Experimental Investigation on Aerosol-Particle Sustaining Characteristics of a Porous-Walled Tube

2018 ◽  
Vol 765 ◽  
pp. 131-135
Author(s):  
Kyung Won Kim ◽  
Brandon Y. Boeur ◽  
Sin Jae Hyun ◽  
Cheol Woo Park
Keyword(s):  
Aerosol Particle ◽  
Tube Wall ◽  
Porous Wall ◽  
Working Fluid ◽  
Particle Sizes ◽  
Tube Model ◽  
Body Temperatures ◽  
Temperature Variations ◽  
Significance Level ◽  
Wall Condition

In the present study, we experimentally investigated the aerosol-particle sustaining features of a porous-walled rubber foam tube model according to outlet humidity and temperature variations. An oleic acid aerosol is used as the inlet working fluid and the embedded particle diameters are in the range of 6–10 μm. To analyze particle size distribution, a wide-ranging particle spectrometer is employed, and particle sizes are measured at the inlet and outlet of the tube. Variance analysis is performed to evaluate the significance level of various tube-wall conditions, including dry and moist aerosol conditions at room and body temperatures. For the cases of larger particle sizes, the sustaining rates are increased when the porous wall condition is moist and at body temperature.

scholarly journals Numerical Analysis on Rib-Tubes of Seawater Open Rack Vaporizer With the Spoiler Lever

2017 ◽  
Vol 24 (s2) ◽  
pp. 14-21
Author(s):  
Su Houde ◽  
Yu Shurong ◽  
Fan Jianling ◽  
Wei Xing
Keyword(s):  
Heat Transfer ◽  
Tube Wall ◽  
Small Difference ◽  
Operating Temperature ◽  
Operating Parameter ◽  
Tube Model ◽  
Heat Transfer Tube ◽  
Transfer Tube ◽  
Gasification Efficiency ◽  
Gas Ratio

Abstract In order to explore a more reasonable structure and operating parameter, guide the design and improve the gasification of seawater Open Rack Vaporizer (ORV), Research on the rules of seawater that flows and heat transfer in the ORV tube was studied in this paper. By simplifying the model, heat transfer tube model with spoiler lever was obtained and simulated, the distribution of temperature field, gas ratio, velocity field and press field in rib tube were analyzed, and different inlet velocity of LNG, roughness of the tube wall both effected on the overall gasification, the results shows that the actual gasification efficiency from heat transfer tube is higher than normal, small difference of gas ratio outlet, velocity and temperature are both lower, LNG could be easer gasified at operating temperature between -162°C~+3°C than that between -162°C~+0°C.

Continuous radio telemetry of hypothalamic temperatures from unrestrained animals

1965 ◽  
Vol 20 (2) ◽  
pp. 321-325 ◽  
Author(s):  
Robert O. Rawson ◽  
Jan A. J. Stolwijk ◽  
Hans Graichen ◽  
Robert Abrams
Keyword(s):  
Motor Activity ◽  
Radio Telemetry ◽  
Temperature Cycle ◽  
Body Temperatures ◽  
Night Temperature ◽  
Hypothalamic Temperature ◽  
Temperature Variations ◽  
Free Running ◽  
Hot Environments

A system of radio telemetry has been designed which continuously records body temperatures of unrestrained animals with a resolution of 0.05 C over transmission distances of 100ˑ1,000 ft, permitting observations on free-running animals for indefinite periods of time. Continuous 24-hr recordings were made of hypothalamic temperatures telemetered from cold-acclimatized and unacclimatized dogs living in cold, neutral, and hot environments. During night hours, dogs usually exhibited a decrease in hypothalamic temperature of 0.5ˑ.0 C below daylight levels. Superimposed on the day-night temperature cycle are marked fluctuations of 0.1ˑ0.5 C at a rate of 0.1 C/min. These variations are associated with the level of motor activity, arousal, and with periods of dozing. Shivering in the cold is exhibited even though hypothalamic temperature may be elevated above a level at which no shivering occurs in a neutral environment. spontaneous hypothalamic temperature variations; cold-acclimatized dogs; day-night temperature cycle Submitted on June 3, 1964

Thermal-Hydraulic Performance of SiC-Water and Al2O3-Water Nanofluids in the Minichannel

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Ji Zhang ◽  
Yanhua Diao ◽  
Yaohua Zhao ◽  
Yanni Zhang
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Volume Concentration ◽  
Working Fluid ◽  
Al2o3 Nanoparticles ◽  
Particle Sizes ◽  
Enhance Heat Transfer ◽  
Flow And Heat Transfer ◽  
Effective Particle Size ◽  
Effective Particle

The single-phase flow and heat transfer behaviors of SiC and Al2O3 nanoparticles dispersed in water were studied experimentally in a multiport minichannel flat tube (MMFT). The volume concentrations of the two nanofluids ranged from 0.001% to 1%. Their effective particle sizes, thermal conductivities, and viscosities were also measured. Results indicated that these nanofluids as a working fluid could enhance heat transfer but increase pressure drop and the Nusselt number by up to 85%. The two nanofluids exhibited a common optimal volume concentration of 0.01% for heat transfer. Effective particle size was also found to have a significant effect on heat transfer.

Effect of Brownian Diffusion and Particle Size on Thermophoretic Flow

1995 ◽  
Author(s):  
S. Jayaraj
Keyword(s):  
Particle Size ◽  
Laminar Flow ◽  
Aerosol Particle ◽  
Particle Deposition ◽  
Brownian Diffusion ◽  
Particle Sizes ◽  
Deposition Mechanism ◽  
Hot Gas ◽  
Grid Adaptation ◽  
Schmidt Numbers

Abstract This work attempts to analyse the aerosol particle deposit on in laminar flow over a flat plate with hot gas flowing over it. Solution is obtined by a finite difference marching procedure with grid adaptation. Prediciton were made about aerosol particle deposition due to Brownian diffusion and also due to the phenomenon of thermophoresis. The regions of importance of the two different mechanisims are approximately predicted by analysis the results for different particle sizes. The results are validated by comparision with similarity solution. It is observed that thermophoresis is the predominant deposition mechanism for Schmidt numbers ranging from 100 to 106, whereas for Schmidt numbers ranging from 100 to 103 Brownian diffusion has a strong effect on the deposition rate.

A comprehensive database of the optical properties of irregular aerosol particles for radiative transfer simulations

2021 ◽  
Author(s):  
Masanori Saito ◽  
Ping Yang ◽  
Jiachen Ding ◽  
Xu Liu
Keyword(s):  
Optical Properties ◽  
Radiative Transfer ◽  
Aerosol Particle ◽  
Volcanic Ash ◽  
Aerosol Particles ◽  
Single Scattering ◽  
Dust Aerosol ◽  
Index Of Refraction ◽  
Particle Sizes

AbstractA database (TAMUdust2020) of the optical properties of irregular aerosol particles is developed for applications to radiative transfer simulations involving aerosols, particularly dust and volcanic ash particles. The particle shape model assumes an ensemble of irregular hexahedral geometries to mimic complex aerosol particle shapes in nature. State-of-the-art light scattering computational capabilities are employed to compute the single-scattering properties of these particles for wide ranges of values of the size parameter, the index of refraction, and the degree of sphericity. The database therefore is useful for various radiative transfer applications over a broad spectral region from ultraviolet to infrared. Overall, agreement between simulations and laboratory/in-situ measurements is achieved for the scattering phase matrix and backscattering of various dust aerosol and volcanic ash particles. Radiative transfer simulations of active and passive spaceborne sensor signals for dust plumes with various aerosol optical depths and the effective particle sizes clearly demonstrate the applicability of the database for aerosol studies. In particular, the present database includes, for the first time, robust backscattering of nonspherical particles spanning the entire range of aerosol particle sizes, which shall be useful to appropriately interpret lidar signals related to the physical properties of aerosol plumes. Furthermore, thermal infrared simulations based on in-situ measured refractive indices of dust aerosol particles manifest the effects of the regional variations of aerosol optical properties. This database includes a user-friendly interface to obtain user-customized aerosol single-scattering properties with respect to spectrally dependent complex refractive index, size, and the degree of sphericity.

20 P 01 Filter pack technique for determination of aerosol particle sizes

1993 ◽  
Vol 24 ◽  
pp. S205-S206 ◽  
Author(s):  
A.K. Budyka ◽  
B.I. Ogorodnikov ◽  
V.I. Skitovitch
Keyword(s):  
Aerosol Particle ◽  
Particle Sizes ◽  
Filter Pack

Improved Cascade Impactor for Measuring Aerosol Particle Sizes

1959 ◽  
Vol 51 (9) ◽  
pp. 1039-1042 ◽  
Author(s):  
R. I. Mitchell ◽  
J. M. Pilcher
Keyword(s):  
Aerosol Particle ◽  
Cascade Impactor ◽  
Particle Sizes

scholarly journals Numerical Analysis for Heat Transfer Augmentation in a Circular Tube Heat Exchanger Using a Triangular Perforated Y-Shaped Insert

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 247
Author(s):  
Lokesh Pandey ◽  
Satyendra Singh
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Friction Factor ◽  
Circular Tube ◽  
Tube Wall ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Tube Heat Exchanger ◽  
Heat Transfer Augmentation ◽  
Plain Tube

The present investigation constitutes CFD analysis of the heat transmission phenomenon in a tube heat exchanger with a Y-shaped insert with triangular perforation. The analysis is accomplished by considering air as a working fluid with a Reynolds number ranging from 3000 to 21,000. The segment considered for analysis consists of a circular tube of 68 mm diameter and 1.5 m length. The geometrical parameter considered is the perforation index (0%, 10%, 20%, and 30%). The constant heat flux is provided at the tube wall and a pressure-based solver is used for the solution. The studies are performed for analyzing the effects of inserts on the heat transfer and friction factor in the circular tube heat exchanger which results in augmented heat transfer at a higher perforation index (PI) and lower friction factor. The investigation results show that the highest heat transfer is 5.84 times over a simple plain tube and the maximum thermal performance factor (TPF) is 3.25 at PI = 30%, Re = 3000.

scholarly journals Development of a new semi-empirical parameterization for below-cloud scavenging of size-resolved aerosol particles by both rain and snow

2013 ◽  
Vol 6 (4) ◽  
pp. 5901-5945 ◽  
Author(s):  
X. Wang ◽  
L. Zhang ◽  
M. D. Moran
Keyword(s):  
Linear Relationship ◽  
Aerosol Particle ◽  
Field Experiments ◽  
Aerosol Particles ◽  
Particle Sizes ◽  
Data Set ◽  
Wide Range ◽  
Cloud Scavenging ◽  
Two Parameters ◽  
Semi Empirical

Abstract. A parameter called the scavenging coefficient Λ is widely used in aerosol chemical transport models (CTMs) to describe below-cloud scavenging of aerosol particles by rain and snow. However, uncertainties associated with available size-resolved theoretical formulations for Λ span one to two orders of magnitude for rain scavenging and nearly three orders of magnitude for snow scavenging. Two recent reviews of below-cloud scavenging of size-resolved particles recommended that the upper range of the available theoretical formulations for Λ should be used in CTMs based on uncertainty analyses and comparison with limited field experiments. Following this recommended approach, a new semi-empirical parameterization for size-resolved Λ has been developed for below-cloud scavenging of atmospheric aerosol particles by both rain (Λrain) and snow (Λsnow). The new parameterization is based on the 90th percentile of Λ values from an ensemble data set containing calculated using all possible "realizations" of available theoretical Λ formulas and covering a large range of aerosol particle sizes and precipitation intensities (R). For any aerosol particle size of diameter d, a strong linear relationship between the 90th-percentile log10(Λ) and log10(R), which is equivalent to a power-law relationship between Λ and R, is identified. The log-linear relationship, which is characterized by two parameters (slope and y-intercept), is then further parameterized by fitting these two parameters as polynomial functions of aerosol size d. A comparison of the new parameterization with limited measurements in the literature in terms of the magnitude of Λ and the relative magnitudes of Λrain and Λsnow suggests that it is a reasonable approximation. Advantages of this new semi-empirical parameterization compared to traditional theoretical formulations for Λ include its applicability to below-cloud scavenging by both rain and snow over a wide range of particle sizes and precipitation intensities, ease of implementation in any CTM with a representation of size-distributed particulate matter, and a known representativeness based on the consideration in its development of all available theoretical formulations and field-derived estimates for Λ(d) and their associated uncertainties.

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