Air Conditioner: Refrigerator or Heat Pump?

[xinlan]

Homework Statement

Air conditioners operate on the same principle as refrigerators. Consider an air conditioner that has 7.00 kg of refrigerant flowing through its circuit each cycle. The refrigerant enters the evaporator coils in phase equilibrium, with 54.0 % of its mass as liquid and the rest as vapor. It flows through the evaporator at a constant pressure and when it reaches the compressor 95% of its mass is vapor. In each cycle, how much heat (Qc) is absorbed by the refrigerant while it is in the evaporator? The heat of vaporization of the refrigerant is 1.50×105 J/kg .

Homework Equations

Qc = Mv*Lv
Mv = Mass of vapor
Lv=heat of vaporization

The Attempt at a Solution

I calculated what is the mass of the vapor
M of liquid = 7 kg *54% = 3.78kg
M of vapor = 7 kg - 3.78kg = 3.22kg
then Qc = Mv*Lv
3.22 * 1.50*10(5) = 483000 J

Please.. help me..
thank you

 

[haruspex]

You have calculated the energy that would be released if all of the vapor condensed. What is wanted is the energy to vaporise an additional (54%-5%) of the total mass.