Ammonia enters the expansion valve of a refrigeration system a temperature of 24oC and pressure of10 bar and exits at 1 bar. If the refrigerant undergoes a throttling process, what is the temperature and quality of the refrigerant exiting the expansion valve? The answers are - 33.6 degrees Celsius and x=.194 but i cannot figure out how to solve.

X=0.194

T=-33.6C

Explanation:

Hello!

To solve this problem use the following steps!

1. We will call the expansion valve inlet 1 and exit 2

2. Through laboratory tests, thermodynamic tables were developed, these allow to know all the thermodynamic properties of a substance (entropy, enthalpy, pressure, specific volume, internal energy etc ...)

through prior knowledge of two other properties such as pressure and temperature.

3. Find the enthalpy of state 1 using pressure and temperature using thermodynamic tables

h1=Enthalpy (Ammonia; T=24C; P=1000kPa) = 312.9KJ/kg

4. An expansion valve is a device which does not have heat or work exchange which means that the enthalpy of state one is equal to that of state 2, so using thermodynamic tables uses the pressure of state 2 and enthalpy of state 1 to find quality and temperature

x2=Quality (Ammonia; P=100kPa; h=h1=312.9KJ/kg) = 0.194

T2=Temperature (Ammonia; P=100kPa; h=h1=312.9KJ/kg) = -33.6C