Mass Transfer between Solid Wall and Fluid Streams. Mechanism and Eddy Distribution Relationships in Turbulent Flow.

Lin, C. B.; Moulton, R. W.; Putnam, G. L.

doi:10.1021/ie50519a048

Cited by 241 publications

(69 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, a continuous correlation for the eddy viscosity was used instead of the correlation proposed by Lin et al (1953). The assumptions in this free-flight model are more physically satisfying than those in Friedlander & Johnstone's work because the initial free-flight velocity is not assigned arbitrarily, but is equal to the local fluid velocity fluctuations at the point at which free flight begins.…”

Section: 54a Free-flight Models For Smooth Surfacesmentioning

confidence: 99%

Particle deposition in ventilation ducts

Sippola¹

2002

View full text Add to dashboard Cite

Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation.Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling.Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 µm were investigated. Deposition rates were measured in straight ducts with 1 2 a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence.Measured deposition rates were generally higher than predicted by published models.A model incorporating empirical equations based on the experimental measurements was applied to evaluate particle losses in supply and return duct runs. Model results suggest that duct losses are negligible for particle sizes less than 1 µm and complete for particle sizes greater than 50 µm. Deposition to insulated ducts, horizontal duct floors and bends are predicted to control losses in duct systems. When combined with models for HVAC filtration and deposition to indoor surfaces to predict the ultimate fates of particles within buildings, these results suggest that ventilation ducts play only a small role in determining indoor particle concentrations, especially when HVAC filtration is present.However, the measured and modeled particle deposition rates are expected to be important for ventilation system contamination. ChairDate

show abstract

Section: 54a Free-flight Models For Smooth Surfacesmentioning

confidence: 99%

Particle deposition in ventilation ducts

Sippola¹

2002

View full text Add to dashboard Cite

show abstract

“…Based on continuity arguments, it is now well accepted that ξ a is proportional to (y + ) 3 in the close vicinity of a wall (Chapman & Kuhn, 1986). The eddy viscosity correlations of Lin et al (1953), Davies (1966a) (with Re = 10 4 ) and Lai & Nazaroff (2000) are plotted in Figure 13 and general agreement among the expressions is observed. …”

Section: Eddy Viscositymentioning

confidence: 68%

“…In addition, a continuous correlation for the eddy viscosity was utilized instead of the correlation proposed by Lin et al (1953). The assumptions in this free-flight model are much more physically satisfying than those in Friedlander & Johnstone's work because the initial free-flight velocity is not assigned arbitrarily, but is equal to the local fluid velocity fluctuations at the point at which free flight begins.…”

mentioning

confidence: 99%

Particle deposition from turbulent flow: Review of published research and its applicability to ventilation ducts in commercial buildings

Sippola¹,

Nazaroff²

2002

View full text Add to dashboard Cite

This report reviews published experimental and theoretical investigations of particle deposition from turbulent flows and considers the applicability of this body of work to the specific case of particle deposition from flows in the ducts of heating, ventilating and air conditioning (HVAC) systems. Particle deposition can detrimentally affect the performance of HVAC systems and it influences the exposure of building occupants to a variety of air pollutants.The first section of this report describes the types of HVAC systems under consideration and discusses the components, materials and operating parameters commonly found in these systems. The second section reviews published experimental investigations of particle deposition rates from turbulent flows and considers the ramifications of the experimental evidence with respect to HVAC ducts. The third section considers the structure of turbulent airflows in ventilation ducts with a particular emphasis on turbulence investigations that have been used as a basis for particle deposition models.The final section reviews published literature on predicting particle deposition rates from turbulent flows.A large quantity of experimental data regarding particle deposition from turbulent flows has been collected using a range of techniques of varying quality. Nearly all of these data have been collected from straight tubes or ducts with a fully developed turbulent flow profile and the data are widely scattered. Most of the data of acceptable quality have been collected from tubes or ducts with hydraulic diameters much smaller than ducts in typical HVAC systems. Particle deposition from turbulent flow with a developing flow profile has not been systematically investigated and only two investigations of particle deposition from turbulent flow through bends have been published. Developing turbulent flow profiles and bends are common in HVAC ducts.Owing to the large number of investigations into particle deposition from turbulent flow, much is known; however, the direct applicability to the case of particles in HVAC ducts is limited. Particle size, turbulence intensity and the roughness and orientation (horizontal or vertical) of the deposition surface are the parameters that control particle deposition rates and all of these factors are likely to be pertinent in HVAC ducts. Particle diameters of concern in HVAC ducts range from about 0.003 to 30 µm and deposition rates are known to vary strongly in this range. Friction velocities in HVAC ducts are iii likely to be in the range 0.1-1 m/s and variations of turbulence intensities in this range are likely to influence deposition rates. Both microscale surface roughness (from less than 1 micron up to hundreds of microns) and macroscale roughness (about 1 mm and larger) have been demonstrated to enhance particle deposition relative to the case of a smooth surface. Microscale roughness intrinsic to the duct material, or due to corrosion or previous deposition of particles, and macroscale roughness from thermal insulation, joi...

show abstract

“…According to the Boussinesq eddy viscosity assumption (Boussinesq, 1877), the logarithmic law for velocity profile was solved by using the mixing length method (Prandtl, 1925;Khan et al, 2017;Zawar et al, 2017). Some vertical velocity distribution laws, such as the power law and the exponential law, are based on experimental considerations or semi-empirical theories (Lin et al, 1953;Deissler, 1954;Afzal et al, 2007). Other laws for turbulent velocity profile or concentration profile are based on an indirect turbulence model (Bucci et al, 2008;Nucci and Fiorucci, 2011).…”

Section: Introductionmentioning

confidence: 99%

Quality indices of groundwater for agricultural use in the Soconusco, Chiapas, Mexico

et al. 2017

View full text Add to dashboard Cite

In Soconusco, Chiapas, in spite of the high availability of surface water, it is resorting to the use of groundwater. Knowledge about the quality of surface or groundwater used to irrigate crops in that region is low. This paper aims to contribute to the knowledge of the quality of groundwater for agricultural use through the characterization of the spatial variability. Assuming a random spatial distribution of 45 samples which were collected in situ were determined: acidity and alkalinity (pH), electrical conductivity (EC), Total Dissolved Solids (TDS), cations and anions and trace elements; in addition to the agricultural index: Sodium Adsorption Ratio (SAR), Residual Sodium Carbonate (RSC), Soluble Sodium Percentage (SSP), Sodium Percentage (% Na), Kelly Ratio (KR), Magnesium Adsorption Ratio (MAR), Permeability Index (PI), Effective Salinity (ES), Salinity Potential (SP) and Osmotic Potential (OP). In general, SSP, % Na, KR, PI are low, there is only one anomalous point (9) with high values at W of the study area. Similarly, PS, ES, Cl, Na and SAR are low except point 16 and conversely, RSC and pH are high, except at this point located in the center of the study area. The results allow us to infer that the water in that aquifer presents no problems or sodicity toxic ions. In 27 sites sampled values above 250 µmhos/cm were found at 25°C, classified as medium to high risk of salinity, unsuitable for agricultural use. Analysis of the combined effect of the presence of sodium (SAR) and salinity (EC or TDS) shows that 27 of analyzing sites have restricted water medium at very high for use in irrigation.

show abstract

Mass Transfer between Solid Wall and Fluid Streams. Mechanism and Eddy Distribution Relationships in Turbulent Flow.

Cited by 241 publications

References 9 publications

Particle deposition in ventilation ducts

Particle deposition in ventilation ducts

Particle deposition from turbulent flow: Review of published research and its applicability to ventilation ducts in commercial buildings

Quality indices of groundwater for agricultural use in the Soconusco, Chiapas, Mexico

Contact Info

Product

Resources

About