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Air Pollutants and Their Adverse Effects
Published in Jeff Kuo, Air Pollution Control Engineering for Environmental Engineers, 2018
A line source is a source of emissions emanates from a linear (one-dimensional) geometry. A highway can be a line source of air pollution. A volume source is a 3-dimensional emission sources. Dust emissions from wind erosion of coal piles and fugitive VOCs emissions from equipment components (e.g., flanges and valves) within an oil refinery are examples of volume sources (see Section 1.3.5 below for definition of fugitive emissions)
Air Pollution and Its Control
Published in Danny D. Reible, Fundamentals of Environmental Engineering, 2017
A highway might be considered a “line-source” of pollution. Integrate Equation 6.52 assuming that the wind is perpendicular to the highway to derive an equation for the concentration as a function of distance from the highway.
Application of an atmospheric tracer ratio method to estimation of PM2.5 emission rates from wheat conveying operations at a wheat pile storage facility
Published in Journal of the Air & Waste Management Association, 2020
Anna Potapova, Brian Lamb, Candis Claiborn
Atmospheric tracer techniques have been widely used in a number of studies and were shown to be a powerful tool to estimate atmospheric emissions of both gaseous and particulate sources (Claiborn et al. 1995; Lamb et al. 2015). Sulfur hexafluoride (SF6) has been utilized as a tracer gas in many studies (Claiborn et al. 1995; Czepiel et al. 1996; Kantamaneni et al. 1996; Lamb et al. 2015, 1995) although nitrous oxide and acetylene have been used in more recent studies mainly focused on emissions from oil and gas facilities (Mitchell et al. 2015; Omara et al. 2016). Application of tracer techniques to emission rate estimation of atmospheric gases has been well studied and reported. The method has been applied to estimate gas emissions from line (Czepiel et al. 1996), point and area (Lamb et al. 1995) sources using both stationary (for example, Mollmann-Coers et al. 2002; Scholtens et al. 2004) and mobile (for example, Daube et al. 2019; Foster-Wittig et al. 2015; Lamb et al. 1995) measurements. Claiborn et al. (1995) were first to introduce the atmospheric tracer method to measure PM emissions (Kantamaneni et al. 1996). In their study SF6 was used as a tracer gas to simulate PM10 emissions from paved and unpaved roads. Both line source and point source tracer release experiments were performed.
Implementation of a top-down noise control strategy for a liquefied natural gas peak-shaving facility
Published in Journal of the Air & Waste Management Association, 2019
The Predictor-LimA model is first configured by importing a Google Earth base map of the study area, which ensures a relatively high degree of accuracy for positions of various structures (buildings and storage tanks) and receiver locations. The model is then used to generate contour lines (isopleths) on a base map showing how noise levels radiate from the collection of sources and the effect of intervening structures and terrain. In industry, the most common noise sources are described as a point source, such as a gas turbine, or a line source, such as a pipeline (Innova undated). The geometric spreading of noise typically depends on whether the source radiates sound in free space away from reflective boundaries (point source), on a wall radiating into half space, or as a line source radiating cylindrically (Bies, Hansen, and Howard 2018). The Predictor-LimA software classifies noise radiating from a wall and roof into free space as emitting façade and emitting roof, respectively. The modeling software classifies all sources in this study as point sources except for feed gas piping, which was modeled as a line source, and building walls and roof, which are modeled as emitting façades and emitting roof, respectively (Softnoise GmbH 2013).
Numerical Analysis of the Effect of Fire Source Configuration on Fire-Wind Enhancement
Published in Heat Transfer Engineering, 2021
Esmaeel Eftekharian, Maryam Ghodrat, Yaping He, Robert H. Ong, Kenny C. S. Kwok, Ming Zhao
Figure 4 compares the distribution of longitudinal velocity at the centerline plane (Y = 0) for line source and point source cases. Dashed lines shown in Figure 4a,b represent the characteristic longitudinal locations at which cross-sectional normalized longitudinal velocity distribution is plotted in Figure 5. In Figure 4, it is seen that velocity is enhanced in both cases. However, the enhancement in the line source case is much stronger than in the point source case even though heat release rate per unit fuel surface area and wind velocity are the same. Figure 4 also demonstrates that in the line source case, the plume is attached to the ground for comparatively a long distance before it is lifted off the ground by buoyancy. This is a manifestation of the Coanda effect that was also observed in a previous study [10]. In the point source case, the Coanda effect is much weaker and almost unobservable. Hence, the plume lifts immediately downstream of the fire source. Moreover, in the line source case, the wind is enhanced in a larger region, compared to the point source case. It is observed that in both Figure 4a,b, wind velocity is significantly reduced downstream of the plume region once the plume lifts from the ground. The buoyancy force creates the upward motion of the fluid and by continuity, the surrounding air needs to move in to replenish the plume region. For the line source fire, in the upstream entrainment, the replenishment is accomplished by wind flow. For the downstream region of the plume, a low-pressure region is created to draw in and replenish the flow. Formation of the low-velocity region downstream of the plume was observed in previous studies investigating jet-cross-flow [78] and buoyant plume-crossflow interactions [58, 79, 80].