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[Ghasem.Bashiri]

Dear experts

I exposed to ethylene dense phase during simulation with Aspen HYSYS.

With such condition, Aspen HYSYS report ethylene as liquid (vap. fraction =0).

Checking of P-H Diagram for ethylene indicates that actual status is dense phase condition.

I need your feedback for such calculation in Aspen HYSYS

 

[MrShorty]

You haven't given any details about the exact condition(s) you are considering. I would guess that it comes down to exactly how you distinguish between "liquid" and "dense phase" and how that differs from how Aspen distinguishes between "liquid" and "dense phase".

 

This page (http://www.jmcampbel...-–-natural-gas/ ) defines the "dense phase" as the region between the critical temperature and the cricondentherm that is above the critical pressure. Of course, for a pure component like ethylene, the critical temperature and the cricondentherm are the same temperature, so we cannot talk about the region between them. However, the page also describes the dense phase as a region with gas-like viscosities and liquid-like densities (whatever those vague terms mean).

 

I expect that the question revolves around exactly how to define a liquid and how to define a dense phase and how your definitions differ from Aspen's definitions.