Example for water pipe

[Islandfigher]

I'm searching for an example for a warm water pipe . I want to simulate a pipe with water and layers of steel and insulation. I tried to use tmp_back for the water part but that doesn't seem to work. Is tmp_back the wrong parameter?

[mcgratta]

When you say that it "doesn't seem to work", what do you mean?

[Islandfigher]

ok, wrong wording. I meant i'm not shure if it is working. I adapted an example of fds and I am not shure if this is permitted in this way. I suppose, the inner of the steel column is filled with water and therfore the inner temperature is 60 °C if we assume this is constant over time. There are not many informations concerning TMP_BAck in the manual or any examples. Therefor I am unsure.

Here is what I did:

Heat up an insulated, hollow column with a small hot block.
The temperature profiles for the comparable interior and exterior
cell should be the same.

&HEAD CHID='insulated_steel_column', TITLE='Hollow, insulated steel column gets hot' /

&MESH IJK=10,10,20, XB=2.3,3.3,0.0,1.0,0.0,2.0 /
&TIME T_END=1800. /
&DUMP DT_PROF=60. /

&MATL ID = 'STEEL'
FYI = 'A242 Steel'
SPECIFIC_HEAT_RAMP = 'c_steel'
CONDUCTIVITY_RAMP = 'k_steel'
DENSITY = 7850. /
&RAMP ID='c_steel', T= 20., F=0.45 /
&RAMP ID='c_steel', T=377., F=0.60 /
&RAMP ID='c_steel', T=677., F=0.85 /
&RAMP ID='k_steel', T= 20., F=48. /
&RAMP ID='k_steel', T=677., F=30. /

&MATL ID = 'INSULATION'
FYI = 'Isolatek BLAZE-SHIELD DC/F'
CONDUCTIVITY_RAMP = 'k_insulation'
SPECIFIC_HEAT_RAMP = 'c_insulation'
DENSITY = 208. /
&RAMP ID='c_insulation', T= 20., F=0.8 /
&RAMP ID='c_insulation', T=677., F=2.0 /
&RAMP ID='k_insulation', T= 20., F=0.05 /
&RAMP ID='k_insulation', T=377., F=0.10 /
&RAMP ID='k_insulation', T=677., F=0.20 /

/&SURF ID='HOT', TMP_FRONT=1000., COLOR='GRAY' /

&SURF ID = 'THICKLY INSULATED COLUMN EXT'
COLOR = 'ANTIQUE WHITE'
BACKING = 'EXPOSED'
MATL_ID(1:2,1) = 'INSULATION','STEEL'
THICKNESS(1:2) = 0.038,0.0063 /

&SURF ID = 'THICKLY INSULATED COLUMN INT'
COLOR = 'BLACK'
TMP_BACK = 60.
BACKING = 'VOID'
MATL_ID(1:2,1) = 'STEEL','INSULATION'
THICKNESS(1:2) = 0.0063,0.038 /

/&OBST XB= 3.1, 3.2, 0.5, 0.6, 0.6, 0.8, SURF_ID='HOT' /

&OBST XB= 2.6, 2.6, 0.4, 0.7, 0.0, 2.0, SURF_ID6(1)='THICKLY INSULATED COLUMN EXT',SURF_ID6(2)='THICKLY INSULATED COLUMN INT' /
&OBST XB= 3.0, 3.0, 0.4, 0.7, 0.0, 2.0, SURF_ID6(2)='THICKLY INSULATED COLUMN EXT',SURF_ID6(1)='THICKLY INSULATED COLUMN INT' /
&OBST XB= 2.6, 3.0, 0.4, 0.4, 0.0, 2.0, SURF_ID6(3)='THICKLY INSULATED COLUMN EXT',SURF_ID6(4)='THICKLY INSULATED COLUMN INT' /
&OBST XB= 2.6, 3.0, 0.7, 0.7, 0.0, 2.0, SURF_ID6(4)='THICKLY INSULATED COLUMN EXT',SURF_ID6(3)='THICKLY INSULATED COLUMN INT' /

&VENT MB='XMIN', SURF_ID='OPEN' /
&VENT MB='XMAX', SURF_ID='OPEN' /
&VENT MB='YMIN', SURF_ID='OPEN' /
&VENT MB='YMAX', SURF_ID='OPEN' /
&VENT MB='ZMIN', SURF_ID='OPEN' /
&VENT MB='ZMAX', SURF_ID='OPEN' /

&SLCF PBZ=1.0,QUANTITY='TEMPERATURE',VECTOR=.TRUE. /

&BNDF QUANTITY='GAUGE HEAT FLUX' /
&BNDF QUANTITY='WALL TEMPERATURE' /
&BNDF QUANTITY='ADIABATIC SURFACE TEMPERATURE' /

&DEVC XYZ=3.00,0.55,0.77,QUANTITY='WALL TEMPERATURE', ID='Temp_ext_IOR=1', IOR= 1 /
&DEVC XYZ=3.00,0.55,0.77,QUANTITY='INSIDE WALL TEMPERATURE', ID='Temp_ins_IOR=1', IOR= 1, DEPTH=0.02 /
&DEVC XYZ=3.00,0.55,0.77,QUANTITY='BACK WALL TEMPERATURE', ID='Temp_int_IOR=1', IOR= 1 /

&DEVC XYZ=2.95,0.55,0.77,QUANTITY='BACK WALL TEMPERATURE', ID='Temp_ext_IOR=-1', IOR=-1 /
&DEVC XYZ=2.95,0.55,0.77,QUANTITY='INSIDE WALL TEMPERATURE', ID='Temp_ins_IOR=-1', IOR=-1, DEPTH=0.0243 /
&DEVC XYZ=2.95,0.55,0.77,QUANTITY='WALL TEMPERATURE', ID='Temp_int_IOR=-1', IOR=-1 /

&PROF XYZ=3.00,0.55,0.77,QUANTITY='TEMPERATURE',ID='PROF_IOR=1' ,IOR= 1 /
&PROF XYZ=2.95,0.55,0.77,QUANTITY='TEMPERATURE',ID='PROF_IOR=-1' ,IOR=-1 /

&TAIL /

[drjfloyd]

TMP_BACK is the initial back surface temperature. You want to set the gas temperature -- TMP_GAS_BACK.

[rmcdermo]

FDS assumes the fluid is an ideal gas. It is not the right solver for water flowing in a pipe. You can use FDS to just do the 1D heat transfer through the pipe metal with assumed boundary conditions on either side. But you should just use an engineering correlation for the convective heat transfer on the water side.

[Islandfigher]

I have a constant and high water flow through the pipe. The heat transfer and the heating of the maintenance room where the pipe runs through is the main focus not the water flow itself

[mcgratta]

OK, if you assume that the back wall temperature is that of the water, you can (maybe) use the model. If, however, you want to perform heat transfer from the water to the wall, you cannot.