Numerical modeling and experimental measurements of a high speed solid-cone water spray for use in fire suppression applications

Yoon, Sam S.; Hewson, John C.; DesJardin, Paul E.; Glaze, D. J.; Black, Amalia R.; Skaggs, R. R.

doi:10.1016/j.ijmultiphaseflow.2004.07.006

Cited by 47 publications

(35 citation statements)

References 30 publications

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“…where cumulative density function (CDF) is the fraction of the total volume contained in drops of diameter less than D. The characteristic droplet size, X , can be expressed as X = D 10 = (1=q + 1) [40], where D 10 is the arithmetic mean diameter. is the gamma function, and q, so-called, 'dispersion coe cient', indicates the width of the distribution.…”

Section: Drop Size Distributionmentioning

confidence: 99%

A nonlinear atomization model for computation of drop size distributions and spray simulations

Park¹,

Yoon

Heister³

2005

Numerical Methods in Fluids

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SUMMARYA model has been developed to provide a comprehensive simulation of a spray formed by a high-speed liquid jet. The primary atomization process is simulated in a completely nonlinear fashion using the boundary element method under the assumption of axisymmetric, inviscid ow. The presence of the oriÿce boundary layer is simulated with a ring vortex whose strength and location are uniquely determined from boundary layer properties at the oriÿce exit plane. Droplet and axisymmetric ligament tracking models have been developed to provide more comprehensive spray simulations. The breakup of the axisymmetric ligaments shed from the parent surface is assessed both in a nonlinear fashion as well as using the linear stability analysis of Ponstein. Using this latter approach, drop size distributions have been generated from ÿrst principles and compared with the popular Rosin-Rammler model.

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Section: Drop Size Distributionmentioning

confidence: 99%

A nonlinear atomization model for computation of drop size distributions and spray simulations

Park¹,

Yoon

Heister³

2005

Numerical Methods in Fluids

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“…This emphasises the importance of nozzle arrangement to ensure effective cooling. Although CFD simulation for water spray performance is a powerful tool, it is a challenging task with respect to spray initialization in Lagrangian modeling approaches [114]. The performance of spray cooling systems is sensitive to initial injection parameters [20,115].…”

Section: Chapter Summarymentioning

confidence: 99%

“…Although CFD simulation for water spray performance is a powerful tool, it is a challenging task with respect to spray initialization into the Lagrangian modeling approaches [114]. While there have been improvements in spray characterisation methods, it is very difficult to accurately predict initial spray characteristics with available breakup models [114].…”

Section: Nozzle Representationmentioning

confidence: 99%

“…While there have been improvements in spray characterisation methods, it is very difficult to accurately predict initial spray characteristics with available breakup models [114]. Moreover, break-up models are not available for all nozzle types.…”

Section: Nozzle Representationmentioning

confidence: 99%

“…The uncertianties in the PDPA measurment of droplet size and droplet velocity are estimated at 10-15% [114]. The PDPA system was positioned on a 3D-traverse system with a positioning accuracy of 10 µm.…”

Section: Spray Characterisationmentioning

confidence: 99%

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

Alkhedhair¹

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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...

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Computational and experimental studies of electrohydrodynamic atomization for pharmaceutical particle fabrication

2012

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Electrohydrodynamic atomization (EHDA) is a promising method for the fabrication of micro‐ and nanosized particles with narrow‐size distribution and better morphologies in comparison to conventional methods of particle fabrication. A computational model was developed in this study to simulate the fluid and particle dynamics in an EHDA chamber, and thereby providing a means of predicting particle collection efficiencies at various operating conditions. Experiments were also conducted using a new design of the EHDA chamber. It was found that nitrogen flow rate, solution flow rate and voltage difference between the nozzle and ring can significantly affect the particle collection efficiency of the EHDA process. Electric field and electric potential profiles in the chamber were significantly affected by the combined voltages of the nozzle and ring. In general, a good qualitative agreement in particle collection efficiencies was obtained from experiments and simulations. The computational model developed in this study provided a means of understanding the various processes involved in micro‐ and nano‐sized particle fabrication using the EHDA methodology. © 2012 American Institute of Chemical Engineers AIChE J, 2012

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Numerical modeling and experimental measurements of a high speed solid-cone water spray for use in fire suppression applications

Cited by 47 publications

References 30 publications

A nonlinear atomization model for computation of drop size distributions and spray simulations

A nonlinear atomization model for computation of drop size distributions and spray simulations

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

Computational and experimental studies of electrohydrodynamic atomization for pharmaceutical particle fabrication

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