Dispersion calculation

Maximum Ground-Level Concentrations The effective height of an emission having been determined, the next step is to study its path downward by using the appropriate atmospheric-dispersion formula. Some of the more popular atmospheric-dispersion calculational procedures have been summarized by Buonicore and Theodore (op. cit.) and include ... 

Gryning, S. E., and Lyck, E., "Comparison between Dispersion Calculation Methods Based on In-Situ Meteorological Measurements and Results from Elevated- Source Tracer Experiments in an Urban Area." National Agency of Environmental Protection, Air Pollution Laboratory, MST Luft - A40. Riso National Laboratory, Denmark, 1980. 

Table 5. Source Terms Used in the Dispersion Calculations.

Three commonly used dispersion calculation methods for the prediction of ground level concentrations are based on the above expression. The variance in each method is the calculation of plume rise, Ah, and the horizontal and vertical plume dispersion parameters. These methods are ... 

Sagendorf, J. F., 1974, A Program for Evaluating Atmospheric Dispersion Calculations Considering Spatial and Temporal Meteorological Variations, NO A A Tech. Memo ERL-ARL-44. 

Start, G. E. and L. L. Wendall, 1974, Regional Effluent Dispersion Calculations Considering... 

Blast scale was determined by use of dispersion calculations to estimate fuel quantity within flammability limits present in the cloud. Initial blast strength was determined by factors which have been found to be major factors affecting the process of turbulent, premixed combustion, for example, the fuel s nature and the existence within the cloud of partial confinement or obstacles. 

The thermal radiation intensity of a flash fire can be calculated after parameters such as cloud shape and gas or vapor concentration distribution have been determined through dispersion calculations. Subsequently, the thermal radiation intensity is calculated through the following steps ... 

In practical applications, dispersion calculations need to be performed in topographically complex environment. Thus, solid obstacles intervening in the area dispersion should be counting in the computations. In previous validation works, it has been proved that CFD codes constitute powerful tools for complex terrain dispersion simulation providing high accuracy results with excellent visualization capabilities, which can be helpful in quantitative risk analysis applications [55]. The dominating mixing mechanism between... 

Once the dispersion calculations are completed, the question arises What concentration is considered dangerous Concentrations based on TLV-TWA values, discussed in chapter 2, are overly conservative and are designed for worker exposures, not short-term exposures under emergency conditions. 

The EPA Risk Management Plan (RMP) defines a worst-case scenario as the catastrophic release of the entire process inventory in a 10-min period (assumed to be a continuous release). The dispersion calculations must be completed assuming F stability and 1.5 m/s wind speed. As part of the RMP rule, each facility must determine the downwind distance to a toxic endpoint. These results must be reported to the EPA and to the surrounding community. 

Despite the technical advances in the past decade, no apparatus for measurement of the odour strength has been developed. Therefore, odour pollution studies cannot be performed without using human noses. In general, the efect of polluting odours can be studied either by direct assessment in the ambient air or by means of a dispersion calculation. The first method requires a number of observers to be placed in the vincinity of the odour source (3,7). The latter a dispersion model and an input value. For reasons of simplicity this method is most frequently used in the Netherlands. 

Other CCPS guidelines provide discharge calculations for various releases, including gas, liquid, and two-phase flow. Dispersion calculations and pool spreading on different materials are also described. 

PHAST (Process Hazard Analysis Software Tool)—This is a conglomerate package for gas dispersion and fire modeling. PHAST is capable of calculating the formation of a cloud or pool to final dispersion calculating concentrations, fire radiation, toxicity, and explosion overpressure endpoints. 

The total extra column dispersion can be easily measured by removing the column and connecting the tube from the sample valve directly to the tube leading to the detector. A very small sample ( 0.2jil or less) is then injected into the system and the dispersion calculated as follows,... 

Brandt C, Kunde R, Dobmeier B et al (2011) Ambient PM10 concentrations from wood combustion - emission modeling and dispersion calculation for the city area of Augsburg, Germany. Atmos Environ 45 3466-3474... 

The problem of the effect of an inaccurate zeroth-order wavefunction on dispersion calculations has been looked at again by Magnasco82 using double perturbation theory for the He---He case. Using hydrogenic, screened hydrogenic, and approxi-... 

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