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Mathematical modelling of distribution of gaseous pollutants in a ground layer of atmosphere from sources of emissions at the gas station

The basic harmful substances allocated from sources vyyobrosov at the gas station, gaseous substances are. In this connection arises neyoobhodimost carrying out of mathematical modelling of distribution of gaseous substances in a ground layer of atmosphere [29, 102].

In a gaseous condition of a particle of a mixture are connected by forces vzaimodejstyovija and dvizhutsja it is free, occupying all volume given to it. First of all it is necessary to know, what probability of hit of particles harmful gayozoobraznogo the substance which are at height of emission point N, on podyostilajushchy a layer of a surface of land, but not further some distance X, otyoschityvaemogo from the place of disintegration of a stream (torch) expiring from a mouth of emission.

On length of a way from disintegration of a stream to a contact with an underlaying layer zemyonoj it will be equal to a surface Xq∕Wx, where q - average vertical sostavyoljajushchaja turbulent subsidence flokkuly gas (in the technical literature this term is used for the characteristic of the size of a described particle which is many times less asking); W - speed of an airflow, km/s.

As after disintegration of a stream of gas last continues the dvizheyonie with the "average" wind which degree of turbulence is equal ε the vector ε∙ W - is casual in the direction. The vector can have any napravleyonie.

The probability of all directions of a vector is identical, then the directed element of a surface will be equal

44 where β - a corner between a vertical axis and a vector direction ε∙ Wo, ψ - shiyorota points of the sphere crossed by this vector.

Probability of a direction - a vector

Vertical component ε-Wxnapravlenija est (ε∙ wx) cos β, and mayotematicheskoe expectation

Horizontal platform only vectors within a corner 0 from top to down can cross... π∕ 2

Let's consider all possible conditions at which the gaseous particle drops out of an air flow:

- The density of harmful gaseous substance is more than airflow density;

- If the density of an airflow above density harmful gayozoobraznogo is less than substance qдолжно to be 0;

- If the density of gaseous substance is equal to density vozdushyonogo a stream, in events when the gas density is equal to air density at the moment of stream disintegration on height N through a height element ∂Hбудут to pass one for another fictitious flokkuly.

That the gaseous particle, being at height N from a land surface, has dropped out of an airflow not further some distance X, neyoobhodimo to be set by a condition

45

Where Y - height of lifting of a particle.

We integrate the equation (2.5) ottogda the required

Probability

The integral (2.7) is defined by means of values which are resulted in the theory of probability [145].

In table 2.1 some values of dependence funkyo are resulted only

tsy R from To (7):

Table 2.1 - Values of dependence of functions Pот To

TO R TO R TO R
-1,5 0,02 -0,30 0,34 0,50 0,76
-1,0 0,08 -0,10 0,44 0,60 0,80
-0,90 0,10 0,00 0,50 0,70 0,84
-0,80 0,13 0,10 0,56 0,80 0,87
-0,60 0,20 0,20 0,61 0,90 0,90
-0,50 0,24 0,30 0,66 1,00 0,92
-0,40 0,28 0,40 0,72 1,50 0,98

The assumptions offered here can affect accuracy of the decision, especially at definition of magnitude of K.Tochnost it will be possible to raise if to take advantage of a method introduced in [95].

If the equations describing movement of a particle gaseous veshcheyostva and an airflow along a surface of land, coincide, then dvizheyonie an airflow and flokkul gas, moving in this stream, will be rasyosmatrivatsja separately.

Having taken advantage of researches [60, 85], we will receive

Where - density of harmful gaseous substance, mg/m3;

- Airflow density, mg/m3;

- Density of gas concerning air.

It is known from [146], that concentration of harmful gaseous substance in a plane, perpendicular to a direction of movement of air-gas stream W χ on distance H from an emission point, is on dependence where A - factor of a turbulent exchange, m2/with.

Let's express factor of a turbulent exchange, having accepted for co-ordinate Y1/2 a point, in which, then

If intensity of a turbulent stream with the account kooryodinaty Y1/2mozhno to receive is known

Whence

Where - speed of a pulsation of a stream, the km/s, defined on [85].

The received mathematical model of distribution gaseous veyoshchestv in a ground layer of atmosphere from sources of emissions at the gas station and zaviyosimost (2.11) allow to define concentration gas vrednostej in any co-ordinates of a plane and a direction of distribution harmful priyomesej from the gas station.

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A source: GARMONOV CYRIL VALEREVICH. the TECHNIQUE of the ESTIMATION of ENVIRONMENTAL SAFETY of CITY GASOLINE STATIONS. The dissertation on competition of a scientific degree of a Cand.Tech.Sci. Voronezh - 2019. 2019

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