Water Boiling Question - Closed Cylinder
 

Hello everyone

I have a general question about thermodynamics/fluids. I did not know which forum should I post this so selected this forum.

Assume I have a perfectly sealed cylinder filled with water completely (no gaps whatsoever). I heat the cylinder from the outside
to 100 degrees C. So will the water boil?

Shree

Your question is not correctly defined. First of all you should define the operating pressure (or lets say the initial pressure) of your water mass.

Assuming you begin with water at atmospheric conditions (p=1bar) then still you need more data about the exact heat you provided. The reason is that at 100C you may have saturated water, saturated steam, or steam and water mixture. You can also see here:
http://en.wikipedia.org/wiki/File:TS...dampf_engl.png

Here you can see the T-s diagram for water. For pressure of 1bar there are infinite possible conditions corresponding to T=100C, all under the saturation curve (the red one).

So, in order to get a definite answer it is essential to know the exact heat provided, through which you can find the enthalpic rise (see http://www.engineeringtoolbox.com/mo...ter-d_308.html). By having specified enthalpy and pressure you have defined a single point.


Note that in reality things are not simple because by heating water, it will expand. Since you perfectly constrain it, heating will pressurize it above the initial pressure. Thus, I think, that is safe to assume that at 100C the water would still be subcooled water, since its pressure will be higher than 1bar.