Fog harvesting from cooling towers using metal mesh: Effects of aerodynamic, deposition, and drainage efficiencies

2019 ◽  
Vol 234 (7) ◽  
pp. 994-1014 ◽  
Author(s):  
Ritwick Ghosh ◽  
Ranjan Ganguly
Keyword(s):  
Fresh Water ◽  
Cooling Tower ◽  
Collection Efficiency ◽  
Fluid Dynamic ◽  
Tangential Velocity ◽  
Cooling Towers ◽  
Metal Mesh ◽  
Computational Fluid Dynamic Analysis ◽  
Fog Collection ◽  
Energy Penalty

Fog harvesting is recognized as an important alternate source of fresh water. Industrial fog can supplement water for industrial requirement. Collection of fog (drift droplets) from cooling tower plumes is a viable mode of industrial fog harvesting. The present study delves deeper into the findings of our earlier pilot investigation, on cooling tower fog harvesting and unravels how the collection efficiency depends on interaction of the mesh with the oncoming flow and the deposited fog droplets. Herein, we quantify the fog collection and explain the rationale of the individual contributions of aerodynamic, deposition, and drainage efficiencies on the overall collection efficiency. The effect of the mesh orientations and the tangential velocity component of the cooling tower plume (arising out of the cooling tower-fan rotation) are considered. Aerodynamic efficiency of the mesh and pressure drop across is estimated through computational fluid dynamic analysis. Also, an analysis of the force interaction between the mesh wires, deposited droplet, and the fog stream is carried out to identify the salient deterring factors like re-entrainment, clogging, and premature dripping of collected water droplets, based on which the regime of collection is mapped. The best collection configuration is found at an inclination of 15° with the vertical, with an overall collection efficiency of about 16%. The best configuration would allow recovery of re-usable fresh water at a nominal energy penalty of ∼3.9 kWh/m3. Our results offer the design bases for developing full-scale fog harvesting setups for industrial cooling towers.

Simulation of indoor comfort level in a building cooled by a cooling tower–concrete core cooling system under hot–semiarid climatic conditions

2016 ◽  
Vol 26 (5) ◽  
pp. 680-693 ◽  
Author(s):  
D. G. Leo Samuel ◽  
S. M. Shiva Nagendra ◽  
M. P. Maiya
Keyword(s):  
Indoor Air ◽  
Cooling Tower ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Climatic Conditions ◽  
Comfort Level ◽  
Passive Cooling ◽  
Computational Fluid Dynamic Analysis ◽  
Concrete Core ◽  
Core Cooling

Concrete core cooling system is an energy efficient alternative to the conventional mechanical cooling system. It provides better comfort due to direct absorption of radiation load, low indoor air velocity, apt vertical temperature gradient and absence of noise. It can be operated at relatively higher water temperature, which facilitates the use of passive cooling strategies. In this study, a cooling tower, which is an ‘evaporative cooling system’, is preferred over other passive cooling options due to its better cooling performance in dry regions and its ability to operate all through the day. This paper presents the results of computational fluid dynamic analysis of a room cooled by concrete core cooling system supported by a cooling tower. The study reveals that for a typical hot–semiarid summer climatic condition in India, the system reduces the average indoor air temperature to a comfortable range of 23.5 to 28℃ from an uncomfortable range of 35.3 to 41℃ in a building without cooling. The average predicted percentage of dissatisfied falls from 99.7% in a building without cooling, to 37.3% if roof and floor of a building are cooled with concrete core cooling system and further to 6.3% if all surfaces are cooled with concrete core cooling system.

Studies on Separation Efficiency and Energy Conservation Through Novel Finned Cyclone Separator

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Mahesh Dasar ◽  
Ranjit S. Patil
Keyword(s):  
Heat Exchanger ◽  
Energy Conservation ◽  
Cross Section ◽  
Separation Efficiency ◽  
Collection Efficiency ◽  
Rectangular Cross Section ◽  
Fluid Dynamic ◽  
Scale Up ◽  
Tangential Velocity ◽  
Cyclone Separator

Abstract In the present study, cylindrical portion of conventional (nonfinned) cyclone separator was reshaped by fixing triangular, semicircular, and rectangular cross section helical fins in order to make it as water wall having fin size 7 mm with fin pitch of 40 mm to improve its separation efficiency and to utilize the cyclone separator as heat exchanger. Fluid dynamic characteristics like axial velocity, tangential velocity, pressure drops were studied by varying the fin geometry (triangular/semicircular/rectangular). For the particles' size less than 3 μm, proposed cyclone separator with triangular helical fin was giving comparatively improved collection efficiency than other selected cyclone separators. Improvement in the collection efficiency of triangular fin-based cyclone separators was perceived from 5% to 10% over the conventional cyclone separator. Hence, helical fins with triangular in cross section were selected further for heat transfer and scale-up studies. It was observed that for the small barrel wall height (h = 400 mm) water temperature was enhanced by 4 °C, and with scale-up (making h = 800 mm) it was increased considerably around 15 °C. Thus based on improved separation efficiency to capture very-fine particulate matter (PM 2.5, which otherwise causes serious health issues) and considerable temperature gain of water noted at lab level scale-up study, triangular helical fins may be to fixed on the inner surface of barrel wall of conventional (nonfinned) cyclone separators in order to use them as heat exchanger for energy conservation in industrial applications.

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.

scholarly journals Cooling tower plume abatement and plume modeling: a review

2021 ◽  
Author(s):  
Shuo Li ◽  
M. R. Flynn
Keyword(s):  
Public Health ◽  
Solar Energy ◽  
Cooling Tower ◽  
Plume Rise ◽  
Cooling Towers ◽  
Moist Air ◽  
Novel Technologies ◽  
Plume Modeling ◽  
Dry Cooling Tower ◽  
Dry Cooling

AbstractVisible plumes above wet cooling towers are of great concern due to the associated aesthetic and environmental impacts. The parallel path wet/dry cooling tower is one of the most commonly used approaches for plume abatement, however, the associated capital cost is usually high due to the addition of the dry coils. Recently, passive technologies, which make use of free solar energy or the latent heat of the hot, moist air rising through the cooling tower fill, have been proposed to minimize or abate the visible plume and/or conserve water. In this review, we contrast established versus novel technologies and give a perspective on the relative merits and demerits of each. Of course, no assessment of the severity of a visible plume can be made without first understanding its atmospheric trajectory. To this end, numerous attempts, being either theoretical or numerical or experimental, have been proposed to predict plume behavior in atmospheres that are either uniform versus density-stratified or still versus windy (whether highly-turbulent or not). Problems of particular interests are plume rise/deflection, condensation and drift deposition, the latter consideration being a concern of public health due to the possible transport and spread of Legionella bacteria.

scholarly journals Optimal Air Conditioner Placement Using a Simple Thermal Environment Analysis Method for Continuous Large Spaces with Predominant Advection

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4663
Author(s):  
Tatsuhiro Yamamoto ◽  
Akihito Ozaki ◽  
Myonghyang Lee
Keyword(s):  
Air Conditioning ◽  
Thermal Environment ◽  
Fluid Dynamic ◽  
Optimal Placement ◽  
Air Conditioner ◽  
Analysis Method ◽  
Computational Fluid Dynamic Analysis ◽  
Environment Analysis ◽  
Air Conditioners ◽  
Energy Simulations

The number of houses with large, continuous spaces has increased recently. With improvements in insulation performance, it has become possible to efficiently air condition such spaces using a single air conditioner. However, the air conditioning efficiency depends on the placement of the air conditioner. The only way to determine the optimal placement of such air conditioners is to conduct an experiment or use computational fluid dynamic analysis. However, because the analysis is performed over a limited period, it is difficult to consider non-stationarity effects without using an energy simulation. Therefore, in this study, energy simulations and computational fluid dynamics analyses were coupled to develop a thermal environment analysis method that considers non-stationarity effects, and various air conditioner arrangements were investigated to demonstrate the applicability of the proposed method. The accuracy verification results generally followed the experimental results. A case study was conducted using the calculated boundary conditions, and the results showed that the placement of two air conditioners in the target experimental house could provide sufficient air conditioning during both winter and summer. Our results suggest that this method can be used to conduct preliminary studies if the necessary data are available during design or if an experimental house is used.

Predicting cooling tower plume dispersion

1997 ◽  
Vol 211 (4) ◽  
pp. 291-297 ◽  
Author(s):  
B E A Fisher
Keyword(s):  
Cooling Tower ◽  
Industrial Process ◽  
Local Environment ◽  
Meteorological Conditions ◽  
Performance Criteria ◽  
Plume Dispersion ◽  
Cooling Towers ◽  
Atmospheric Conditions ◽  
Operating Characteristics

An assessment of the effects of visible cooling tower plumes on the local environment can be a necessary part of any proposal for a new large industrial process. Predictions of the dispersion of plumes from cooling towers are based on methods developed for chimney emissions. However, the kinds of criteria used to judge the acceptability of cooling tower plumes are different from those used for stack plumes. The frequency of long elevated plumes and the frequency of ground fogging are the two main issues. It is shown that events associated with significant plume visibility are dependent both on the operating characteristics of the tower and on the occurrence of certain meteorological conditions. The dependence on atmospheric conditions is shown to be fairly complex and simple performance criteria based on the exit conditions from the tower are not sufficient for assessments.

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