scholarly journals HORIZONTAL DIFFUSION IN TIDAL MODELS AND SCALING CRITEREA FOR THERMAL-HYDRAULIC MODEL TESTS

1976 ◽  
Vol 1 (15) ◽  
pp. 176
Author(s):  
Gerd Flugge
Keyword(s):  
Nuclear Power ◽  
Waste Heat ◽  
Water Discharge ◽  
Electric Energy ◽  
Cooling Water ◽  
Model Tests ◽  
West Germany ◽  
Energy Output ◽  
Heat Output ◽  
Storm Tide

Near Brokdorf at the lower Elbe river (West Germany) a nuclear power plant is projected. The electric energy output shall be 1300 MWe; therefore the waste heat output will be about 2600 MWe. The maximum allowed temperature rise in the condenser amounts to 10 K. Accordingly the cooling water discharge is about 61 m /s in case of the provided once through cooling. For the purpose of the mixing and spreading of the discharged cooling water by mean tidal conditions and storm-tide conditions model tests have been carried out at the Franzius-Institut of the Technical University of Hannover.

scholarly journals ADAPTABILITY OF PREDICTION METHOD OF HYDRAULIC MODEL EXPERIMENT FOR THERMAL DIFFUSION

1976 ◽  
Vol 1 (15) ◽  
pp. 175 ◽  
Author(s):  
Masanobu Kato ◽  
Akira Wang
Keyword(s):  
Heat Exchange ◽  
Nuclear Power ◽  
Water Discharge ◽  
Cooling Water ◽  
Prediction Method ◽  
Hydraulic Model ◽  
Surface Heat ◽  
Horizontal Scale ◽  
Vertical Scale ◽  
Surface Heat Exchange

In formation processes of the region of water temperature rise caused by the cooling water discharge from thermal and nuclear power stations located on the site facing the ocean, flow of discharged cooling water itself, current and turbulence existing in the sea region play an important role. Their motions are predominant in the horizontal direction in the sea region. The horizontal scale of thermal extent is, therefore, extremely larger than the vertical scale of thermal extent. Therefore, whenever the diffusion experiments of discharged warm water in the far field are conducted by hydraulic model method, the model which has a difference in the geometrical reduced rate between the horizontal and vertical directions, what is called, the distorted model must be used, so that the effects of the viscosity and the surface tension on the experimental model can be avoided. In such a model, the horizontal scale is determined by the relation between the size of the experimental water basin and the surface area of the sea region to be reproduced. But, there is no clear method of choosing the vertical scale, though there are some suggestions about it. For example, the similarity of the 4/3 power law of the diffusion coefficient gives a relation between the vertical scale and the horizontal scale of the hydraulic model. On the other hand, the similarity of the surface heat exchange coefficient gives another relation between the vertical scale and the horizontal scale of hydraulic model if the surface heat exchange coefficients of hydraulic model and prototype are not same. Therefore, it is better to give some allowance in the determination of the vertical scale of the hydraulic model within the range where the reproducibility of the diffusion phenomena can be conserved.

scholarly journals THERMAL DISCHARGES: PROTOTYPE vs. HYDRAULIC MODEL

1976 ◽  
Vol 1 (15) ◽  
pp. 173
Author(s):  
Gary C. Parker ◽  
C.S. Fang ◽  
Albert Y. Kuo
Keyword(s):  
Nuclear Power ◽  
Water Discharge ◽  
Cooling Water ◽  
Hydraulic Model ◽  
Physical Parameters ◽  
Thermal Discharge ◽  
James River ◽  
Model Experiments ◽  
Model Predictions ◽  
Physical Effects

Data on physical parameters in the James River around the condenser cooling water discharge of the Surry Nuclear Power Plant, taken prior to and during plant operation, were analyzed to determine the physical effects of the thermal discharge on the area and to compare the prototype distribution of excess temperature to predictions based on hydraulic model experiments. The results of this investigation indicated that the increase in water temperatures due to the thermal discharge did not represent a significant alteration of the physical environment outside the mixing zone. The thermal discharge experienced turbulent mixing and entrainment near the outfall and temperatures decreased rapidly in this region. Field data on temperature distributions around the discharge, when compared to predictions based on hydraulic model experiments, indicate that the model predictions were conservative.

Thermal Effects of Nuclear Power Stations

1974 ◽  
Vol 9 (1) ◽  
pp. 188-195
Author(s):  
G. Bethlendy
Keyword(s):  
Thermal Effects ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Sea Water ◽  
Waste Heat ◽  
Thermal Power ◽  
Cooling Water ◽  
District Heating ◽  
Before And After

Abstract Even with the latest technology, more than 60% of the heat produced by any thermal engine - whether the fuel is coal, oil, gas or uranium - must be taken back into the environment by cooling water or exhaust gas. For economical reasons, the usual means of disposing of the “waste” heat from a thermal-power plant is to pump river, lake or sea water through the parts of the plant concerned. Nuclear power plants use their heat as efficiently as older thermal plants, 30–33%. Modern thermal plants, however work with as high as 40% efficiency, and release about 10–13% of their total fuel-heat into the air through the stack. As a result of the combination of all these factors, nuclear power plants release about 68–70% of total input heat into the cooling water. In practice this means that the plant must be able to draw upon a source of cooling water which is large enough, which flows quickly or is cold enough not to be seriously effected by the return of warmed-up water from the power station. Where this is not possible, it may be necessary to build relatively expensive cooling ponds and/or towers so that the heat is also released to the air rather than only to a local body of water. The thermal effects could be detrimental or beneficial depending on the utilization of the water body. At the present time the utilities are aware of these problems and very extensive aquatic studies are being made before and after the construction of the plants. Some beneficial uses of waste heat are being sought via research and demonstration projects (e.g. in agriculture, aquaculture, district heating, etc.).

Research on the Law of Thermal Effect of Floating Nuclear Power Plants Thermal Discharge

2015 ◽  
Vol 799-800 ◽  
pp. 734-738
Author(s):  
Tian Qi Dai ◽  
Shi Wei Yao ◽  
Zhi Guo Wei
Keyword(s):  
Thermal Effect ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Water Discharge ◽  
Cooling Water ◽  
Cross Flow ◽  
Pollution Prevention ◽  
Thermal Pollution ◽  
Thermal Discharge

The waste heat emissions of thermal discharge from floating nuclear power plants may have a negative thermal effect on the environment. Study on the dilution and diffusion of cooling water plays an important role in thermal pollution prevention. The cooling water discharge process can be condensed into the thermal jet in cross flow. According to the theory of computational fluid dynamics, the mathematical model of round horizontal thermal jets in cross flow is established. The 3D numerical simulation of thermal jets based on finite volume method is achieved by using the Realizable k-ε turbulence model and the Semi-implicit method for pressure linked equations, and the three-dimensional trajectory of thermal jet are obtained. The rationality of analysis method is approved by comparing calculation value with experimental value. The temperature distributions in thermal jets are studied through the numerical experiments conducted under different cross-flow velocity and different emission angle. As a result, the impacts of these conditions on thermal pollution area are found, and the theoretic bases are provided for the design of the cooling water discharge pipe.

scholarly journals COOLING PROBLEMS IN THERMALLY POLLUTED RECIPIENTS

1973 ◽  
Vol 4 (4) ◽  
pp. 237-255
Author(s):  
TODOR MILANOV
Keyword(s):  
Waste Heat ◽  
Water Discharge ◽  
Cooling Water ◽  
Thermal Pollution ◽  
Warm Water ◽  
Excess Temperature ◽  
Receiving Waters

The extension of the warm water plume in receiving waters used as recipients for thermal pollution has been studied using a meteorological approach. For some real cases the area of excess temperature has been examined and compared to the conditions when heat is transferred to the atmosphere only. Numerical values are given for the warm water areas for different localities in Sweden for cooling water discharge corresponding to 2000 MW waste heat.

scholarly journals Reduction of CO2 Emissions in Steelmaking by Means of Utilization of Steel Plant Waste Heat to Stabilize Seasonal Cooling Water Temperature

2021 ◽  
Vol 13 (11) ◽  
pp. 5957
Author(s):  
Tomas Mauder ◽  
Michal Brezina
Keyword(s):  
Continuous Casting ◽  
Water Temperature ◽  
Co2 Emissions ◽  
Waste Heat ◽  
Cooling Water ◽  
Main Idea ◽  
Casting Process ◽  
Spray Cooling ◽  
Steel Plant ◽  
Cooling Water Temperature

Production of overall CO2 emissions has exhibited a significant reduction in almost every industry in the last decades. The steelmaking industry is still one of the most significant producers of CO2 emissions worldwide. The processes and facilities used at steel plants, such as the blast furnace and the electric arc furnace, generate a large amount of waste heat, which can be recovered and meaningfully used. Another way to reduce CO2 emissions is to reduce the number of low-quality steel products which, due to poor final quality, need to be scrapped. Steel product quality is strongly dependent on the continuous casting process where the molten steel is converted into solid semifinished products such as slabs, blooms, or billets. It was observed that the crack formation can be affected by the water cooling temperature used for spray cooling which varies during the year. Therefore, a proper determination of the cooling water temperature can prevent the occurrence of steel defects. The main idea is based on the utilization of the waste heat inside the steel plant for preheating the cooling water used for spray cooling in the Continuous Casting (CC) process in terms of water temperature stabilization. This approach can improve the quality of steel and contribute to the reduction of greenhouse gas emissions. The results show that, in the case of billet casting, a reduction in the cooling water consumption can be also reached. The presented tools for achieving these goals are based on laboratory experiments and on advanced numerical simulations of the casting process.

scholarly journals Techno-economic feasibility analysis of a 3-kW PV system installation in Nepal

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ramhari Poudyal ◽  
Pavel Loskot ◽  
Ranjan Parajuli
Keyword(s):  
Net Present Value ◽  
Meteorological Data ◽  
Electric Energy ◽  
Simulation Software ◽  
Economic Feasibility ◽  
Performance Ratio ◽  
Energy Output ◽  
Solar Pv ◽  
Economic Returns ◽  
Pv System

AbstractThis study investigates the techno-economic feasibility of installing a 3-kilowatt-peak (kWp) photovoltaic (PV) system in Kathmandu, Nepal. The study also analyses the importance of scaling up the share of solar energy to contribute to the country's overall energy generation mix. The technical viability of the designed PV system is assessed using PVsyst and Meteonorm simulation software. The performance indicators adopted in our study are the electric energy output, performance ratio, and the economic returns including the levelised cost and the net present value of energy production. The key parameters used in simulations are site-specific meteorological data, solar irradiance, PV capacity factor, and the price of electricity. The achieved PV system efficiency and the performance ratio are 17% and 84%, respectively. The demand–supply gap has been estimated assuming the load profile of a typical household in Kathmandu under the enhanced use of electric appliances. Our results show that the 3-kWp PV system can generate 100% of electricity consumed by a typical residential household in Kathmandu. The calculated levelised cost of energy for the PV system considered is 0.06 $/kWh, and the corresponding rate of investment is 87%. The payback period is estimated to be 8.6 years. The installation of the designed solar PV system could save 10.33 tons of CO2 emission over its lifetime. Overall, the PV systems with 3 kWp capacity appear to be a viable solution to secure a sufficient amount of electricity for most households in Kathmandu city.

scholarly journals Polycrystalline SnSe with a thermoelectric figure of merit greater than the single crystal

2021 ◽  
Author(s):  
Chongjian Zhou ◽  
Yong Kyu Lee ◽  
Yuan Yu ◽  
Sejin Byun ◽  
Zhong-Zhen Luo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Single Crystal ◽  
High Performance ◽  
Figure Of Merit ◽  
Waste Heat ◽  
Electric Energy ◽  
Cost Effective ◽  
Tin Selenide ◽  
Tin Oxides ◽  
Thermally Conductive

AbstractThermoelectric materials generate electric energy from waste heat, with conversion efficiency governed by the dimensionless figure of merit, ZT. Single-crystal tin selenide (SnSe) was discovered to exhibit a high ZT of roughly 2.2–2.6 at 913 K, but more practical and deployable polycrystal versions of the same compound suffer from much poorer overall ZT, thereby thwarting prospects for cost-effective lead-free thermoelectrics. The poor polycrystal bulk performance is attributed to traces of tin oxides covering the surface of SnSe powders, which increases thermal conductivity, reduces electrical conductivity and thereby reduces ZT. Here, we report that hole-doped SnSe polycrystalline samples with reagents carefully purified and tin oxides removed exhibit an ZT of roughly 3.1 at 783 K. Its lattice thermal conductivity is ultralow at roughly 0.07 W m–1 K–1 at 783 K, lower than the single crystals. The path to ultrahigh thermoelectric performance in polycrystalline samples is the proper removal of the deleterious thermally conductive oxides from the surface of SnSe grains. These results could open an era of high-performance practical thermoelectrics from this high-performance material.

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