solar furnace in Cologne. Firstly the feasibility of a solar decomposition of sulfuric acid in a receiver-reactor containing volumetric absorbers was investigated and proven. Then the reactor was qualified at different operating points. Finally the receiver-reactor and strategy of operation was iteratively optimized with respect to chemical conversion and reactor efficiency. Several test series were performed with variation of the absorber temperature, the mass flow and the dilution rate. Partial pressure of SO3, residence time, absorber temperature, and the kind of catalyst applied were identified and quantified as parameters with the most relevant influence on chemical conversion and reactor efficiency. The operation behavior observed and the detailed knowledge of dependencies of different operation parameters assist in evaluating the potential of scaling up the described technology.
Comparison of Stratification in a Water Tank and a PCM-Water Tank
Authors: Castell A. , Sole´ C. , Medrano M. , Nogue´s M. , Cabeza L. F.
Published: February 2009

Most of the storage systems available on the market use water as storage medium. Enhancing the storage performance is necessary to increase the performance of most systems. The stratification phenomenon is employed to improve the efficiency of storage tanks. Heat at an intermediate temperature, not high enough to heat up the top layer, can still be used to heat the lower, colder layers. There are a lot of parameters to study the stratification in a water tank such as the Mix Number and the Richardson Number among others. The idea studied here was to use these stratification parameters to compare two tanks with the same dimensions during charging and discharging processes. One of them is a traditional water tank and the other is a PCM-water (a water tank with a Phase Change Material). A PCM is good because it has high energy density if there is a small temperature change, since then the latent heat is much larger than the sensible heat. On the other hand, the temperature change in the top layer of a hot water store with stratification is usually small as it is held as close as possible at or above the temperature for usage. In the system studied the Phase Change Material is placed at the top of the tank, therefore the advantages of the stratification still remain. The aim of this work is to demonstrate that the use of PCM in the upper part of a water tank holds or improves the benefit of the stratification phenomenon.
Iran’s Seas and Lakes Sustainable Energy Potential
Authors: Zabihian Farshid
Published: February 2009

The objective of this paper is to study the positions and features of the boundary and domestic seas and lakes of Iran and possibility of using these energy sources and proposed approaches to do so. Generally the potential energies in the seas and oceans are classified in five groups, which are: wave energy, tidal energy, ocean thermal energy, ocean current energy, and salinity gradient energy. Regarding the variety of the country’s bodies of water other than ocean current energy it is possible to use rest of these energy resources. Each bodies of water of Iran are suitable for specific kind of seas energies. There are great sources of tidal energy in Persian Gulf coasts especially in west side of it. For thermal energy the ideal sites are located in the Caspian Sea coasts and wave energy can economically be extracted in Gulf of Oman coasts, especially in remote islands which are not connected to the grid. Finally, the Urmia Lake is best location for salinity gradient energy. This study shows that more investment is required in this area for research and small scale plants.
Solar Energy, Collected, Concentrated, Transported, and Distributed as Light With No Energy Conversion Via a Hybrid Solar Lighting System
Authors: Beshears David L. , Earl D. Duncan , Lapsa Melissa Voss , Maxey L. Curt , Muhs Jeff D. , Ward Christina D. , Morris John D.
Published: February 2009

Hybrid solar lighting (HSL) is a technology in which sunlight is collected and distributed via optical fibers into the interior of buildings. Analogous to hybrid electric vehicles that use both batteries and internal combustion engines to power cars, hybrid lighting employs roof-mounted collectors to concentrate sunlight into flexible optical fibers and carry it inside buildings to “hybrid” light fixtures that also contain electric lamps. As the two light sources work in tandem, control systems keep lighting levels constant by dimming the electric lights when sunlight is bright, and turning them up as the sky darkens with weather conditions or nightfall. Data indicate that on a bright, sunny day the power consumption for lighting can be reduced by 50% or more. Today, lighting in U.S. residential and commercial buildings consumes close to 5 quadrillion BTUs of primary energy and one-fifth of all electricity. In commercial buildings, one-quarter of all energy demand is for lighting. With a forecasted doubling of commercial floor space by the year 2020 comes an urgent and growing need to find more efficient ways of lighting our nation’s buildings. Typically, less than 25 percent of the electrical energy consumed for lighting actually produces light; the rest generates heat, which increases the need for air-conditioning. Unlike conventional electric lamps, the sunlight from HSL systems produces virtually no waste heat. A nationwide field trial program is under way to provide system performance data and user-feedback essential for the successful commercialization of HSL. Field trial installations include San Diego State University, San Diego, CA; Pacific Northwest National Laboratory, Richland, WA; Sacramento Municipal Utility District, Sacramento, CA; Wal-Mart, McKinney, TX; Aveda Corp., Minneapolis, MN; Staples, Long Island, NY; Braden’s Furniture, Knoxville, TN; Multipurpose Research Facility, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN; University of Nevada-Las Vegas, Las Vegas, NV; Hybrid Lighting Laboratory, ORNL, Oak Ridge, TN. This paper describes the field trial program and summarizes the results to date from the field trial installations.
Establishing Standard Source Energy and Emission Factors for Energy Use in Buildings
Authors: Deru Michael
Published: February 2009

Energy use in buildings is most commonly analyzed by using the energy measured at the site. Some analysts also calculate the source energy and emissions from the site energy. Source energy use and emission profiles offer better indicators of the environmental impact of buildings and allow other metrics for comparison of performance. However, there are no standard factors for calculating the source energy and emissions from the site energy. The energy and emission factors used are derived from different data using different methods resulting in wide variations, which makes comparisons difficult. In addition, these factors do not include the full life cycle of the fuels and energies, but only the combustion and transmission portions of the life cycle. The recently available U.S. Life Cycle Inventory (LCI) Database provides LCI data for energy, transportation, and common materials. The LCI data for fuels include all the energy and emissions associated with the extraction, transportation, and processing of the fuels. This paper describes how the LCI data, along with other emissions data and energy consumption data from the Energy Information Administration, were used to generate source energy and emission factors specifically for energy use in buildings. The factors are provided on national, interconnect, and state levels. This effort was part of the U.S. Department of Energy Performance Metrics Project, which worked to establish standard procedures and performance metrics for energy performance of buildings.
Impact of Precooling Control on Reducing Electrical Peak Demand for Commercial Buildings in Tunisia
Authors: Khaled Nizar , Krarti Moncef
Published: February 2009

This paper summarizes the results of a series of simulation-based analyses to investigate the suitability of simplified pre-cooling control strategies in commercial buildings in Tunisia. The simulation results have indicated that pre-cooling building thermal mass during unoccupied period can provide a reduction of peak cooling loads as well as a time shift of when the electrical peak demand occurs during the day. The reduction in peak demand due to precooling controls was found to be more significant for buildings with high mass.
Solid Particle Receiver Flow Characerization Studies
Authors: Siegel Nathan , Kolb Greg , Kim Kibum , Rangaswamy Vijayarangan , Moujaes Samir
Published: February 2009

The solid particle receiver (SPR) is a direct absorption central receiver that can provide a solar interface with thermal storage for thermochemical hydrogen production processes requiring heat input at temperatures up to 1000 C. In operation, a curtain consisting of ∼690 μm ceramic particles is dropped within the receiver cavity and directly illuminated by concentrated solar energy. The heated particles exit the receiver and may either be stored or sent through a heat exchanger to provide process heat input. The performance of the receiver is dependent on the characteristics of the particle flow including velocity and opacity (optical density). In addition, because the SPR will have an open aperture there is also a possibility that the flow may be disturbed by high ambient winds. Computational models have been and are currently being used to simulate receiver performance at power levels up to several MWt. However, due to the complex two-phase nature of the solid particle flow, such models rely on experimental data both to provide physical input, such as boundary conditions, as well as to provide a point of comparison for model validation. In this paper, we present experimental results from tests performed using a small scale unheated solid particle curtain. These tests focus on the measurement of the flow characteristics of the solid particle curtain as it falls from a near-zero velocity discharge slot to a collection point three meters below. The results include measured values for the variation of velocity, solids volume fraction, curtain width, and curtain opacity along the length of the curtain.
Discharge of Thermal Storage Tanks via Immersed Baffled Heat Exchangers: Numerical Model of Flow and Temperature Fields
Authors: Su Yan , Davidson Jane H.
Published: February 2009

A model of a thermal storage tank in which stored energy is extracted via an immersed heat exchanger is presented and used to predict transient temperature and velocity fields in tanks with and without baffles. The heat exchanger is modeled as a porous medium within the storage fluid. A simple cylindrical baffle that creates an annular space in which a coiled tube heat exchanger is positioned provides a modest increase in the rate of energy extraction compared to a tank with no baffle. The improved discharge rate is attributed to an increase in the flow speed across the heat exchanger. A baffle with greater hydraulic resistance slows the flow and reduces performance.
Numerical Investigation on Optimal Design of Solid Particle Solar Receiver
Authors: Chen Huajun , Chen Yitung , Hsieh Hsuan-Tsung , Kolb Greg , Siegel Nathan
Published: February 2009

Solar thermo-chemical processes often require high temperatures that can be achieved by direct absorption of solar energy. The solid particle solar receiver can be used to heat ceramic particles that may serve as a heat transfer and storage medium or as a substrate on which chemical reaction may be performed directly. Using solid particles enclosed in a cavity to absorb concentrated solar radiation can provide efficient absorption of concentrated sunlight. In this work, different solid particle solar receiver designs have been investigated by using computation fluid dynamics (CFD) technique. The gas particle flow with the solid particle solar receiver was simulated by using two-way coupled Euler-Lagrange method. The direct illumination energy source that results from incident solar radiation was predicted by a solar load model using a solar ray tracing algorithm. The detailed information to guide the experiment, such as the particle and gas velocity, temperature, particle solid volume fraction, and cavity efficiency under different designs has been analyzed.
Predicted Efficiency of a Nanofluid-Based Direct Absorption Solar Receiver
Authors: Tyagi Himanshu , Phelan Patrick , Prasher Ravi
Published: February 2009

Due to its renewable and non-polluting nature solar energy is often used in applications such as electricity generation, thermal heating and chemical processing. The most cost-effective solar heaters are of the “flat-plate” type, but these suffer from relatively low efficiency and outlet temperatures. The present study theoretically investigates the feasibility of using a direct absorption solar receiver (DAR) and compares its performance with that of a typical flat-plate collector. Here a nanofluid—a mixture of water and aluminum nanoparticles—is used as the absorbing medium. A two-dimensional heat transfer analysis was developed in which direct sunlight was incident on a thin flowing film of nanofluid. The effects of absorption and scattering within the nanofluid were accounted for. In order to evaluate the temperature profile and intensity distribution within the nanofluid the energy balance equation and heat transport equation were solved numerically. It was observed that the presence of nanoparticles increases the absorption of incident radiation by more than 9 times over that of pure water. According to the results obtained from this study, under similar operating conditions, the efficiency of a DAR using nanofluid as the working fluid is found to be up to 10% higher (on an absolute basis) than that of a flat-plate collector.