Which property parameters should be used for Aspen to simulate the vaporization of liquid ammonia?
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Which property parameters should be used for Aspen to simulate the vaporization of liquid ammonia? Thank you.
There’s still an error; did I make a mistake somewhere?
If it is only about calculating the properties of ammonia, chemical calculation apps can do this very easily, and the results obtained are more accurate than those from the PR equation and the RKS equation. The PR equation is not very accurate for calculating the liquid phase volume.
It says that you lack the antoine parameters for ammonia, but Aspen already has these values for ammonia. As for the liquid phase volume, Aspen isn’t that stupid either – it uses the PR equation to calculate it. By default, Aspen also employs the DIPPR105 empirical formula; it doesn’t use the liquid phase root of the PR equation.
So the question arises: the DIPPR equation is only applicable to the calculation of the volume of saturated liquids. What about supercooled liquids? :lol
DIPPR is merely an empirical formula for density and temperature; the supercooled liquid provides the supercooling temperature, and the density can be determined accordingly. I’m not sure what you mean by this For most equation of state and empirical formulas, the liquid density is independent of pressure (the liquid is incompressible); when the liquid temperature is the same but the pressure varies, the densities obtained using most of these equation of state and empirical formulas remain identical. If one really wants to obtain the relationship between pressure and density, there are a few equations in ASPEN that can be used for such calculations; for more details, refer to the help documentation.
What I mean is: the density calculated by DIPPR is the density of the saturated liquid at temperature t. Taking water as an example, DIPPR calculates the density at 20°C (saturation pressure: 0.0023393 MPa(a)). But if I want to calculate the density of water at 20°C and 101.325 kPa, this may not be accurate. Fortunately, the difference between these two densities isn’t significant, so they can be used together.
I also mentioned what you’re talking about: for liquids, which are incompressible fluids, most equations of state do not take into account the effect of pressure on density; a few do consider this factor, but it is completely meaningless in engineering applications. If research is to be conducted on this topic, the calculation methods can be altered in the molar volume section, by choosing equations that allow for the calculation of pressure changes.
I don’t understand.:lol:lol