Hello everyone,
I have two graphs which I need to find explanations for the physicalities, however I am finding difficulties for one of them, heat flow related. I'll post both here because one may help the other.
1. This is the evaporation process in a tube. It start as a mixture and becomes superheated. It data point is a cell of the tube.
2. The heat transfer coefficient increases until the superheated point is met, because of how the mass quality increases.
3. What is an explanation for the heat flow during evaporation being almost constant? There's a really small slope from the beginning of the process to the superheated point.
Thank you!
What's going on with the wall and bulk temperatures? Might DeltaT be coincidently compensating for HTC?
This shouldn't be surprising and is typical in an evaporator or condenser where there are many industrial examples.
@Lucas Goulart duarte
I have some thoughts in mind, but I am not sure yet. Are those cells representing the whole tube or you have more cells after the heat transfer drop?
There can be many explanations
1 - temperature gradient between fluid and tube remains nearly constant. But for an specific cell the gradient also decreases, causing the heat transfer to drop from cell 12;
2 - this could be associated with the drop in specific heat, which is lower for vapor than for liquid ?
Good luck
Consider these things: 1) the effective specific heat (Cp) is essentially infinite under the vapor dome as dH0 and dT=0; 2) if the process is nearly isobaric (dP≈0), then it must be nearly isothermal (dT≈0) for either boiling or condensation; 3) if the ⌂T is nearly constant, then Q must also be nearly constant.
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