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Evaporation model, why the fluid temperature is NOT constant? |
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#1 |
New Member
Vincenzo
Join Date: Sep 2017
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I'm simulating evaporation through a pipe. Water is flowing inside it and it gets heated with certain heat flux (1077328 W/m^2). It's subcooled water, it enters at 20°C and 2000 PSI, over a 16 m leght it must evaporate around 80% of the fluid. The thing is, I do get the fraction correct, around 80% but when I plot the temperature of the liquid to check the leght when starts the evaporation I found that the temperature of the liquid along the leght keeps rising! it gets more than 1000 K which is impossible since all the energy is used to change the phase and not to increase the temperature.
So, what's happening? Did I miss something to configurate? Is a flaw in the model? My boundaries conditions are: Pressure based 2D symmetrical Turbulent k-epsilon Water liquid (propierties are piecewise linear to get more close to real values, beacuase water at 320°C has a Cp over 6400 J/kg K) Water vapor (properties remains constant) steel (properties constant) Inlet: velocity Liquid V=0,484 m/s T=293K Vapor V=0, Fraction=0 Outlet: Pressure Gauge pressure= 0 Backflow Temperature=335,472 °C (Saturation temperature) Vapor Blackflow =0 Wall Heated: Wall Thermal q=1077328 W/m^2 Axis: Axis Operating conditions: 2000 psi Phase 1: Liquid Phase 2: Vapor Interaction: evaporation condensation Frequency 0.1 Saturation temp: 335,472 °C Everything else is default. So what i'm doing wrong? I'm missing something? can someone help? Thanks for your time! |
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#2 |
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Join Date: Jun 2017
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I would say that this effect would depend on the fluid properties and the vaporization model you're using. I suggest you to check in the theory manual the equations you're using.
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Tags |
evaporation, fluent, temperature |
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