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Problem water properties in supercritical conditions

Juan Sebastián Alvarez Rincón

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Hello
I'm working with water at supercritical conditions and am trying to configure the properties of this in comsol, I'm modifying the properties are the density (rho) in comsol, heat capacity (cp), thermal conductivity (k) and viscosity (etha) the problem is that I have such data on the density and temperature at a pressure of 24 MPa, the METI data in Material> Water> basic (def)> and I comsol interpolation curve plotted me very well, but when I run the simulation in the model that I have integrated the turbulent flow model (ke) and heat transfer fluids, generates an error saying that the matrices Na ... not converge.

perform a polynomial regression of degree 6 to enter it in comsol in Material> Water> basic (def)> piecewise shift 3 (rho) with the following equation

164945.1013728440-1590.8033424291 * T * T ^ 1 ^ 2 6.2306828798-1.2604555138E-2 * T ^ 3 1.3899313851E-5 * T ^ 4-7.9433978593E-9 * T ^ 5 1.8438357144E-12 * T ^ 6

temperatures between 318 642 and 1023.53 and I generated a curve different from that of being but I run the simulation and not an error converges with pardiso.

when you put a comsol polynomial regression of order 4, the graph is not very accurate but the model converges

I want to know how to add the trend of the density of water at supercritical conditions either piecewise (regression) or Interpolation (X and Y coordinates).

attachment behavior graph the density of water at supercritical conditions, here are the values ​​of this curve and the results that throws me comsol.

thanks

Juan Sebastián

3 Replies Last Post Nov 21, 2012, 8:08 p.m. EST
Juan Sebastián Alvarez Rincón

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Posted: 1 decade ago Nov 21, 2012, 8:03 p.m. EST
density behavior of the water in supercritical conditions

density behavior of the water in supercritical conditions


Juan Sebastián Alvarez Rincón

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Posted: 1 decade ago Nov 21, 2012, 8:07 p.m. EST
Comsol results after add polynomial regression .

and points of the curve Density right column(Kg/m¨3) vs Temp left column (K)

318.642 1009.99
372.395 975.37
424.081 940.76
469.559 881.35
519.172 821.94
570.850 752.63
595.651 693.19
622.516 618.88
630.779 584.20
641.103 514.82
649.362 455.36
653.447 212.49
663.775 157.98
669.972 128.25
721.657 93.64
773.347 78.85
820.903 69.01
872.594 59.17
926.353 54.30
971.843 54.37
1023.53 49.49
Comsol results after add polynomial regression . and points of the curve Density right column(Kg/m¨3) vs Temp left column (K) 318.642 1009.99 372.395 975.37 424.081 940.76 469.559 881.35 519.172 821.94 570.850 752.63 595.651 693.19 622.516 618.88 630.779 584.20 641.103 514.82 649.362 455.36 653.447 212.49 663.775 157.98 669.972 128.25 721.657 93.64 773.347 78.85 820.903 69.01 872.594 59.17 926.353 54.30 971.843 54.37 1023.53 49.49

Juan Sebastián Alvarez Rincón

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Posted: 1 decade ago Nov 21, 2012, 8:08 p.m. EST
result of comsol
result of comsol

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