Buildings.Media.GasesConstantDensity

Information

Medium models in this package use a constant mass density.

The use of a constant density avoids having pressure as a state variable in mixing volumes. Hence, fast transients introduced by a change in pressure are avoided. The drawback is that the dimensionality of the coupled nonlinear equation system is typically larger for flow networks.

Note that models in this package implement the equation for the internal energy as

u = h - p ⁄ ρ_stp,

where u is the internal energy per unit mass, h is the enthalpy per unit mass, p is the static pressure and ρ_stp is the mass density at standard pressure and temperature. The reason for this implementation is that in general,

h = u + p v,

from which follows that

u = h - p v = h - p ⁄ ρ = h - p ⁄ ρ_std,

because ρ = ρ_std in this medium model.

Package Content

Name	Description
MoistAir	Package with moist air model with constant density
MoistAirUnsaturated	Package with moist air model that decouples pressure and temperature and that has no liquid water
SimpleAir	Package with dry air model that decouples pressure and temperature
Examples	Collection of models that illustrate model use and test models