Analysis for Influence upon Local Climate Factors of Reservoir Area of Hydropower Station after Water Storage

2012 ◽  
Vol 212-213 ◽  
pp. 245-252 ◽  
Author(s):  
Wen Yong Wang ◽  
Wen Liu ◽  
Xiao Juan Ma
Keyword(s):  
Numerical Model ◽  
Water Storage ◽  
Concentration Field ◽  
Water Area ◽  
Atmospheric Pollutants ◽  
Hydropower Station ◽  
Land Breeze ◽  
Climate Factors ◽  
Local Climate ◽  
Average Temperature

An artificial reservoir will be formed at the dam upstream in a large hydropower station after the station put into use, and with water area expanding, the local climate will change. This paper takes mesoscale meteorological numerical model WRF to simulate a certain hydropower station in Sichuan to obtain the impacting situation of the local climate after the water storage. The result indicates as follows: firstly, the wind field has been greatest changed after the water storage. Except in the winter, we can found obvious lake-land breeze in the spring and the summer and the flow field is very evident; secondly, the temperature is rising or falling; except for a little change in the spring, the average temperature falls 1.27°C in the summer but rises at 1.28°C in the winter. In addition, the humidity around the reservoir is changed distinctly; the average humid degree rises mostly at 4.56% in the winter, moderately at 2.25% in the spring but a little change at 0.94% in the summer. It is since the climate factors have been changed that the concentration field of atmospheric pollutants which generated by the industrial and mining enterprises around the reservoir has been changed at all.

scholarly journals Numerical Investigation of a Radially Cooled Turbine Guide Vane Using Air and Steam as a Cooling Medium

Computation ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 63
Author(s):  
Sondre Norheim ◽  
Shokri Amzin
Keyword(s):  
Numerical Model ◽  
Gas Turbines ◽  
Guide Vane ◽  
Axial Direction ◽  
Average Error ◽  
Inlet Temperature ◽  
Average Temperature ◽  
Cooling Medium ◽  
Turbine Guide Vane ◽  
Steam Cooling

Gas turbine performance is closely linked to the turbine inlet temperature, which is limited by the turbine guide vanes ability to withstand the massive thermal loads. Thus, steam cooling has been introduced as an advanced cooling technology to improve the efficiency of modern high-temperature gas turbines. This study compares the cooling performance of compressed air and steam in the renowned radially cooled NASA C3X turbine guide vane, using a numerical model. The conjugate heat transfer (CHT) model is based on the RANS-method, where the shear stress transport (SST) k−ω model is selected to predict the effects of turbulence. The numerical model is validated against experimental pressure and temperature distributions at the external surface of the vane. The results are in good agreement with the experimental data, with an average error of 1.39% and 3.78%, respectively. By comparing the two coolants, steam is confirmed as the superior cooling medium. The disparity between the coolants increases along the axial direction of the vane, and the total volume average temperature difference is 30 K. Further investigations are recommended to deal with the local hot-spots located near the leading- and trailing edge of the vane.

scholarly journals Pool Boiling of Nanofluids on Biphilic Surfaces: An Experimental and Numerical Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 125
Author(s):  
Eduardo Freitas ◽  
Pedro Pontes ◽  
Ricardo Cautela ◽  
Vaibhav Bahadur ◽  
João Miranda ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Numerical Model ◽  
Heat Dissipation ◽  
Numerical Study ◽  
Pool Boiling ◽  
Temperature Drop ◽  
Surface Cooling ◽  
Average Temperature ◽  
Gold Silver

This study addresses the combination of customized surface modification with the use of nanofluids, to infer on its potential to enhance pool-boiling heat transfer. Hydrophilic surfaces patterned with superhydrophobic regions were developed and used as surface interfaces with different nanofluids (water with gold, silver, aluminum and alumina nanoparticles), in order to evaluate the effect of the nature and concentration of the nanoparticles in bubble dynamics and consequently in heat transfer processes. The main qualitative and quantitative analysis was based on extensive post-processing of synchronized high-speed and thermographic images. To study the nucleation of a single bubble in pool boiling condition, a numerical model was also implemented. The results show an evident benefit of using biphilic patterns with well-established distances between the superhydrophobic regions. This can be observed in the resulting plot of the dissipated heat flux for a biphilic pattern with seven superhydrophobic spots, δ = 1/d and an imposed heat flux of 2132 w/m2. In this case, the dissipated heat flux is almost constant (except in the instant t* ≈ 0.9 when it reaches a peak of 2400 W/m2), whilst when using only a single superhydrophobic spot, where the heat flux dissipation reaches the maximum shortly after the detachment of the bubble, dropping continuously until a new necking phase starts. The biphilic patterns also allow a controlled bubble coalescence, which promotes fluid convection at the hydrophilic spacing between the superhydrophobic regions, which clearly contributes to cool down the surface. This effect is noticeable in the case of employing the Ag 1 wt% nanofluid, with an imposed heat flux of 2132 W/m2, where the coalescence of the drops promotes a surface cooling, identified by a temperature drop of 0.7 °C in the hydrophilic areas. Those areas have an average temperature of 101.8 °C, whilst the average temperature of the superhydrophobic spots at coalescence time is of 102.9 °C. For low concentrations as the ones used in this work, the effect of the nanofluids was observed to play a minor role. This can be observed on the slight discrepancy of the heat dissipation decay that occurred in the necking stage of the bubbles for nanofluids with the same kind of nanoparticles and different concentration. For the Au 0.1 wt% nanofluid, a heat dissipation decay of 350 W/m2 was reported, whilst for the Au 0.5 wt% nanofluid, the same decay was only of 280 W/m2. The results of the numerical model concerning velocity fields indicated a sudden acceleration at the bubble detachment, as can be qualitatively analyzed in the thermographic images obtained in this work. Additionally, the temperature fields of the analyzed region present the same tendency as the experimental results.

scholarly journals Lake and wetland ecosystem services measuring water storage and local climate regulation

2017 ◽  
Vol 53 (4) ◽  
pp. 3197-3223 ◽  
Author(s):  
Christina P. Wong ◽  
Bo Jiang ◽  
Theodore J. Bohn ◽  
Kai N. Lee ◽  
Dennis P. Lettenmaier ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Water Storage ◽  
Wetland Ecosystem ◽  
Local Climate ◽  
Climate Regulation

scholarly journals Numerical Calculations of WR-40 Boiler Based on its Zero-Dimensional Model

2014 ◽  
Vol 35 (2) ◽  
pp. 173-180 ◽  
Author(s):  
Bartłomiej Hernik
Keyword(s):  
Numerical Model ◽  
Flue Gases ◽  
Balance Model ◽  
Furnace Chamber ◽  
Gas Temperature ◽  
Cfd Modelling ◽  
Boiler Furnace ◽  
Average Temperature ◽  
Furnace Outlet ◽  
Dissipation Model

Abstract Generally, the temperature of flue gases at the furnace outlet is not measured. Therefore, a special computation procedure is needed to determine it. This paper presents a method for coordination of the numerical model of a pulverised fuel boiler furnace chamber with the measuring data in a situation when CFD calculations are made in regard to the furnace only. This paper recommends the use of the classical 0-dimensional balance model of a boiler, based on the use of measuring data. The average temperature of flue gases at the furnace outlet tk" obtained using the model may be considered as highly reliable. The numerical model has to show the same value of tk" . This paper presents calculations for WR-40 boiler. The CFD model was matched to the 0-dimensional tk" value by means of a selection of the furnace wall emissivity. As a result of CFD modelling, the flue gas temperature and the concentration of CO, CO2, O2 and NOx were obtained at the furnace chamber outlet. The results of numerical modelling of boiler combustion based on volumetric reactions and using the Finite-Rate/Eddy-Dissipation Model are presented.

Simulation and Comparative Analysis on Environmental Control in Subway

2012 ◽  
Vol 209-211 ◽  
pp. 1068-1072
Author(s):  
Ming Liu ◽  
Bao Gang Zhang ◽  
Liu Wen ◽  
Zhong Zhi Huang
Keyword(s):  
Temperature Field ◽  
Energy Consumption ◽  
Comparative Analysis ◽  
Environmental Control ◽  
Thermal Environment ◽  
Airflow Velocity ◽  
Waiting Room ◽  
Local Climate ◽  
Average Temperature ◽  
Environment Control

To ensure passengers can have a comfortable thermal environment in the subway waiting room is one of the main targets in subway environment control. By using the CFD software, this paper takes an island platform with double-layer of Shenyang as the object to simulate the thermal environment of platform screen door and ventilation in the open system, then detailed analysis on the variation of the temperature field, airflow velocity field in the typical position. The results indicated that average temperature of no-PSD system platform is 2.5 ~3 °C higher than that of PSD system, standing room is 1.5 °C higher than that of PSD system , but these also meet the requirement of the standards of the environmental control and passengers’ thermal comfort. Meanwhile, through the comparative analysis to the energy consumption of the two systems, we find ventilating condition has superior to PSD system in energy saving, and it is more suitable for the local climate in the northeast.

Urban water storage capacity inferred from observed evapotranspiration recession 

2021 ◽  
Author(s):  
Harro Jongen ◽  
Gert-Jan Steeneveld ◽  
Jason Beringer ◽  
Krzysztof Fortuniak ◽  
Jinkyu Hong ◽  
...  
Keyword(s):  
Storage Capacity ◽  
Water Storage ◽  
Urban Water ◽  
Natural Forests ◽  
Local Climate ◽  
Water Storage Capacity ◽  
Vegetation Fraction ◽  
Local Climate Zones ◽  
Order Of Magnitude ◽  
Neighborhood Scale

<p>The amount and dynamics of urban water storage play an important role in mitigating urban flooding and heat. Assessment of the capacity of cities to store water remains challenging due to the extreme heterogeneity of the urban surface. Evapotranspiration (ET) recession after rainfall events during the period without precipitation, over which the amount of stored water gradually decreases, can provide insight on the water storage capacity of urban surfaces. Assuming ET is the only outgoing flux, the water storage capacity can be estimated based on the timescale and intercept of its recession. In this paper, we test the proposed approach to estimate the water storage capacity at neighborhood scale with latent heat flux data collected by eddy covariance flux towers in eleven contrasting urban sites with different local climate zones, vegetation cover and characteristics and background climates (Amsterdam, Arnhem, Basel, Berlin, Helsinki, Łódź, Melbourne, Mexico City, Seoul, Singapore, Vancouver). Water storage capacities ranging between 1 and 12 mm were found. These values correspond to e-folding timescales lasting from 2 to 10 days, which translate to half-lives of 1.5 to 7 days. We find ET at the start of a drydown to be positively related to vegetation fraction, and long timescales and large storage capacities to be associated with higher vegetation fractions. According to our results, urban water storage capacity is at least one order of magnitude smaller than the known water storage capacity in natural forests and grassland.</p>

scholarly journals Evaporation suppression and energy balance of water reservoirs covered with self-assembling floating elements

2018 ◽  
Vol 22 (7) ◽  
pp. 4015-4032 ◽  
Author(s):  
Milad Aminzadeh ◽  
Peter Lehmann ◽  
Dani Or
Keyword(s):  
Energy Balance ◽  
Water Storage ◽  
Climatic Conditions ◽  
Heat Fluxes ◽  
Conservation Strategy ◽  
Radiative Energy ◽  
Water Reservoirs ◽  
Local Climate ◽  
Self Assembling ◽  
Evaporation Suppression

Abstract. The growing pressure on natural freshwater resources and the projected climate variability are expected to increase the need for water storage during rainy periods. Evaporative losses present a challenge for the efficiency of water storage in reservoirs, especially in arid regions with chronic water shortages. Among the available methods for suppressing evaporative losses, self-assembling floating elements offer a simple and scalable solution, especially for small reservoirs. The use of floating elements has often been empirically based; we thus seek a framework for systematic consideration of floating element properties, local climate and reservoir conditions to better predict evaporative loss, energy balance and heat fluxes from covered water reservoirs. We linked the energy balance of the water column with energy considerations of the floating elements. Results suggest significant suppression of evaporative losses from covered reservoirs in which incoming radiative energy is partitioned to sensible and long wave fluxes that reduce latent heat flux and thus increase the Bowen ratio over covered water reservoirs. Model findings were consistent with laboratory-scale observations using an uncovered and covered small basin. The study offers a physically based framework for testing design scenarios in terms of evaporation suppression efficiency for various climatic conditions; it hence strengthens the science in the basis of this important water resource conservation strategy.

scholarly journals ANALYSIS OF FACTORS THAT INFLUENCE THE USE OF IRRIGATION TECHNOLOGIES AND WATER MANAGEMENT PRACTICES IN ARKANSAS

2017 ◽  
Vol 49 (2) ◽  
pp. 159-185 ◽  
Author(s):  
QIUQIONG HUANG ◽  
YING XU ◽  
KENT KOVACS ◽  
GRANT WEST
Keyword(s):  
Water Management ◽  
Management Practices ◽  
Sprinkler Irrigation ◽  
Climate Factors ◽  
Average Temperature ◽  
Sprinkler Systems ◽  
Irrigation Technologies ◽  
The Impact

AbstractThis study investigates which factors may influence producers’ use of irrigation technologies and/or water management practices (WMPs). One major finding is that Arkansas producers are more likely to rely on WMPs instead of sprinkler irrigation as a response to changes in depth to water and drought occurrences. This finding highlights the importance of expanding the existing literature that focuses mostly on more efficient irrigation technologies, especially in areas where WMPs are more prevalent. Climate factors also play a role. Sprinkler systems are more prevalent in regions with lower average temperature. WMPs are used to mitigate the impact of more frequent droughts.

Research on Numerical Simulations of Pollutant of Sewage

2014 ◽  
Vol 522-524 ◽  
pp. 615-618
Author(s):  
Ying Wang ◽  
Wei Ye ◽  
Ming Chang Li
Keyword(s):  
Water Quality ◽  
Numerical Simulations ◽  
Environmental Problem ◽  
Concentration Field ◽  
Water Area ◽  
Marine Water ◽  
Tidal Water ◽  
Hydrodynamic Feature ◽  
And Diffusion

To study the ocean environmental problem, the article analyses and predicts the hydrodynamic feature of study area on the basis of Ecom model. After simulation of the contributed concentration field, the paper assesses the influence of the cyanide in discharge of sewage on the marine water quality nearby. Research shows that the results reflected the rules of transportation and diffusion of pollutants in the tidal water area bitterly.

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