bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple Plastic Strain Cycles Effects on Structural Reliability Analysis of Pipes
Authors: Ernst Hugo A. , Passarella Diego N. , Bravo Richard E. , Daguerre Federico
Published: October 2008

The reeling process is one of the most important methods for offshore installations of linepipes. Pipe segments are welded onshore and subsequently bent over a cylindrical rigid surface (reel) in a laying vessel. In a standard cycle the welded pipes are reeled onto a drum, reeled off, aligned and straightened. High plastic deformation is introduced in the pipe. Due to the high loading condition, the high costs of operations and the severe failure consequences, it is necessary to guarantee the integrity of the components during the process. Conventional defect assessment procedures are not explicitly developed for situations with large cyclic plastic strains. In previous work, a fracture mechanics based methodology was developed to obtain an appropriate specific method to assess the structural reliability of reeled pipes. A description of the material resistance toughness and the crack driving force evolution through strain cycles was proposed. This methodology was experimentally verified. In order to expand this model, in this work the case where several reeling cycles are applied is considered. In addition to the fracture mechanics methodology previously developed, a fatigue crack growth (FCG) formulation controlled by ΔJ parameter was developed. This formulation accounts for the crack growth produced during subsequent reeling cycles. Several fatigue laws and methods to calculate ΔJ were evaluated. An experimental program was carried out. Girth welded joints from two different seamless steel pipes were analyzed. Monotonic and cyclic fracture mechanics tests were performed using single edge notch tension (SENT) specimens. Cyclic tests were used to determine experimentally the cyclic crack growth. Experimental measurements were compared to predicted fatigue crack growths for different ΔJ calculation methods and fatigue laws. Comparison between theoretical and experimental results led to the selection of the most realistic fatigue law. A methodology to assess the reliability of pipes during multiple reeling cycles, based on fracture and elastic-plastic fatigue crack growth, was developed. A particular case of interest was presented, tolerable defect sizes were determined for different number of applied reeling cycles. The proposed methodology seems to be an accurate method to assess cases where multiple plastic cycles are taken into account.
Smart Kids Play Safe
Authors: Pedro Antonio B. , Manzano Carlos A. C. , d’Oliveira Celso A. , de Jesus Jorge L. B. , Diesel Karin , Puga Patri´cia C. , Celullar Paulo R. A. , Chiappetta Paulo R. C. , Loureiro Regis R.
Published: October 2008

Pipeline construction inevitably interferes with people’s lives whenever they cross densely populated urban areas or communities. Therefore, besides all the efforts to assure the work safety, working it is also important to consider the safety of people living in such areas. Petrobras Engineering, through the Smart Kids Play Safe program avoided accidents involving members of the communities, during pipeline construction. Safety, environmental and health information was disseminated among children, their relatives and teachers during pipeline construction as well as on the daily acquaintance with area residents.
On the Estimation of Failure Rates of Multiple Pipeline Systems
Authors: Caleyo F. , Alfonso L. , Alca´ntara J. A. , Hallen J. M. , Ferna´ndez Lagos F. , Chow H.
Published: October 2008

In this work, the statistical methods for the reliability of repairable systems have been used to produce a methodology capable to estimate the annualized failure rate of a pipeline population from the historical failure data of multiple pipelines systems. The proposed methodology provides point and interval estimators of the parameters of the failure intensity function for two of the most commonly applied stochastic models; the homogeneous Poisson process and the power law process. It also provides statistical tests to assess the adequacy of the stochastic model assumed for each system and to test whether all systems have the same model parameters. In this way, the failure data of multiple pipeline systems are only pooled to produce a generic failure intensity function when all systems follow the same stochastic model. This allows addressing both statistical and tolerance uncertainty adequately. The proposed methodology is outlined and illustrated using real life failure data of multiple oil and gas pipeline systems.
On the Influence of Crystallographic Texture on HIC
Authors: Caleyo F. , Venegas V. , Hallen J. M. , Araujo J. E. , Baudin T.
Published: October 2008

This work presents the results of ongoing investigations aimed at determining the influence of crystallographic texture, microtexture and mesotexture on hydrogen induced cracking (HIC) in low carbon pipeline steels. HIC samples of two steels were investigated using X-ray diffraction texture measurement and Orientation Imaging Microscopy (OIM™). The first steel is a low strength API 5L X46 retired from service and the second is a low sulfur ASTM A106 steel. The results of this work confirm the feasibility of improving the HIC resistance of pipeline steels through crystallographic texture control and grain boundary engineering. Controlled rolling schedules can be proposed in order to induce a crystallographic texture dominated by the {112}//ND, {111}//ND and {011}//ND fibres. Such a texture is expected to decrease significantly the steel susceptibility to HIC by: (i) reducing the number of available transgranular and intergranular low resistance cleavage paths provided by the {001}//ND oriented grains, (ii) reducing the probability of crack coalescence and stepwise HIC propagation and (iii) increasing the number of high resistance intergranular crack paths provided by coincidence site lattice (CSL) and low angle boundaries with the lowest possible energy.
Management System Approach to Pipeline Integrity
Authors: Colquhoun Iain , Calvi Christian , MacPherson Harry
Published: October 2008

The development and implementation of specific technical procedures tend to be emphasized as key measures required to ensure the integrity of pipeline systems. These activities are clearly of vital importance. However, the integration of these activities and associated integrity programs with the overall management of the business also plays an important role in guaranteeing success of the programs. This paper describes a typical pipeline integrity management system, its objectives, and its links to other enterprise management systems. The paper also outlines simple methods that can be used to evaluate any given integrity management system’s components with a view to evaluating the programs effectiveness and driving continual improvement. These methods involve the identification of gaps with respect to specified benchmarks, and the design and implementation of risk-based programs to close the gaps. The benefits claimed include: • A comprehensive and holistic approach to pipeline integrity management aligned with company goals and objectives. • Engagement of company-wide technical expertise. • Buy-in and validation by all levels of company management. • Promotion of a company culture that encourages sustainable development of integrity management programs.
Methodology to Develop Fitness-for-Service Assessments for Crack Detection In-Line Inspection Data
Authors: Shanks David , Leeson Rob , Blaga Corina , Mora Rafael G.
Published: October 2008

Implementation of Integrity Management Programs (IMP) for pipelines has motivated the design of Fitness-For-Service methodologies to assess Stress Corrosion Cracking (SCC) and fatigue-dependent features reported by Ultrasonic Crack Detection (UTCD) In-Line Inspections. The philosophical approach defined by the API 579 [1] “Fitness-For-Service” from the petrochemical industry in conjunction with Risk-based standards and regulations (i.e. CSA-Z662-2003 [2] and US DOT 49 Parts 192 [3] and 195 [4]) and in-line inspection validation (i.e. API 1163 [5]) approaches from the pipeline industry have provided the engineering basis for ensuring the safety, reliability and continued service of the in-line inspected pipelines. This paper provides a methodology to develop short and long-term excavation and re-inspection programs through a four (4) phase-process: Pre-Assessment, Integrity Criticality Assessment, Remediation and Repair, Remaining Life Extension and In-Service Monitoring. In the first phase, Pre-assessment, areas susceptible to Stress Corrosion Cracking (SCC) and fatigue-dependent features are correlated to in-line inspection data, soil modeling, pipeline and operating conditions, and associated consequences in order to provide a risk-based prioritization of pipeline segments and technical understanding for performing the assessment. The second phase, Integrity Criticality Assessment, will develop a short-term maintenance program based on the remaining strength of the in-line inspection reported features previously correlated, overlaid and risk-ranked. In addition, sites may be identified in Phase 1 for further investigation. In the third phase, a Remediation and Repair program will undertake the field investigation in order to repair and mitigate the potential threats as well as validating the in-line inspection results and characterization made during the Pre-assessment and Integrity Criticality Assessment (Phases 1 & 2). With the acquired knowledge from the previous three (3) phases, a Remaining Life Extension and In-Service Monitoring program will be developed to outline the long-term excavation and re-inspection program through the use of SCC and Fatigue crack growth probabilistic modeling and cost benefit analysis. The support of multiple Canadian and US pipeline operating companies in the development, validation and implementation of this methodology made this contribution possible.
Qualification and Certification of Inspection Personnel in Brazil: Petrobras Experience
Authors: Oliveira Ailton C. , Barbosa Jose´ A. B. , Rabello Jose´ M. B.
Published: October 2008

The purpose of this paper is to present Petrobras experience in the activity of qualification and certification of inspectors of onshore pipelines, based on Petrobras standard N2776. N2776 structure showing inspector duties and responsibilities in the various stages of the construction and assembly of onshore pipelines is also presented as well as pre-requirements for qualification: education level, physical aptitude, professional experience and training. The scheme of theoretical and practical exams required for qualification is also detailed. The advantages and difficulties arising out of the use of certified labor for quality control activities is discussed and both technical and social aspects are approached.
Modeling and Simulation Use for Terminal Sizing and Decision Support
Authors: Leite Cesar Lellis Ferreira , Barbosa Guilherme de Aquino , Lima Ma´rio Jorge
Published: October 2008

Modeling and simulation techniques were used for sizing and management of tank farm facilities. Probabilistic models representing interfaces (market, supply, production, laboratory, etc.) were represented in the model. The technique allows simulation of the logistic costs and service level in different scenarios, subsidizing technical and managerial decisions leading to optimization of inventories. Major advantages are: 1 – once it is created, a model can be used several times to assess the proposed projects and policies; 2 – the analysis methodology used by simulation enables the assessment of a proposed system, even if the entry data are still under form of schemes or drafts; 3 – simulation is generally easier to be applied than analytical methods; A partnership was created among several of Petrobras’ managers for the development of the so-called “Integral and Integrated Model of Transfer and Storage”. Examples of application of such model to some terminals and the relevant results obtained will be shown.
A New Approach to Gas Control Simulation
Authors: Carter Richard G. , Rachford Henry H. , Dupont Todd F.
Published: October 2008

Gas Pipelines are usually designed to operate in steady state, but in practice most pipelines deliver transient loads. Transient loads degrade total delivery capacity and lose revenue. This paper uses simple examples to quantify such losses and shows how to keep from losing more in practice. The challenge to pipeline operators is to minimize lost capacity by choosing opportunities wisely and exercising skillful control. Look-forward hydraulic simulation has long been used to evaluate spot transportation opportunities and their impact on prior delivery commitments. Gas Control tests control strategies with simulation using a “What-if Study”: If a load appears, “What if we respond this way?” The control selection is often driven by the number of alternate strategies that can be analyzed in the time available for a decision. Thus, while the selected strategy might be reasonable, it may not be optimal for the pipeline company, just the best they had time to try. Through studying example events, this paper describes a completely new approach to What-if Studies. It introduces the use of real-time transient optimization technology to allow the engineer, operator, or even the marketer to get answers for the completely different “What-if” question, namely “What control strategy is best if the network must respond to a specific event?” This replaces manual-iterative look-ahead simulations by mathematical optimization. For each possible load event this cutting-edge technology presents the highest-profit strategy, if one is feasible. Moreover, if delivering the load is infeasible it can determine the alternate strategy that makes the most profit, such as which loads to shed, when, and by how much.
Using CCTV to Support Remote Operation
Authors: Nunes Marcelo D. , Nunes Ildemar P.
Published: October 2008

In 2005, TBG deployed a CCTV system at its compressor stations to support the pipeline operators in their daily duties, specifically compressor’s start and stop when the station is unmanned. Fixed cameras are installed inside the compressors building and a pan/tilt/zoom dome camera is installed at a high location that allows an overall view of the facility and its surroundings. The system also improves operational safety by enabling faster fire detection. The cameras connect to a digital video recorder that stores all motion detection events in a hard disk. Live video and recordings are available to any authorized user in TBG’s corporate network.
Minimizing Fuel Consumption of Crude and Products Pipelines Using Continuous-State Dynamic Programming
Authors: Modisette Jason P.
Published: October 2008

Dynamic programming (DP) has had a successful 40-year history in the field of optimizing pipeline operations so as to minimize fuel consumption. One of the drawbacks of DP is that it is usually based on a discrete representation of the possible states of each pump (or compressor) station. In reality, the station suction and discharge pressures and pump speeds might have any value from the least allowed operating pressure (LAOP) to the maximum allowed operating pressure (MAOP), they are not limited to a discrete mesh (e.g. 100 psi, 105 psi, 110 psi, etc.) This inaccuracy can lead to accumulated roundoff errors that become significant over the length of a pipeline, and can also cause the solver to be unnecessarily slow in order to achieve the desired accuracy. This article discusses a new approach to DP-based optimization that correctly represents the possible pressures as continua. There are two main advantages to this approach: the accuracy of the optimum can be enforced directly through adaptive mesh techniques that use a detailed description of the pressures where it is necessary, and the speed of the solver can be improved by using a less detailed description where the behavior of the system is linear. This paper discusses the theory behind the new method, compares this approach with the usual DP formulation, and talks about an installed application of this method to a crude-oil pipeline and a products pipeline.
The Challenges of Wide Ranging Viscosity Fluids on Liquid Ultrasonic Flowmeters
Authors: Walters Jeffrey L.
Published: October 2008

Wide ranging viscosities in ultrasonic flow measurement for liquids is a common pipeline scenario. With ever maturing oil fields and the growth in oilsands production, the trend appears to be towards the higher end viscosities and/or novel approaches towards reducing the viscosities for transportation such as heating. The variable viscosities of the fluids provide some unique challenges to ultrasonic flowmeters not only in terms of flow profile modeling, but also in acoustic signal propagation and application to elevated temperature fluids which likewise affect the accuracy or performance of the measurement. The flow profile interrogation techniques will be discussed with an emphasis on a distributed chord model together with the use of a waveguide technology that minimizes acoustic and fluid temperature effects. A combination of R&D, calibration and field testing data will both demonstrate these challenges as well as show the increased performance that results from the application of these approaches.
Performance of In-Line Inspection Tools and Their Influence on the Structural Reliability of Corroded Pipeline
Authors: de Jesu´s Leal Carvajalino Jose´ , de Castro Marangone Fa´bio , Freire Jose´ Luiz de Franc¸a
Published: October 2008

This paper presents: i) the assessment of in-line inspection (ILI) tools’ performance in the measurement of defects caused by corrosion; ii) different methods for calculating the probability of failure (POF) of corroded pipeline based on the ILI report. The ILI report is compared to the geometry of defects measured by a reference tool (field measurements) and the errors associated with each measurement system are analyzed and assessed through different statistical methods. The minimum number of field measurements necessary to verify the performance of the ILI in sizing the corrosion defects is determined by implementing a test based on sequential analysis. The POF of a pipeline is calculated using two methods: i) first order reliability method (FORM) and ii) propagation of uncertainties. The comparison between calculated and acceptable POF enables the determining of the next reinspection period. When the calculated POF exceeds the acceptable POF before completing the amount of time desired for the next inspection, the developed procedure enables determining the number of repairs that must be made to reach the desired time when the next ILI will be performed. Finally, a software in Visual Basic® language was developed to implement this work.
An Optimization Model for the Energy Consumption vs. Gas Cooling Requirements in a Large NPS 56 Gas Transmission System
Authors: Razi Neda
Published: October 2008

Optimization of a large gas transmission pipeline results in reduced fuel consumption or higher capability and improves pipeline operation. In the current study, we have done an extensive research to optimize the operation of a huge NPS 56 pipeline system using gas cooling. This gas transmission line (the 4th major gas transmission pipeline of the National Iranian Gas Company, NIGC, or IGAT4) is designed to move over 110 MMSCMD (4.0 BCFD) of natural gas from the Assaluyeh Gas Refinery. This gas refinery which in turn receives gas from the huge gas reservoir of the South Pars Field (Iranian off-shore) is located in the south of Iran. The length of this system is over 800 kms (500 miles) with over 700 MW of compression power and aerial coolers at all compressor stations. This system passes through a very tortuous terrain with significant changes in elevation and ambient temperature which makes the optimization process even more challenging. The main objective of this project was to develop a customized tool to optimize the operation (energy consumption) of this gas transmission pipeline with all the existing system variables. The emphasis was on the impact of gas cooling (effective operation of aerial coolers) on the optimization process which in turn leads to the fuel minimization or higher capability. In this process, the impact of ambient temperature, soil temperature throughout the entire route of the pipeline, cost of electricity & fuel gas, heat transfer and Joule-Thompson effect were carefully considered. The tool was finally developed and was successfully tested on this gas transmission system which resulted in extremely accurate results. This tool could be further generalized to be used for other transmission systems.
Stress Concentration Factors of Dented Pipelines
Authors: Pinheiro Bianca de Carvalho , Pasqualino Ilson Paranhos , Barros da Cunha Se´rgio
Published: October 2008

A nonlinear finite element model was developed to assess stress concentration factors induced by plain dents on steel pipelines subjected to cyclic internal pressure. The numerical model comprised small strain plasticity and large rotations. Six small-scale experimental tests were carried out to determine the strain behavior of steel pipe models during denting simulation followed by the application of cyclic internal pressure. The finite element model developed was validated through a correlation between numerical and experimental results. A parametric study was accomplished, with the aid of the numerical model, to evaluate stress concentration factors as function of the pipe and dent geometries. Finally, an analytical formulation to estimate stress concentration factors of dented pipelines under internal pressure was proposed. These stress concentration factors can be used in a high cycle fatigue evaluation through S-N curves.
Quantification of Nano-Sized Precipitates in Microalloyed Steels by Matrix Dissolution
Authors: Lu Junfang , Ivey Douglas , Henein Hani
Published: October 2008

Microalloyed steels possess good strength, toughness and excellent weldability, all of which are necessary attributes for oil and gas pipelines in northern climates. These properties are attributed in part to the presence of nano-sized Nb/Ti carbide precipitates. In order to understand the strengthening mechanisms and to optimize the strengthening effects, it is necessary to quantify the size distribution, volume fraction and chemical speciation of these precipitates. However, characterization techniques suitable for quantifying fine precipitates are limited. A matrix dissolution method has been developed to extract the nano-sized precipitates from microalloyed steels. The results from Grade 100 microalloyed steel are presented in this paper.
MIAB Welding of Oil and Gas Pipelines
Authors: Fletcher Leigh , Stecher Gabriel , Stubbs Cec , Norrish John , Cuiuri Dominic , Moscrop Jeff
Published: October 2008

Magnetically impelled arc butt (MIAB) welding is a “single shot” method of joining pipe and tube which is used in highly automated factory production lines in high volume industries such as automotive manufacture. The entire weld over the full joint thickness is made in one single operation, instead of using several passes as in conventional welding. It is believed to be capable of making finished welds in pipe from small diameters of around 75mm (DN75) up to around DN450, and to around 10mm wall thickness. The welding time is around 10 to 15 seconds, and the joint to joint cycle time will be about 1 minute. Under the right circumstances this means that pipelines in this size range could be welded at a rate of up to around 7.5km per day or more, with only a single small welding crew and a substantial reduction in overall cost. Whilst the circumstances that allow construction spreads to take advantage of that potential speed will not exist on every pipeline, there are still major economic and technical advantages to be had from using the process at more moderate rates. The present target thickness limit of 10mm will make it possible to weld Class 900 DN450 pipelines with maximum allowable operating pressures of up to 15 MPa. The use of MIAB welding will enable the entire paradigm of pipeline construction to be changed, and will lead to reductions in construction cost of around 15% or more when the process is first implemented. Larger savings are expected in the longer term.
Thaw Responses in Degrading Permafrost
Authors: Oswell Jim , Skibinsky Darren
Published: October 2008

The Norman Wells pipeline has operated for over 20 years, transporting crude oil from Norman Wells, Northwest Territories to Zama, Alberta. The pipeline route traverses 869 km of discontinuous permafrost. The stability of the slopes along the route required that rapid thawing of ice-rich permafrost be avoided, lest the high porewater pressures that develop on thawing would cause instability. To reduce the thawing rate, a layer of wood chips was used as surface insulation. Approximately one-half of the insulated slopes were instrumented with thermistors and piezometers to monitor the thawing and the development of porewater pressures. This paper compares the actual performance of the insulated and non-insulated slopes to the original design predictions. Thaw depth is presented in terms of the square root of time. The likely original design intent of insulated sites was to restore a level of surface insulation that would represent a “cleared but otherwise undisturbed surface condition”. The actual performance of most of these sites was more dramatic than this. Factors that may have contributed to the greater than expected thawing are examined, including site orientation, preclearing, and soil type.
A Guideline: Using or Creating Incident Databases for Natural Gas Transmission Pipelines
Authors: Bolt R. , Hilgenstock A. , Kolovich C. , Velez Vega D. , Cappanera A. , Rasmussen O.
Published: October 2008

This report details the work undertaken by the International Gas Union (IGU) Study Group 3.4 during the triennium 2003–2006. The initiative that launched this work came during the 22nd World Gas Conference where it was noticed that use of pipeline incident information often is not fit for purpose. A comparative analysis has been carried out considering the most frequently used and reliable high pressure gas pipeline incident databases. The four main objectives of the analysis were to determine the differences and similarities of existing databases, create a reference model to be used when developing a new pipeline incident database, assess if harmonization of existing databases is possible and to provide recommendations regarding the above.
CFD-Based Parametric Analysis on the Performance of Personalized Partition Air Distribution Systems
Authors: Jeong Kybum , Krarti Moncef , Zhai Zhiqiang
Published: October 2008

The partition air distribution systems evaluated in this study allow occupants to control the system mode (on/off) and the supply air velocity and direction with similar flexibility as occupants in automobiles. To find optimal specifications for the partition air distribution systems that are able to achieve comfortable micro-environment, a CFD modeling tool was used to simulate the airflow and thermal performance of the partition air distribution systems in a typical office space. By analyzing the distribution characteristics of indoor air temperature, air velocity and thermal comfort index, the study assessed the performance of the partition air distribution systems with different operating parameters. The simulation results were analyzed and evaluated to assess both occupant’s thermal comfort and system energy consumption. The study shows that space cooling energy can be reduced while maintaining acceptable indoor thermal comfort level using a partition air distribution system with a higher supply air temperature.
Numerical Study of Optimal Building Scales With Low Cooling Load in Both Hot and Mild Climatic Regions
Authors: Zhai Zhiqiang
Published: October 2008

Natural ventilation is one of the primary strategies for buildings in hot and mild climatic regions to reduce building cooling energy requirement. This paper uses a building energy simulation program and a computational fluid dynamics program to investigate the influence of building scales on building cooling energy consumption with and without natural ventilation. The study examines the energy performance of buildings with different L/W and H/W ratios in both Miami, FL and Los Angeles, CA. The simulation results show the varying trends of natural ventilation potential with increased building scale ratio of L/W and H/W. The comparison of the predicted energy consumptions for twenty buildings discloses the most energy-efficient building scales for rectangular-shape buildings in both hot and mild climates with and without natural ventilation. The study indicates that natural ventilation is more effective in mild climates than in hot climates, which may save cooling energy by 50% and vent fan energy by 70%. The paper analyzes the most suitable seasons for natural ventilation in Miami and Los Angeles. Further simulations indicate that extra cooling benefits associated with more natural ventilation cannot compensate additional heat gains through larger windows.
Evaluating the Impact of Solar Radiation on Outdoor Thermal Comfort by the Development and Validation of a Simple Urban Climatic Model
Authors: Zhu Yuemei , Liu Jing , Yao Yang , Ma Zuiliang , Hagishima Aya , Tanimoto Jun
Published: October 2008

In this paper, in order to predict the outdoor thermal environment, a simple multi-layer canopy model coupled with calculation of outdoor thermal comfort was developed. SET* value was used to estimate the pedestrian level of thermal comfort in the outdoor thermal environment. Preliminary verification of this model using observational data on the outdoor thermal conditions showed good results. In addition, the results show that outdoor thermal comfort is significantly different with air temperature. Except for air temperature, both solar radiation and humidity play important roles on outdoor thermal comfort.
Experimental Study and Application Analysis on Ground-Water Source Heat Pump In North China
Authors: Yu Zhun , Jing Youyin , Xie Yingbai , Zhang Xutao
Published: October 2008

To describe the economical performance and operational characteristic of ground-water source heat pump system (GWSHPS) in North China, GWSHPS was compared with traditional central air-conditioning system (TCACS) for their total investments based upon a GWSHPS demonstration project in Beijing (88000 m2 covered area, 4572 kW heat exchange amount). At the same period, an experimental system of GWSHPS in Hebei was investigated with its operational data such as coefficient of performance (COP). The results of the demonstration project showed that the total investment for GWSHPS was 15.2% lower than TCACS, while annual operating cost for GWSHPS was 42.2% lower than TCACS. The test data of the system in Hebei showed that heating coefficient of performance of the heat pump and primary energy ratio (PER) were raised while heating water temperature was decreased. The entering water temperature to the unit ranged from 13.1°C to 17.4°C, with an average value of 15 °C, the heating water temperature varied from 40°C to 50°C, with the standard work condition of 45°C. The COPHP was about 4.12 at the minimum of heating water temperature, while it was about 3.47 at the maximum of heating water temperature and fluctuated between these values in other temperature. The results of the present work implies that GWSHPS is favorable for North China. However, buildings in North China have high heat load in winter, consequently, GWSHPS designed upon heat load will cause a waste in summer, thus, the solar-assisted ground-water source heat pump system (SAGWSHPS) which combines heat pump with solar water heater can be suggested as the best solution in North China.
Prediction of Photovoltaic Power Output Considering Weather Conditions
Authors: Furushima Kaoru , Nawata Yutaka , Sadatomi Michio
Published: October 2008

A reasonable construction of photovoltaic (PV) system would be possible if the electrical output from the PV can be predicted accurately from weather data before the construction. The electrical output can be calculated theoretically from the voltage-current characteristics equation for a silicon solar cell, if the solar irradiance and the cell temperature are known. However, it is not easy to predict the cell temperature because it depends on several physical and environment factors; in particular, it is difficult to estimate a heat transfer from PV surface to surrounds. In this study, firstly, we confirmed that the electrical output can be predicted accurately by a modified equation of traditional voltage-current characteristic equation when the irradiance and the cell temperature are given. Secondly, we estimated the average heat transfer coefficient from PV surface as a function of wind speed using the experimental data on the PV system obtained in this study and compared it with three kinds of data in references. As a result, the estimated values agree with the references’ results in their accuracy of the data.
Numerical Study of Thermal Stratification in a Liquid Storage Tank With a Porous Manifold
Authors: Brown N. M. , Lai F. C.
Published: October 2008

A numerical model has been developed to study the effects of a porous manifold on thermal stratification in a storage tank. The model is used to predict the development of flow and temperature fields during a charging process. Computations have covered a wide range of the Grashof number (1.8 × 105 < Gr < 1.8 × 108) and Reynolds number (10 ≤ Re ≤ 104), or in terms of the Richardson number, 0.1 < Ri < 105. The results obtained compare favorably well with the experimental data. In addition, the present results have confirmed the effectiveness of porous manifold in the promotion of thermal stratification and provide useful information for the design of such system.
Renewable Biodiesel From CSO: A Fuel Option for Diesel Engines
Authors: Murali Krishna B. , Mallikarjuna J. M.
Published: October 2008

The petroleum-based fuels are limited reserve fuels, with our present known reserves and the growing rate of consumption, it is feared that they are not going to last long. These finite resources of petroleum and highly concentrated in certain regions of the world has given rise to frequent disruptions and uncertainties in its supply and as well as price. This situation has created a problem to increase the prices of these oils. The growing dependence on oil has created great scarcities and hardships with serious economic imbalance. A part from the problem of fast vanishing reserves, Petroleum fueled vehicles discharge significant amount of pollutants. In view of these problems attempts must be made to develop the technology of alternate clean burning fuels. The alternative, which satisfies all these requirements, is bio-diesel. Bio-diesel is methyl or ethyl ester of fatty acid made from virgin or used vegetable oils (both edible and non-edible) and animal fat, by converting the triglyceride oils to methyl (or ethyl) esters with a process known as transesterification. Bio-fuels are important now and offer increase in potential for the future. This paper consists two phases. The phase one dealt with preparation of bio-diesel from Cotton Seed Oil (C.S.O), which is available at cheaper price, as it is byproduct from cotton industries. Its properties were determined experimentally and compared with the conventional diesel fuel. The second phase dealt with conduction of experiments on a single cylinder, 4-stroke, direct injection Diesel Engine without modifications at constant speed 1500 rpm for various loads using 100% bio-diesel and conventional diesel fuel. It noticed that, the performance of the engine is not severely deviated by the substituted renewable biodiesel inaddition considerable decrease in smoke level. It is concluding that the biodiesel is superior fuel from the environmental and performance point of view, addition to this reducing the import of oil and consequentially improving energy security as a renewable alternate fuel.
Analysis of a Solar Assisted Heat Pump Dryer With a Storage Tank
Authors: Xie Yingbai , Song Leina , Liu Chuntao
Published: October 2008

In north china, agriculture products may be harvested above safe storage moistures to prevent excessive field losses. A solar-assisted heat pump drying system (SAHP) with an energy storage tank has been proposed to meet the demand in this field. The drying system is designed in such a way that some of the components can be isolated depending on the weather conditions and usage pattern. The performance of the whole system has been modeled and investigated under a typical summer day of the city Baoding, China. Results show that the coefficient of performance (COP) of the SAHP drying system is 5.369, while it is 3.411 without solar energy inputs. With an energy storage tank, the SAHP drying system performs more stable and modulates the mismatch between solar radiation and the energy needed in the night. Other discussions on collector numbers, drying time and drying temperature are also processed, which will be helpful to apply the system in China.
Evaluating the Performance of Single Slope Passive Solar Still for Different Slope of Cover and Water Depths by Thermal Modeling: In Moderate Climatic Condition
Authors: Tiwari Anil Kr. , Tiwari G. N.
Published: October 2008

In this communication, the comparative performance of three passive solar distillation units is studied simultaneously having three different inclinations of condensing covers namely 15°, 30° and 45° of same basin area of 1m2 for varying water depths lower (0.04m), medium (0.08m) and higher (0.12m) respectively. The convective and evaporative heat transfer coefficients are evaluated by regression analysis and further used in thermal modeling to predict the yield. The effect of inclination at different water depths has been studied by conducting outdoor experiments for Delhi climatic conditions in the month of March 2005. The hourly variations of water, vapor, and cover temperatures along with yield insolation, ambient air velocity for three distillation units at different water depths have been measured as observations. A fair agreement has been observed between theoretical and experimental results by using the evaluated internal heat transfer coefficients based on inner glass cover temperature.
A Two-Step Water Splitting With Ferrite Particles and Its New Reactor Concept Using an Internally Circulating Fludized-Bed
Authors: Gokon Nobuyuki , Mizuno Takayuki , Takahashi Shingo , Kodama Tatsuya
Published: October 2008

A thermochemical two-step water splitting cycle using a redox system of iron-based oxides or ferrites is one of the promising processes for converting and storing solar energy into a fuel in sunbelt regions. The ZrO2-supported ferrite (or the ferrite/ZrO2) powders exhibit superior performances on activity and repeatability of the cyclic reactions when compared to conventional unsupported ferrites. In the first step at 1400°C under an inert atmosphere, ferrite on ZrO2 support is thermally decomposed to the reduced phase of wustite that is oxidized back to ferrite on ZrO2 with steam in a separate second step at 1000°C. In this paper, a number of ZrO2-supporetd ferrites, Mn-, Mg-, Co-, Ni- and Co-Mn-ferrites, are examined on activity. The NiFe2O4/ZrO2 powder was found to have a greatest activity between them. This paper also describes a new concept of a windowed solar chemical reactor using an internally circulating fluidized bed of ferrite/ZrO2 particles. In this concept, concentrated solar radiation passes downwards through the transparent window and directly heats the internally circulating fluidized bed. The exploratory experimental studies on this reactor concept are carried out in a laboratory scale for the thermal decomposition of NiFe2O4/ZrO2 particle bed as part of two-step water splitting cycle.
H2 Generation by Two-Step Water Splitting With CeO2-MOx Using Concentrated Solar Thermal Energy
Authors: Kaneko Hiroshi , Ishihara Hideyuki , Miura Takao , Nakajima Hiromitsu , Hasegawa Noriko , Tamaura Yutaka
Published: October 2008

CeO2-MOx (M = Mn, Fe, Ni, Cu) reactive ceramics, having high melting points and high conductivities of O2−, were synthesized with the combustion method from their nitrates for solar hydrogen production. The prepared CeO2-MOx samples were solid solutions between CeO2 and MOx with the fluorite structure through XRD. Two-step water splitting reactions with CeO2-MOx reactive ceramics proceeded at 1573–1773K for the O2 releasing step and at 1273K for the H2 generation step by irradiation of infrared imaging furnace as a solar simulator. The amounts of O2 evolved in the O2 releasing reaction with CeO2-MOx and CeO2 systems increased with the increase of the reaction temperature. The amounts of H2 evolved in the H2 generation reaction with CeO2-MOx systems except for M = Cu were more than that of CeO2 system after the O2 releasing reaction at the temperatures of 1673 and 1773K. The largest amount of H2 was generated with CeO2-NiO after the O2 releasing reaction at 1573, 1673 and 1773K. The O2 releasing reaction at 1673K and H2 generation reaction at 1273K with CeO2-Fe2O3 were repeated four times with the evolving of O2 (1.3cm3/g-sample) and H2 (2.3cm3/g-sample) gases, respectively. The possibility of solar hydrogen production with CeO2-MOx (M = Mn, Fe, Ni) reactive ceramics system by using concentrated solar thermal energy was suggested.
SOLREF: Development of an Advanced Solar High-Temperature Reformer
Authors: Mo¨ller Stephan , Friedmann Sven , Walter Michael , ten Dam Jos
Published: October 2008

The main target of the EU project SOLREF (solar steam reforming) is to develop a highly efficient and cost effective solar reactor for high-temperature reforming. This was reached by designing a new more compact reformer with innovative solutions. In addition to construction solutions in interaction between DLR and HyGear, the layout of the absorber was done at DLR by using simulations tools (HELIOS, SORSIM, VORECO) augmented or developed at DLR. First, the geometry of the absorber was optimized during an iteration process using the results of SORSIM simulation runs, which generated flux density distributions on the absorber. Secondly, the final output was used as the input for the VORECO software, which simulated the mass and heat transfer inside the absorber of the reformer. The resulting layout data are as follows: • Absorbed power: approx. 400 kWth; up to 500kWth can be possible. • Methane conversion level, overall: 80–90%. • Temperature of the product gas, receiver exit: approx. 900°C. • Operating pressure: 15 bars (optimal: 10 bars). • Fluid inlet temperature: approx. 450°C. Furthermore, the paper discusses the temperature distribution in the absorber (one-dimensional) and on the absorber surface. Due to the fact that hot spots reduce the catalyst activity significantly and also lead to the destruction of the absorber material, the absorber will have different mass flow regulations. Experimental experiences from the previous project SOLASYS and actual simulations show that the adapted mass flow regulations will reduce the maximum absorber temperature from 1100°C down to below 1000°C and the temperature differences in and on the absorber from 200–300K down to about 100K or less.
Dendro: Biomass Power From, By, and For the People of Sri Lanka
Authors: Weaver Bryn M. , Wickramasinghe Harsha
Published: October 2008

Sri Lanka’s power crisis presents considerable challenges and opportunities as attempts are made to electrify the remaining 30% of non-grid connected areas and generate reliable power in a sustainable manner. Fifty percent of the energy needs in the country are being met with biomass, 70% of these are domestic rural users. Meeting Sri Lanka’s ever-growing electricity demand with fossil fuel imports is siphoning off 30% of export earnings annually. Biomass based electricity generation, commonly referred to as dendro power, has emerged as the most sustainable option in Sri Lanka to meet spiking demand. The Sri Lankan government’s Inter-Ministerial Working Committee (IMWC) on Electricity Generation from Biomass through Dendro Thermal Technology has developed a dendro thermal program whose salient feature is to add 100 MW of dendro capacity to the grid by 2010. Energy plantations of the woody plant, Gliricidia sepium, would extend over 200,000 hectares of land currently considered to be waste cropland. Income opportunities are expected for 100,000 families if the program is successful. Dendro, as a carbon-neutral source, offers a dual-purpose vehicle for rural citizens to be benefited with income and energy. The dendro program aims to supply grid, off-grid, rural industrial and household energy. This national program could result in significant environmental benefits, opportunities for poverty alleviation and support mechanisms for traditional rural industries. This report is a summary of IMWC’s Dendro Thermal Program, focusing on income avenues and economic impacts.
Cost-Benefit Analysis of Net Zero Energy Campus Residence
Authors: Raffio Gregory , Mertz George , Kissock Kelly
Published: October 2008

In response to both global and local challenges, the University of Dayton is committed to building a net-zero energy student residence, called the Eco-house. A unique aspect of the Ecohouse is its cost effectiveness. This paper discusses both the design and cost-benefit analysis of a net-zero energy campus residence. Energy use of current student houses is presented to provide a baseline for determining energy savings. The use of the whole-system inside-out approach to guide the overall design is described. Using the inside-out method, the energy impacts of occupant behavior, appliances and lights, building envelope, energy distribution systems and primary energy conversion equipment are discussed. The designs of solar thermal and solar photovoltaic systems to meet the hot water and electricity requirements of the house are described. Ecohouse energy use is compared to the energy use of the existing houses. Cost-benefit analysis is first performed on house components and then on the whole house. At a 5% discount rate, 5% borrowing rate for a 20 year mortgage, a 35 year lifetime, and an annual fuel escalation rate of 4%, the Ecohouse can be constructed for no additional lifetime cost.
Operation and Performance of the Amonix High Concentration Photovoltaic System at the University of Nevada, Las Vegas During the Second Year of Operation
Authors: Stone Kenneth W. , Garboushian Vahan , Hurt Rick , Gray Allison , Boehm Robert , Fletcher Thomas , Hale Mary Jane
Published: October 2008

This paper discusses the operation and performance of the Amonix High Concentration Photovoltaic (HCPV) System at the Center for Energy Research at the University of Nevada, Las Vegas (UNLV) from the start of operation in March 2004. The objectives and current status of this two-phase project are discussed, including: a brief description of the system, daily operation, and system maintenance. Also included are: the performance data of Phase I and Phase II showing a typical daily power profile, the accumulated energy generated, daily peak power and daily generated energy, normalized peak power, normalized energy performance, and an estimate of the annual energy performance based upon the actual measured energy during the operation of the system. System reliability data, in terms of mean-time-between-failure, are also presented.