If i am given the volume (m^3) of a pressure container as well as the total amount of distilled water (kg) in there and pressure (abs---bar) on the container, how do i find the amount of LIQUID water in the system, AND the internal energy of the system?



Is it correct to just look at a SATURATED water table at "3bar", then look at the specific volume Vvapour and Vliq to find quality x. This quality will tell us the % of vapour and liquid in the saturated system. (I assume it is saturated???? if not, why not, if so, why so?)

And to find the internal energy of the system is quite simple once we know the quality, since
U(sys) = x(Vvapour) + (1-x)(Vliq).


Just looking for some insight or explanation.

Use the tables?
saturated water means 0% vapor

This post was edited by saber_x3 on May 6 2013 10:17pm

i think you're getting confused with saturated liquid, or fluid.

the saturated water table shows equilibrium info between pressure, temp, specific vol/etc of water coexisting in equilibrium with liq and vapour.

Given pressure , Specific volume (if sp volume is not given, it's found by known volume/given mass, assume it fills entire container)
Find: amount of water in the container.
water= liquid water =/= vapor
----------


1. pressure table,
2. where is your specific volume fall for the given pressure? Inbetween V_spLiquid , V_spvapor ?
3. If it falls in between then you have a quality X. Do you need help finding that?
4. If you have quality, you can find what internal energy is for that quality.
5. Multiply by mass to get totals

It's so funny - i did it this EXACT way after spending ~2 hours at university studying it today.... sheeeesh.

And how do i find the specific volume of it if i then increase the pressure to XX bar?

do i:
1. look at sat pressure table at XX bar.

aaaand then???

Don't worry found out how to do it all.

EXCEPT one LAST and FINAL question:

if i were to sketch the path of this on a diagram (probs a p-v diagram) of this compression process, it should look like this i presume:
http://i.imgur.com/0RC2qaj.png

How come you think specific volume does not change?
It'll change, very little

because it's the same 82kg of water (whether vapour or gas [[[i.e the quality changes]]]) in a 1 cuboc mtr container, the specific volume will not change?

this is correct, or not correct?

This post was edited by LilGugz on May 8 2013 05:17pm