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Algorithms IV · software · air pollution effects

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 F_b < 55,

(DT)_c=0.0297 T_s(v_s/d_s²)^1/3      (9)

and for F_b >= 55,

(DT)_c=0.00575 T_s(v_s²/d_s)^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, x_f, is assumed to be 3.5x^*, where x^* is the distance at which atmospheric turbulence begins to dominate entrainment. The value of x_f is calculated as follows:

for F_b < 55:

x_f=49F_b^5/8      (11)

and for F_b >= 55:

x_f=119F_b^2/5     (12)

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

for F_b < 55:

h_e=h_s+(21.425 F_b^3/4/u_s)    (13)

and for F_b = 55:

h_e=h_s+(38.71 F_b^3/5/u_s)          (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:

h_e=h_s+3d_s(v_s/u_s)     (15)

Briggs suggests that this equation is most applicable when v_s/u_s is greater than 4.

software · air pollution effects

DISPER software solutions: This application has been used in great number of environmental reports, air pollution courses and air pollution studies in the last years. We currently have users in more than 10 countries.

Chichester - air pollution dispersion - dispersion of air pollution - gaussian air dispersion equation -

City of London - air pollution dispersion models - air pollution dispersion model - air dispersion equation -

Coventry - air voc - air indoor - industrial dispersion - air modelling -

Derby - air modeling - dust dispersion - air parameters -

Derry - air model - air dust - dispersion diffusion -

Dundee - air pollution meteorology and dispersion - dispersion of air pollutants - and dispersion of air pollutants -

Durham - co2 dispersion - atmosphere dispersion - air transport -

Edinburgh - air industrial - air atmosphere - control air -

Ely - air diffusion - air reflection - air calculation -

Exeter - air mixing - air refraction - dispersion simulation -

Glasgow - air gas - air process - air simulation -

Gloucester - air equation - air pression - dispersion light -

Hereford - air co2 - air algorithm - air temperature -

Manchester - pressure dispersion - process dispersion -

Preston - air quality dispersion models - air quality dispersion model - air dispersion models -

Stoke-on-Trent - air standards - pollution air - air monitoring -

Sunderland - air emissions - air environment - dispersion equation - air source -

Swansea - air emission - data dispersion - air environmental -

Truro - pollutants dispersion - air levels - air pollutants -

Wakefield - air epa - air smog - dispersion calculation -

Wells - air pollutant - air models - air stability -

Westminster - air stack - air concentration - air health -