CoolProp
Issue with Helium properties at low temperatures
Description
Hello,
I am using MATLAB to design a cryogenic refrigerator using helium, and coolprop to obtain the properties of helium.
I am using the twoPhaseFluidTables function from MATLAB (https://www.mathworks.com/help/physmod/simscape/ref/twophasefluidtables.html) to generate a fluid properties table and link it to a simulink block.
The problem is that I keep getting the following error:
It seems there is missing data around the limit of supercritical gas and liquid. For example for a pressure of 0.29 bar, the thermal conductivity has some discontinuities around 5.2 K.
This kind of discontinuities constantly appear below the supercritical or in the liquid phase, not only in thermal conductivity but in temperature or other variables
¿Any solution to this problem?
Thank you in advance
Versions
CoolProp Version: 6.4.1 Operating System and Version: Windows 10 Access Method: MATLAB (tried with python with same result)
This seems to be a failure in the P,U flash routines to calculate temperature and density for this fluid and state space. But that problem is not very evident in the consistency plots: http://www.coolprop.org/fluid_properties/fluids/Helium.html#consistency-plots . Someone (not me) needs to look into this.
On Wed, Oct 28, 2020 at 3:01 PM CarlosHernando16 [email protected] wrote:
Description
Hello,
I am using MATLAB to design a cryogenic refrigerator using helium, and coolprop to obtain the properties of helium.
I am using the twoPhaseFluidTables function from MATLAB ( https://www.mathworks.com/help/physmod/simscape/ref/twophasefluidtables.html) to generate a fluid properties table and link it to a simulink block.
The problem is that I keep getting the following error:
[image: imagen] https://user-images.githubusercontent.com/67965162/97483488-c43b4580-1957-11eb-8de1-67fb8c5264fb.png
It seems there is missing data around the limit of supercritical gas and liquid. For example for a pressure of 0.29 bar, the thermal conductivity has some discontinuities around 5.2 K. [image: imagen] https://user-images.githubusercontent.com/67965162/97483275-88a07b80-1957-11eb-91d0-d490e093086f.png
This kind of discontinuities constantly appear below the supercritical or in the liquid phase, not only in thermal conductivity but in temperature or other variables
¿Any solution to this problem?
Thank you in advance Versions
CoolProp Version: 6.4.1 Operating System and Version: Windows 10 Access Method: MATLAB (tried with python with same result)
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Hi, I am having a very similar problem. I am using MATLAB to create two-phase fluid table for helium, but I get the error : "Error in CoolProp_TwoPhaseFluidTable (line 16) HeTables = twoPhaseFluidTables([-6.5,10000],[0.16 ,0.22],40,40,80,...
Caused by: Error using CoolProp/CoolProp.__Props_err2 (line 344) Python Error: ValueError: unable to solve 1phase PY flash with Tmin=4.7537, Tmax=3000 due to error: HSU_P_flash_singlephase_Brent could not find a solution because Umolar [37976.3 J/mol] is above the maximum value of 37435.9882569 J/mol : PropsSI("D","P",160000,"U",9487893.687,"Helium")"
It seems that the problem is in Helium properties because for R134a the function twophasefluidtable works just fine.
I would very much appreciate your help with this problem. Sincerely, Saara
I'm having a possibly related issue with computing the temperature of Helium for a given enthalpy and pressure near the critical point. For example: `P = 2e5 # Pressure in Pa H = np.linspace(5,20,1000)*1e3 # Enthalpy in J/kg T = cp.PropsSI("T","P",P,"H",H, "He") # Temperature in K
plt.figure() plt.plot(H/1e3,T) plt.xlabel("Enthalpy [J/kg]") plt.ylabel("Temperature [K]") plt.title(f"Temperature as a function of enthalpy for Helium at {P/1e5:.2f} bar") `
A single point in the problem region gives the following error: `P = 2e5 # Pressure in Pa
H = 6.4e3 # Enthalpy in J/kg
T = cp.PropsSI("Hmolar","P",P,"H",H, "He") # Temperature in K`
ValueError: unable to solve 1phase PY flash with Tmin=2.1758, Tmax=5.02545 due to error: HSU_P_flash_singlephase_Brent could not find a solution because Hmolar [25.6167 J/mol] is above the maximum value of 25.2954263088 J/mol : PropsSI("Hmolar","P",200000,"H",6400,"He")
