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#1 |
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Join Date: May 2016
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I have to perform a calculation on a heat exchanger in which one of the fluid is CO2. I created a CFX RGP file covering the liquid, the gas and the supecritcal region of the phase state diagram. But I met one problem about CFX-solver.
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#2 |
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Yuva
Join Date: Oct 2015
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Hello
Are you solving the problem on one machine Windows or on Cluster platform Linux ? Did you create the RGP file by yourself or you import it from NIST ? AND you need to specify the competent name (CO2 for ur case ) of the fluid exactly as it is written inside the RGP file when you upload the file in CFX Tell me if it works windows.JPG |
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#3 |
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https://www.reddit.com/r/CFD/comment...al_properties/
There is a RGP and i changed it according to my need.But there was a problem when i upload the file in CFX.And i specify the competent name of the fluid exactly as it is written insisde the RGP |
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#4 |
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Lauren Blanchette
Join Date: Mar 2016
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Hello,
I am trying to create a RGP table for sCO2 as well to use in CFX. For this I am creating metastable state tables in which gas properties go into the liquid region. I have created the table but when I try to solve I receive an error stating "Encountered problem reading superheat data". I have gone off of the .rgp file attached to this thread but the only thing that I do not understand is how the saturation temperature and property dependent on the pressure was created at the end of each superheat table. Can anyone explain the way they got there values within the table? Most of my properties are beyond the critical point and thus they do not return a saturation temperature with the known pressure. Any help would be greatly appreciated. Thanks, Lauren |
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#5 | |
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Yafei Li
Join Date: Jul 2018
Location: CHIAN
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Quote:
How to define the Liquid property in the RGP file. Can you give me an example. |
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#6 |
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ANTALYA
Join Date: Sep 2017
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Hi, I have been trying to import the RGP file for supercritical CO2 to Ansys CFX. But I met one problem with CFX-solver as follows:
Thank you for your recommendations. Regards. +--------------------------------------------------------------------+ | Buoyancy Reference Information | +--------------------------------------------------------------------+ Domain Group: Default Domain Buoyancy has been activated. The absolute pressure will include hydrostatic pressure contribution, using the following reference coordinates: (-5.44926E-17, 6.31409E-20, 3.00000E-04). Fatal bounds error detected --------------------------- Variable: Thermal Conductivity Locale : Default Domain +--------------------------------------------------------------------+ | Writing crash recovery file | +--------------------------------------------------------------------+ Details of error:- ---------------- Error detected by routine MAKDAT CDANAM = LVAR CDTYPE = INTR ISIZE = 140 CRESLT = OLD Current Directory : /FLOW/ALGORITHM/ZN1/SYSTEM/VARIABLES +--------------------------------------------------------------------+ | An error has occurred in cfx5solve: | | | | The ANSYS CFX solver exited with return code 1. No results file | | has been created. | +--------------------------------------------------------------------+ End of solution stage. |
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#7 |
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Glenn Horrocks
Join Date: Mar 2009
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The error message says exactly what is going on.
The first section is a comment about how it is setting up the buoyancy calculation. You should read this and check that it is doing the correct thing. This is not an error or warning, just a message. The second bit says there is a bounds error on thermal conductivity. This usually means the pressure or temperature has gone outside of the range of your material properties table. This table may have been defined by your RGP file or it could have come form elsewhere. Either way, the simulation went outside the range you defined. This might mean a bit of the simulation exceeds the range you defined (so you need to extend the range to cover the entire actual range) or your simulation has some numerical problems leading to non-physical values. Maybe it will converge and come good after a while, or maybe it will diverge.
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#8 |
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Erik
Join Date: Feb 2011
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What temperature and pressure are you at?
Are you using the liquid or vapor property tables from your .rgp file? My guess is you may be using the wrong phase, hence variables are out of range in that table. |
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#9 | |
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ANTALYA
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Quote:
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#10 | |
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ANTALYA
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Quote:
$$$$HEADER $$$CO2 1 $$PARAM 26 DESCRIPTION CO2 (LIQUID) NAME CO2 INDEX CO2 DATABASE NIST PROPERTY DATABASE MODEL 3 UNITS 1 PMIN_SUPERHEAT 7494582.6347656 PMAX_SUPERHEAT 8494319.9687500 TMIN_SUPERHEAT 250.0000066 TMAX_SUPERHEAT 750.0000199 TMIN_SATURATION 0.0000000 TMAX_SATURATION 304.1282000 P_CRITICAL 7377300.0000000 P_TRIPLE 517964.3433553 T_CRITICAL 304.1282000 T_TRIPLE 216.5920000 GAS_CONSTANT 188.9240578 TABLE_1 800 800 TABLE_2 800 800 TABLE_3 800 800 TABLE_4 800 800 TABLE_5 800 800 TABLE_6 800 800 TABLE_7 800 800 TABLE_8 800 800 TABLE_9 800 800 $$$CO2VAP 1 $$PARAM 26 DESCRIPTION CO2 (VAPOR) NAME CO2VAP INDEX CO2VAP DATABASE NIST PROPERTY DATABASE MODEL 3 UNITS 1 PMIN_SUPERHEAT 7494582.6347656 PMAX_SUPERHEAT 8494319.9687500 TMIN_SUPERHEAT 250.0000066 TMAX_SUPERHEAT 750.0000199 TMIN_SATURATION 250.0000066 TMAX_SATURATION 750.0000199 P_CRITICAL 7377300.0000000 P_TRIPLE 517964.3433553 T_CRITICAL 304.1282000 T_TRIPLE 216.5920000 GAS_CONSTANT 188.9240578 TABLE_1 800 800 TABLE_2 800 800 TABLE_3 800 800 TABLE_4 800 800 TABLE_5 800 800 TABLE_6 800 800 TABLE_7 800 800 TABLE_8 800 800 TABLE_9 800 800 $$$$DATA $$$CO2 1 $$PARAM 26 DESCRIPTION CO2 (LIQUID) NAME CO2 INDEX CO2 DATABASE NIST PROPERTY DATABASE MODEL 3 UNITS 1 PMIN_SUPERHEAT 7494582.6347656 PMAX_SUPERHEAT 8494319.9687500 TMIN_SUPERHEAT 250.0000066 TMAX_SUPERHEAT 750.0000199 TMIN_SATURATION 250.0000066 TMAX_SATURATION 750.0000199 P_CRITICAL 7377300.0000000 P_TRIPLE 517964.3433553 T_CRITICAL 304.1282000 T_TRIPLE 216.5920000 GAS_CONSTANT 188.9240578 TABLE_1 800 800 TABLE_2 800 800 TABLE_3 800 800 TABLE_4 800 800 TABLE_5 800 800 TABLE_6 800 800 TABLE_7 800 800 TABLE_8 800 800 TABLE_9 800 800 $$SUPER_TABLE values are continuing. |
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#11 | |
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Glenn Horrocks
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Quote:
* save a results file just before the error and have a look at it. Is it physically realistic? * Look at the convergence. Is it converging? If it appears to be converging and realistic then you might need to increase the range. If it is not converging then you need to fix the convergence problem. If it is not realistic then you need to look at your simulation to see if it is correctly set up.
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#12 |
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Erik
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The fluid is using either one table or the other based on the the name you set them to (CO2 or CO2VAP) which are the names of the liquid and vapor tables. They are two different phases, and if you specified the table name to be "CO2" then you are using the liquid table, not the vapor table. In CFX, in the material properties, you have to use component name "CO2VAP" to use the vapor table. At 80 bar, you are supercritical, therefore you should be using only the vapor table, not the liquid table.
As I said in my last post: "My guess is you may be using the wrong phase, hence variables are out of range in that table." Which I'm now more confident in. You are using the liquid table, not the vapor table as you should. So of course, data is out of range of the liquid table at 80 bar since CO2 is "vapor" above 73 bar. |
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