Class: `Methane`

Description

The Methane class represents the properties and constants for Methane (CH₄).
It provides physical and thermodynamic properties required in process engineering simulations and calculations.
All constants are from Perry's Chemical Engineers' Handbook, 8th ed., Section 2 (compound no. 193).

Properties

name (string): Methane
formula (string): CH₄
molecular_weight (float): 16.042 g/mol

Class Reference

class Methane()

Parameters:
* temperature: Temperature, default = Temperature(25,"C")
* pressure: Pressure, default = Pressure(1,"atm")
* density: Density, default = None
* specific_heat: SpecificHeat, default = None
* viscosity: Viscosity, default = None
* thermal_conductivity: ThermalConductivity, default = None
* vapor_pressure: Pressure, default = None
* enthalpy: HeatOfVaporization, default = None
* phase: str, default = None ("liquid" or "gas" overrides the vapor-pressure test)

Methods

The properties of the Methane class are calculated using the following methods, inherited from the base Component class.

phase(): Detects the phase of the substance ("liquid" or "gas") by comparing the system pressure and vapor pressure. (At standard conditions methane is a gas, above its critical temperature (190.564 K); it boils at 111.7 K (-161.5 °C) at 1 atm by its Table 2-8 row.)
density():
Liquid Phase: DIPPR Eq. 105 (Perry's Table 2-32)
Gas Phase: Uses the Ideal Gas Law
specific_heat():
Liquid Phase: Perry's Table 2-153, Eq. (2), a function of reduced temperature
Gas Phase: Ideal-gas heat capacity (Cp), DIPPR Eq. 107 (Perry's Table 2-156)
viscosity():
Liquid Phase: DIPPR Eq. 101 (Perry's Table 2-313)
Gas Phase: Uses Sutherland’s Law with the base class's air constants (no gas viscosity data for this component yet)
thermal_conductivity():
Liquid Phase: Polynomial function of temperature (Perry's Table 2-315)
Gas Phase: Vapor thermal conductivity (k), DIPPR Eq. 102 (Perry's Table 2-314)
vapor_pressure(): DIPPR Eq. 101 (Perry's Table 2-8). Above the critical temperature, as at 25 °C here, the value is the correlation extrapolated past its range: phase() uses it, but it is not a physical vapor pressure.
enthalpy(): Enthalpy of vaporization (ΔHvap), DIPPR Eq. 106 (Perry's Table 2-150). It is 0 above the critical temperature.

Examples

from processpi.components import Methane
from processpi.units import *

ch4 = Methane(temperature=Temperature(25, "C"))
print(ch4.phase())
print(ch4.density().to("kg/m3"))
print(ch4.viscosity().to("Pa·s"))
print(ch4.specific_heat().to("J/kgK"))
print(ch4.thermal_conductivity().to("W/mK"))
print(ch4.vapor_pressure().to("Pa"))
print(ch4.enthalpy().to("J/kg"))

Output

gas
0.655701 kg/m3
1.8e-05 Pa·s (dynamic)
2224.085851 J/kgK
0.034185 W/mK
61834055.697315 Pa
0.0 J/kg

Class: Methane