liquid-helium-svp

Python functions for properties of liquid helium-4 at saturated vapour pressure.

Installation

python -m pip install liquid-helium-svp

Usage

import liquid_helium_svp as helium

density = helium.density(4.2)       # kg/m^3
pressure = helium.pressure_SVP(4.2) # Pa

Functions accept scalars, Python lists, and one-dimensional NumPy arrays where applicable. Temperatures are in kelvin, pressures are in pascals, densities are in kg/m^3, and velocities are in m/s unless stated otherwise.

Available properties

The library describes helium-4 at saturated vapour pressure using fits and interpolations based primarily on Donnelly and Barenghi (1998). The input temperature is normally named TemperatureK and the input pressure PressurePa.

For low-temperature pressure corrections, the following functions accept both pressure and temperature arrays. They are based on Abraham et al. (1970):

The fits are intended for the temperature and pressure ranges covered by the source data. Values outside those ranges may be extrapolated by SciPy and should be treated with caution.

The module is based on publication by:

Russell J. Donnelly and Carlo F. Barenghi J. Phys. Chem. Ref. Data 27, 1217 (1998); http://dx.doi.org/10.1063/1.556028 "The Observed Properties of Liquid Helium at the Saturated Vapor Pressure"

In addition to the replication of the publication, the module has a function to infer temperature of liquid helium from saturated vapour pressure.

import liquid_helium_svp as helium

temperature = 4.2  # K

pressure = helium.pressure_SVP(temperature)
recovered_temperature = helium.temperature_from_pressure_SVP(pressure)

print(f'Liquid helium at {temperature} K has vapour pressure of {pressure:.2f} Pa')
print(f'{pressure:.2f} Pa corresponds to {recovered_temperature:.2f} K')

License

MIT