# Example Problem with Complete Solution

2C-1 : Specific Volume of Saturated Mixtures 4 pts
Calculate the specific volume for the following situations:
a.) Water at 300oC and 72% quality
b.) R-134a at -50oC and 83% quality
c.) Ammonia at 750 kPa and 48% quality

Read : This is an exercise designed to drive home the meaning and use of the new concept of the quality of a saturated mixture.  It is crucial to remember that if a quality is given, then the system contains a saturated mixture and you probably need to look up properties of both the saturated liquid and the saturated vapor.
Given: a.) Water T 300 oC x 0.72 kg vap/kg tot
b.) R134a T -50 oC x 0.83 kg vap/kg tot
c.) Ammonia P 750 kPa x 0.48 kg vap/kg tot
Find: V ??? m3/kg for each of the three parts of this problem.
Assumptions: None.
Equations / Data / Solve:
Part a.) Data from the Saturation Temperature Table of the Steam Tables at 300oC: Vsat liq 0.0014042 m3/kg
Vsat vap 0.02166 m3/kg
P* 8587.9 kPa
The key equation for this problem is the relationship between the properties of a saturated mixture and the properties of saturated liquid and vapor and the quality. Eqn 1
Now, we can plug numbers into Eqn 1 to answer this part of the question. V 0.01599 m3/kg
Notice that I kept 4 significan figures in this answer istead of the usual 2 or 3 because there are 4 significant digits in the sat'd liquid and sat'd vapor values.  Perhaps I should have only retained 2 significant digits because there only appear to be 2 significant digits in the quality.  I have assumed that there are more than 2, really 4 or more, digits in the quality.  This may not be a good assumption.
Part b.) Data from the Saturation Temperature Table of the R-134a Tables at -50oC: Vsat liq 0.00069142 m3/kg
Vsat vap 0.60620 m3/kg
P* 29.451 kPa
Now, we can plug numbers into Eqn 1 to answer this part of the question. V 0.50326 m3/kg
Significant figures are a bit tricky here.
Part c.) Data from the Saturation Pressure Table of the Ammonia Tables at 400 kPa: Vsat liq 0.0016228 m3/kg
Vsat vap 0.16980 m3/kg
Tsat 15.88 oC
Now, we can plug numbers into Eqn 1 to answer this part of the question. V 7.7095 m3/kg
Significant figures are a bit tricky here as well.
Verify: No assumptions to verify.
Answers : a.) V 0.015988 m3/kg b.) V 0.50326 m3/kg
c.) V 7.7095 m3/kg 