bluuebunny/crossref_metadata_2025 huggingface dataset:
Advanced Parabolic Trough Field Testing: Real-Time Data Collection, Archiving, and Analysis for the Solargenix Advanced Parabolic Trough
Authors: Hurt Rick , Yim Wooson , Boehm Robert , Hale Mary Jane , Gee Randy
Published: October 2008

Solargenix Energy is currently constructing a 64-MWe parabolic trough solar plant in Eldorado Valley, Nevada, just south of Las Vegas. As part of the preparation for construction and operation of the new utility-scale solar plant, Solargenix has collaborated with UNLV and NREL to build a collector test row. The test row is serving as a platform for field testing advanced parabolic trough components before their large-scale deployment. The test row consists of two Solargenix Solar Collector Assemblies (SCAs); each SCA has 12 collector modules (space frames and mirrors). This facility has been used to field test new Solargenix designs for first and second generation collector space frames, advanced reflectors, advanced local controllers (AdLoCs), a hydraulic-based drive system, receiver support arms, low-cost injection-molded bearings, ball joints and collector support pylons. The test-row facility also has equipment for monitoring the following weather data: direct normal irradiance, dry bulb temperature, relative humidity, wind speed and precipitation. Data logging equipment is used to record and track weather data as well as SCA parameters. Site instrumentation is solar-powered (photovoltaics) and uses cellular technology to transmit data to a web-based data collection system. This paper describes construction of this facility, the installation of the data-collection system and some data collected to date.
A Zero Carryover Liquid-Desiccant Air Conditioner for Solar Applications
Authors: Lowenstein Andrew , Slayzak Steve , Kozubal Eric
Published: October 2008

A novel liquid-desiccant air conditioner that dries and cools building supply air has been successfully designed, built and tested. The new air conditioner will transform the use of direct-contact liquid-desiccant systems in HVAC applications, improving comfort and indoor air quality, as well as providing energy-efficient humidity control. Liquid-desiccant conditioners and regenerators are traditionally implemented as adiabatic beds of contact media that are highly flooded with desiccant. The possibility of droplet carryover into the supply air has limited the sale of these systems in most HVAC applications. The characteristic of the new conditioner and regenerator that distinguishes them from conventional ones is their very low flows of liquid desiccant. Whereas a conventional conditioner operates typically at between 10 and 15 gpm (630 and 946 ml/s) of desiccant per 1000 cfm (0.47 m3/s) of process air, the new conditioner operates at 0.5 gpm (32 ml/s) per 1000 cfm (0.47 m3/s). At these low flooding rates, the supply air will not entrain droplets of liquid desiccant. This brings performance and maintenance for the new liquid-desiccant technology in line with HVAC market expectations. Low flooding rates are practical only if the liquid desiccant is continually cooled in the conditioner or continually heated in the regenerator as the mass exchange of water occurs. This simultaneous heat and mass exchange is accomplished by using the walls of a parallel-plate plastic heat exchanger as the air/desiccant contact surface. Compared to existing solid and liquid desiccant systems, the low-flow technology is more compact, has significantly lower pressure drops and does not “dump” heat back onto the building’s central air conditioner. Tests confirm the high sensible and latent effectiveness of the conditioner, the high COP of the regenerator, and the operation of both components without carryover.
Exergetic Analysis for Improving the Operation of Building Mechanical Systems: Results and Recommendations
Authors: George Erin N. , Bailey Margaret B.
Published: October 2008

A review of past research reveals that while exergetic analysis has been performed on various building mechanical systems, there has not been extensive efforts in the areas of retrocommissioning air distribution systems or fault detection for cooling plants. Motivations for this new work include demonstrating the merits of exergetic analysis in association with retrocommissioning (RCX) an existing building air handling unit (AHU), as well as conducting an advanced analysis on an existing chiller for the purposes of health monitoring. The following research demonstrates the benefits of including a second law analysis in order to improve equipment operation based on lowered energy consumption and improved operation, and as a means for system health monitoring. Particularly, exergetic analysis is not often performed in the context of RCX, therefore this research will provide insight to those considering incorporating exergetic analysis in their RCX assessments. A previously developed RCX test for assessing an AHU on a college campus, as well as data collected from the testing is utilized for an advanced thermodynamic analysis. The operating data is analyzed using the first and second laws of thermodynamics and subsequent recommendations are made for retrofit design solutions to improve the system performance. The second law analysis provides beneficial information for determining retrofit solutions with minimal additional data collection and calculations. The thermodynamic methodology is then extended to a building’s cooling plant which utilizes a vapor compression refrigeration cycle (VCRC) chiller. Existing chiller operational data is processed and extracted for use in this analysis. As with the air handling unit analysis, the second law analysis of the VCRC chiller provides insight on irreversibility locations that would not necessarily be determined from a first law analysis. The VCRC chiller data, originally collected several years ago for the design of an automated fault detection and diagnosis methodology, is utilized. Chiller plant data representing normal operation, as well as faulty operation is used to develop a chiller model for assessing component performance and health monitoring. Normal operation and faulty operation data is analyzed to determining the viability of using existing data and performing an exergy analysis for the purposes of health monitoring. Based on RCX activities and thermodynamic analyses, conclusions are drawn on the utility of using exergetic analysis in energy intensive building mechanical systems in order to improve system operation. The results show the utility of the analysis and illustrate system performance.
Development of a Renewably-Based Hydrogen Generation/Utilization System
Authors: Boehm R. , Baghzouz Y. , Hurt R. , Mauldin R. , Bulla E. , Fifield R. , Gardner J. , Maloney T.
Published: October 2008

A major effort to develop a renewably-based hydrogen generation/utilization system is described. This system consists of PV-powered electrolysis and compression units and hydrogen-fueled vehicles. Both conventional and high-pressure PEM electrolysis units are included. On the utilization side, both fuel cell and ICE powered vehicles are being developed. Each of these aspects is described in the paper.
Wet or Dry Cooling?
Authors: Khalil Ibrahim , Sahm Aaron , Boehm Robert
Published: October 2008

Two major aspects related to water use in solar power plants are examined. First we compare the water used in various approaches to power generation. These include water requirements for cooling (where applicable) and other needs within the plant. Included is attention to water requirements for makeup in Rankine cycles, as well as for cleaning of concentrating solar systems. In the second thrust, we examine the impacts of using dry cooling for Rankine cycles. It is generally established that this approach requires premiums in both capital and operating costs (the latter is dependent upon the cost of water), as well as a penalty in performance when compared to wet systems. We examine the trends associated with this technology and outline some for the current performance issues with various cooling approaches.
Monitoring of a Zero-Energy-House
Authors: Rosta S. , Hurt R. , Boehm R. , Hale M. J.
Published: October 2008

A comparative study is being conducted to measure the actual performance of a Zero Energy House design. Ideally, a zero energy house produces as much energy as it consumes in a year’s time. Two identically-sized houses (1610 sq ft), constructed side-by-side in southwest Las Vegas, Nevada, are equipped with a network of sensors that measure every aspect of energy usage in each home. One house is used as a baseline (standard comparison) house and was built using conventional construction techniques. The other house, the Zero Energy House, employs many energy saving features, solar power generation, and supplemental solar water heating. Both houses are utilized as model homes in an actual housing development, so it is reasonable to believe that both will experience similar and consistent usage. The data logged onsite are automatically collected every day (in an almost real-time basis) and sent via telephone connection to the Center for Energy Research at UNLV for analysis. Results are posted on the web. This paper describes the differences in construction details between the two houses. It also gives a summary of the ways the performance data are being acquired and processed. Finally, the methods used to represent the data are outlined.
Increasing the Productivity of Solar Photovoltaic Systems
Authors: Torrey David A. , Kokernak James M.
Published: October 2008

State-sponsored incentives have played a significant role in driving the demand for residential and small commercial photovoltaic (PV) systems. All state incentive programs are tied to the power rating of the system, though some states also offer energy production incentives. Unfortunately, there is a disconnect between the power rating of a PV system and the energy that system produces over its lifetime. It is extremely important to consider system productivity, which goes well beyond the efficiency of the components. System productivity is tied directly to the structure of the array, not just the efficiency of the components and the quality of the installation. This paper examines the issues associated with improving solar PV system productivity. The focus is on comparing a series-parallel array configuration to a series-string array configuration and the impact on energy production. Partial shade is used to highlight substantial differences between the operation of the two array configurations.
Research on the Energy Saving Performance of the Enthalpy Recovery Ventilator in Chinese Residential Buildings
Authors: Liu Junjie , Wang Bin , Xu Youhao
Published: October 2008

In order to fulfill the indoor comfort and health requirements, people need to supply a large amount of outdoor fresh air into the indoor environment. In the past, because of the poor airtight performance of the residential buildings in China, there is usually no mechanical ventilator installed, almost all of the outdoor air infiltrates from the leaks through the windows and doors. Recently, in order to improve the energy saving performance, the windows and doors of the residential buildings become more and more airtight so that the outdoor air can’t infiltrate into the rooms easily, but it results in the worse and worse indoor air quality. People need supply enough outdoor fresh air into the rooms without increasing the energy consumption greatly. The installation of the enthalpy recovery ventilator (ERV) is an effective method. It can transfer heat and moisture from the exhaust air into the outdoor fresh air to save energy. Nowadays, ERV has been widely used in the commercial and industry buildings, and started in the residential buildings in China. But ERV is not always energy saving in anywhere and anytime. Its energy saving performance depends on a lot of factors, such as the outdoor environmental condition, the enthalpy effectiveness of the enthalpy recovery medium, the Coefficient of Performance (COP) of the air condition system and so on. Based on the weather data, this paper calculates the hourly energy saving performance of ERV for residential buildings that are hypothetically located in five Chinese representative cities of five different climate zones in summer. It gives the definition of the cooling ventilation season and studies the influence factors related to the energy saving performance of ERV.
Usage of Earth Observation for Solar Energy Market Development: Lessons Learned
Authors: Schroedter-Homscheidt M. , Bofinger S. , Breitkreuz H. , Heilscher G. , Stettler S.
Published: October 2008

Within the Earth Observation Market Development (EOMD) program of the European Space Agency (ESA) the ENVISOLAR project aims at an intensified usage of earth observation based information products in the solar energy industries. Existing services for investment decision, plant management, load forecasting, and science and consulting rely on high quality surface solar irradiance measurements and reliable processing chains to deliver such information regularly. Requirements for earth observation data as well as blockages preventing their use have been identified. In consequence, existing data processing chains are analyzed as to their conformity with the needs of the solar industry. The paper focuses on how earth observation itself can contribute to the market development of solar energy technologies. Issues like quality of irradiance data for planning and managing solar energy systems, reliability and availability of earth observation information, requirements as to temporal, spatial and spectral resolution of earth observation data, and the cost-effectiveness of satellite based information compared to maintenance costs for a large set of on-site measurement devices are addressed.
Overview of Solar Air Drying Systems in India and His Vision of Future Developments
Authors: Khanzode Anand U. , Karale Sachin R.
Published: October 2008

Solar Air Drying is one of the oldest method of food preservation. For several thousand years people have been preserving grapes, herbs, Potato’s, corn, milk, fruits, vegetables, spices, meat and fish by drying. Until canning was developed at the end of the 18th century, drying was virtually the only method of food preservation. It is still the most widely used method. Solar Drying is an excellent way to preserve food and solar food dryers are an appropriate food preservation technology for a sustainable world. This technology makes it possible to dehydrate and preserve food professionally without compromising on quality, color, texture, enzymes, vitamins, taste and nutritional values of foods in the process. Food scientists have found that by reducing the moisture content of food to between 10 and 20%, bacteria, yeast, mold and enzymes are all prevented from spoiling it. India is blessed with an abundance of sunlight, water and biomass. Vigorous efforts during the past two decades are now bearing fruit as people in all walks of life are more aware of the benefits of renewable energy, especially solar energy in villages and in urban or semi-urban centers of India. Industries that can benefit from application of solar energy to heat air are Food, Textiles, Dairies, Pharma and Chemical. This paper reviews the present scenario of Solar Air Dryer and strategies for future developments in India.
Calorimetric Measurements of the Input Power Into a 500 kW High Concentration Solar Energy Volumetric Receiver
Authors: Miron Gideon , Reich Eliezer , Kagan Jacob , Segal Akiba
Published: October 2008

A Solar Thermal Demonstration Power Plant with a high concentration central volumetric air receiver was built at the Weizmann Institute of Science (WIS). The plant was based on the Beam Down/Tower Reflector concept with a secondary Compound Parabolic Concentrator (CPC). Initial solar tests were carried out during 2001 in order to demonstrate the feasibility of a large-scale central solar receiver. The receiver was tested initially under low and medium solar power inputs. Thermal output power of 210 kW and air outlet temperature of 580 °C were measured. The evaluation of solar power input into the receiver was based on a ray tracing program. More tests, with a refurbished solar field, were planned for 2004. In order to validate the calculated input power it was decided to measure the solar power directly at the receiver’s inlet. Water calorimetric measurement was selected as the preferred method. A 450 mm diameter cylindrical calorimeter was selected, designed and manufactured by Rotem’s engineers. The calorimeter was installed during March 2004. Measurements were taken successfully during the next weeks, with various heliostats’ combinations. The measured solar power values were compared to calculations with the ray tracing program. The results show that a good agreement could be achieved between the two by adjustment of the Beam Quality parameter. However, the results also showed that the actual inlet power to the receiver could not be expected to exceed 350–400 kW. Based on these results, further tests with the receiver were suspended. The calorimeter is used at the WIS as a calibration tool for further projects run on the same platform.
The Impact of Climate Changes in the Renewable Energy Resources in the Caribbean Region
Authors: Angeles M. E. , Gonza´lez J. E. , Erickson D. J. , Herna´ndez J. L.
Published: October 2008

Assessment of renewable energy resources, such as surface solar radiation and wind current has great relevance in the development of local and regional energy policies. This paper examines the variability and availability of these resources as a function of possible climate changes for the Caribbean region. Global climate changes have been reported in the last decades, causing changes in the atmospheric dynamics which affects the net solar radiation balance at the surface and the wind strength and direction. For this investigation, the future climate changes for the Caribbean are predicted using the Parallel Climate Model (PCM) and it is coupled with the Regional Atmospheric Modeling System (RAMS) to simulate the solar and wind energy spatial patterns changes for the specific case of the island of Puerto Rico. Numerical results from PCM indicate that the Caribbean basin from 2041 to 2055 will experience a slight decrease in the net surface solar radiation (with respect to the years 1996–2010), which is more pronounced in the western Caribbean Sea. Results also indicate that the easterly winds have a tendency to increase in its magnitude, especially from the years 2070 to 2098. The regional model showed that important areas to collect solar energy are located in the eastern side of Puerto Rico, while the more intense wind speed is placed around the coast. A future climate change is expected in the Caribbean that will result in higher energy demands, but both renewable energy sources will have enough intensity to be used in the future as an alternative energy sources to mitigate future climate changes.
Development of a Computational Model for a Prototype Testing Room With Integrated ABE System
Authors: Xu Xu , Van Dessel Steven
Published: October 2008

Active Building Envelope (ABE) systems are a new enclosure technology which integrate photovoltaic (PV) and thermoelectric (TE) technologies. In ABE systems, a PV system is used to transfer solar energy directly into electrical energy, which is used to power a TE heat-pump system for space cooling or heating. In this study, we have built a computational model to predict the indoor temperature of an outdoor testing room and its integrated ABE system. The computational model uses the finite differential method, and includes the computation of solar radiation, heat transfer through the testing room surfaces and the ABE-window, and a model for the indoor air. We have verified the model’s accuracy by comparing the simulation results of this model with actual temperature data. We have found that there was good correlation between the model’s prediction for indoor temperature, and the actual temperature measurements for our testing room. The model will be used in further studies to assess the effectiveness of the ABE system.
Solar-Assisted Small Solar Tower Trigeneration Systems
Authors: Buck R. , Friedmann S.
Published: October 2008

Solar-hybrid gas turbine power systems offer a high potential for cost reduction of solar power. Such systems were already demonstrated as test systems. For the market introduction of this technology, microturbines in combination with small solar tower plants are a promising option. The combination of a solarized microturbine with an absorption chiller was studied, the results are presented in this paper. The solar-hybrid trigeneration system consists of a small heliostat field, a receiver unit installed on a tower, a modified microturbine and an absorption chiller. The components are described, as well as the required modifications for integration to the complete system. Several absorption chiller models were reviewed. System configurations were assessed for technical performance and cost. For a representative site a system layout was made, using selected industrial components. The annual energy yield in power, cooling and heat was determined. A cost assessment was made to obtain the cost of electricity and cooling power, and eventually additional heat. Various load situations for electric and cooling power were analyzed. The results indicate promising niche applications for the solar-assisted trigeneration of power, heat and cooling. The potential for improvements in the system configuration and the components is discussed, also the next steps towards market introduction of such systems.
Genetic-Algorithm Based Controls for Daylighting
Authors: Khlifi Abderrezek , Krarti Moncef
Published: October 2008

This paper describes a daylighting control strategy suitable to operate the electrical lighting fixtures in order to maintain a desired illuminance level for one or several specific working locations. The control is based on genetic algorithm to minimize energy use of electrical lighting systems. The algorithm has been developped using experimental data obtained for an office space in Boulder, Colorado. The GA-based control can be coupled with any switching settings to operate the electrical lighting systems such as on-off, stepped, and dimming. The analysis indicated that the GA-based control can save up to 70% of total electrical lighting energy use for the case study of the office building in Boulder, Colorado.
Impact of Solar Model Selection on Building Energy Analysis for Kuwait
Authors: Al-Anzi Adnan , Seo Donghyun , Krarti Moncef
Published: October 2008

This paper summarizes the results of a comparative analysis for four models utilized to predict solar radiation in Kuwait City, Kuwait. The four models include the Kasten model, Zhang and Huang model, Muneer model, and neural network based model. The analysis was based on hourly measured solar data for Kuwait City. The measured hourly solar radiation data are obtained for the year 1994 and include global, direct, and diffuse solar radiation. Non-solar weather data for the same year and site are obtained from the US National Climatic Data Center (NCDC). Weather files suitable for building energy simulation are developed using measured data as well as predictions from the four solar models. A series of simulation analysis to determine the impact of solar model selection for the weather file on the energy use predictions from a whole-building simulation program using office buildings in Kuwait. The results of the validation analysis and the simulation evalaution indicate that Zhang and Huang model is suitable for the predicting hourly solar radiation suitable for energy analysis of buildings in Kuwait.
Practical Field Alignment of Parabolic Trough Solar Concentrators
Authors: Diver Richard B. , Moss Timothy A.
Published: October 2008

In this paper a new technique for parabolic trough mirror alignment based on the use of an innovative Theoretical Overlay Photographic (TOP) approach is described. The technique is a variation on methods used to align mirrors on parabolic dish systems. It involves overlay of theoretical images of the Heat Collection Element (HCE) in the mirrors onto carefully surveyed photographic images and adjustment of mirror alignment until they match. From basic geometric principles, for any given viewer location the theoretical shape and location of the reflected HCE image in the aligned mirrors can be predicted. The TOP approach promises to be practical and straightforward and inherently aligns the mirrors to the HCE. Alignment of an LS-2 mirror module on the rotating platform at the National Solar Thermal Test Facility (NSTTF) with the TOP technique along with how it might be implemented in a large solar field is described. Comparison of the TOP alignment to the distant observer approach on the NSTTF LS-2 is presented and the governing equations used to draw the theoretical overlays are developed. Alignment uncertainty associated with this technique is predicted to be less than the mirror slope error.
Impacts on Building Return Water Temperature in District Cooling Systems
Authors: Wang Gang , Zheng Bin , Liu Mingsheng
Published: October 2008

A high temperature differential between supply and return water is most cost effective in district cooling systems. The chilled water supply temperature relies on central plant operation while the chilled water return temperature mainly depends on cooling coil performance of air handling units (AHU) at consumers. Many factors affect the AHU cooling coil performance at the consumers, such as cooling coil size, chilled water supply temperature, AHU supply air temperature, space cooling load, outside airflow and conditions, cooling coil fouling condition and cooling coil control valves types. The AHU chilled water return temperature may deviate from its design valve under off-design conditions. The common method to maintain the required consumer chilled water return temperature is to install a bypass bridge between the chilled water supply and return at consumer connections. This paper studies the impact of these factors on the AHU chilled return water temperature and finally develops the improved chilled water return temperature control method.
Reducing the Risk of Natural Ventilation With Flexible Design
Authors: Greden Lara V. , Glicksman Leon R. , Lo´pez-Betanzos Gabriel
Published: October 2008

Performance uncertainty is a barrier to implementation of innovative technologies. This research investigates the potential of flexible design — one that enables future change — to improve the economic performance of a naturally ventilated building. The flexible design of the naturally ventilated building enables future installation of a mechanical cooling system by including features such as space for pipes and chillers. The benefits of the flexible design are energy savings, delay of capital costs and capability of mitigating the risk of a failed building (by installing the mechanical cooling system). To evaluate the flexible design, building energy simulation is conducted over a multi-year time period with stochastic outdoor temperature variables. One result is a probability distribution of the time when the maximum allowable indoor temperature under natural ventilation is exceeded, which may be “never.” Probability distributions are also obtained for energy savings and cost savings as compared to a mechanically cooled building. Together, these results allow decision-makers to evaluate the long-term performance risks and opportunities afforded by a flexible implementation strategy for natural ventilation. It is shown that the likelihood of future installation of mechanical cooling is most sensitive to design parameters. The impact of increased climate variability depends on the local climate. The probability of installing the mechanical system also depends on the comfort criteria. The results show that capital costs for cooling equipment are much greater than the present value of 10 years of cooling energy costs. This result motivates consideration of flexible design as opposed to hybrid cooling designs (which have immediate installation of mechanical cooling). Future work will study the impact of uncertain energy prices on investment attractiveness of naturally ventilated buildings. Other applications of the framework presented herein include replacing the building energy model with a model of another climate-dependent system, such as solar photovoltaic arrays.
Design of Grid Connected-PV System for a Hydrogen Refueling Station
Authors: Deshmukh Sachin , Baghzouz Yahia , Boehm Robert F.
Published: October 2008

This paper describes the design of a 14 kW grid-tied photovoltaic system for powering a hydrogen generation and refueling station that is being constructed at the Las Vegas Valley Water District. The fixed array layout is determined by considering the available space, aesthetics and impact of shading on annual energy production. Computer simulations using PV-DesignPro software and area hourly solar radiation data are conducted to simulate the energy flow into and out of the electric utility grid for different profiles of hydrogen use. Stand-alone system operation is also simulated to estimate the maximum amount of hydrogen that can be produced under limited storage.
Materials Development for the CR5 Solar Thermochemical Heat Engine
Authors: Miller James E. , Evans Lindsey R. , Stuecker John N. , Allendorf Mark D. , Siegel Nathan P. , Diver Richard B.
Published: October 2008

The counter-rotating-ring receiver/reactor/recuperator (CR5) solar thermochemical heat engine is a new concept for production of hydrogen that allows for thermal recuperation between solids in an efficient counter-current arrangement. At the heart of the CR5 system are annular rings of a reactive solid ferrite that are thermally and chemically cycled to produce oxygen and hydrogen from water in separate and isolated steps. This design is very demanding from a materials point of view. The ferrite rings must maintain structural integrity and high reactivity after months of thermal cycling and exposure to temperatures in excess of 1100 °C. In addition, the design of the rings must have high geometric surface area for gas-solid contact and for adsorption of incident solar radiation. After performing a series of initial screenings, we chose Co0.67Fe2.33O4 as our baseline working material for a planned demonstration of CR5 and have begun additional characterization and development of this material. Our results to date with powders are consistent with the expectation that small particle sizes and the application of a support to inhibit ferrite sintering and enhance the chemistry are critical considerations for a practical operating device. Concurrent with the powder studies, we are using Robocasting, a Sandia-developed technique for free form processing of ceramics, to manufacture monolithic structures with complex three-dimensional geometries for chemical, physical, and mechanical evaluation. We have demonstrated that ferrite/zirconia mixtures can be fabricated into small three-dimensional monolithic lattice structures that give reproducible hydrogen yields over multiple cycles.
Preliminary Validation of Urban Building Integrated PV System Simulation Software
Authors: Rapolu Kalyan , Sites Kaylan , Guragain Mandeep , Singh Pritpal
Published: October 2008

The objective of the present project is to develop a software simulation tool to accurately estimate the power generated from solar energy absorbed by photovoltaic panels mounted on the fac¸ade of a building in an urban environment, taking into account shading and reflection from neighboring buildings. The software tool has been designed and modeled in AutoCAD, with the help of AccuRender/Ecotect. We have previously presented the modeling approach [1]. We have recently established a test facility in which a 50W BP Solar module surrounded by several glass panels in wood frames has been used to simulate a BIPV system with neighboring buildings. Current-voltage characteristics at different times of day for different months are in the process of being recorded together with solar insolation data. These data will be used to perform preliminary validation of the simulation software. A preliminary comparison of the collected experimental solar module performance data with the computer simulated data will be presented.
Comprehensive Study of Applications of Combined Heat and Power Systems in Tropical Locations
Authors: Alva-Solari L. H. , Gonza´lez J. E.
Published: October 2008

A simple payback and present worth analyses are conducted in this paper to evaluate the economical feasibility of small combined, heat and power (CHP) projects for the industry and business in hot and humid climates using the island of Puerto Rico as a reference case. Two fuels are considered in the analysis, diesel #2 and propane, along with a wide range of values for their cost and electricity rates. Several CHP scenarios are investigated including; power and cooling, power and steam, and power, cooling and steam. The CHP systems are compared with conventional methods used to supply the same power, cooling or steam loads. It was found from the analysis that for the cases in which the price of propane ranges from $1.3 to $1.5 per gallon, CHP systems are an excellent alternative over conventional grid connected generation.
Uncertainty Calculations in Pyranometer Measurements and Application
Authors: Kratzenberg M. G. , Beyer H. G. , Colle S. , Albertazzi A.
Published: October 2008

The uncertainty of pyranometer measurements should be traced back to the World Radiation Reference (WRR), a standard that is specified by the mean sensitivity of the World Standard Group (WSG). The WSG is build up by 7 primary standard pyrheliometers, operated at Davos, Switzerland. Analyzing the complete calibration chain for an individual field pyranometer, usually the uncertainty of its calibration constant is extracted as a unique figure depending on the calibration method. The common representation of the expanded uncertainty, specified by the manufacturer is global information on the accuracy of daily averages. For the use of pyranometers for e.g. test of solar energy components as solar collectors, this information on the global daily accuracy of the pyranometer is not sufficient. As the response of a solar collector to the irradiance shows nonlinearities, a more detailed analysis of the pyranometer uncertainties is necessary. This will be demonstrated for the analysis of the uncertainties of the test results — i.e. the collector coefficients and their uncertainties — and the resulting predictions of the energy gain by these devices. Ancillary information by the manufacturers will be used to discuss the uncertainty of individual measurements depending on e.g. ranges of those parameters that originate the uncertainties, depending on the geometry (incidence angle), ambient temperature and the sky conditions. Based on this information the inter-comparability of test performed at different times or with different instruments will be discussed.
Analysis of Demand Side Management Measures for Residential Buildings
Authors: Dark Jayme , Krarti Moncef
Published: October 2008

As part of a utility program to explore implementation of demand charges and time of use utility rates for residential buildings, impact of commonly used energy efficiency measures on the reduction of electricity demand in residential homes are explored in this paper. The study presented in the paper focus on homes located in the Denver-Boulder area. Detailed energy audit and simulation analyses are conducted to obtain detailed data relevant to energy performance of 13 homes. Simplified analysis method is outlined to estimate the energy use of residential homes as well as electrical peak demand. Moreover, general guidelines are provided to effectively reduce peak demand for homes.
Novel Proton Exchange Membrane Utilizing Nano Composite for Fuel Cell Application
Authors: Nguyen Khe C. , Do Sinh T. , De Thong V.
Published: October 2008

In the present report, we conducted the study of chemical top down process which seems to provide better efficiency and better cost saving than the physical top down in the fabrication of nano scale, especially, when applying to carbon materials. It is found that the chemical top down performs effectively with multiple attachments of electrolytic groups onto the surface of the carbon powder by diazo coupling reaction. As a result, we are able to isolate the nano scale of carbon particles with strong polar solvents such as water and believe that it is due to electrostatic repulsive force between same sign charges existing in the polarized electrolytic groups... The cleavage of azo bond in a naked carbon product can occur above 110oC in ambient condition but can also escape by a nano composite structure using specific emulsion polymer as binder matrix. Electrolytic groups carry charge from ionization are proven to reduce electron transport but enhance proton transport capability of carbon material, have successfully demonstrated a proton exchange membrane (PEM) which exhibits better heat resistance and higher current density than the commercial Nafion product in the PEM fuel cell application. The diazo coupling product of carbon exhibits a core-shell structure composed of a nano scale hydrophobic core and electrolytic shell, showing apparent “solubility” and named as “liquid” nano carbon (LNC).
Thermal Conductivity of Ultem™/Carbon Nanofiller Blends
Authors: Ghose S. , Watson K. A. , Delozier D. M. , Working D. C. , Connell J. W. , Smith J. G. , Sun Y. P. , Lin Y.
Published: October 2008

In an effort to improve polymer thermal conductivity (TC), Ultem™ 1000 was compounded with nano-fillers of carbon allotropes. As-received and modified multiwalled carbon nanotubes (MWCNTs), vapor grown carbon nanofibers (CNF) and expanded graphite (EG) were investigated. Functionalization of MWCNTs was performed to improve the TC compatibility between the resin and MWCNTs. It was postulated that this may provide an improved interface between the MWCNT and the polymer which would result in enhanced TC. The nano-fillers were mixed with Ultem™ 1000 in the melt and in solution at concentrations ranging from 5 to 40 wt%. Ribbons were extruded from the blends to form samples where the nano-fillers were aligned to some degree in the extrusion direction. Samples were also fabricated by compression molding resulting in random orientation of the nano-fillers. Thermal properties of the samples were evaluated by Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analyzer (TGA). Tensile properties of aligned samples were determined at room temperature. As expected, increased filler loading led to increased modulus and decreased elongation with respect to the neat polymer. The degree of dispersion and alignment of the nanofillers was determined by high-resolution scanning electron microscopy (HRSEM). HRSEM of the ribbons revealed that the MWCNTs and CNFs were predominantly aligned in the flow direction. The TC of the samples was measured using a Nanoflash™ instrument. Since the MWCNTs and CNF are anisotropic, the TC was expected to be different in the longitudinal (parallel to the nanotube and fiber axis) and transverse (perpendicular to the nanotube and fiber axis) directions. The largest TC improvement was achieved for aligned samples when the measurement was performed in the direction of MWCNT and CNF alignment (i.e. longitudinal axis). Unaligned samples also showed a significant improvement in TC and may be potentially useful in applications when it is not possible to align the nano-filler. The results of this study will be presented.
Powder Rolling of Carbon Nanotube-Reinforced Aluminium
Authors: Esawi Amal M. K. , El Borady Mostafa A.
Published: October 2008

Powder Rolling is a traditional technique for the fabrication of metal strips in which metal powder is continuously fed into a rolling mill and compacted into strip. Recently, carbon nanotubes (CNTs) have emerged as promising new materials with exceptional properties. This has stimulated interest in their use to reinforce polymer, and ceramic matrices. In spite of their potential technological importance, a few research groups have investigated their use to reinforce metal matrices. In this paper, the powder rolling technique is used for the first time to fabricate aluminium strips reinforced with carbon nanotubes. Mixtures of aluminium powder and various wt% catalytic multi-wall carbon nanotubes (MWCNT) were roll compacted and sintered to form thin strips. CNTs were observed to be aligned in the in-plane direction. Tension tests were conducted on the strips to investigate the effect of the carbon nanotubes on the mechanical properties. Although the yield strength for the 0.5 wt% CNT samples increased, the ultimate strength and strain-to-failure for all samples with CNT were mostly lower than the base metal. This was attributed to the observed clustering of the CNTs, especially in higher wt% CNT samples. Provided the CNT clustering problem is overcome, the process promises many advantages; namely, its low cost, the ease of incorporating the carbon nanotubes and the potential important applications for the carbon nanotube-metal strips.
Biodistribution of Dendrimer Nanocomposites for Nano-Radiation Therapy of Cancer
Authors: Balogh Lajos P. , Khan Mohamed K.
Published: October 2008

Multifunctional nanocomposites have an enormous scientific and practical future in medicine, especially in biomedical imaging and targeted delivery. Multifunctional composite nanodevices (CND) possess chemical and physical properties of all components, while interactions with the environment of the nanoparticle are dominated by the contact surface of the host molecule. Thus, if the surface is dominated by the organic component of a nano-sized organic-inorganic composite particle, an inorganic particle property can be manipulated in a biologic environment as if it belonged to an organic macromolecule. Composition, charge, and size of are critical in determining nanoparticle trafficking and uptake by organs, and therefore this knowledge is crucial for the development of cancer imaging and therapies. Specific biokinetics and biodistribution then can be influenced by correctly selecting size, and modifying surface characteristics, such as covalently attaching various targeting moieties to the surface forming biohybrids, regulating the surface charge, etc. Dendrimer nanocomposites are recently developed nearly monodisperse hybrid nanoparticles composed of macromolecular hosts and very small, uniformly dispersed inorganic guest domains combining desirable properties of the components. The surface groups control the interaction of these nanodevices with the biological environment. As a result of various synthetic options, the interior and/or the exterior of the host can be cationic, anionic, or non-ionic, depending on their termini and interior functionalities and the pH, and may involve multiple targeting moieties. We have synthesized gold/dendrimer nanocomposites to carry payload radiation and/or diagnostic moiety to specific targets. We examined the biodistribution of the templates and the corresponding gold/dendrimer nanocomposites. We employed the same dendrimer template and systematically varied the size, the surface charge and the composition. Biodistribution of {Au} gold/dendrimer nanodevices of various size (5, 12 and 22 nm) and surface charge (positive, negative) was investigated in mice models (B16 melanoma and DU145 human prostate cancer). Isotope neutron activation analysis (INAA) was used to measure the presence of Au(0) in the tissue sample. All {Au} gold/dendrimer-nanocomposites were assayed for their quantitative short-term (1hr), intermediate (1 day) and long-term (4 days) biodistribution throughout organs for clinical toxicity. Delivery of radiation dose was achieved by radioactive {198Au} composites in a mice model. We have shown that modulating surface charge and composition will greatly change the biodistribution characteristics of the nanodevices. Rigorous testing of the principles that govern nanoparticle interactions with the complex environment of biological systems will be critical for an understanding of how these nanodevices will behave in vivo.
Measurement of Mechanical Strength of Nano Composite Fabricated by Nano Composite Deposition System (NCDS)
Authors: Kim Sung-Geun , Chu Won-Shik , Kim Hyung-Jung , Ahn Sung-Hoon
Published: October 2008

The rapid prototyping (RP) technology has been advanced for various applications such as verification of design, functional test. Recently, researchers have studied various materials to fabricate functional RP parts. In this research, a nano composite deposition system (NCDS), which can fabricate various nano composites using polymer resins with various nano particles, was introduced. The NCDS is a hybrid system in which material removal process by mechanical micro machining and/or the deposition process is combined. To predict the mechanical behavior of nano composite part made by NCDS, it is critical to understand the mechanical properties of the NCDS material. The NCDS process was characterizes by process parameters such as raster orientation, bead width, weight percent, and curing condition. Tensile strengths and compressive strengths of fabricated specimens with various raster orientation were measured, and various sample parts made of nano composites were fabricated using NCDS.
Mode II Interlaminar Fracture Toughness of CNF-CFRP Hybrid Composite
Authors: Arai Masahiro , Sugimoto Koh-Ichi , Endo Morinobu
Published: October 2008

Interlaminar fracture toughness for mode II deformation were investigated for carbon fiber (CF)/epoxy laminates toughened by carbon-nano-fiber/epoxy interlayer. Vapor grown carbon fiber (VGCF) and vapor grown carbon ‘nano’ fiber (VGNF) were chosen as the stiffeners for the interlayer. In order to illustrate the effect of the interlayer on the model II fracture toughness of the laminates, several types of CFRP/CNF hybrid laminates were fabricated, which are composed of unidirectional prepregs and carbon nano fiber varying the thickness of the interlayer. Mode II interlaminar fracture toughnesses of the hybrid composites were evaluated by end notched flexure (ENF) test using short-type beam specimens. The fracture toughnesses were calculated by traditional beam theory using the energy release rate of the crack. From the experimental results, it is confirmed that the mode II interlaminar fracture toughnesses for hybrid laminates are from 2.0 to 3.0 times higher than that of original CFRP laminates, and the optimal thickness (area density) of the CNF interlayer exists. The difference in the effect of the interlayer fracture properties under mode II deformation was discussed on the bases of fractographic observations derived from scanning electric microscope.
Electro-Mechanically Robust, Flexible Carbon Nanotube-PDMS Composite for High Performance Field Emission
Authors: Soldano Caterina , Kar Swastik , Jung Yung Joon , Ajayan Pulikel M.
Published: October 2008

We present a method for fabricating flexible multi-wall carbon nanotubes (MWNTs)-polymer (poly-dimethylsiloxane, PDMS) composites for high performance field emission devices and other flexible electronic applications. The polymer matrix isolates individual nanotubes on its surface, reducing mutual [1] and give rise to impressive field emission properties. The MWNT-PDMS composites are extremely flexible and electro-mechanically robust since they remain electrically conducting under large strains. The above mentioned features make these MWNT-PDMS composites suitable for future applications as multifunctional flexible devices such as pressure and gas sensors as well as flexible sensors and display devices.