Temperature change across expansion valve?

[zzinfinity]

Homework Statement

Refrigerant 134-a enters the expansion valve of a refrigeration system at 160 psia as a saturated liquid and leaves at 30 psia. Determine the temperature and internal energy changes across the valve.

Homework Equations

Δu=cv*ΔT

The Attempt at a Solution

I'm not sure how to get the temperature change. Since we know it is initially a saturated liquid, I was able to get the initial temperature from a property table to be 109.5 °F

Is there a way to tell if the refrigerant is a saturated mixture or a superheated vapor after the pressure change? Can we assume its a saturated mixture?

 

[LawrenceC]

Hint: Is there any work being done? Think first law for a flow situation.