Numerical simulation of water spray in natural draft dry cooling towers with a new nozzle representation approach

Alkhedhair, Abdullah M.; Jahn, Ingo; Gurgenci, Hal; Guan, Zhiqiang; He, Suoying; Lu, Yuanwei

doi:10.1016/j.applthermaleng.2015.10.118

Cited by 47 publications

(22 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Only a brief summary of the numerical model is provided here. The model has been validated against experimental studies in an experimental rig of the same geometry [126].…”

Section: Numerical Details and Spray Generationmentioning

confidence: 99%

“…Since previous studies are limited to single point injection, this study investigate the spray characteristics parameters that determine an effective nozzle design in terms of spray cooling performance using a practical nozzle representation approach developed by Alkhedhair [126]. The implemented nozzle representation method allows describing nozzle behaviour at the breakup length in a 3D form which relates to the performance of a real nozzle.…”

Section: Approachmentioning

confidence: 99%

“…Furthermore, within the spray cloud, there is a radial variation of droplet size distribution. A novel nozzle representation method developed by Alkhedhair [126] has been implemented which accounts for the droplet size radial variation by defining the initial spray characteristics with different concentric circles that have different initial spray characterises. This approach also accounts for the momentum exchange in the primary atomization region by using the water jet velocity.…”

Section: Figure 2 Computational Domainmentioning

confidence: 99%

“…The D10 and D32 values were obtained at the breakup length along the spray centre lines. The separation distance between measurement points is 12-13 mm and based on the spray plume widths at their breakup lengths [126]. …”

Section: Experimental Observationsmentioning

confidence: 99%

See 3 more Smart Citations

Modelling and experimental study of spray cooling systems for inlet air pre-cooling in natural draft dry cooling towers

Alkhedhair¹

View full text Add to dashboard Cite

Geothermal energy is a promising renewable energy to be used for baseload electricity. Most potential sites with high geothermal temperature are mostly located in remote areas where water is limited. This is besides water scarcity and environmental protection, which made dry cooling systems a better alternative solution for heat rejection of power plants. Furthermore, natural draft cooling towers have the advantage of avoiding parasitic losses introduced by the fans at mechanical draft cooling towers. However, power plants utilizing dry cooling technologies experience a significant reduction in power generation during high ambient temperature periods. This reduction often goes along with the peak power demand which results in a great loss for the power plant owners. In certain instances, dry cooling tower performance can be enhanced during these periods by pre cooling of the inlet air by spraying atomized water into the inlet air.The present study introduces the use of spray cooling for inlet air pre-cooling in natural draft cooling towers. Spray cooling is investigated in this study due to its simplicity, low capital cost, ease of operation and maintenance, and capability of increasing power plant efficiency while consuming only a small amount of water compared to wet cooling towers or other evaporative cooling methods. Although spray cooling has found successful applications in process coolers and gas turbine inlet air cooling, the large scale applications in power industry have been limited.Several issues limit the application in power industry. The main one is the incomplete evaporation of water droplets which can cause corrosion and scaling of heat exchanger surface. Incomplete evaporation also increases operational cost due to water consumption. To the best of our knowledge, a detailed investigation of the spray cooling performance in natural draft dry cooling towers operating environment has not yet been performed. The aim of the current work is to optimise a spray cooling system for inlet air pre-cooling in natural draft dry cooling towers.In the present study, an Eulerian-Lagrangian 3-D numerical model was developed which is capable of simulating evaporating water sprays produced by real nozzles. In order to reproduce real nozzle characteristics in the simulation, a new adaptable method for hollow-cone spray representation in Eulerian-Lagrangian numerical models was developed. This allows real nozzles characterised during experiments to be included in the simulation, thereby correctly accounting for radial evolution of droplet size distribution and air/droplets momentum exchange. The CFD model was applied to calculate local droplet transport and evaporation, and spray cooling efficiency at different operating conditions for spray cooling systems optimisation under typical Natural Draft Dry Cooling Tower conditions.iii Experimental measurements from a wind tunnel test rig simulating Natural Draft Dry Cooling Tower inlet flow conditions have been performed in order to investigate droplet transport...

show abstract

“…Only a brief summary of the numerical model is provided here. The model has been validated against experimental studies in an experimental rig of the same geometry [126].…”

Section: Numerical Details and Spray Generationmentioning

confidence: 99%

Section: Approachmentioning

confidence: 99%

Section: Figure 2 Computational Domainmentioning

confidence: 99%

Section: Experimental Observationsmentioning

confidence: 99%

See 2 more Smart Citations

Modelling and experimental study of spray cooling systems for inlet air pre-cooling in natural draft dry cooling towers

Alkhedhair¹

View full text Add to dashboard Cite

show abstract

“…A key aspect in spray system design is the fluid delivery, particularly the nozzle design (Alkhedhair et al, 2016).…”

Section: Experimental Spray Analysismentioning

confidence: 99%

On the Usage of Saline Water in Spray Assisted Natural Draft Dry Cooling Towers

Sadafi¹

View full text Add to dashboard Cite

Cooling towers are used to reject heat to the surrounding air in power plants. In thermal power plants the hot temperature of the cycle reaches up to 600-700 o C. As power plant thermal efficiency is limited by the Carnot efficiency (1-Tc/Th), it is important to minimize the heat rejection temperature (Tc) to increase total efficiency. When water is available, wet cooling towers are a good solution. However due to water scarcity and reduced energy consumption during their lifetime, dry cooling towers are becoming the preferred alternative.In dry cooling towers, air is either pushed through the heat exchangers using fans or using the chimney effect. Dry cooling relies on air-dry bulb temperature, which can affect power generation during hot summer days. The efficiency losses during hot days (high Tc) can be mitigated by spray cooling the inlet air. This reduces the air temperature to the wet-bulb temperature, thereby increasing the dry cooling tower efficiency significantly.Industry currently uses fresh water for hybrid cooling, which is expensive and can lead to environmental issues. An alternative is to use saline water or water containing dissolved solids that is created as an industrial by-product. This work focuses on coal seam gas (CSG) water that is produced during the production of natural gas from coal-bed methane and is readily available in arid regions of Queensland.To investigate saline water spray this project is divided into three parts: analysis of single droplet evaporation, investigation of saline water spraying, and performance evaluation between saline water and pure water sprays.To investigate the evaporation from single droplets, an improved four-stage model is presented. This captures the size, temperature, and evaporation rate of solid containing droplets more accurately than those in literature. This new model includes an additional stage that models the transient formation of the crust which starts from the bottom until the entire droplet is enclosed. Based on the wide-ranged experimental tests in this study, a comparison of evaporation potential (ability to absorb energy) of pure and saline droplets was performed. This showed that saline droplet consume less energy per unit mass (7.3% for 3% salinity) due to a portion of the weight being occupied by dissolved solids.After understanding the evaporation process of a single saline water droplet, a lower order numerical model to simulate saline droplets in a spray was developed. This model uses a standard multicomponent droplet model, which is fine tuned using data obtained from observing NaCl crystals using scanning electron microscope, to set correct evaporation properties and to create the correct solid particles. The resulting modelling framework was III used to analyse the effect of saline water on spray cooling. The sensitivity study showed that initial droplets size and water mass flow rate have the largest impact on the minimum distance between nozzle and heat exchangers (wet length) and cooling efficiency. The wet length ...

show abstract

Adiabatic Efficiency of Monoblock Air Supply Unit with Humidification Module Based on Porous Rotating Atomizers

Sibgatullin

Сафиуллин

2022

Lecture Notes in Civil Engineering

View full text Add to dashboard Cite

Numerical simulation of water spray in natural draft dry cooling towers with a new nozzle representation approach

Cited by 47 publications

References 31 publications

Modelling and experimental study of spray cooling systems for inlet air pre-cooling in natural draft dry cooling towers

Modelling and experimental study of spray cooling systems for inlet air pre-cooling in natural draft dry cooling towers

On the Usage of Saline Water in Spray Assisted Natural Draft Dry Cooling Towers

Adiabatic Efficiency of Monoblock Air Supply Unit with Humidification Module Based on Porous Rotating Atomizers

Contact Info

Product

Resources

About