PropsSI returns Q value of -1

[Sampath]

Hi everyone,

I am using CoolProp v6.4.1 with the MATLAB wrapper. I am trying to extract the quality of carbondioxide as a function of pressure and temperature, or pressure and enthalpy using PropsSI. However, CoolProp returns only a value of '-1' for any given combination of the input values. I tested this issue further by changing the fluid. Even in the case of water for a combination of T = 300 K and P=101325 Pa using PropsSI (PhaseSI for this combination returns 'liquid'), I am getting a value of -1. I need the value of Q to calculate to calculate two-phase mixture properties. Can anyone suggest where I am going or how to interpret these results?

[Ian Bell]

Seems like a bug, but can you please show your code? 

On Fri, Nov 4, 2022, 7:31 PM Sampath <sampathk....@gmail.com> wrote:

Hi everyone,

I am using CoolProp v6.4.1 with the MATLAB wrapper. I am trying to extract the quality of carbondioxide as a function of pressure and temperature, or pressure and enthalpy using PropsSI. However, CoolProp returns only a value of '-1' for any given combination of the input values. I tested this issue further by changing the fluid. Even in the case of water for a combination of T = 300 K and P=101325 Pa using PropsSI (PhaseSI for this combination returns 'liquid'), I am getting a value of -1. I need the value of Q to calculate to calculate two-phase mixture properties. Can anyone suggest where I am going or how to interpret these results?

--
You received this message because you are subscribed to the Google Groups "coolprop-users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to coolprop-user...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/coolprop-users/5916b364-5b30-4ecd-9f7e-984a20be0d3bn%40googlegroups.com.

[Sampath]

Hi Ian, thank you for the prompt reply. Attached is a screen grab of the issue in the case of Water as the fluid at 300 K and 101325 Pa.

I am noticing the same issue while running CoolProp in python too.

[Ian Bell]

The rule in CoolProp is that 0 to 1 is two phase and all other values are homogeneous.  It is supposed to be the case that subcritical liquid is q less than 0 and subcritical vapor is q greater than 1.  Recommend you use the low level interface and then you can check the phase flags. 

[Sampath]

Hi Ian, thank you for the suggestions. I will try the low level interface and get back to you. This may take some time since I am new to CoolProp.