Errors Resulting From Excluding the Effects of Humidity on the Performance of Combustion Turbine Plants Equipped With Evaporative Coolers

2010 ◽  
Author(s):  
John Sasso
Keyword(s):  
The United States ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Cooling Systems ◽  
Combustion Gas ◽  
Ambient Temperatures ◽  
The Past ◽  
Potential Impact ◽  
And Performance ◽  
The Impact

Combustion turbine combined cycle (CTCC) plants have generally been the “power plant of choice” over the past two decades for a number of reasons, including first cost, efficiency, and low emissions. Combustion (Gas) turbine (CT) based plants now account for over 30% of the electric power capacity in the United States. Despite the significant reliance on this technology, the electric Independent System Operators (ISOs) have yet to recognize and acknowledge in their production templates, test forms and performance predicting software the Brayton Cycle limitations, most notably how humidity affects output for CT plants equipped with evaporative cooling systems. Such plants account for an estimated 48% of the CT power installed in the last 10 years. Ignoring the impact of humidity on these plants can lead to errors in production predictions beyond the normal tolerance band of 3% to as high as 9% during peak ambient temperatures for certain units. As such the electric ISO’s prediction of available generation and the associated capacity reserve margins have the potential to be overestimated. The article explores the situation in more depth, presents examples within the NYISO, quantifies the potential impact and recommends easy solutions to close the gap.

scholarly journals Energy analysis of municipal waste in Dubrovnik

2018 ◽  
pp. 40-48
Author(s):  
Paweł Król ◽  
Goran Krajačić
Keyword(s):  
Waste Management ◽  
Biogas Production ◽  
Rankine Cycle ◽  
Waste Utilization ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Waste Production ◽  
Technical Issues ◽  
Potential Impact ◽  
The Impact

In each touristic city waste management system has to overcome the impact of visitors. Dubrovnik, famous as popular touristic destination, particularly notices tourists visiting city. Therefore potential impact of waste management in touristic cities, such as Dubrovnik, is presented. The paper includes estimation of yearly waste production by inhabitants and tourists visiting those city. Waste digestion is a method for biogas production. On the basis of the preceding estimation combined-cycle installation generating heat and electricity is proposed. The model combines Brayton cycle with low temperature Kalina model based on Rankine cycle. Literature analysis presents state of the art in this field. The simulation is prepared in Cycle-Tempo. Numerical analyses lead to technical issues, which have to be taken into consideration during waste utilization with such installation. Thus benefits and threats are discussed. The presented analysis assesses the maximal electric gain, which subsequently should consider waste preparation and purification

Economic and Performance Evaluation of Heat Sink Options in Combined Cycle Applications

2005 ◽  
Vol 127 (2) ◽  
pp. 397-403 ◽  
Author(s):  
Rattan Tawney ◽  
Zahid Khan ◽  
Justin Zachary
Keyword(s):  
Heat Sink ◽  
Power Plants ◽  
Combined Cycle ◽  
Appropriate Technology ◽  
Site Location ◽  
Cooling Systems ◽  
Wastewater Disposal ◽  
Plant Operations ◽  
And Performance ◽  
The Impact

This paper is a guideline to selecting the most appropriate technology for the power plant heat sink based on water availability, site location, and wastewater disposal requirements. The paper discusses wet as well as dry cooling systems and evaluates the impact of the heat sink technology on the performance and cost of combined cycle power plants. Cogeneration applications and cycling plant operations are also considered. For each proposed option, the performance, relative costs, and noise issues will be presented.

scholarly journals Evaluation of a Water-Cooled Gas Turbine Combined Cycle Plant

1978 ◽  
Author(s):  
A. Caruvana ◽  
W. H. Day ◽  
G. B. Manning ◽  
R. C. Sheldon
Keyword(s):  
Gas Turbine ◽  
The United States ◽  
Combined Cycle ◽  
Preliminary Design ◽  
Plant Design ◽  
General Electric ◽  
Design Work ◽  
Combined Cycle Plant ◽  
And Performance ◽  
The Impact

General Electric initiated the development of a water-cooled gas turbine in the early 1960’s. The first laboratory model of a water-cooled rotor, 9.7 in. (24.7 cm) was successfully tested in 1973 at sustained firing temperatures of 2850 F (1556 C) and 16 atm pressure while maintaining bucket surface temperatures of 1000 F (583 C) or less. Maximum firing temperatures of 3500 F (1927 C) were also attained during this period. The Electric Power Research Institute (EPRI) funded initial preliminary design work which utilized the water-cooled turbine concept in a combined cycle starting in 1974. Development work to define and resolve potential barrier problems was also funded by EPRI in the original and subsequent follow-on contracts. The United States Energy Research and Development Administration (ERDA) awarded a contract to the General Electric Company in May 1976 to conduct a preliminary design study which incorporates the water-cooled gas turbine concept in a combined cycle plant. The design is based on a gas turbine firing temperature (gas temperature entering the first-stage buckets) of 2600 F (1427 C) utilizing a coal-derived low-Btu gas or coal-derived liquid. This paper presents the results of the ERDA Program. Particular emphasis is devoted to the description of the overall plant design and performance. Turbine subsystems of the water-cooled concept and the alternate cooling concepts considered are also presented in this paper. The operating features and characteristics of an advanced fixed-bed gasifier and associated gas cleanup systems are also discussed relative to the impact on the overall system design and performance.

Pupil with Obsessive-Compulsive Disorder

2017 ◽  
Vol 7 (2) ◽  
pp. 7-25
Author(s):  
Karolina Diallo
Keyword(s):  
Obsessive Compulsive Disorder ◽  
School Performance ◽  
School Environment ◽  
Detrimental Effect ◽  
Obsessive Compulsive ◽  
Compulsive Disorder ◽  
The Past ◽  
And Performance ◽  
The Impact

Pupil with Obsessive-Compulsive Disorder. Over the past twenty years childhood OCD has received more attention than any other anxiety disorder that occurs in the childhood. The increasing interest and research in this area have led to increasing number of diagnoses of OCD in children and adolescents, which affects both specialists and teachers. Depending on the severity of symptoms OCD has a detrimental effect upon child's school performance, which can lead almost to the impossibility to concentrate on school and associated duties. This article is devoted to the obsessive-compulsive disorder and its specifics in children, focusing on the impact of this disorder on behaviour, experience and performance of the child in the school environment. It mentions how important is the role of the teacher in whose class the pupil with this diagnosis is and it points out that it is necessary to increase teachers' competence to identify children with OCD symptoms, to take the disease into the account, to adapt the course of teaching and to introduce such measures that could help children reduce the anxiety and maintain (or increase) the school performance within and in accordance with the school regulations and curriculum.

scholarly journals Impact of temperature and relative humidity on the transmission of COVID-19: a modelling study in China and the United States

BMJ Open ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. e043863
Author(s):  
Jingyuan Wang ◽  
Ke Tang ◽  
Kai Feng ◽  
Xin Lin ◽  
Weifeng Lv ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Relative Humidity ◽  
Human Mobility ◽  
The United States ◽  
Reproductive Number ◽  
Cross Sectional ◽  
The Usa ◽  
Higher Temperature ◽  
Potential Impact ◽  
The Impact

ObjectivesWe aim to assess the impact of temperature and relative humidity on the transmission of COVID-19 across communities after accounting for community-level factors such as demographics, socioeconomic status and human mobility status.DesignA retrospective cross-sectional regression analysis via the Fama-MacBeth procedure is adopted.SettingWe use the data for COVID-19 daily symptom-onset cases for 100 Chinese cities and COVID-19 daily confirmed cases for 1005 US counties.ParticipantsA total of 69 498 cases in China and 740 843 cases in the USA are used for calculating the effective reproductive numbers.Primary outcome measuresRegression analysis of the impact of temperature and relative humidity on the effective reproductive number (R value).ResultsStatistically significant negative correlations are found between temperature/relative humidity and the effective reproductive number (R value) in both China and the USA.ConclusionsHigher temperature and higher relative humidity potentially suppress the transmission of COVID-19. Specifically, an increase in temperature by 1°C is associated with a reduction in the R value of COVID-19 by 0.026 (95% CI (−0.0395 to −0.0125)) in China and by 0.020 (95% CI (−0.0311 to −0.0096)) in the USA; an increase in relative humidity by 1% is associated with a reduction in the R value by 0.0076 (95% CI (−0.0108 to −0.0045)) in China and by 0.0080 (95% CI (−0.0150 to −0.0010)) in the USA. Therefore, the potential impact of temperature/relative humidity on the effective reproductive number alone is not strong enough to stop the pandemic.

scholarly journals What If the Influenza Vaccine Did Not Offer Such Variable Protection?

2020 ◽  
Vol 222 (7) ◽  
pp. 1138-1144 ◽  
Author(s):  
Sarah M Bartsch ◽  
Elizabeth A Mitgang ◽  
Gail Geller ◽  
Sarah N Cox ◽  
Kelly J O’Shea ◽  
...  
Keyword(s):  
Influenza Vaccine ◽  
Compartment Model ◽  
Medical Costs ◽  
The United States ◽  
Individual Factors ◽  
Policy Makers ◽  
Direct Medical Costs ◽  
Productivity Losses ◽  
Potential Impact ◽  
The Impact

Abstract Background The protection that an influenza vaccine offers can vary significantly from person to person due to differences in immune systems, body types, and other factors. The question, then, is what is the value of efforts to reduce this variability such as making vaccines more personalized and tailored to individuals. Methods We developed a compartment model of the United States to simulate different influenza seasons and the impact of reducing the variability in responses to the influenza vaccine across the population. Results Going from a vaccine that varied in efficacy (0–30%) to one that had a uniform 30% efficacy for everyone averted 16.0–31.2 million cases, $1.9–$3.6 billion in direct medical costs, and $16.1–$42.7 billion in productivity losses. Going from 0–50% in efficacy to just 50% for everyone averted 27.7–38.6 million cases, $3.3–$4.6 billion in direct medical costs, and $28.8–$57.4 billion in productivity losses. Going from 0–70% to 70% averted 33.6–54.1 million cases, $4.0–$6.5 billion in direct medical costs, and $44.8–$64.7 billion in productivity losses. Conclusions This study quantifies for policy makers, funders, and vaccine developers and manufacturers the potential impact of efforts to reduce variability in the protection that influenza vaccines offer (eg, developing vaccines that are more personalized to different individual factors).

scholarly journals Co-Occurrence of 35 Mycotoxins: A Seven-Year Survey of Corn Grain and Corn Silage in the United States

Toxins ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 516
Author(s):  
Alexandra C. Weaver ◽  
Daniel M. Weaver ◽  
Nicholas Adams ◽  
Alexandros Yiannikouris
Keyword(s):  
United States ◽  
Animal Health ◽  
Fusaric Acid ◽  
Fumonisin B1 ◽  
The United States ◽  
Ultra Performance Liquid Chromatography ◽  
Liquid Chromatography Tandem Mass ◽  
And Performance ◽  
The Impact ◽  
Corn Grain

Mycotoxins contaminate crops worldwide and play a role in animal health and performance. Multiple mycotoxins may co-occur which may increase the impact on the animal. To assess the multiple mycotoxin profile of corn (Zea mays), we conducted a 7-year survey of new crop corn grain and silage in the United States. A total of 711 grain and 1117 silage samples were collected between 2013 and 2019 and analyzed for the simultaneous presence of 35 mycotoxins using ultra-performance liquid chromatography–tandem mass spectrometry. The measured mean number of mycotoxins per sample were 4.8 (grain) and 5.2 (silage), ranging from 0 to 13. Fusaric acid (FA) was most frequently detected in 78.1 and 93.8% of grains and silages, respectively, followed by deoxynivalenol (DON) in 75.7 and 88.2% of samples. Fumonisin B1 (FB1), fumonisin B2 and 15-acetyl-deoxynivalenol (15ADON) followed. The greatest (p < 0.05) co-occurrence was between FA and DON in 59.1% of grains and 82.7% of silages, followed by FA with FB1, DON with 15ADON, and FA with 15ADON. Although many samples had lower mycotoxin concentrations, 1.6% (grain) and 7.9% (silage) of tested samples had DON ≥ 5000 µg/kg. Fumonisins were detected ≥ 10,000 µg/kg in 9.6 and 3.9% of grain and silage samples, respectively. Concentrations in grain varied by year for eight mycotoxin groups (p < 0.05), while all 10 groups showed yearly variations in silage. Our survey suggest that multiple mycotoxins frequently co-occur in corn grain and silage in the Unites States, and some of the more prevalent mycotoxins are those that may not be routinely analyzed (i.e., FA and 15ADON). Assessment of multiple mycotoxins should be considered when developing management programs.

scholarly journals Monetary Policy and Inequality

2020 ◽  
Vol 12 (4) ◽  
pp. 006-017
Author(s):  
Alexander A. Rakviashvili ◽  
Keyword(s):  
Monetary Policy ◽  
Wealth Inequality ◽  
The United States ◽  
Central Banks ◽  
Distribution Of Wealth ◽  
The Past ◽  
High Propensity ◽  
Debt Market ◽  
The Impact ◽  
American Economy

The article provides a literature review of studies of the impact of monetary policy on income and wealth inequality. Based on the analysis and systematization of the articles mainly written over the past 25–30 years as well as articles written by central bank authorities, the main approaches to assessing the extent to which the Fed's actions are responsible for the growth of wealth inequality in the United States, which began in the 1970s, are identified. It was revealed that the relative unanimity of economists on this issue was replaced by significant pluralism of opinions after the crisis of 2007–2009. Among other reasons this was caused by the activity of central banks and their use of non-conventional approaches in conducting the monetary policy. In addition, the channels through which the actions of central banks affect the distribution of wealth in the economy are identified. In total, five such channels were singled out. Thus, changes in the monetary policy affect the debt market and the structure of assets and liabilities of households, while households with fixed incomes and with a high propensity to use cash are more likely to suffer losses during the expansionary monetary policy. And the fifth channel, which is less popular among the economists, the "Cantillon effect", leads to an increase in the wealth of the first recipients of the issued money at the expense of those who are farthest from the center of emission. The article provides empirical evidence of why this effect is significant for the American economy, and theoretical arguments indicating that taking the Cantillon effect into account can add certainty to studies of both monetary policy costs and institutional changes caused by rising inequality.

scholarly journals Impact of Gulfstream-IV Dropsondes on Tropical Cyclone Prediction in a Regional OSSE System

2019 ◽  
Vol 147 (8) ◽  
pp. 2961-2977 ◽  
Author(s):  
Kelly Ryan ◽  
Lisa Bucci ◽  
Javier Delgado ◽  
Robert Atlas ◽  
Shirley Murillo
Keyword(s):  
Tropical Cyclone ◽  
Real Time ◽  
Environmental Conditions ◽  
The United States ◽  
Track Forecast ◽  
Deterministic Models ◽  
Research Division ◽  
Sensitivity Studies ◽  
Potential Impact ◽  
The Impact

Abstract Aircraft reconnaissance missions remain the primary means of collecting direct measurements of marine atmospheric conditions affecting tropical cyclone formation and evolution. The National Hurricane Center tasks the NOAA G-IV aircraft to sample environmental conditions that may impact the development of a tropical cyclone threatening to make landfall in the United States or its territories. These aircraft data are assimilated into deterministic models and used to produce real-time analyses and forecasts for a given tropical cyclone. Existing targeting techniques aim to optimize the use of reconnaissance observations and partially rely on regions of highest uncertainty in the Global Ensemble Forecast System. Evaluating the potential impact of various trade-offs in the targeting process is valuable for determining the ideal aircraft flight track for a prospective mission. AOML’s Hurricane Research Division has developed a system for performing regional observing system simulation experiments (OSSEs) to assess the potential impact of proposed observing systems on hurricane track and intensity forecasting. This study focuses on improving existing targeting methods by investigating the impact of proposed aircraft observing system designs through various sensitivity studies. G-IV dropsonde retrievals were simulated from a regional nature run, covering the life cycle of a rapidly intensifying Atlantic hurricane. Results from sensitivity studies provide insight into improvements for real-time operational synoptic surveillance targeting for hurricanes and tropical storms, where dropsondes released closer to the vortex–environment interface provide the largest impact on the track forecast. All dropsonde configurations provide a positive 2-day impact on intensity forecasts by improving the environmental conditions known to impact tropical cyclone intensity.

scholarly journals Patterns of Change in ACGME-Accredited Residency Programs and Positions: Implication for the Adequacy of GME Positions and Supply of Physicians in the United States

2014 ◽  
Vol 6 (2) ◽  
pp. 399-403 ◽  
Author(s):  
Kathleen D. Holt ◽  
Rebecca S. Miller ◽  
Ingrid Philibert ◽  
Thomas J. Nasca
Keyword(s):  
Medical Education ◽  
Medical School ◽  
Graduate Medical Education ◽  
Primary Care Physicians ◽  
Population Data ◽  
The United States ◽  
Graduate Medical ◽  
The Past ◽  
Accredited Institutions ◽  
The Impact

Abstract Background Recent studies suggest that the supply of primary care physicians and generalist physicians in other specialties may be inadequate to meet the needs of the US population. Data on the numbers and types of physicians-in-training, such as those collected by the Accreditation Council for Graduate Medical Education (ACGME), can be used to help understand variables affecting this supply. Objective We assessed trends in the number and type of medical school graduates entering accredited residencies, and the impact those trends could have on the future physician workforce. Methods Since 2004, the ACGME has published annually its data on accredited institutions, programs, and residents to help the graduate medical education community understand major trends in residency education, and to help guide graduate medical education policy. We present key results and trends for the period between academic years 2003–2004 and 2012–2013. Results The data show that increases in trainees in accredited programs are not uniform across specialties, or the types of medical school from which trainees graduated. In the past 10 years, the growth in residents entering training that culminates in initial board certification (“pipeline” specialties) was 13.0%, the number of trainees entering subspecialty education increased 39.9%. In the past 5 years, there has been a 25.8% increase in the number of osteopathic physicians entering allopathic programs. Conclusions These trends portend challenges in absorbing the increasing numbers of allopathic and osteopathic graduates, and US international graduates in accredited programs. The increasing trend in subspecialization appears at odds with the current understanding of the need for generalist physicians.

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