scholarly journals Numerical Study on the Attenuation Effect of Water Mist on Thermal Radiation

2020 ◽  
Vol 34 (4) ◽  
pp. 7-12
Author(s):  
Gwon Hyun Ko
Keyword(s):  
Thermal Radiation ◽  
Droplet Size ◽  
Numerical Study ◽  
Water Mist ◽  
Spray Angle ◽  
Fire Dynamics ◽  
Radiation Attenuation ◽  
Attenuation Effect ◽  
Spray Droplets ◽  
Hot Surface

A numerical study was conducted to investigate the effects of the spray characteristics of water mist on the attenuation of thermal radiation. The attenuation process of the thermal radiation, generated from a hot surface panel, passing through the water mist was calculated via Fire Dynamics Simulator (FDS), and the effects of the flow rate, droplet mean diameter, and spray injecting angle of the water mist were analyzed. The results indicated that the increase in flowrate and decrease in droplet size led to an increase in the attenuation of thermal radiation. As the thermal radiation passed through the spray droplets, the effect of the spatial distribution of spray droplets was verified by calculating the thermal radiation attenuation at different spray injecting angles. The results indicated that the radiation attenuation increases as the spray angle increases. This implies that a wider distribution of spray droplets, irrespective of the droplet size and flowrate, increases the attenuation effect on thermal radiation.

scholarly journals Examination on Effects of Spray Characteristics of Water Mist on Thermal Radiation Attenuation Using Fire Dynamics Simulator

2021 ◽  
Vol 35 (1) ◽  
pp. 1-10
Author(s):  
Jae Geun Jo ◽  
Chi Young Lee
Keyword(s):  
Numerical Simulation ◽  
Thermal Radiation ◽  
Droplet Size ◽  
Flow Rate ◽  
Water Mist ◽  
Spray Angle ◽  
Fire Dynamics ◽  
Spray Characteristics ◽  
Radiation Attenuation ◽  
Fire Dynamics Simulator

In this study, numerical simulations to investigate the effects of the spray characteristics of water mist on thermal radiation attenuation were performed using fire dynamics simulator (FDS). The droplet size, flow rate, and spray angle of the water mist were 100-300 µm, 1-3 L/min, and 60-180°, respectively. As the droplet size decreased and flow rate increased, the thermal radiation attenuation increased. When the spray angles decreased and increased behind the near nozzle center and behind a certain remote distance from the nozzle center, respectively, the thermal radiation attenuation increased. The peak thermal radiation attenuation increased with decreases in droplet size and spray angle and an increase in flow rate, whereas the average thermal radiation attenuation increased with a decrease in droplet size and increases in flow rate and spray angle. Under the numerical simulation conditions of this study, the peak and average thermal radiation attenuations were significantly altered by the ratios of droplet size and flow rate and by that of flow rate, respectively. However, their variations with the ratio of spray angle were the smallest.

Experimental and numerical study on attenuation of thermal radiation from large-scale pool fires by water mist curtain

2015 ◽  
Vol 33 (4) ◽  
pp. 269-289 ◽  
Author(s):  
Pei Zhu ◽  
Xishi Wang ◽  
Zhigang Wang ◽  
Haiyong Cong ◽  
Xiaomin Ni
Keyword(s):  
Thermal Radiation ◽  
Large Scale ◽  
Numerical Study ◽  
Water Mist ◽  
Pool Fires

Numerical Study on the Interaction of Water Mist with a Fire Plume

2011 ◽  
Vol 130-134 ◽  
pp. 1730-1733
Author(s):  
Xiang Di Zhao ◽  
Hong Li Xu ◽  
Xi Shi Wang
Keyword(s):  
Velocity Field ◽  
Droplet Size ◽  
Mass Flow ◽  
Numerical Study ◽  
Critical Value ◽  
Water Mist ◽  
Temperature History ◽  
Fire Plume ◽  
Plume Temperature ◽  
Fluent Software

A numerical study on the interaction of water mist with a fire plume was conducted using FLUENT software. The effects of different mist characteristics, such as droplet size and spray intensity, was considered in this simulation. The fire plume temperature history and velocity field were investigated. The results show that with a certain droplet size of water mist, the extinguishing time will be shorter when the mass flow of water increases, but this effect is no longer distinct after the mass flow of water mist increased to a critical value.

scholarly journals Experimental Study on Thermal Radiation Attenuation Using Water Mist of Twin-fluid Atomizer

2021 ◽  
Vol 35 (4) ◽  
pp. 24-32
Author(s):  
Jae Geun Jo ◽  
Chi Young Lee
Keyword(s):  
Thermal Radiation ◽  
Water Flow ◽  
Flow Rate ◽  
Air Flow ◽  
Water Flow Rate ◽  
Water Mist ◽  
Air Flow Rate ◽  
Radiation Attenuation ◽  
Rate Condition ◽  
Flow Rates

In this study, the thermal radiation attenuation performance of water mist was investigated using twin-fluid atomizers. The water and air flow rates of Small atomizer were 36~105 g/min and 10~30 L/min, whereas those of Large atomizer were 37~300 g/min and 20~60 L/min, respectively. In the present experimental range, the thermal radiation attenuation of Small atomizer and Large atomizer were 6.1~11.9% and 5.2~14.6%, respectively. With the increase in water and air flow rates, the thermal radiation attenuation increased, and under similar water and air flow rate conditions, Small atomizer showed higher thermal radiation attenuation than Large atomizer. Based on the present experimental data, it was found that the air (gas) discharge area is a potentially important factor in determining the thermal radiation attenuation performance. Additionally, through the analysis of thermal radiation attenuation per unit water flow rate, it was confirmed that the twin-fluid atomizer can result in higher thermal radiation attenuation than the single-fluid atomizer under the same water flow rate condition.

Effect of soot on thermal radiation shielding performance of water mist

2021 ◽  
Vol 123 ◽  
pp. 103363
Author(s):  
Hiroki Gonome ◽  
Yuto Takagi ◽  
Taichi Nagao ◽  
Mizuho Ono
Keyword(s):  
Thermal Radiation ◽  
Water Mist ◽  
Radiation Shielding

scholarly journals Numerical Study toward Optimization of Spray Drying in a Novel Radial Multizone Dryer

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1233
Author(s):  
Umair Jamil Ur Rahman ◽  
Artur Krzysztof Pozarlik ◽  
Thomas Tourneur ◽  
Axel de Broqueville ◽  
Juray De Wilde ◽  
...  
Keyword(s):  
Spray Drying ◽  
Droplet Size ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Three Dimensional ◽  
Droplet Size Distribution ◽  
Vortex Chamber ◽  
Temperature Pattern ◽  
Multiphase Model ◽  
Drying Technology

In this paper, an intensified spray-drying process in a novel Radial Multizone Dryer (RMD) is analyzed by means of CFD. A three-dimensional Eulerian–Lagrangian multiphase model is applied to investigate the effect of solids outlet location, relative hot/cold airflow ratio, and droplet size on heat and mass transfer characteristics, G-acceleration, residence time, and separation efficiency of the product. The results indicate that the temperature pattern in the dryer is dependent on the solids outlet location. A stable, symmetric spray behavior with maximum evaporation in the hot zone is observed when the solids outlet is placed at the periphery of the vortex chamber. The maximum product separation efficiency (85 wt %) is obtained by applying high G-acceleration (at relative hot/cold ratio of 0.75) and narrow droplet size distribution (45–70 µm). The separation of different sized particles with distinct drying times is also observed. Smaller particles (<32 µm) leave the reactor via the gas outlet, while the majority of big particles leave it via the solids outlet, thus depicting in situ particle separation. The results revealed the feasibility and benefits of a multizone drying operation and that the RMD can be an attractive solution for spray drying technology.

Fire Suppression by Water-Mist Sprays: Experimental and Numerical Analysis

2010 ◽  
Author(s):  
Paolo E. Santangelo ◽  
Paolo Tartarini ◽  
Beatrice Pulvirenti ◽  
Paolo Valdiserri ◽  
Andre´ W. Marshall
Keyword(s):  
Numerical Analysis ◽  
Fire Suppression ◽  
Test Chamber ◽  
Water Mist ◽  
Specific Reference ◽  
Test Case ◽  
Fire Dynamics ◽  
Suppression Mechanism ◽  
Thermal Transient ◽  
Combustion Tests

Water-mist systems have become a promising technology in the fire-fighting field over the last twenty years. The present work is aimed at employing the available knowledge on water-mist sprays in an experimental and numerical analysis of the suppression mechanism. Therefore, a water-mist system has been operated within a typical fire case. Most notably, this latter is constituted by a heptane pool fire: experiments have been carried out inside a test chamber, where a set of thermocouples has conveniently been placed to evaluate the thermal transient at different locations of interest. Some free-combustion tests have been run as a benchmark to validate combustion models. Then, a typical water-mist nozzle has been inserted and activated to realize control, suppression and potential extinction of the generated fire. The recognized FDS (Fire Dynamics Simulator) and Fluent® codes have been challenged in reproducing the test case: thermal transient and suppression time have been considered as parameters for validation. Therefore, the water-mist spray has been modeled and the already mentioned results about its characterization have been implemented as initial or boundary conditions. Moreover, the fire scenario has been modeled as well. A good agreement between experimental and numerical results has been obtained, even under some approximations, with specific reference to combustion mechanisms.

Theoretical and numerical study on ignition behaviour of coal dust layers on a hot surface with corrected kinetic parameters

2019 ◽  
Vol 368 ◽  
pp. 156-162 ◽  
Author(s):  
Dejian Wu ◽  
Zeyang Song ◽  
Martin Schmidt ◽  
Qi Zhang ◽  
Xinming Qian
Keyword(s):  
Kinetic Parameters ◽  
Numerical Study ◽  
Coal Dust ◽  
Hot Surface
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