### HYSYS Peng Robinson EOS Liquid density correction - volume shift

HYSYS volume translation for Peng robinson equation seems not right. I get completly wrong liquid densities when i copy PVTSim Cpen data to HYSYS. Is there anybody facing the same problem?

#### 1 Answer

If you are transfering PVTSim EOS volume shift values to the HYSYS, then be aware that HYSYS has an error in their implementation of volume shift where they require input of the "negative" of the actual value for "c" (volume shift with units) instead of the original-published and industry-implemented volume shift which is defined as:

v(adjusted) = v(EOS) - c.

However HYSYS implemented v(adjusted) = v(EOS) + c

(where v(EOS) is the molar volume from the original 2-constant (a,b) EOS of SRK or PR.

I hope this helps.

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