Aerosol.f

Summary

Aerosol.f
Functions
compute_gas_diffusivity	Computes gas-phase diffusivity in air.
gerber_wet_diameter	Computes wet diameter based on Gerber’s formula.
compute_collision_integral	Computes the “collision integral” for gas-phase diffusion, based on Lennard-Jones potential.
compute_condensation_transfer_rate	Computes condensation transfer rate for a given species.
compute_quadratic_mean_velocity	Computes condensation transfer rate for a given species.
compute_saturation_concentration	Computes saturation concentration of an organic species.
compute_kelvin_coefficient	Computes the correction factor due to the Kelvin effect on the aerosol surface concentration.

Functions

compute_gas_diffusivity

subroutine compute_gas_diffusivity( temperature,
pressure,
$ diameter,
weight,
collision,
diffusivity )

Computes gas-phase diffusivity in air.

Parameters

temperature	Temperature (K).
pressure	Atmospheric pressure (Pa).
diameter	Molecular diameter (Angstrom).
weight	Molecular weight (g/mol).
collision	Collision factor.

Returns

diffusivity

Gas-phase diffusivity (m^2/s).

gerber_wet_diameter

subroutine gerber_wet_diameter( relative_humidity,
temperature,
$ dry_diameter,
wet_diameter )

Computes wet diameter based on Gerber’s formula.

Parameters

relative_humidity	Relative humidity.
temperature	Temperature (K).
dry_diameter	Aerosol dry diameter (micrometer).

Returns

wet_diameter

Aerosol wet diameter (micrometer).

compute_collision_integral

subroutine compute_collision_integral( x,
omega )

Computes the “collision integral” for gas-phase diffusion, based on Lennard-Jones potential. Computation is based on tabulations from: Hirschfelder, J.O., Curtiss, C.O., and Bird, R.B, Molecular Theory of Gases and Liquids, Wiley, New York, 1954. See also Poling, B.E., Prausnitz, J.M., and O’Connell, J.P, The Properties of Gases and Liquids, McGraw-Hill, 2000.

Parameter

x	x is equal to “k T / e” where k is the Boltzmann constant, T is the temperature and e is the Lennard-Jones molecular interaction parameter.

Returns

omega

The collision integral.

compute_condensation_transfer_rate

subroutine compute_condensation_transfer_rate( diffusivity,
$ velocity,
accomodation,
wet_diameter,
rate )

Computes condensation transfer rate for a given species.

Parameters

diffusivity	Gas-phase diffusivity (m^2/s).
velocity	Quadratic mean velocity (m/s).
accomodation	Accomodation coefficient.
wet_diameter	Aerosol wet diameter (micrometer).

Returns

rate	Condensation/evaporation transfer rate (m^3/s). The condensation growth rate is then given by “rate * (c^g -- c^s)” where c^g is the gaseous concentration and c^s is the concentration at the aerosol surface.

compute_quadratic_mean_velocity

subroutine compute_quadratic_mean_velocity( temperature,
weight,
$ velocity )

Computes condensation transfer rate for a given species.

Parameters

temperature	Temperature (K).
weight	Molecular weight (g/mol).

Returns

velocity

Quadratic mean molecular velocity (m/s).

compute_saturation_concentration

subroutine compute_saturation_concentration( temperature,
weight,
$ enthalpy,
saturation_pressure,
concentration )

Computes saturation concentration of an organic species. The reference temperature is 298 K.

Parameters

temperature	Temperature (K).
weight	Molecular weight (g/mol).
enthalpy	Enthalpy of vaporization (J/mol).
saturation_pressure	Saturation vapor pressure (Pa).

Returns

concentration

Saturation concentration (microgram/m^3).

compute_kelvin_coefficient

subroutine compute_kelvin_coefficient( temperature,
weight,
$ surface_tension,
wet_diameter,
density,
coefficient )

Computes the correction factor due to the Kelvin effect on the aerosol surface concentration.

Parameters

temperature	Temperature (K).
weight	Molecular weight (g/mol).
surface_tension	Aerosol surface tension (N/m).
wet_diameter	Aerosol wet diameter (micrometer).
density	Aerosol mass density (kg/m^3).

Returns

coefficient

Kelvin effect coefficient.

subroutine compute_gas_diffusivity( temperature,
pressure,
$ diameter,
weight,
collision,
diffusivity )

Computes gas-phase diffusivity in air.

subroutine gerber_wet_diameter( relative_humidity,
temperature,
$ dry_diameter,
wet_diameter )

Computes wet diameter based on Gerber’s formula.

subroutine compute_collision_integral( x,
omega )

Computes the “collision integral” for gas-phase diffusion, based on Lennard-Jones potential.

subroutine compute_condensation_transfer_rate( diffusivity,
$ velocity,
accomodation,
wet_diameter,
rate )

Computes condensation transfer rate for a given species.

subroutine compute_quadratic_mean_velocity( temperature,
weight,
$ velocity )

Computes condensation transfer rate for a given species.

subroutine compute_saturation_concentration( temperature,
weight,
$ enthalpy,
saturation_pressure,
concentration )

Computes saturation concentration of an organic species.

subroutine compute_kelvin_coefficient( temperature,
weight,
$ surface_tension,
wet_diameter,
density,
coefficient )

Computes the correction factor due to the Kelvin effect on the aerosol surface concentration.