The Effect of Windscreens and Walkways On Air-cooled Condenser Performance and Fan Blade Dynamic Loading

2021 ◽  
Author(s):  
Fredrik Simon Marincowitz ◽  
Michael Owen ◽  
Jacques Muiyser
Keyword(s):  
Thermal Performance ◽  
Mitigation Measures ◽  
Blade Loading ◽  
Robust Solution ◽  
Wind Speeds ◽  
Performance Deterioration ◽  
Forced Draft ◽  
Fan Blade ◽  
Low Wind Speeds ◽  
The Impact

Abstract This paper presents a relative comparison of the impact of cruciform screens, perimeter screens and walkways on 3 × 6 cell forced draft air-cooled condenser's (ACC) thermal performance and dynamic fan blade loading under windy conditions. Numerical simulations were carried out for the three mitigation measures at two fan platform heights, four wind speeds and three wind directions. The results indicate that walkways are a robust solution to ACC wind effects and offer benefits in terms of thermal performance and dynamic blade loading under all wind conditions considered. Cruciform screens offered the most effective mitigation of wind-related thermal performance deterioration under certain wind conditions, but the impact of these screens is sensitive to the wind direction. The dynamic blade loading impact of cruciform screens is variable, and these screens are not recommended for dynamic blade loading mitigation. Perimeter screens offered the most effective mitigation of dynamic blade loading and were particularly effective at high wind speeds but often exacted a penalty in terms of thermal performance at moderate to low wind speeds. The results of this study indicate that a correctly configured wind mitigation system, potentially consisting of more than one individual mechanism, could help improve thermal performance and simultaneously reduce dynamic blade loading under windy conditions resulting in a robust, wind resistant condenser.

scholarly journals Experimental Study of Drop Impact on Deep-Water Surface in the Presence of Wind

2018 ◽  
Vol 48 (2) ◽  
pp. 329-341 ◽  
Author(s):  
Xinan Liu
Keyword(s):  
Deep Water ◽  
Water Surface ◽  
Water Drop ◽  
Threshold Value ◽  
Impact Angle ◽  
Drop Impact ◽  
Wind Speeds ◽  
Secondary Droplets ◽  
Low Wind Speeds ◽  
The Impact

AbstractThe effects of wind on the impact of a single water drop on a deep-water surface are studied experimentally in a wind tunnel. Experiments are performed by varying impacting drop diameters, ranging from 2.5 to 4.1 mm and wind speeds up to 6.7 m s−1. The sequence of splashing events that occurred during drop impacts is recorded with a backlit, cinematic shadowgraph technique. The experimental results show that for low wind speeds, an asymmetrical crown forms on the leeward of the periphery of the colliding region after the drop hits the water surface, while a wave swell forms on the windward. Secondary droplets are generated from the crown rim. For high wind speeds with large drop diameters, ligaments are generated from the crown rim on the leeward of the drop impact site. The ligaments grow, coalesce, and fragment into secondary droplets. It is found that both the drag force and surface tension play important roles in the evolution process of the ligaments. The nondimensional K number (K = WeOh−0.4, where We is the Webber number and Oh is the Ohnesorge number) is used to describe the splashing-deposition limit of drop impact. The threshold value of this K number changes with the wind velocity and/or drop impact angle.

scholarly journals 46 The impact of heat stress on feedlot operations; nutritional and breeding options to reduce its impact

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 37-38
Author(s):  
Jenny Jennings
Keyword(s):  
Heat Stress ◽  
Management Strategies ◽  
Past Research ◽  
Mitigation Strategies ◽  
Economic Losses ◽  
Feeding Strategies ◽  
Wind Speeds ◽  
Diet Formulation ◽  
Low Wind Speeds ◽  
The Impact

Abstract Heat stress can and always will be an issue in the feedlot industry. Heat stress can decrease performance in feedlot animals leading to substantial economic losses. High environmental temperatures, relative humidity, solar radiation, and low wind speeds can be life-threatening to beef cattle when these conditions occur simultaneously. Management strategies to decrease or alleviate heat stress-related production losses have been a focus of research for a long period of time. There is a plethora of research completed on the additions of shades, sprinklers, air circulation of covered pens, as well as the physiological changes cattle experience. The physiological discoveries have revealed a lot about how the animal copes with certain stressors and has aided in potential mitigation strategies. The use of sprinklers and shades are the most popular additions to feedlots; however, certain nutritional management strategies and breed selection can be viable options as well. My objectives to address those management strategies were to compile and review past research that specifically addresses bunk management, diet formulation, feeding strategies, and breed characteristics as well as incorporate current information available on the cattle we feed today.

scholarly journals Optimizing the Power Generation of a Wind Farm in Low Wind Speed Regions

2021 ◽  
Vol 13 (9) ◽  
pp. 5110
Author(s):  
Hanan M. Taleb ◽  
Bassam Abu Hijleh
Keyword(s):  
Power Generation ◽  
Wind Farm ◽  
Simulation Software ◽  
Energy Output ◽  
Wind Speeds ◽  
Low Wind Speed ◽  
Gcc Countries ◽  
New Locations ◽  
Low Wind Speeds ◽  
The Impact

The aim of this research is to optimize the power generation of a wind farm (WF) in order to maximize the energy output, especially in low wind speeds regions such as UAE. A new WF was proposed to be built in Sir Bani Yas Island in the UAE. This project was chosen to act as the main case configuration for this research. Four configuration parameters were proposed and assessed as follows: (1) inserting smaller turbines between the original larger main turbines; (2) changing the spacing between the turbines; (3) substituting new higher efficiency turbines in place of the existing ones; (4) moving the WFs to completely new locations in different emirates within the UAE. Through using the WindFarm simulation software, the impact of these four strategies was analyzed and calculated. The main finding of this research indicates that introducing more efficient WT units has a great impact in that it can increase output by 24.5%. Bearing in mind that the UAE has a vision for a renewable energy, as well as the Gulf Cooperation Council (GCC) countries, this paper will draw a novel recommendation to optimize the wind power generation in this low-speed region.

scholarly journals Analysis of summer O<sub>3</sub> in the Madrid air basin with the LOTOS-EUROS chemical transport model

2019 ◽  
Author(s):  
Miguel Escudero ◽  
Arjo Segers ◽  
Richard Kranenburg ◽  
Xavier Querol ◽  
Andrés Alastuey ◽  
...  
Keyword(s):  
Transport Model ◽  
Chemical Transport ◽  
Horizontal Resolution ◽  
Vertical Transport ◽  
Mitigation Measures ◽  
Chemical Transport Model ◽  
Photochemical Pollution ◽  
Wind Speeds ◽  
Low Wind Speeds ◽  
Surface O3

Abstract. Tropospheric O3 remains a major air-quality issue in the Mediterranean region. The combination of large anthropogenic emissions of precursors, transboundary contributions, a warm and dry aestival climate and topographical features results in severe cases of photochemical pollution. Chemical transport models (CTMs) are essential tools for studying O3 dynamics and for assessing mitigation measures but they need to be evaluated specifically for each air basin. In this study, we present an optimisation of the LOTOS-EUROS CTM for the Madrid air basin. Five configurations using different meteorological datasets (from the European Centre for Medium Weather Forecast (ECMWF) and Weather Research and Forecasting (WRF)), horizontal resolution and number of vertical levels were compared for July 2016. LOTOS-EUROS responded satisfactorily in the five configurations reproducing observations of surface O3 with notable correlation and reduced bias and errors. However, the best-fit simulations for surface O3 were obtained by increasing spatial resolution and using a large number of vertical levels to reproduce vertical transport phenomena and the formation of reservoir layers. Using the optimal configuration obtained in the evaluation, three characteristic events have been described: recirculation (REC) episodes and northern and southern advection (NAD and SAD, respectively) events. REC events were found to produce the highest O3 due to the reduced ventilation associated with low wind speeds and the contribution of reservoir layers formed by vertical transport of O3 formed near the surface in the previous days of the event. NAD events, usually associated with higher wind speeds, present the lowest ground-level O3 concentrations in the region. During SAD episodes, external contributions along with low wind speeds allow O3 to increase considerably, but not as much as in REC events because steady southerly winds disperse local emissions and hinder the formation of reservoir layers.

scholarly journals Formation of wind-captured disks in supergiant X-ray binaries

2019 ◽  
Vol 622 ◽  
pp. A189 ◽  
Author(s):  
I. El Mellah ◽  
A. A. C. Sander ◽  
J. O. Sundqvist ◽  
R. Keppens
Keyword(s):  
Angular Momentum ◽  
Compact Object ◽  
Roche Lobe ◽  
X Ray ◽  
Wind Speeds ◽  
Close Orbit ◽  
Low Wind Speeds ◽  
The Impact ◽  
X Ray Binaries ◽  
Hydrodynamics Equations

Context. In supergiant X-ray binaries (SgXB), a compact object captures a fraction of the wind of an O/B supergiant on a close orbit. Proxies exist to evaluate the efficiency of mass and angular momentum accretion, but they depend so dramatically on the wind speed that given the current uncertainties, they only set loose constraints. Furthermore, these proxies often bypass the impact of orbital and shock effects on the flow structure. Aims. We study the wind dynamics and angular momentum gained as the flow is accreted. We identify the conditions for the formation of a disk-like structure around the accretor and the observational consequences for SgXB. Methods. We used recent results on the wind launching mechanism to compute 3D streamlines, accounting for the gravitational and X-ray ionizing influence of the compact companion on the wind. Once the flow enters the Roche lobe of the accretor, we solved the hydrodynamics equations with cooling. Results. A shocked region forms around the accretor as the flow is beamed. For wind speeds on the order of the orbital speed, the shock is highly asymmetric compared to the axisymmetric bow shock obtained for a purely planar homogeneous flow. With net radiative cooling, the flow always circularizes for sufficiently low wind speeds. Conclusions. Although the donor star does not fill its Roche lobe, the wind can be significantly beamed and bent by the orbital effects. The net angular momentum of the accreted flow is then sufficient to form a persistent disk-like structure. This mechanism could explain the proposed limited outer extension of the accretion disk in Cygnus X-1 and suggests the presence of a disk at the outer rim of the neutron star magnetosphere in Vela X-1 and has dramatic consequences on the spinning up of the accretor.

scholarly journals Analysis of summer O<sub>3</sub> in the Madrid air basin with the LOTOS-EUROS chemical transport model

2019 ◽  
Vol 19 (22) ◽  
pp. 14211-14232 ◽  
Author(s):  
Miguel Escudero ◽  
Arjo Segers ◽  
Richard Kranenburg ◽  
Xavier Querol ◽  
Andrés Alastuey ◽  
...  
Keyword(s):  
Transport Model ◽  
Chemical Transport ◽  
Vertical Transport ◽  
Mitigation Measures ◽  
Chemical Transport Model ◽  
Photochemical Pollution ◽  
Medium Range Weather Forecast ◽  
Wind Speeds ◽  
Low Wind Speeds ◽  
Surface O3

Abstract. Tropospheric O3 remains a major air-quality issue in the Mediterranean region. The combination of large anthropogenic emissions of precursors, transboundary contributions, a warm and dry aestival climate, and topographical features results in severe cases of photochemical pollution. Chemical transport models (CTMs) are essential tools for studying O3 dynamics and for assessing mitigation measures, but they need to be evaluated specifically for each air basin. In this study, we present an optimisation of the LOTOS-EUROS CTM for the Madrid air basin. Five configurations using different meteorological datasets (from the European Centre for Medium-Range Weather Forecast, ECMWF; and the Weather Research and Forecasting Model, WRF), horizontal resolution and number of vertical levels were compared for July 2016. LOTOS-EUROS responded satisfactorily in the five configurations reproducing observations of surface O3 with notable correlation and reduced bias and errors. However, the best-fit simulations for surface O3 were obtained by increasing spatial resolution and using a large number of vertical levels to reproduce vertical transport phenomena and the formation of reservoir layers. Using the optimal configuration obtained in the evaluation, three characteristic events have been described: recirculation (REC) episodes and northern and southern advection (NAD and SAD, respectively) events. REC events were found to produce the highest O3 due to the reduced ventilation associated with low wind speeds and the contribution of reservoir layers formed by vertical transport of O3 formed near the surface in the previous days of the event. NAD events, usually associated with higher wind speeds, present the lowest ground-level O3 concentrations in the region. During SAD episodes, external contributions along with low wind speeds allow O3 to increase considerably but not as much as in REC events because steady southerly winds disperse local emissions and hinder the formation of reservoir layers.

scholarly journals Five Years (2014–2018) of Beta Activity Concentration and the Impact of Synoptic and Local Meteorological Conditions in Bilbao (Northern Spain)

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1323
Author(s):  
Natalia Alegría ◽  
Miguel Ángel Hernández-Ceballos ◽  
Margarita Herranz ◽  
Raquel Idoeta ◽  
Fernando Legarda
Keyword(s):  
Surface Activity ◽  
Ground Level ◽  
Beta Activity ◽  
Northern Spain ◽  
Gross Beta ◽  
Factors Affecting ◽  
Wind Speeds ◽  
Activity Concentrations ◽  
Low Wind Speeds ◽  
The Impact

The aim of this paper is to statistically characterize gross beta activity concentrations in ground-level air in Bilbao (northern Spain) by analysing five years (2014–2018) worth of weekly measurements in aerosols collected in filters to analyse the impact of local meteorological parameters on concentrations. In addition, synoptic meteorological scenarios associated with anomalous beta surface activity concentrations were identified. Over this five-year period, beta activity concentrations ranged from 35.45 µBq/m3 to 1778 µBq/m3 with a mean of 520.12 ± 281.77 µBq/m3. A positive correlation was found with the alpha concentrations (0.67), with an average of 0.138 for the alpha/beta ratio, and a low correlation was found with 7Be (0.16). Statistical analysis identified a seasonal component in the time series, increasing, on average, beta activity concentrations from winter to autumn. The highest beta activity concentrations were measured under the arrival of southerly land winds with low wind speeds, while the wind analysis (surface winds and air masses) of two different seasonal periods (autumn 2015 and winter 2017) have highlighted how small variations in synoptic and local winds highly influence beta activity concentrations. These results are relevant to understand the meteorological factors affecting beta activity concentrations in this area and hence to define meteorological scenarios that are in favour to high/anomalous surface activity concentrations that are harmful to the environmental and public health.

scholarly journals Building Resilience of Critical Infrastructure: A Case of Impacts of Cyclones on the Power Sector in Odisha

Climate ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 73 ◽  
Author(s):  
Sujit Kumar Mohanty ◽  
Ranit Chatterjee ◽  
Rajib Shaw
Keyword(s):  
State Government ◽  
Critical Infrastructure ◽  
Management Training ◽  
The State ◽  
Mitigation Measures ◽  
Economic Losses ◽  
Master Planning ◽  
Power Sector ◽  
Wind Speeds ◽  
The Impact

Odisha is multi-hazard-prone state in the eastern part of India. Among the various disasters, the frequency and severity of cyclones have increased at an alarming rate in the last two decades, which is attributed to climatic change. The state government of Odisha has made great strides in reducing the lives lost in the state, but an increase in economic losses and damage to critical infrastructure has become a point of worry. Considering the power sector as the most crucial of all critical infrastructures, this paper explores the impact that cyclones have had on the sector in the last two decades in Odisha. The 4R concept of robustness, redundancy, rapidity and resourcefulness is applied to the power sector, and how this is supported by governance is studied. The study points towards need for the master planning of critical infrastructure, based on the risk assessment, establishment of funding mechanisms for mitigation measures and the standardization and quality checking of power sector equipment to withstand the wind speeds of category 4 and above. There needs to be a good coordination between the power sector and the disaster management sector with proper legislative provision. Knowledge management, training and capacity building is another important issue which needs to be focused on.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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