Psychrometrics

Psychrometric functions.

ambient.air.STANDARD_PRESSURE = 101325

Standard atmospheric pressure [Pa].

ambient.air.SATURATED_HUMIDITY_RATIO = inf

Specifies humidity ratio at saturation.

class ambient.air.FlowType(value)

Bases: enum.IntEnum

Type of air flow.

MASS = 1

Mass flow rate [kg / s].

VOLUME = 2

Volumetric flow rate [m^3 / s].

class ambient.air.PropertyType(value)

Bases: enum.IntEnum

Type of psychrometric property.

HUMIDITY_RATIO = 1

Humidity ratio [kg_w / kg_da].

RELATIVE_HUMIDITY = 2

Relative humidity [%].

SPECIFIC_ENTHALPY = 3

Specific enthalpy [kJ / kg_da].

SPECIFIC_VOLUME = 4

Specific volume [m^3 / kg_da].

WETBULB = 5

Wetbulb temperature [K].

DEWPOINT = 6

Dewpoint temperature [K].

class ambient.air.MoistAir(property_type, property_value, drybulb, flow_rate_type=<FlowType.MASS: 1>, flow_rate_value=None, pressure=101325)

Bases: object

Class for psychrometric calculations.

property degree_of_saturation

Calculate the degree of saturation of moist air.

property relative_humidity

Calculate the relative humidity of moist air.

property specific_volume

Calculate the specific volume of moist air.

References

2017 ASHRAE Handbook - Fundamentals, Chapter 1, Equation 26

property specific_density

Calculate the density of moist air.

property specific_enthalpy

Calculate the specific enthalpy of moist air.

property wetbulb

Calculate the wet-bulb temperature of moist air.

property dewpoint

Calculate the dew-point temperature of moist air.

ambient.air.celsius_to_kelvin(temperature)

Convert celsius temperature to kelvin.

ambient.air.kelvin_to_celsius(temperature)

Convert kelvin temperature to celsius.

ambient.air.standard_pressure(altitude)

Calculate the standard pressure from altitude.

Parameters

altitude – The altitude in meters.

Returns

Standard pressure in Pa.

Return type

float

ambient.air.standard_temperature(altitude)

Calculate the standard temperature from altitude.

Parameters

altitude – The altitude in meters.

Returns

Standard temperature in K.

Return type

float

ambient.air.saturation_pressure(temperature)

Calculate the saturation pressure based on temperature.

Parameters

temperature – Temperature in K.

Returns

Saturation pressure in Pa.

Return type

float

ambient.air.partial_pressure_water(humidity_ratio, pressure)

Calculate the partial pressure of water vapour.

ambient.air.humidity_ratio_saturation(temperature, pressure)

Calculate the saturation humidity ratio for a given temperature and pressure.

ambient.air.enthalpy_water_condensed_saturated(temperature)

Calculate the enthalpy of water in saturated liquid or solid form.

Parameters

temperature – Temperature of the water [K].

Returns

Enthalpy of saturated water at the given temperature [kJ / kg_w].

Return type

float

ambient.air.enthalpy_water_vapour_saturated(temperature)

Calculate the enthalpy of saturated water vapour.

Parameters

temperature – Temperature of the water [K].

Returns

Enthalpy of saturated water vapour at the given temperature [kJ / kg_w].

Return type

float