Numerical Study of the Effects of Injection Fluctuations on Liquid Nitrogen Spray Cooling

Xue, Renyu; Ruan, Yixiao; Liu, Xiufang; Chen, Liang; Liu, Liqiang; Hou, Yu

doi:10.3390/pr7090564

Cited by 12 publications

(9 citation statements)

References 30 publications

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Section: Degree Of Superheat Under Different Release Pressuresmentioning

confidence: 99%

“…It is reported that the flow and diffusion characteristics will be greatly affected in a complex unsteady flow field yielded by the different release pressures [20]. Different from the conventional liquid jet, which is greatly dependent on the surface evaporation of the broken liquid droplets, the thermodynamic parameters are the main factors that affect the jet characteristics of the gas fire extinguishing agent.…”

Section: Degree Of Superheat Under Different Release Pressuresmentioning

confidence: 99%

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Flow and Diffusion Characteristics of Typical Halon Extinguishing Agent Substitute under Different Release Pressures

et al. 2020

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To provide guidance towards reducing the weight of the HFC-125 storage vessel by reducing the release pressure and to reveal the effects of release pressure on the extinguishing efficiency of HFC-125, we investigated the flow and diffusion characteristics of HFC-125 under six release pressures in the present study. The influence of release pressure on the degree of superheat, injection duration, pressure loss, jet angle, and concentration distribution were analyzed. Results show that the degree of superheat and the injection duration both decreased with the release pressure. The bubble expansion in the HFC-125 could slow down the pressure decrease in the storage vessel. The flow process in the pipeline can be divided into three phases: pipeline filling, stable flow, and mixed gases release. Both of the maximum and mean values of the pipeline pressure loss increased with the release pressure. The maximum concentration value decreased with the increase of the distance from the nozzle. The maximum concentration value in the near field from the nozzle increased with the release pressure. The concentration and holding time (duration above 17.6% volume concentration) of HFC-125 in the near field from the nozzle met the requirements of minimum performance standards (MPS) for HFC-125.

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Section: Degree Of Superheat Under Different Release Pressuresmentioning

confidence: 99%

Section: Degree Of Superheat Under Different Release Pressuresmentioning

confidence: 99%

Flow and Diffusion Characteristics of Typical Halon Extinguishing Agent Substitute under Different Release Pressures

et al. 2020

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“…Due to the particularity of the aircraft as an important air traffic tool, extremely high requirements for both reliability and economy are put forward for the performance of its fire extinguishing system [2][3][4][5]. As an important component of fire extinguishing systems, nozzles usually have a vital impact on the flow and release characteristics of the extinguishing agent, and their release performance has become one of the hot spots of the fire extinguishing technology research in recent years [6][7][8][9][10][11][12][13][14]. Studies have shown that even if the nozzle structure is axisymmetric, the flow field inside it will be asymmetrically distributed [14].…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles

He²,

Chen³

et al. 2021

Symmetry

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In order to guide the optimization design of the nozzle of the aircraft-fixed gas fire extinguishing system, we studied the influence of nozzle geometric parameters including outlet–inlet area ratio, length–diameter aspect ratio, and wall roughness on the distribution of pressure and velocity in the nozzle on the basis of CFD simulations. Although the structure of the nozzle is axisymmetric, the spatial distribution of the pressure and velocity during the flow and release of gas extinguishing agent is not completely symmetric. It was found that both of the outlet–inlet area ratio (δ) and the length–diameter aspect ratio (ξ) had a significant impact on the distribution characteristics of the pressure and axial velocity in the nozzle. With the increase of δ, the average pressure at the outlet cross-section of the nozzle decreased monotonically, while the average axial velocity at the outlet increased approximately linearly. When ξ≥2, the uniformity of the pressure and velocity distribution at the nozzle outlet was significantly improved. Moreover, with the increase of ξ, the average pressure and the average axial velocity of the outlet both showed a non-monotonic change trend, and the optimal value of ξ should be about 3.0. Compared with δ and ξ, the influence of the nozzle wall roughness (εN) on the flow and release characteristics of the extinguishing agent was weak. With the increase of εN, the average pressure of the nozzle outlet increased slightly, while the average axial velocity at the nozzle outlet decreased slightly.

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“…The application was used as an open cycle in a cooling system. Moreover, Xue et al [15] showed in their study, the influence of different injection pressures on the nozzle inside diameter, the mass flow rate, drop size distribution, discharge coefficient, spray flow pattern, and spray cone angle were studied. Most recently, Wang et al [16] were conducted theoretical analysis and numerical study liquid nitrogen spray as a cryogenic cooling fluid in electronic equipment under low pressure.…”

Section: Introductionmentioning

confidence: 99%

Prediction of the Initial Drop Size and Velocity Distribution in the Cold Cryogenic Spray

Majhool¹,

Jasim²

2020

IJHT

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The polydispersed nature of the spray is captured through the use of probability density functions based on the maximum entropy method to stand for the complete atomization characteristics of spray dynamics. The droplet and velocity size distributions are practical tools for the analysis of sprays cooling. The special benefit of the model is a Eulerian based which is less computationally intensive when compared to models that are based on the Lagrangian approach that tracks droplet parcel. The accuracy of using Lagrangian approach in polydispersed phase is always accurately less than Eulerian approach because it depends on the number of parcels while in Eulerian approach it depends on the proposed continuous distribution function. The main intent of the current work is to evaluate the capability of using the model for the initial predictions of the droplet size and velocity distribution for liquid nitrogen spray of solid-cone pressure swirl nozzle. The use of liquid injection pressure cases of up to 0.6MPa and spray cone angles of just 30◦ from three different sets of experimental data. The results being characterized are spray drop size distribution, liquid volume fraction and spray cone angle values. The unsteady analyses of the effect of injection pressure are studied on the cryogenic liquid nitrogen. The numerical results show that the maximum entropy method applies to liquid cryogenic spray and indicates that the model reacts correctly to changes in different injection pressures. Comparisons are also made with measured drop size distribution data that are reasonably captured and the spray cone angle is found to be in good agreement during initial and far-field spray angles.

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Numerical Study of the Effects of Injection Fluctuations on Liquid Nitrogen Spray Cooling

Cited by 12 publications

References 30 publications

Flow and Diffusion Characteristics of Typical Halon Extinguishing Agent Substitute under Different Release Pressures

Flow and Diffusion Characteristics of Typical Halon Extinguishing Agent Substitute under Different Release Pressures

Numerical Study on Effects of Geometric Parameters on the Release Characteristics of Straight Sudden Expansion Gas Extinguishing Nozzles

Prediction of the Initial Drop Size and Velocity Distribution in the Cold Cryogenic Spray

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