scholarly journals Performance Analysis for Mechanical Draft Cooling Tower

2009 ◽  
Author(s):  
Si Y. Lee ◽  
James S. Bollinger ◽  
Alfred J. Garrett ◽  
Larry D. Koffman
Keyword(s):  
Water Droplet ◽  
Cooling Tower ◽  
Waste Heat ◽  
National Laboratory ◽  
Ambient Air ◽  
Savannah River ◽  
Ambient Conditions ◽  
Integral Test ◽  
Counter Current ◽  
The Impact

Industrial processes use mechanical draft cooling towers (MDCT’s) to dissipate waste heat by transferring heat from water to air via evaporative cooling, which causes air humidification. The Savannah River Site (SRS) has cross-flow and counter-current MDCT’s consisting of four independent compartments called cells. Each cell has its own fan to help maximize heat transfer between ambient air and circulated water. The primary objective of the work is to simulate the cooling tower performance for the counter-current cooling tower and to conduct a parametric study under different fan speeds and ambient air conditions. The Savannah River National Laboratory (SRNL) developed a computational fluid dynamics (CFD) model and performed the benchmarking analysis against the integral measurement results to accomplish the objective. The model uses three-dimensional steady-state momentum, continuity equations, air-vapor species balance equation, and two-equation turbulence as the basic governing equations. It was assumed that vapor phase is always transported by the continuous air phase with no slip velocity. In this case, water droplet component was considered as discrete phase for the interfacial heat and mass transfer via Lagrangian approach. Thus, the air-vapor mixture model with discrete water droplet phase is used for the analysis. A series of parametric calculations was performed to investigate the impact of wind speeds and ambient conditions on the thermal performance of the cooling tower when fans were operating and when they were turned off. The model was also benchmarked against the literature data and the SRS integral test results for key parameters such as air temperature and humidity at the tower exit and water temperature for given ambient conditions. Detailed results will be published here.

scholarly journals CFD Modeling Analysis of Mechanical Draft Cooling Tower

2008 ◽  
Author(s):  
Si Y. Lee ◽  
James S. Bollinger ◽  
Alfred J. Garrett ◽  
Larry D. Koffman
Keyword(s):  
Water Droplet ◽  
Cooling Tower ◽  
Waste Heat ◽  
National Laboratory ◽  
Ambient Air ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Test Results ◽  
Savannah River ◽  
The Impact

Industrial processes use mechanical draft cooling towers (MDCT’s) to dissipate waste heat by transferring heat from water to air via evaporative cooling, which causes air humidification. The Savannah River Site (SRS) has a MDCT consisting of four independent compartments called cells. Each cell has its own fan to help maximize heat transfer between ambient air and circulated water. The primary objective of the work is to conduct a parametric study for cooling tower performance under different fan speeds and ambient air conditions. The Savannah River National Laboratory (SRNL) developed a computational fluid dynamics (CFD) model to achieve the objective. The model uses three-dimensional momentum, energy, continuity equations, air-vapor species balance equation, and two-equation turbulence as the basic governing equations. It was assumed that vapor phase is always transported by the continuous air phase with no slip velocity. In this case, water droplet component was considered as discrete phase for the interfacial heat and mass transfer via Lagrangian approach. Thus, the air-vapor mixture model with discrete water droplet phase is used for the analysis. A series of the modeling calculations was performed to investigate the impact of ambient and operating conditions on the thermal performance of the cooling tower when fans were operating and when they were turned off. The model was benchmarked against the literature data and the SRS test results for key parameters such as air temperature and humidity at the tower exit and water temperature for given ambient conditions. Detailed modeling and test results will be presented here.

Economical Optimization of Integrated Cooling Tower by Solar Energy

2009 ◽  
Author(s):  
Mohammad Hassan Panjeshahi ◽  
Lena Ahmadi ◽  
Mona Gharaie
Keyword(s):  
Solar System ◽  
Solar Energy ◽  
Cooling Tower ◽  
Waste Heat ◽  
Weather Conditions ◽  
Ambient Air ◽  
Operational Conditions ◽  
Practical Applications ◽  
Economical Analysis ◽  
Economical Optimization

Nowadays, the visible impact of releases to the ambient has become a matter of greater concern due to the awareness of environmental degradation and protection among the society. Therefore, the contribution of renewable energies as the free and clean sources can provide environment-friendly solutions. However, little attention has been paid to the practical applications of the renewables. Cooling towers are widely used in industries and commercial buildings to dissipate waste heat to the ambient environment. During unfavorable weather conditions, the exhaust of the wet cooling tower remixes with the cooler ambient air and as it cools down the excess moisture condenses in small fog droplets, creating visible plume. The generated plume sometime can extend up to few hundred meters and causes invisibility and darkness problem. In this study, solar energy is integrated into wet cooling tower to reduce the visible plume formation. In this method, optimum solar system is achieved taking into consideration the economical analysis. Also, the operational conditions of cooling tower at various environmental states have been incorporated in targeting the optimum solar system through different scenarios. Related coding in MATLAB version 7.1 is developed for computations.

The Challenges of Turbocharger Matching for North American Freight Locomotives

2019 ◽  
Author(s):  
Thomas Lavertu ◽  
Matthew Hart ◽  
Christopher Homison ◽  
Preeti Vaidya
Keyword(s):  
North American ◽  
Engine Performance ◽  
Ambient Air ◽  
Ambient Conditions ◽  
Efficient Operation ◽  
Engine Efficiency ◽  
Air Temperatures ◽  
Wide Range ◽  
The Impact ◽  
Operating Points

Abstract Engine development is centered on developing a solution for best performance while meeting emissions and operational requirements. This will lead to a tradeoff between engine efficiency and emissions across a wide range of load and ambient operating points. Proper airflow to the engine through turbocharger matching is critical to ensure efficient operation and to meet emissions. This study addresses the challenges of turbocharger matching for vehicle advanced emissions control using a North American freight locomotive application as an example. The airflow trends in moving across the various operating points will be shown along with the impact on both the turbocharger and engine performance. First, the airflow trends across the locomotive load set points will be discussed along with the performance and emissions tradeoffs to meet required airflows. Results on the impact on turbocharger performance such as speed will be shown along with the engine efficiency and emissions implications. Next, the ambient operating requirements for a locomotive will be reviewed and the impact on turbocharger matching. Locomotives operate in a wide range of ambient conditions, including altitudes up to 3,050 meters and across ambient air temperatures ranging from −40 °C to well over 38 °C (including higher temperature operation). This thermal swing provides stress on the turbocharger to efficiently deliver the necessary airflow across all conditions. Trends in turbocharger performance will be reviewed and discussed across this range of ambient conditions. In addition, challenges unique to locomotive applications, such as unventilated tunnel operation and vibrational loading, will be reviewed. Finally, potential for advanced technologies such as variable geometry turbines and their applicability to locomotive operation will be discussed.

scholarly journals Comparative analysis and estimation of amounts of exhaust gas waste heat from the Tier III-compliant dual-fuel low-speed marine main engines

Pomorstvo ◽  
2021 ◽  
Vol 35 (1) ◽  
pp. 128-140
Author(s):  
Piotr Kamil Korlak
Keyword(s):  
Comparative Analysis ◽  
Co2 Emissions ◽  
Least Squares Method ◽  
Waste Heat ◽  
Emissions Reduction ◽  
Exhaust Gas ◽  
Ambient Conditions ◽  
Medium Speed ◽  
Technical Solutions ◽  
The Impact

Existing and future IMO restrictions on emission of harmful substances contained in exhaust gas have introduced an obligation to implement technical solutions to reduce NOX, SOX and CO2 emissions. Reduction in NOX and SOX emissions has been achieved by systems (i.e. SCR and EGR) ensuring Tier III-compliant exhaust gas composition. SCR and EGR systems have also affected the amount of exhaust gas waste heat. Therefore reduction in CO2 emissions has mostly been dependent on available amount of exhaust gas waste heat to produce electricity using waste heat recovery generator unit instead of medium-speed diesel generating set. Comparative analysis of amounts of exhaust gas waste heat in LNG and MGO modes under ISO ambient conditions has been carried out with particular emphasis on the impact of different variants of SCR and EGR systems. Formulae to estimate the amounts of exhaust gas waste heat have been determined using least squares method.

scholarly journals THEORETICAL ANALYSIS OF A WET COOLING TOWER FOR FRESH WATER FROM PLUME AND ANALYZING AN INDUSTRIAL COOLING TOWER BASED ON RESULTS

2017 ◽  
Vol 13 (10) ◽  
pp. 5892-5898
Author(s):  
Sella Muthu ◽  
C Manoharan ◽  
R Senthilkumar
Keyword(s):  
Theoretical Analysis ◽  
Mass Flow Rate ◽  
Fresh Water ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling Tower ◽  
Waste Heat ◽  
Water Flow Rate ◽  
Ambient Air ◽  
Water Yield

A cooling tower is a heat rejection device which rejects waste heat to the atmosphere through the cooling of a water stream to a lower temperature. The stream of saturated exhaust air leaving the cooling tower called the plume is visible when water vapor it contains condenses in contact with cooler ambient air, like the saturated air in one's breath fogs on a cold day. Under certain conditions, the cooling tower plume may present fogging or icing hazards to its surroundings and gives some environmental problems. To find the solution for this problem a cooling tower has been analysed based on air flow rate through the tower and the cooling load to obtain fresh water yield by utilising plume from cooling tower top. The theoretical analysis gives the values of important parameters Theoretical analysis has been done on wet cooling tower by varying the water flow rate through which affect the performance of a cooling tower such as the cooling range, effectiveness, approach, fresh water yield etc. Then with the conditions of a trials from the analysis, the mass flow rate of water in the cooling tower was scaled up to match the mass flow rate of water in an industrial cooling tower. This helps in obtaining the mass flow rate of the air and fresh water yield through the industrial cooling tower.

Case study: Theoretical calculation model and variable condition analysis research on the water-splashing noise for natural draft wet cooling towers

2020 ◽  
Vol 68 (2) ◽  
pp. 137-145
Author(s):  
Yang Zhouo ◽  
Ming Gao ◽  
Suoying He ◽  
Yuetao Shi ◽  
Fengzhong Sun
Keyword(s):  
Theoretical Model ◽  
Sound Pressure Level ◽  
Water Droplet ◽  
Water Distribution ◽  
Sound Pressure ◽  
Cooling Tower ◽  
Distribution Patterns ◽  
Calculation Model ◽  
Pressure Level ◽  
Cooling Towers

Based on the basic theory of water droplets impact noise, the generation mechanism and calculation model of the water-splashing noise for natural draft wet cooling towers were established in this study, and then by means of the custom software, the water-splashing noise was studied under different water droplet diameters and water-spraying densities as well as partition water distribution patterns conditions. Comparedwith the water-splashing noise of the field test, the average difference of the theoretical and the measured value is 0.82 dB, which validates the accuracy of the established theoretical model. The results based on theoretical model showed that, when the water droplet diameters are smaller in cooling tower, the attenuation of total sound pressure level of the water-splashing noise is greater. From 0 m to 8 m away from the cooling tower, the sound pressure level of the watersplashing noise of 3 mm and 6 mm water droplets decreases by 8.20 dB and 4.36 dB, respectively. Additionally, when the water-spraying density becomes twice of the designed value, the sound pressure level of water-splashing noise all increases by 3.01 dB for the cooling towers of 300 MW, 600 MW and 1000 MW units. Finally, under the partition water distribution patterns, the change of the sound pressure level is small. For the R s/2 and Rs/3 partition radius (Rs is the radius of water-spraying area), when the water-spraying density ratio between the outer and inner zone increases from 1 to 3, the sound pressure level of water-splashing noise increases by 0.7 dB and 0.3 dB, respectively.

Key Aspects of Assessing Effectiveness and Efficiency of Implementation of the Federal Clean Air Project on the Example of the Comprehensive Emission Reduction Action Plan in Nizhny Tagil

2020 ◽  
pp. 48-60
Author(s):  
SV Yarushin ◽  
DV Kuzmin ◽  
AA Shevchik ◽  
TM Tsepilova ◽  
VB Gurvich ◽  
...  
Keyword(s):  
Emission Reduction ◽  
Action Plan ◽  
Local Population ◽  
Ambient Air ◽  
Ambient Air Pollution ◽  
Mortality And Morbidity ◽  
Industrial Enterprises ◽  
Clean Air ◽  
Effectiveness And Efficiency ◽  
The Impact

Introduction: Key issues of assessing effectiveness and economic efficiency of implementing the Federal Clean Air Project by public health criteria are considered based on the example of the Comprehensive Emission Reduction Action Plan realized in the city of Nizhny Tagil, Sverdlovsk Region. Materials and methods: We elaborated method approaches and reviewed practical aspects of evaluating measures taken in 2018–2019 at key urban industrial enterprises accounting for 95 % of stationary source emissions. Results: Summary calculations of ambient air pollution and carcinogenic and non-carcinogenic inhalation health risks including residual risks, evaluation of the impact of air quality on urban mortality and morbidity rates, economic assessment of prevented morbidity and premature mortality cases have enabled us not only to estimate health effects but also to develop guidelines for development and implementation of actions aimed at enhancing effectiveness and efficiency of industrial emission reduction in terms of health promotion of the local population. Conclusions: We substantiate proposals for the necessity and sufficiency of taking remedial actions ensuring achievement of acceptable health risk levels as targets of the Comprehensive Emission Reduction Action Plan in Nizhny Tagil until 2024 and beyond.

scholarly journals The impact of measures to reduce ambient air PM<sub>10</sub> concentrations originating from road dust, evaluated for a street canyon in Helsinki

2019 ◽  
Vol 19 (17) ◽  
pp. 11199-11212 ◽  
Author(s):  
Ana Stojiljkovic ◽  
Mari Kauhaniemi ◽  
Jaakko Kukkonen ◽  
Kaarle Kupiainen ◽  
Ari Karppinen ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Air Quality ◽  
Street Canyon ◽  
Dust Emission ◽  
Road Dust ◽  
Ambient Air ◽  
Air Quality Measurements ◽  
Emission Models ◽  
The Impact ◽  
Quality Measurements

Abstract. We have numerically evaluated how effective selected potential measures would be for reducing the impact of road dust on ambient air particulate matter (PM10). The selected measures included a reduction of the use of studded tyres on light-duty vehicles and a reduction of the use of salt or sand for traction control. We have evaluated these measures for a street canyon located in central Helsinki for four years (2007–2009 and 2014). Air quality measurements were conducted in the street canyon for two years, 2009 and 2014. Two road dust emission models, NORTRIP (NOn-exhaust Road TRaffic Induced Particle emissions) and FORE (Forecasting Of Road dust Emissions), were applied in combination with the Operational Street Pollution Model (OSPM), a street canyon dispersion model, to compute the street increments of PM10 (i.e. the fraction of PM10 concentration originating from traffic emissions at the street level) within the street canyon. The predicted concentrations were compared with the air quality measurements. Both road dust emission models reproduced the seasonal variability of the PM10 concentrations fairly well but under-predicted the annual mean values. It was found that the largest reductions of concentrations could potentially be achieved by reducing the fraction of vehicles that use studded tyres. For instance, a 30 % decrease in the number of vehicles using studded tyres would result in an average decrease in the non-exhaust street increment of PM10 from 10 % to 22 %, depending on the model used and the year considered. Modelled contributions of traction sand and salt to the annual mean non-exhaust street increment of PM10 ranged from 4 % to 20 % for the traction sand and from 0.1 % to 4 % for the traction salt. The results presented here can be used to support the development of optimal strategies for reducing high springtime particulate matter concentrations originating from road dust.

scholarly journals The Impact of Ambient Atmospheric Mineral-Dust Particles on the Calcification of Lungs

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 125
Author(s):  
Mariola Jabłońska ◽  
Janusz Janeczek ◽  
Beata Smieja-Król
Keyword(s):  
Mineral Dust ◽  
Smoking Habit ◽  
Lower Lobe ◽  
Ambient Air ◽  
Dust Particles ◽  
Masking Effect ◽  
Amorphous Calcium Carbonate ◽  
Calcium Salts ◽  
The Impact ◽  
First Time

For the first time, it is shown that inhaled ambient air-dust particles settled in the human lower respiratory tract induce lung calcification. Chemical and mineral compositions of pulmonary calcium precipitates in the lung right lower-lobe (RLL) tissues of 12 individuals who lived in the Upper Silesia conurbation in Poland and who had died from causes not related to a lung disorder were determined by transmission and scanning electron microscopy. Whereas calcium salts in lungs are usually reported as phosphates, calcium salts precipitated in the studied RLL tissue were almost exclusively carbonates, specifically Mg-calcite and calcite. These constituted 37% of the 1652 mineral particles examined. Mg-calcite predominated in the submicrometer size range, with a MgCO3 content up to 50 mol %. Magnesium plays a significant role in lung mineralization, a fact so far overlooked. The calcium phosphate (hydroxyapatite) content in the studied RLL tissue was negligible. The predominance of carbonates is explained by the increased CO2 fugacity in the RLL. Carbonates enveloped inhaled mineral-dust particles, including uranium-bearing oxides, quartz, aluminosilicates, and metal sulfides. Three possible pathways for the carbonates precipitation on the dust particles are postulated: (1) precipitation of amorphous calcium carbonate (ACC), followed by its transformation to calcite; (2) precipitation of Mg-ACC, followed by its transformation to Mg-calcite; (3) precipitation of Mg-free ACC, causing a localized relative enrichment in Mg ions and subsequent heterogeneous nucleation and crystal growth of Mg-calcite. The actual number of inhaled dust particles may be significantly greater than was observed because of the masking effect of the carbonate coatings. There is no simple correlation between smoking habit and lung calcification.

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