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-   -   Partially Premixed Combustion - Direct Fired Boiler (http://www.cfd-online.com/Forums/fluent/99730-partially-premixed-combustion-direct-fired-boiler.html)

oknus April 10, 2012 10:52

Partially Premixed Combustion - Direct Fired Boiler
 
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Hi All Fluent Users,

I am trying to solve a problem which is related to the partially premixed combustion and water heating in a domestic hot water (direct fired) heater.

Since, modeling the whole geometry of combustion room of heater will create a huge amount of volume elements, I have prefered to model only the middle slice of the combustion room which includes only 1/15 of the heating pipe, the surface increaser plates on the pipes and the related combustion volume around those materials.

The air/fuel mixture and oxid are entering the domain at the bottom of the model and progressing and getting fired in +Y axis. Heating pipes are laid in X axis app. 150mm above the entering zone. Please see attached "geometry" picture. The top face is the pressure outlet of the combustion.

I have 7 different cell zones:
1) Main combustion Gas (Fluid)
2) Heating Pipes (Solid)
3-7) Water Regions (Fluid)

When I'm setting up my case, I'm specifying the water zones as "water / liquid" from fluent database. Until I have get my case started, Fluent is never giving me an error about anything. And then I'm initializing the case regularly, with respect to the instructions of partially premixed combustion model. However, Fluent does not iterate and is giving the following errors:


999999 (..\src\mpsystem.c@1149): mpt_read: failed: errno = 10054

999999: mpt_read: error: read failed trying to read 4 bytes: No such file or directory

job aborted:
rank: node: exit code[: error message]
0: iyu-PC: -1073741819: process 0 exited without calling finalize
1: iyu-PC: -1073741819: process 1 exited without calling finalize
2: iyu-PC: -1073741819: process 2 exited without calling finalize
3: iyu-PC: -1073741819: process 3 exited without calling finalize
4: iyu-PC: -1073741819: process 4 exited without calling finalize
5: iyu-PC: -1073741819: process 5 exited without calling finalize
6: iyu-PC: -1: process 6 exited without calling finalize
7: iyu-PC: -1: process 7 exited without calling finalize
8: iyu-PC: -1: process 8 exited without calling finalize
9: iyu-PC: -1073741819: process 9 exited without calling finalize
The Parallel FLUENT process could not be started.


There is a strange point. If I specify the material of water region as "pdf-mixture" which is being used for combustion; the Fluent is perfectly working and is giving reasonable results. The pdf_mixture in the pipes is getting heated. and If I increase the speed of pdf-mixture flow in the pipes in order to increase the heat convection coefficient; it is also affecting the results as I estimated.

Hence; the problem is; I can not specify the material of pipe inner regions as "Water/Liquid".

I am looking forward to hear your solution suggestions.


Regards,


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