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COMMANDS:

Input data I

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Input data III

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average

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commands

 

ALGORITHMS:

Algorithms I

Algorithms II

Algorithms III

Algorithms IV

Algorithms V

Algorithms VI

Algorithms VII

Algorithms VIII

Algorithms IX

Algorithms X

 

EMISSIONS:

Emissions I

Emissions II

Emissions III

Pollutants I

Pollutants II

 

GRAPHS:

Graphs I 

Graphs II

Graphs III 

Graphs IV

 

  

Algorithms IV ˇ DISPER software

                 

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Unstable or Neutral - Crossover Between Momentum and Buoyancy

For cases with stack gas temperature greater than or equal to ambient temperature, it must be determined whether the plume rise is dominated by momentum or buoyancy. The crossover temperature difference, (DT)c, is determined as follows:

for Fb < 55,

(DT)c=0.0297 Ts(vs/ds2)1/3      (9)

and for Fb >= 55,

(DT)c=0.00575 Ts(vs2/ds)1/3     (10)

If DT, exceeds or equals (DT)c, plume rise is assumed to be buoyancy dominated, otherwise plume rise is assumed to be momentum dominated.

Unstable or Neutral - Buoyancy Rise

For situations where DT exceeds (DT)c as determined above, buoyancy is assumed to dominate. The distance to final rise, xf, is assumed to be 3.5x*, where x* is the distance at which atmospheric turbulence begins to dominate entrainment. The value of xf is calculated as follows:

for Fb < 55:

xf=49Fb5/8      (11)

and for Fb >= 55:

xf=119Fb2/5     (12)

The final effective plume height, he (m), is determined as

for Fb < 55:

he=hs+(21.425 Fb3/4/us)    (13)

and for Fb = 55:

he=hs+(38.71 Fb3/5/us)          (14)

Unstable or Neutral - Momentum Rise

For situations where the stack gas temperature is less than or equal to the ambient air temperature, the assumption is made that the plume rise is dominated by momentum. If DT is less than (DT)c, the assumption is also made that the plume rise is dominated by momentum. The plume height is calculated as:

he=hs+3ds(vs/us)     (15)

Briggs suggests that this equation is most applicable when vs/us is greater than 4.

 

Algorithms I - Algorithms II - Algorithms III - Algorithms IV - Algorithms V Algorithms VI - Algorithms VII - Algorithms VIII - Algorithms IX - Algorithms X

 

 

 

Air pollution map (XY-Plane) produced by continuous discharge in time (three stacks). The red colour represents high pollutant concentrations. Wind: SW (225 degrees).

 

Pollution map (XY-Plane) produced by continuous discharge in a road region. The fucshia squares represent the road line (position of the different point sources) in a XY-Plane. The red colour represents high pollutant concentrations.

 

Canarina Algoritmos Numéricos, S.L.

Environmental software solutions

Canary Islands, Spain

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CANARINA: Home - Air pollution ˇ DISPER - Noise pollution ˇ CUSTIC - Water pollution ˇ DESCAR - Contact us

DISPER: Air pollution dispersion ˇ DISPER - Solutions - Data - Algorithms - Emissions - Graphs - ISC3 (VOL. 2)

SOLUTIONS: Air pollution dispersion ˇ DISPER - Software solutions - Software advantages - Price - DEMO download

COMMANDS: Input data I - Input data II - Input data III - Input data IV - Temporal average - Import and export data - Software commands

ALGORITHMS: Algorithms I - Algorithms II - Algorithms III - Algorithms IV - Algorithms V Algorithms VI - Algorithms VII - Algorithms VIII - Algorithms IX - Algorithms X

EMISSIONS: Emissions I - Emissions II - Emissions III - Pollutants I - Pollutants II

GRAPHS: Graphs I - Graphs II - Graphs III - Graphs IV