Learning Forum

[sachintom1992]

I have performed subcooled flow boiling simulations of water in an annulus with :

1. saturation temperature fixed based on outlet pressure conditions
2. saturation temperature as a function of pressure (i.e. by considering piece-wise linear variation).

The results obtained with saturation temperature as constant was matching with experimental results whereas with the function of pressure is not predicting good results i.e.deviation is more wrt experimental results i.e. it is over predicting radial vapor fraction values considerably.

Why is it so? I am using the thermal-phase change model for interfacial mass transfer. Is that model meant to fix the saturation temperature as fixed?

Regards,

Sachin

[Amine Ben Hadj Ali]

Are we talking about 1 to 10% difference? What about the material properties and Latent heat?

[sachintom1992]

Sir I simulated low-pressure subcooled flow boiling of the water case. The radial vapor fraction trend is not at all followed in the case of saturation temperature as a function of local pressure. The vapor fraction considerably moves on to the core region here whereas in the experiment such a variation is not there.
The liquid properties are given as a function of temperature and vapor properties at Pressure outlet-based saturation temperature.
Latent heat is given as constant at pressure outlet-based Tsat.
Can we give latent heat variation with Tsat?

Regards Sachin