I have defined CaCl2Brine properties as Hypo component (these were taken from DIPPR)

The purpose was to have an x3 effect evaporation unit; so I had Duhring chart to know that at what temperature; mixture of a specified w.t% CaCl2 will boil.

This binary plot was constructed using HYSYS (w.t%)

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If you compare this with following Duhring plot

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My PFD (using NRTL no BIPs)

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You will see that HYSYS under-predicts BPE. For instance if my last effect is going to achieve 60w.t% of CaCl2 solution the temperature of that separator per Duhring is to be ~160C (ACTUALLY IT IS) but HYSYS predicts ~135C

My question is what property while defining Hypo effects this behaviour? How can I make binary plot somewhat closer to Duhring plot?