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Need some suggestions on artificial ground freezing
Posted 10 set 2010, 09:25 GMT-4 2 Replies
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Hello all,
I am interesting about the modeling of artificial ground freezing by COMSOL. In the application of AGF, steel tube was buried under ground vertically, the coolant(brine) circled in the tube, then the heat of original soil was brought by the coolant, the temperature of soil around the tube was decreased, when the temperature lower than -2?( or even more) ,the soil become frozen.
I am a beginner of COMSOL, so I have some doubts about the modeling.
1) When the brine coolant circle in the tube, the temperature of brine is about -28?, and the temperature of steel tube which contain the brine is about -27? or -26?, it was to say that the temperature of brine and tube is known. how to consider the temperature? Set the temperature as a boundary condition of fixed temperature? or consider the coolant as a heat sink? Modeling the coolant by fluid flow? But the diameter of steel tube is very small than the whole model.
2) the physics of this application should include the conduction and convection of heat and moisture in soil, and the phase change when temperature is enough low. so latent heat should be considered also. I want to add the conduction and convection of heat and fluid flow all in Earth Science Model. Which model suitable for modeling the driving force of cryogenic suction(moisture move from high temperature to low temperature)?
Any suggestion will be appreciated. Thanks in advance.
Best regards!
Joe Seung
I am interesting about the modeling of artificial ground freezing by COMSOL. In the application of AGF, steel tube was buried under ground vertically, the coolant(brine) circled in the tube, then the heat of original soil was brought by the coolant, the temperature of soil around the tube was decreased, when the temperature lower than -2?( or even more) ,the soil become frozen.
I am a beginner of COMSOL, so I have some doubts about the modeling.
1) When the brine coolant circle in the tube, the temperature of brine is about -28?, and the temperature of steel tube which contain the brine is about -27? or -26?, it was to say that the temperature of brine and tube is known. how to consider the temperature? Set the temperature as a boundary condition of fixed temperature? or consider the coolant as a heat sink? Modeling the coolant by fluid flow? But the diameter of steel tube is very small than the whole model.
2) the physics of this application should include the conduction and convection of heat and moisture in soil, and the phase change when temperature is enough low. so latent heat should be considered also. I want to add the conduction and convection of heat and fluid flow all in Earth Science Model. Which model suitable for modeling the driving force of cryogenic suction(moisture move from high temperature to low temperature)?
Any suggestion will be appreciated. Thanks in advance.
Best regards!
Joe Seung
2 Replies Last Post 11 set 2010, 20:56 GMT-4
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Posted:
1 decade ago
Hi
you have many questions there, and I do not have answers to all, but one thing I can suggest is for your two scales of models:
a) "small" tubing and fluidics,
b) "large" soil exchange and behaviour,
This can also be done in two steps "segregated" in the sense you make a detailed model of a tube and liquid, with inlow outflow of both heat and fluid, then you extract the temperature profile along the tube length.
For the second model you define only the tube external surface (+ heat capacity and conduction if you are in transient) onto where you wrap/extrude the previous results and run your "large" model.
Probably you have several tubes in your soild too.
linking both in a transiet analysis is then possible as last step, but more complex since you need more physicals couplings for the thermal (heat capacities and conductions)
--
Good luck
Ivar
you have many questions there, and I do not have answers to all, but one thing I can suggest is for your two scales of models:
a) "small" tubing and fluidics,
b) "large" soil exchange and behaviour,
This can also be done in two steps "segregated" in the sense you make a detailed model of a tube and liquid, with inlow outflow of both heat and fluid, then you extract the temperature profile along the tube length.
For the second model you define only the tube external surface (+ heat capacity and conduction if you are in transient) onto where you wrap/extrude the previous results and run your "large" model.
Probably you have several tubes in your soild too.
linking both in a transiet analysis is then possible as last step, but more complex since you need more physicals couplings for the thermal (heat capacities and conductions)
--
Good luck
Ivar
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Posted:
1 decade ago
Hi Ivar,
Thank you so much for your reply. Your advice broaden my thoughts, just as you have guessed, the whole model have many tubes for coolant cycling, they arranged on three circle diameters, so as you say, the tube component should be studied first alone.
I have study this model by finite difference software FLAC3D before, but the thermal analysis of it is very limited, and the "couple" between the moisture is not the really couple, but calculate alternately. Now I study COMSOL from scratch, I think I will be happy with it, COMSOL is so cool : )
I have read some articles about soil freezing, it seems that, in some extent, the moisture movement in soil can be simulate by Dacy's law. I will check it.
Best regards!
Joe seung
Thank you so much for your reply. Your advice broaden my thoughts, just as you have guessed, the whole model have many tubes for coolant cycling, they arranged on three circle diameters, so as you say, the tube component should be studied first alone.
I have study this model by finite difference software FLAC3D before, but the thermal analysis of it is very limited, and the "couple" between the moisture is not the really couple, but calculate alternately. Now I study COMSOL from scratch, I think I will be happy with it, COMSOL is so cool : )
I have read some articles about soil freezing, it seems that, in some extent, the moisture movement in soil can be simulate by Dacy's law. I will check it.
Best regards!
Joe seung