Manuel Pacherres
Subscriber

Hello, good morning.
I managed to perform more iterations under the specifications for the materials (according to thermodynamic tables) and the boundary conditions that can be seen in figure 1, figure 2, figure 3 and figure 4 for water and steam.
For water entering at 22.5°C at ambient pressure and steam entering at 105°C with its saturation pressure. 

With 300 iterations, the result is a steam outlet temperature of 76°C and water outlet temperature of 80 °C. With 500 iterations a steam outlet temperature at 75°C and water at 80°C. 

With 700 iterations a steam outlet temperature at 71 °C and water at °C. With 1000 iterations a steam outlet temperature at 64 °C and water at 79 °C.
Where it can be seen that already with 1000 iterations my problem does not converge (in figure 5 I attach the image of my residual). It can also be seen that the heat exchanger changes temperatures significantly (figure 6, 7 and 8), but more on the steam side than on the water side. While in the steam temperature I have a variation of 18°C (it varied more or less from 82°C to 64°C); on the water side I have only a variation of 1°C in all iterations (it varied from 80 to 79°C). 
I would like to know if the phenomenon that is occurring in relation to this variation is coherent or not? Anyway I will continue with the iterations, but I don't know how many more iterations I have to do to make the problem converge?

Also in Figure 9, which is a view of the heat exchanger in CFD-POST, you can notice that at the end of the second step and to start the third step, the colors of the temperature contour change as can be seen inside the circles, as if it were cooling, for which I made a measurement of both temperatures but the temperatures of both sides are the same. But I would like to know if regardless of the colors that you have in the visualization and also have the same temperatures, that is consistent?

I hope you can help me

 

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6 

Figure 7 

Figure 8

Figure 9