bluuebunny/crossref_metadata_2025 huggingface dataset:
Operating Experience and Improvements After Major Steam Generator Upgrades to New Coal Pulverizers From Rotary Ball Mill Equipment
Authors: Costello Patrick A.
Published: December 2008

In 2002 & 2003, the Ameren UE Meramec plant carried out complete coal pulverizer design upgrades and installations on the plants two largest operating units. These units were designed and constructed in the late 1950’s and early 1960’s. The coal pulverizer replacement project involved the removal of six rotary coal ball mills and the installation of twelve new state of the art coal pulverizers. This technical paper examines the resulting operating experience demonstrated and achieved as a result of the new coal pulverizer installation on the plants two largest generating units.
Gas Turbine Inlet Air Cooling: Determination of Parameters to Evaluate Fogging Nozzle’s Atomizing Performance
Authors: Mahapatra Sanjay , Gilstrap Jeffrey K.
Published: December 2008

Gas turbine inlet air-cooling using a fogging system is accomplished by using an array of high-pressure nozzles that inject micron-sized droplets in air stream. These droplets evaporate and diffuse in the air stream resulting in cooling and humidification of air. The cooled and moist inlet air increases net turbine power output, improves heat rate and reduces Nitrogen Oxides formation (NOx). The evaporation and mass diffusion of these droplets are influenced, among other factors, by its surface area to volume ratio. Large surface area facilitates drop interfacial heat transfer and smaller volume or weight aids higher droplet residence times. A fogging nozzle’s atomizing performance can be evaluated from its spray properties that include a mean drop size, droplet distribution, numerical droplet density, spray cone angle, and spray penetration. The spray industry adopts various definitions of mean drop size that suits its application and objective. Mean drop sizes or more commonly droplet diameters used in the gas turbine inlet air fogging industry are 90% cumulative volume frequency, Dv0.90 and the Sauter Mean Diameter, D32. Two sprays having identical mean or representative diameter are not necessarily similar in performance. Further, a spray from nozzle ‘A’ having a Dv0.90 less than another nozzle ‘B’ does not necessarily imply that ‘A’ is superior to ‘B’. This paper explains why the use of one or both of the above characteristic diameters does not effectively reflect a fog nozzle’ atomizing performance. This paper also analyzes various characteristic diameters and their relevance to evaporative cooling using fog nozzles. In fogging applications, the smallest and/or the largest sized drops in a spray will have significant impact on performance and neither Dv0.90 nor D32 can independently provide this information. Therefore, at least one other parameter such as the droplet distribution must be known in order to qualitatively define a spray from a fogging nozzle. This paper also determines these parameters such as the Relative Span Factor and Dispersion Boundary Factor and analyzes their importance to fogging performance.
Expressions for the Efficient Analysis of Buried Cracks Near to the Bore of Steam Turbine Rotors
Authors: Carnero P. Antonio , Garci´a G. Rodolfo , Dorantes G. Oscar
Published: December 2008

When a mechanical component present cracks, the determination of the critical size of these cracks, as well as their speed of growth, it is essential in order to assure a reliable operation of the component. The correct estimate of the growth of the crack permit the taking of technical decisions related with the rehabilitation or opportune substitution before a catastrophic failure. Exist several manuals of cracks [1,2] with analytic solutions in order to determine the stress intensity factor of very diverse geometric configurations of cracks and of types of stress. However, most of manual statements consider the cracks in an infinite body or on the surface. In the case of cracks of turbine rotors, they are located near the surface of the central bore, for what they could not be tried neither like superficial cracks neither like cracks buried in an infinite body. In this paper, they come the results of the numeric models of elliptic and tunnel buried cracks near to the surface applying the Finite Element Method. They were carried out several FEM models considering several ligaments between the tip of the crack and the surface. The results of finite element were normalized for later one stablish a polynomial that corresponds to the factor of geometric correction “F” for elliptic cracks buried near the surface. The results obtained with our expression to elliptic cracks, they are compared with the results of Saxena, obtaining a good agreement to the analysis of the grown of the crack of the Gallantin rotor.
H2/O2 Cycles: Thermodynamic Potentialities and Limits
Authors: Gambini M. , Guizzi G. L. , Vellini M.
Published: December 2008

In this paper, the thermodynamic potentialities and limits of the H2/O2 cycles are investigated. Starting from the conventional gas turbine and steam turbine technology, the paper qualitatively tackles problems related to a change of oxidizer and fuel: from these considerations, an internal combustion steam cycle (ICSC) is analyzed where steam, injected in the combustion chamber together with oxygen and hydrogen, is produced in a regenerative way and plays the important role of inert. A proper parametric analysis is then performed in order to evaluate the influence of the main working parameters on the overall performance of H2/O2 cycles. All the results are carried out neglecting the energy requirements for O2 and H2 production systems, but taking into account their work compression only. This choice permits great freedom in the definition of these thermodynamic cycles and allows general considerations because there is no need of any specification about H2 and/or O2 production systems and their integration with thermodynamic cycles. Therefore this paper can be framed in a context of oxygen and hydrogen centralized production (by nuclear or renewable energy sources for example) and in their distribution as pure gases in the utilization place. Adopting realistic assumptions, TIT of about 1350°C, the potentialities of H2/O2 cycles are very limited: the net efficiency attains a value of about 50%. Instead, adopting futurist assumptions, TIT = I700°C, a different H2/O2 cycle scheme can be proposed and more interesting performance is attained (a net efficiency value over 60%). The thermodynamic and technological aspects are completely addressed in the paper, underlining the great importance of the choice of the main working parameters.
Slag Monitoring Using Strain Gages at Georgia Power Plant Bowen
Authors: Breeding Charlie , Bentley Chris
Published: December 2008

Georgia Power Plant Bowen is a 4 unit plant. Unit 1 is a 930 MW plant with a Combustion Engineering boiler. A slag monitoring system was installed on the leading side of the reheater pendant. Monitors were also installed on portions of the economizer. The key element of the system is strain gages that are installed on the rods that hang the pendant and economizer from the building steel. Monitoring of the gages was done during the restart of the unit from a major maintenance outage. Data from the system will be presented. The amount of deposits and their location is the intended output from the system and this data will be presented. The long range goal of the system is automatic operation of soot blowers based on the output from the monitoring system.
LCC/RAM Simulation in Support of Gas Turbine Power Plant Forecasting
Authors: Winchester Neil , Hall Steve
Published: December 2008

The activity of Life-Cycle Cost (LCC) forecasting using Reliability, Availability, and Maintainability (RAM) modeling techniques is not new, but there have been recent developments which have resulted in a fundamental change in the usefulness of LCC forecasting to designers, owners, operators, and maintainers of power plants. These changes provide the means for optimizing Operation and Maintenance (O&M) activities many years in advance with a high degree of accuracy. The primary changes have been advances in technology and the introduction of Monte Carlo-based discrete event simulation technology to perform RAM forecasting. Simulation based LCC forecasting can be used to determine the optimum operating and maintenance support scenarios. Main areas of optimization include the initial and through life cost, spares inventory holding, maintenance scheduling, logistics, etc. By allowing various scenarios to be explored in a simulation environment, LCC forecasting provides an accurate and cost effective method for optimizing costs — an activity with a very high Return On Investment (ROI) value proposition. This paper describes the methodology undertaken and the results that can be obtained from the application of automated, simulation-based LCC forecasting technology to the analysis of gas turbine based generating units.
Modeling of a 27 MW Combined Cycle Cogeneration Plant With Central Cooling Facility
Authors: Nayak Sandeep , Ozkirbas Erol , Radermacher Reinhard
Published: December 2008

This paper describes the modeling of a 27 MW combined cycle cogeneration plant with 10,000 tons chilled water central cooling facility. The cogeneration plant is designed to provide heating, cooling and electricity from a single fuel source viz., natural gas, though the gas turbines do have an inbuilt dual fuel combustion system. The topping cycle of the combined cycle cogeneration plant consists of two gas turbines each producing 11 MW of electric power at full load. The energy of the exhaust gases from these gas turbines is then utilized to generate steam in two heat recovery steam generators. The heat recovery steam generators are duct fired using natural gas to meet the peak steam load. In the bottoming part of the combined cycle, the steam from the heat recovery steam generators is expanded in a backpressure steam turbine to supply steam to the campus at about 963 kPa, generating an additional 5.5 MW of electric power in this process. There is no condenser wherein the campus acts as a sink for the steam. The central cooling facility is designed to supply 10,000 tons of chilled water out of which 3800 tons is supplied by two steam driven centrifugal chillers, which utilize a part of the steam supplied to the campus and the remaining by the centrifugal electric chillers. The combined cycle cogeneration plant along with the central chilled watercooling facility is modeled in a commercially available flexible cogeneration software package. The model is built based on the design data available from design manuals of gas turbines, heat recovery steam generators, backpressure steam turbine and centrifugal chillers. A parametric study is also done on the model to study the effect of different parameters like fuel flow rate, temperature etc on the output of the turbine and efficiency of the plant. Modeling of the inlet air-cooling of the gas turbine using an absorption chiller and electric chiller is also presented. Finally the paper discusses these results.
Using Torsional Vibration Spectra to Monitor Machinery Rotor Integrity
Authors: Sza´sz Gyo¨rgy , Guindon Edward J.
Published: December 2008

Machine degradation has become a key issue with respect to the operational and maintenance costs associated with industrial and power generation facilities. Current online techniques for monitoring rotor integrity are largely based on lateral overall vibration levels that may provide only a very short notice of impending failure. As an alternative, shifts in rotor torsional natural frequencies could be used as early indicators. Torsional vibration spectra have been gathered on numerous horizontal hydro turbine generator shafts at two Southern Company owned hydro plants. The data was trended for approximately 2 years and changes were compared against findings from visual and nondestructive testing. It was determined that in the very early stages of failure the torsional frequency shifts are minute and may be masked by or be indistinguishable from other phenomena but are detectable. As the degradation progresses, the frequencies shifts may increase greatly with the crack size and are easily discerned. While the degree of early warning capability based on this technique will more than likely vary with each failure occurrence, it should generally outperform existing lateral vibration based techniques.
Cylindrical Foaming Reactor: Electrical Discharge in Foam Bubbles
Authors: Pawlat Joanna , Hensel Karol , Mizuno Akira , Yamabe Chobei
Published: December 2008

The method of generation of hydroxyl peroxide and ozone using the cylindrical foaming apparatus are presented in this paper. High concentration of H2O2 and low concentration of ozone were obtained as a result of the electrical discharge in humid foam environment. Despite of the small amount of required liquid, this system could be applied not only for polluted gas treatment but also for specific type of water and wastewater purification.
Bundling Advanced Technologies to Achieve Maximum Efficiency and Environmental Acceptability in a Modern Coal-Fired Power Plant
Authors: Gardner David , Fontes Roger , Casey Richard
Published: December 2008

Fifteen municipal electric utilities are jointly studying the feasibility of developing a 500 MW to 1,000 MW coal-fired generation project. The project will combine advanced technologies seeking maximum performance, minimal risk and outstanding environmental acceptability. This paper describes engineering and financial studies comparing coal-firing technology alternatives such as Pulverized Coal (PC), Circulating Fluidized Bed and Integrated Gasifier Combined Cycle, and PC refinements including supercritical steam conditions and innovative use of gas turbine feedwater heating. The paper also examines options to minimize environmental impact. Use of high-efficiency steam plant technologies is found to be an environmental advantage. A prudent combination of sophisticated technologies is found to be cost-effective. Finally, the paper describes the project’s innovative joint development process.
Dual Fuel Application of SCR for Gas Turbines: LES Salt Valley
Authors: Langaker John T. , Bakenhus Byron
Published: December 2008

Lincoln Electric System, the public power utility of Lincoln, Nebraska, will complete a multiple LM6000 gas turbine station project at the end of 2003 that features Selective Catalytic Reduction (SCR) for both combined cycle as well as simple cycle. Furthermore, the facility will be capable of meeting ultra low emissions levels of nitrogen oxides when firing both natural gas and Number 2 fuel oil. This discussion explores the selection and implementation of these emission control systems from procurement through first fire. Burns and McDonnell, of Kansas City, Missouri, led the design effort of this green field site and co-authors with members of the utility.
Numerical Model for Steamtight Analysis of High Pressure Casing of Turbine
Authors: Xie Yonghui , Zhang Di
Published: December 2008

The high temperature and large pressure of inlet steam lead to large thermal stress and large thermal deformation in high pressure casing of turbine, it has an apparent effect on the reliability of casing and may lead to steamtight problem of the casing. Based on the temperature filed analysis and elastic contact theory, a three dimensional Finite Element model to analyze the deformation and stress of casing has been developed. And then the high pressure casing of a 100 MW steam turbine is analyzed, some numerical results such as temperature distribution, stress and deformation are obtained. It is shown that with higher temperature and larger pressure, larger prestressing of bolt is necessary to guarantee the steamtightness of casing, the operation experience of real casing shows the numerical analysis can provide usable data for casing design and improve its reliability.
Construction Management for Today’s Power Plant Outage (Or, How to Keep Those Shut-Downs on Target)
Authors: Hessler Peter G.
Published: December 2008

Today’s power plant outages are much more time, quality and dollar sensitive than ever before. At $600,000 of lost revenues per calendar day, along with the multi-million dollar outage costs for a 500 MW unit while out of service, today’s owners want to know that everything possible is being done to return their units back on-line, on target. It is the outage manager, working in close concert with his labor force and outside contractors, who is usually charged with making this happen. His job is tough, it’s stressful and in these days of leaner staffs, he needs all of the support he can get. That’s the objective of this paper, to offer him that support and ideas on how to keep those shut-downs on target. In this paper, outage management skills are addressed, from the perspective of the owner and his general contractor as well as from their various contractors’ perspectives. Starting with the initial specification development, the bidding process is reviewed. Then, the structuring of the construction contract is discussed with the objective of devising a win-win document. Properly setting up the site operations and then managing the work within the constraints of the originally defined scope, schedule and budget are reviewed. And finally, specific tools and techniques are introduced to keep the plan in focus. Managing a power plant outage can be a daunting undertaking and if not properly managed, from the conceptual phase right through to the final completion, the outage target dates will never be assured. However, this paper shows that if properly structured and properly managed, a very successful project can result.
Experience With Early Distributed Generation Systems
Authors: Rosse Frederick R.
Published: December 2008

This paper describes the performance and operating experience with two residential sized Combined Heat and Power units which were in operation from 1979 through 1995. The first unit was an automatic coal fired steam electric Combined Heat and Power system, based on the Rankine Steam Cycle. The unit was initially fired in 1979, operating with a steam turbine-generator for two years, and was modified with a reciprocating expander for an additional two years operation. The unit functioned reliably, with only four forced outages during the four years of operation. The second system was diesel engine-generator based, again a Combined Heat and Power System, which was started in 1987 and operated for seven seasons into 1995. The system efficiency averaged 90% during the heating season, and showed remarkably low machinery wear and minimal maintenance during the eight year run. A technical description and performance characteristics are provided for each unit. Relevant design features, design challenges arising during operation, and details of operating experiences are discussed. Photographs, System Diagrams, and Performance Graphs of these early prototype units are included within the paper. Recommended design criteria for optimized small Distributed Generation/Combined Heat and Power units is developed in the paper.
Flywheel Energy Matrix Systems: Today’s Technology Enables Efficient Combined Cycle Operation
Authors: Rojas Alex , Lazarewicz Matthew
Published: December 2008

Based on field-tested performance and third-party evaluations, Beacon Power has demonstrated that high-energy flywheel systems are a sustainable energy storage option for many electrical applications. Successful power quality implementations range from low-power telecommunications equipment (low-kW for hours) to high-power industrial support (hundreds of kW for seconds). Using this proven technology, Beacon Power has begun development of a modular, high-energy system to deliver robust and responsive megawatt output levels — for seconds, minutes and even hours. This flywheel energy matrix would be ideal for grid stabilization, spinning reserves, renewable power, and distributed resource applications. For example, a system such as this would have sufficient energy to provide the minutes needed for ride-through capability to start smaller gas turbine-powered generators. This paper describes thc tecchnical feasibility of combining thc best features of flywheel energy storage with standard high-power electronics for energy storage and delivery. Two system-level configuration options are discussed: 1) Fixed installations, comprising a matrix of flywheels installed in a building with the Power Conversion System (PCS); and, 2) Deployable, portable equipment, based on a system-modular approach comprising an array of flywheels and PCS packaged in a standard shipping container to be easily dispatched for grid stabilization or load support. The technical discussion includes a building block-level component description of the flywheel and its motor/generator drive, electrical ratings, mechanical ratings and more. At a system level, an overview of component interconnection is provided, including links to the PCS. In addition, footprint and weight values are illustrated for both proposed system configuration options. This paper also includes a more detailed examination of ways in which this innovative energy storage solution can be economically used in electric supply systems. The flywheel’s deep discharge and resilient, high-power cyclic capability, combined with a long design life, make it an ideal solution for voltage and frequency stabilization as well as an attractive, passive alternative for spinning reserves. The paper focuses and expands upon the strengths and limitations of today’s flywheel technologies. Finally, the effects and impact of the ways that energy is produced, delivered, and consumed are summarized.
Improving Turbine Performance by Use of Simple Computational Means
Authors: Sieros Giorgos , Papailiou Kyriakos D. , Kundera R.
Published: December 2008

A design effort was undertaken to improve the efficiency of the turbine that is used in a turbo-generator unit. Based on an existing design, an improved two-stage axial turbine was designed and tested. The design procedure and guidelines are described. For this redesign effort simple computational tools were used. The resulting turbine was manufactured and tested at PBS. Results from the tests and a comparison with the existing turbine are given.
Risk Assessment of Nuclear Steam Turbine Destructive Overspeed
Authors: Orsagh Rolf , Meyer Theodore , Hesler Stephen
Published: December 2008

In electric power generation facilities, steam turbine disk rupture due to overspeed can produce high-energy projectiles that may penetrate the turbine casing and damage other plant systems. While such projectiles could seriously damage a fossil fired plant, the risks are even greater for nuclear plants where a projectile could strike safety related systems. Plant maintenance personnel routinely test overspeed protection systems according to the manufacturer’s recommended schedule, but such tests require interruptions in normal steady state operation, and sometimes lead to undesirable events such as reactor SCRAMs. This risk evaluation of steam turbine destructive overspeed for nuclear power generation units reexamines the probability of an overspeed protection system failure, with the goal of optimizing maintenance practices and providing a basis for overspeed trip system testing intervals. Industry reliability databases and plant maintenance records are utilized to develop component and system failure probabilities and models that account for the impact of condition monitoring and periodic testing on overspeed protection system availability.
Optimum Turbine Extraction Pressures for Maximum Efficiency in Steam Power Plant Cycle
Authors: Sanaye Sepehr , Farshi Behrooz , Turk Hashem
Published: December 2008

In design of a real steam power plant cycle with seven or eight open and closed feed water heaters, choosing the appropriate turbine extraction pressures has important effect on the cycle efficiency. By considering the steam cycle thermal efficiency as an objective function, various optimization techniques including the Full Search, Hook-Jeeves and Nelder-Mead schemes were applied for selecting the proper arrangement of feed water heaters and the optimum steam turbine extraction pressures. In order to optimally design and accurately analyze the behavior of steam power plant cycles, a modular software based on object oriented programming has been developed. Steam cycle elements used in this software while forming a set of independent objects, collectively present an inter-related behavior. In the design environment of the software, a complete steam cycle power plant can be visually designed and analyzed. The correct performance of this software in calculation of the state variations at various cycle points and the cycle thermal efficiency was checked and verified. The values of extraction pressures and mass flow rates at the optimum design point were assessed and found to be in agreement with the corresponding values of existing power plants. Based on the literature available, incorporation of all the design features involving modular aspect with optimization search using several algorithms and comparisons made of the results with actual power plant performances have not yet been successfully accomplished in a software package.
Shading Analysis for a Zero Energy House
Authors: Wilkinson E. , Boehm R.
Published: December 2008

Las Vegas, Nevada, is one of the country’s most rapidly growing cities. To accommodate this growth, a great deal of home building takes place in Clark County, where the city is located. Builders can sell virtually as many houses as they can construct. All of these houses require utility services that, in general, have to be developed. These, of course, include water, electrical power and natural gas. With the high cooling loads required in this environment, the summer demand peaks for electricity are particularly severe. This paper represents a case study of the effects of shading for a planned zero energy home for the Southern Nevada area. The main emphasis of the research is placed on the methods of energy conservation for residential construction type housing and considers the advantages of the use of two different types of horizontal shading for the given geographical location. The technique employed for the analysis is a computer simulation package Energy 10 version 1.6. The software allows modeling and simulating of building performance based on the inputs such as geographical location, building type, orientation, construction materials used, and others. The model selected for this study is a single-family one story, 1610 ft2 residential house with north facing facade.
Sun Tracking Photo-Sensor for Solar Thermal Concentrating System
Authors: Aiuchi Kosuke , Yoshida Kazuo , Katayama Yukuo , Nakamura Minoru , Nakamura Katsushige
Published: December 2008

This paper presents the structure and application of a sun tracking photo-sensor, which controls the direction of a reflected solar radiation to be constant. The sensor has a very simple structure, in which two photo-cells are placed side by side in the bottom of a box with an aperture. When the reflected solar radiation passes through the aperture, the photo-cells are fractionally illuminated, and a electric current, which is proportional to the illuminated area, is generated on each photo-cell. The direction of the reflected solar radiation is kept to be constant by controlling the angle of the reflection mirror to make the two currents equal. The performance of the photo-sensor was tested with a mirror-telescope system and the sun tracking error was estimated to be less than 0.6 mrad on sunny day. To ascertain the applicability of the photo-sensor, a sensor-controlled heliostat, in which no computer-control system and rotary encoders were installed, was manufactured. The performance of the heliostat was evaluated by observing the radiation on the target screen which was placed 70 m south side of the heliostat, and the angular error within 2 mrad was achieved on sunny days, while the tracking error increased in various ways in cloudy weather. This photo-sensor is applicable for small solar furnace, sun lighting system, and sun tracking photovoltaic system.
Photoelectrochemical Water Splitting for Hydrogen Production Using Combination of CIGS2 Solar Cell and RuO2 Photocatalyst
Authors: Dhere Neelkanth G. , Jahagirdar Anant H. , Avachat Upendra S. , Kadam Ankur A.
Published: December 2008

This paper presents the development of photoelectrochemical (PEC) setup using multiple bandgap combination of CuIn1−xGaxS2 (CIGS2) thin-film photovoltaic (PV) cell and ruthenium oxide (RuO2) photocatalyst. FSEC PV Materials Lab has developed a PEC setup consisting of two illuminated CIGS2 cells, a ruthenium oxide (RuO2) anode deposited on titanium sheet for oxygen evolution and a platinum foil cathode for hydrogen evolution. With this combination, a PEC efficiency of 4.29% has been achieved.
Development of Heat Storage System Using Metal Hydride: Experiment of Performance by the Actual Loading Condition
Authors: Koseki Takami , Takeda Harunobu , Iijima Kazuaki , Murai Masamitu , Matsufuji Hisayoshi , Kawaguchi Osamu
Published: December 2008

An innovative heat storage system with metal hydride (MH) applied to air conditioning of buildings is investigated. The characteristics that metal hydride generates heat at absorption process and absorbs heat at desorption process is useful for new air conditioning system without chlorofluorocarbon (CFC). The trial system is composed of two heat storage vessels of a “shell and tube type” heat exchanger with heat transfer fins and filled with MH and a compressor equipped for hydrogen transfer. The system proposed in this paper is simple because the heat storage vessel has two functions of heat source and heat storage, and suitable for environment because of no usage of CFC. The purpose of heat storage is to decrease the difference of the electric power demand at daytime and that at night. That is to say, the effective heat storage system consumes electric power at night and requires no power at daytime. In the innovative heat storage system with metal hydride, the hydrogen is transferred using electric power at night and transferred in reverse only by the pressure difference between two heat storage vessels at daytime. The trial system was operated at actual loading condition, and the performance of the MH heat storage system was evaluated. As the experimental result, heat storage finishes in a limited time, and heat quantity for cooling was 13.5MJ, which was sufficient for the heat capacity to cool the 10m2 room for 3 hours. In addition, the coefficient of performance of the system is 2.44.
Analysis of Daylighting Benefits for Office Buildings in Egypt
Authors: El Mohimen Mostafa Abd , Hanna George , Krarti Moncef
Published: December 2008

This paper summarizes the results of a simulation analysis to determine the effectiveness of daylighting in reducing electrical energy consumption for office buildings in Egypt. Specifically, the impact on daylighting performance is investigated of window size, building size, daylighting control, and glazing type for three geographical locations in Egypt. It was determined that a window to wall area ratio of 0.20 minimizes the total annual electricity use for office buildings in three Egyptian locations, Cairo, Alexandria, and Aswan. A simplified analysis method is developed based on the analysis results to estimate the annual electrical energy savings attributed to daylighting.
Experimental Analysis of Thermal Comfort-Based Controls
Authors: Mun Junghyon , Krarti Moncef
Published: December 2008

Under laboratory conditions, an experimental analysis is carried to evaluate the performance of thermal comfort-based controls compared to temperature-based controls. In this analysis, the Fanger model used to estimate a thermal comfort indicator that can be utilized to control a mechanical cooling system. Specifically, the Predicted Mean Value (PMV) of Fanger model was determined using two methods. In the first method, a commercially available thermal comfort sensor was used to measure an equivalent temperature which is then converted into PMV. In the second method, air temperature, air velocity, relative humidity, and mean radiant temperature were monitored and the PMV is calculated for a given occupant metabolic rate of occupant and clothing level. The results obtained for the second method was used to calibrate the thermal comfort sensor. In this paper, the results of a series of experiments are presented to determine if thermal comfort-based controls can save energy (while maintaining adequate thermal comfort) when compared to conventional control strategies based on maintaining indoor temperature within given set-points. It was found that when the PMV is set to 0.5, the thermal comfort based controls use 10% less energy than conventional controls. The energy savings are reduced to about 7% when the PMV is set to 0 (neural level).
Development of TiN/MoS2 Composite Tribological Coatings for Cryocoolers
Authors: Dhere Neelkanth G. , Pai Anil U.
Published: December 2008

Hydrogen is a clean and sustainable form of carrier of energy that can be used in mobile and stationary applications. At present hydrogen is produced mostly from fossil sources. Solar photoelectrochemical processes are being developed for hydrogen production. Storing hydrogen can be done in three main ways: in compressed form, liquid form and by chemical bonding. Near term spaceport operations are one of the prominent applications for usage of large quantities of liquid hydrogen as a cryogenic propellant. Efficient storage and transfer of liquid hydrogen is essential for reducing the launch costs. A Two Stage Reverse Turbo Brayton Cycle (RTBC) CryoCooler is being developed at University of Central Florida. The cryocooler will be used for storage and transport of hydrogen in spaceport and space vehicle application. The efficiency of the compressor and motor of the cryocooler depends mainly on the friction and wear between the mating parts. Tribological coatings having extremely high hardness, ultra-low coefficient of friction, and high durability at temperatures lower than 60 K are being developed with an aim to reduce the friction and wear, thereby resulting in improved efficiency of the cryocooler. Extremely hard and extremely low friction coatings of DLC, TiN coatings and DLC/MoS2 and TiN/MoS2 bilayer coatings have been chosen as part of this ongoing research aimed for this application. This paper presents preparation; characterization (SEM and XRD), microhardness and tribological measurements carried out on TiN and TiN/MoS2 coatings on aluminum and glass substrate.
Scaling in Polymer Tubes Used in Solar Water Heating Systems
Authors: Wang Yana , Davidson Jane H. , Francis Lorraine F.
Published: December 2008

An experimental study of the growth of calcium carbonate (commonly termed scaling) on copper, nylon 6,6, semiaromatic high temperature nylon, polypropylene, polybutylene, and Teflon tubes exposed to hard water is presented. The objective of the study is to gain qualitative information on the scaling of polymer tubes in nonisothermal, flowing conditions expected in heat exchangers and solar absorbers. The 89-cm long tubes were placed in tube-in-shell heat exchangers. Water prepared from 10 °C tap water with a total calcium concentration of 4×10−3 M, and a pH of 9.0 was pumped through the tubes at 4 cm/s. A 50 percent propylene glycol solution at 60 °C was maintained on the shell-side of the heat exchanger. The experiment was carried out for 540 hours with these conditions. Sections of the tubes were removed periodically to determine the extent of scaling. Results include scanning electron microscope images of the tube surfaces before and after exposure to the flowing water, X-ray diffraction to determine the crystalline phase content of the observed deposits, and chemical analysis to determine the mass of calcium carbonate per unit surface area and to estimate the scaling rate. A model of the scaling process is presented to help interpret the data. The data show conclusively that polymer tubes are prone to scaling. With the exception of nylon 6,6, the scaling rate on the polymers is about the same as that on copper. The nylon 6,6 substrate appears to enhance scaling.
Optimal Operation and Control of Heat Recovery System in the Laboratory Air Handling Unit (LAHU) System
Authors: Cui Yujie , Liu Mingsheng
Published: December 2008

Optimal operation and control of heat recovery in the Laboratory Air Handling Unit (LAHU) system differs from the optimal control and operation schedule used in 100% outside air AHU. In the LAHU system, economizers can be used in both the office section and the laboratory section. An optimal operation and control schedule for the heat recovery systems has been developed by using the first derivative test for local extreme values to minimize the total thermal energy consumption. The schedule turns off the heat recovery system when the outside air temperature is higher than the LAHU free cooling temperature, which is much lower than the AHU discharge air temperature. The optimal schedule actually also reduces the electricity consumption of heat recovery water circulation pump and improves room relative humidity condition. The optimal operation and control schedule developed in the paper also applies to AHUs where economizer is used. The study also found that a heat recovery system may not be necessary for LAHUs under certain conditions.
Potential and Use of Solar Energy in Primorye Region (Russia)
Authors: Kovalev Oleg P. , Volkov Alexandr V.
Published: December 2008

During long-term time, the laboratory of non-traditional energetic is been busy with development and introduction of solar water heating systems for hot water supply. The systems with solar collectors of 40 m2 area have been developed and introducted. For estimation of their efficiency we should know flux density of solar radiation, proceeding to surface at the given place. However in Primorye Region at actinometrical watching only four meteostations in the Southern part are carrying out straight measurements of solar radiation flux, and the others record data which concern only solar radiation regime (the amount of solar radiation hours, relation of watching duration of solar radiation to possible duration, the amount of days without sun, etc.). We suggested the expression, which according to know data of solar radiation and cloudiness, recorded practically on all meteorological stations gives possibility to calculate for Primorye Region month sums of total radiation proceeding to horizontal surface. The comparison of estimated values with measured ones gives the error to 3...9% with regard to average many years values, and are in the range of variability of measured values for separate years. In Primorye Region more than 250 m2 of solar collectors were installed; and among them 150 m2 were developed with the laboratory, to position on 2003.11.01.   NOTE: This paper was presented at the 2004 International Solar Energy Conference and was inadvertently omitted from the 2004 ASME proceedings. The page range refers to the 2005 International Solar Energy Conference Print Proceedings, where it was subsequently published.
Carbonate Composite Catalyst With High-Temperature Thermal Storage for Use in Solar Tubular Reformers
Authors: Hatamachi Tsuyoshi , Kodama Tatsuya , Isobe Yuuki
Published: December 2008

The composite materials of Ni-applied, porous zirconia balls with molten Na2CO3 salt were examined for use in solar thermochemical reforming of methane as the catalyst with high-temperature thermal storage. The millimeter-sized composite balls were tested on the heat discharge property and the catalytic activity for CO2 reforming of methane in a laboratory-scale reactor. The high heat capacity and large latent heat (heat of solidification) of the composite molten salt circumvented the temperature dropping of the catalyst bed, which resulted in the alleviation of rapid decay in chemical conversion during cooling mode of the reactor. The composite catalyst is expected to realize stable operation in the solar reformer under fluctuation of insolation by a cloud passage.
Two-Step Water Splitting With Ni-Ferrite System for Solar H2 Production Using Concentrated Solar Radiation
Authors: Aoki Hirofumi , Kaneko Hiroshi , Hasegawa Noriko , Ishihara Hideyuki , Takahashi Yoichiro , Suzuki Akio , Tamaura Yutaka
Published: December 2008

Two-step water splitting with Ni-ferrite (NiFe2O4) system for H2 production using concentrated solar thermal was examined. The O2 releasing reaction proceeded in air at 1800K by irradiation with Xe lamp beams which were used as a solar simulator. The stoichiometry and the reaction mechanism of the O2 releasing step were investigated by XRD. The reaction yield was estimated to be 48% from the calculation of the spinel phase lattice constant, and the XRD showed that the solid solution phase of (Ni, Fe)O between NiO and FeO was formed. The (Ni, Fe)O solid solution could lower the O2 releasing reaction temperature. In the H2 generating step for the sample obtained by the O2 releasing step, the reaction proceeded very fast and its yield was 90% of the theoretical one at 1123K. The XRD measurement indicated that the (Ni, Fe)O solid solution phase was changed to the spinel phase of Ni-ferrite in the H2 generation step.
Degradation of VOCs With Pt-TiO2 Photocatalyst and Concentrated Sunlight
Authors: Sano Taizo , Negishi Nobuaki , Takeuchi Koji , Matsuzawa Sadao
Published: December 2008

A Parabolic trough concentrator (PTC) and a photocatalytic reactor with Pt-deposited TiO2 Photocatalyst were designed and constructed for the degradation of volatile organic compounds (VOCs). The temperature of photocatalyst coated on the sunlight receiver was easily elevated to around 473 K by PTC, and 79% of toluene or 93% of acetaldehyde was removed continuously, when gaseous toluene (15ppm) or acetaldehyde (400ppm) was passed through the reactor. The combination of sunlight concentrator and Pt-TiO2 catalyst exhibited the enhancement of complete degradation of VOCs, the inhibition of deactivation, and the reactivation of photocatalyst. The contributions of photocatalytic and catalytic activities of Pt-TiO2 were analyzed by using UV lamp and electric heater. Acetaldehyde was thermocatalytically degraded by photodeposited Pt on TiO2 at 343–463 K without UV irradiation, however the UV irradiation was necessary for the complete oxidation of acetaldehyde into CO2.
An Alternative Approach to PV System Life Cycle Cost Analysis
Authors: Larsen Chris , Szaro Jennifer , Wilson William
Published: December 2008

This analysis uses actual installed system costs from available data to better assess and understand the real installed and life cycle costs for small-scale photovoltaic (PV) installations. Most PV systems are sold on the basis of first cost, but in addition to these first costs, system owners must consider operation and maintenance (O&M) costs and down time, as well as energy savings [1]. The challenge in developing realistic life cycle costs is that most databases have only new data available, and only one database — that maintained by the Florida Solar Energy Center (FSEC) — contains performance information along with cost and maintenance data. The goals of this effort are to: 1. Characterize the actual life cycle costs (LCC) of PV systems installed in Florida and tracked since 1998. 2. Develop a benchmark of PV LCC that will aid in prioritizing cost improvement steps and feed into the U.S. Department of Energy and its subcontractors’ efforts to develop a baseline for grid-connected small residential and larger commercial PV system costs. 3. Develop an easy to use and modify LCC model that allows sensitivity analysis and input of new data as it becomes available. The PV system LCC model developed and used here is based on statistical methods, which provide us with a range of expected outcomes. The Monte Carlo technique allows the use of repeated simulation iterations to mimic a population sample. For inputs, the model relies largely on data from FSEC’s performance and maintenance databases, and where appropriate simplifying assumptions are explained. Beyond establishing an LCC baseline, this project considers the sensitivity of the total LCC to various inputs and thereby provides guidance on the question of where to put valuable resources to substantially reduce PV system costs. Further discussion is offered concerning the additional value of this model in determining the impact of various methods of PV system performance tracking.
Continuous Flow Density Driven Passive Solar Water Pasteurization
Authors: Duff William S. , Hodgson David
Published: December 2008

A solar water pasteurization system with a total collector area of 0.45 m2, an operating temperature of 80°C, and a holding time of 30 seconds has been constructed. The system was most recently tested in Fort Collins, Colorado during September/October of 2003. The system is capable of producing 80–90kg of treated water during a sunny day. To establish the potential effectiveness of the system, studies on the thermal resistance of waterborne pathogens that the World Health Organization has classified as having high health significance have been assembled and evaluated. It was determined that the process should be highly effective against most enteric pathogens. However, more information is needed about thermal resistance of some important virus families.
Development of In-Situ Fan Curve Measurement for VAV AHU Systems
Authors: Liu M. , Liu G. , Joo I. , Song L. , Wang G.
Published: December 2008

Currently there is no reliable and accurate method available for building pressure control due to the difficulties of accurate airflow measurement. Recently, a fan airflow station was developed that measures the fan airflow using fan head, fan speed, and fan curve. Both the fan speed and the fan head can be measured accurately using existing sensors and transducers. Therefore, the accuracy of the fan airflow station depends on the accuracy of the fan curve. An experimental method has been developed to determine the in-situ fan curve without interrupting the normal system operations. This paper presents the theoretical background, experimental methodology, implementation procedures, and verification results in the laboratory as well as existing buildings.
By-Pass Blending Station: An Innovative Secondary In-Building Pump System for District Heating and Cooling Systems
Authors: Liu M. , Barnes D. , Bunz K. , Rosenberry N.
Published: December 2008

An innovative secondary in-building pump system called the By-pass Blending Station (BBS) has been developed to reduce building pump energy consumption and maintain the desired return water temperatures in district heating and cooling systems. This method applies where district systems provide sufficient pump head for in-building water circulation. The BBS moves only the returned by-pass flow. Therefore, it uses less pump energy than the ASHRAE recommended method, which moves the entire building water flow by using in-building pump. The pump in the BBS is smaller than that of the ASHRAE recommended in-building secondary pump system. The BBS can be used in both constant and variable flow secondary systems. This paper compares the ASHRAE recommended secondary in-building pump with BBS systems using chilled water systems. The BBS only applies to cases where the primary distribution systems provide sufficient pump head for in-building circulation, which are typically found in commercial district cooling and heating systems.