The influence of wake chopping on wet-steam turbine modelling

Abstract The formation of water droplets within condensing steam turbines is a complex process that occurs at supersaturated, non-equilibrium conditions and is influenced by the unsteady segmentation of blade wakes by successive blade rows. This is often referred to as ‘wake chopping’, and its effect on the condensation process is the subject of this paper. The practical significance is that thermodynamic ‘wetness losses’ (which constitute a major fraction of the overall loss) are strongly affected by droplet size. Likewise, droplet deposition and the various ensuing two-phase phenomena (such as film migration and coarse-water formation) also depend on the spectrum of droplet sizes in the primary fog. The majority of wake-chopping models presented in the literature adopt a stochastic approach, whereby large numbers of fluid particles are tracked through (some representation of) the turbine flowfield, assigning a random number at each successive blade row to represent the particle’s pitchwise location, and hence its level of dissipation. This study contributes to the existing literature by adding: (a) a comprehensive study of the sensitivity to key model parameters (e.g., blade wake shape and wake decay rate); (b) an assessment of the impact of circumferential pressure variations; (c) a study of the implications for wetness losses and (d) a study of the implications for deposition rates.General Electri

Effects of regulating the European Internal Market on the integration of variable renewable energy

ABSTRACT: The new proposal for regulating the European Internal Market for Electricity (EIME) can motivate the harmonization of the various National markets. The process of harmonizing the day-ahead markets (DAMs) is at an advanced stage, with an efficiency in the use of interconnectors of 86%. However, the harmonization of both intraday (IDMs) and balancing markets (BMs) is still in its infancy, with an efficiency in the use of interconnectors of 50 and 19%, respectively. The new proposal brings new targets to DAMs, and European countries should make efforts to comply with them. The same is true for IDMs and BMs, but involving more ambitious targets, requiring higher efforts to be accomplished. Both the analysis of the various National markets (according to their compliance with the new proposal for regulating the EIME) and the advantages of the new proposal for key market participants (particularly, consumers, variable renewable generation, and conventional generation) are presented. The analysis indicates that the proposal contributes to a potential increase of the general welfare of market participants. However, some aspects of the proposal can negatively affect the revenue obtained from the National markets, notably for variable renewable generation and conventional generation. This article is categorized under: Wind Power > Systems and Infrastructure Energy Policy and Planning > Economics and Policy Energy Systems Analysis > Economics and Policy Energy and Development > Economics and Policyinfo:eu-repo/semantics/publishedVersio

Association between loop diuretic dose changes and outcomes in chronic heart failure: observations from the ESC-EORP Heart Failure Long-Term Registry

[Abstract] Aims. Guidelines recommend down-titration of loop diuretics (LD) once euvolaemia is achieved. In outpatients with heart failure (HF), we investigated LD dose changes in daily cardiology practice, agreement with guideline recommendations, predictors of successful LD down-titration and association between dose changes and outcomes. Methods and results. We included 8130 HF patients from the ESC-EORP Heart Failure Long-Term Registry. Among patients who had dose decreased, successful decrease was defined as the decrease not followed by death, HF hospitalization, New York Heart Association class deterioration, or subsequent increase in LD dose. Mean age was 66±13 years, 71% men, 62% HF with reduced ejection fraction, 19% HF with mid-range ejection fraction, 19% HF with preserved ejection fraction. Median [interquartile range (IQR)] LD dose was 40 (25–80) mg. LD dose was increased in 16%, decreased in 8.3% and unchanged in 76%. Median (IQR) follow-up was 372 (363–419) days. Diuretic dose increase (vs. no change) was associated with HF death [hazard ratio (HR) 1.53, 95% confidence interval (CI) 1.12–2.08; P = 0.008] and nominally with cardiovascular death (HR 1.25, 95% CI 0.96–1.63; P = 0.103). Decrease of diuretic dose (vs. no change) was associated with nominally lower HF (HR 0.59, 95% CI 0.33–1.07; P = 0.083) and cardiovascular mortality (HR 0.62 95% CI 0.38–1.00; P = 0.052). Among patients who had LD dose decreased, systolic blood pressure [odds ratio (OR) 1.11 per 10 mmHg increase, 95% CI 1.01–1.22; P = 0.032], and absence of (i) sleep apnoea (OR 0.24, 95% CI 0.09–0.69; P = 0.008), (ii) peripheral congestion (OR 0.48, 95% CI 0.29–0.80; P = 0.005), and (iii) moderate/severe mitral regurgitation (OR 0.57, 95% CI 0.37–0.87; P = 0.008) were independently associated with successful decrease. Conclusion. Diuretic dose was unchanged in 76% and decreased in 8.3% of outpatients with chronic HF. LD dose increase was associated with worse outcomes, while the LD dose decrease group showed a trend for better outcomes compared with the no-change group. Higher systolic blood pressure, and absence of (i) sleep apnoea, (ii) peripheral congestion, and (iii) moderate/severe mitral regurgitation were independently associated with successful dose decrease

Sex- and age-related differences in the management and outcomes of chronic heart failure: an analysis of patients from the ESC HFA EORP Heart Failure Long-Term Registry

Aims: This study aimed to assess age- and sex-related differences in management and 1-year risk for all-cause mortality and hospitalization in chronic heart failure (HF) patients. Methods and results: Of 16 354 patients included in the European Society of Cardiology Heart Failure Long-Term Registry, 9428 chronic HF patients were analysed [median age: 66 years; 28.5% women; mean left ventricular ejection fraction (LVEF) 37%]. Rates of use of guideline-directed medical therapy (GDMT) were high (angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, beta-blockers and mineralocorticoid receptor antagonists: 85.7%, 88.7% and 58.8%, respectively). Crude GDMT utilization rates were lower in women than in men (all differences: P\ua0 64 0.001), and GDMT use became lower with ageing in both sexes, at baseline and at 1-year follow-up. Sex was not an independent predictor of GDMT prescription; however, age >75 years was a significant predictor of GDMT underutilization. Rates of all-cause mortality were lower in women than in men (7.1% vs. 8.7%; P\ua0=\ua00.015), as were rates of all-cause hospitalization (21.9% vs. 27.3%; P\ua075 years. Conclusions: There was a decline in GDMT use with advanced age in both sexes. Sex was not an independent predictor of GDMT or adverse outcomes. However, age >75 years independently predicted lower GDMT use and higher all-cause mortality in patients with LVEF 6445%

Nowoczesne wymagania prawnych regulacji dla transportu w miastach i potrzeba stworzenia strategii sektora w celu harmonizacji z innymi rodzajami transportu

Crucial problem of transport in the cities, as a source of pollution of the environment, are uncontrolled individual motorization, permanently increasing number of motor vehicles on the roads and streets that expels human primary need for walking. Reduced social area is also loaded with vibrations and increased sound pressure which often exceeds recommended 80 dB/A. Accent is on ecological problems caused by: polluted air, which comes from gas emissions (full of aerosol, metals, dust, soot, smoke), cutting and disappearance of green areas in order to provide space for transport, making huge amount of secondary waste (e. g. tyres, metal, used oil, liquids). To improve present sequences and reduce negative effects in the future it is necessary to take different measures: fiscal, administrative, educational, which will restrict use of individual, particularly car traffic. Same measures should be used to encourage users to use public transportation. Transport in the cities, with all weaknesses and comparative advantages, should be separately analyzed mode of road transport and also be an individual part in strategic documents. The most important questions that such strategy of transport in the cities should include are: regulation, privatization or other more efficient mode of organization in public transport of passengers, as well as urban elements of sustainable development of the urban areas and transport.Podstawowym problemem transportu w miastach, jako źródła zanieczyszczeń środowiska, jest niekontrolowana indywidualna motoryzacja, notorycznie zwiększająca ilość pojazdów na drogach, która wypiera podstawową potrzebę człowieka, jaką jest chodzenie. Zmniejszone obszary nie będące ulicami są narażone na wibracje i zwiększony hałas, który często przekracza zalecane 80 dB/A. Akcent postawiono na problemy ekologiczne spowodowane przez: zanieczyszczone powietrze, które pochodzi z emisji spalin (pełne aerozolu, metali ciężkich, pyłu, siarki i dymu), wycinanie zielonych obszarów w celu zapewnienia odpowiedniej przestrzeni dla transportu, tworzenie dużej ilości odpadów (na przykład opony, metal, zużyte paliwo, ciecze). Aby poprawić obecne następstwa i zredukować negatywne efekty w przyszłości, konieczne jest podjęcie różnych kroków: fiskalnych, administracyjnych, edukacyjnych, które ograniczą indywidualne użytkowanie samochodów i ograniczą ruch. Transport w miastach, ze wszystkimi swymi słabościami i zaletami, powinien być osobno analizowanym rodzajem transportu i być osobną częścią w dokumentach strategicznych. Najważniejsze sprawy, które taka strategia transportu powinna obejmować to: regulacje, prywatyzacja lub zorganizowanie innych bardziej wydajnych rodzajów transportu publicznego pasażerów, jak również miejskie elementy ciągłego wzrostu obszarów miejskich i transportu

The influence of wake chopping on wet-steam turbine modelling

The formation of water droplets within condensing steam turbines is a complex process that occurs at supersaturated, nonequilibrium conditions and is influenced by the unsteady segmentation of blade wakes by successive blade rows. This is often referred to as 'wake chopping', and its effect on the condensation process is the subject of this paper. The practical significance is that thermodynamic 'wetness losses' (which constitute a major fraction of the overall loss) are strongly affected by droplet size. Likewise, droplet deposition and the various ensuing two-phase phenomena (such as film migration and coarse-water formation) also depend on the spectrum of droplet sizes in the primary fog. The majority of wake-chopping models presented in the literature adopt a stochastic approach, whereby large numbers of fluid particles are tracked through (some representation of) the turbine flowfield, assigning a random number at each successive blade row to represent the particle's pitchwise location, and hence its level of dissipation. This study contributes to the existing literature by adding: (a) a comprehensive study of the sensitivity to key model parameters (e.g., blade wake shape and wake decay rate); (b) an assessment of the impact of circumferential pressure variations; (c) a study of the implications for wetness losses and (d) a study of the implications for deposition rates