# Vapor Quality calculation

1. Feb 15, 2010

### banerjeerupak

Water is being used as a coolant by flowing through a channel. I know the mass flow rate of water. And i know the inlet properties of water. I also know that the water is coming out of the channel at a vapor quality of 1. How do i calculate the heat flux that the water is subjected to during flowing through the channel. I need the formula or the direction in which i can think to figure out the question.

2. Feb 15, 2010

### Q_Goest

Hi baner,
The easiest thing to do is just use steam tables. The heat removed is equal to the difference in enthalpy.
dQ = dH

3. Feb 16, 2010

### banerjeerupak

Thank you Q,

-Rupak

4. Feb 16, 2010

### banerjeerupak

now there is a change in the calculations i need to perform. I have the heat flux and the mass flow rate. How should i go about calculating the vapor quality. I couldn't remember the formula, so thought of asking here.

5. Feb 16, 2010

### Q_Goest

You can use the same method.
Qin = Hout - Hin
so
Hout = Qin - Hin
Note: the above Qin and H have units of energy per unit time. H therefore, is the specific enthalpy (h) times mass flow rate.

Once you have hout (units are energy per unit mass) go to your steam tables. Given the pressure on the outlet, you can determine the quality by applying the following and solving for x :
hout = hf + x hfg