Heat Exchange in the Evaporator
According to a recent new law, refrigeration systems are no longer allowed
to use refrigerant R-12 due to environmental concerns.
A cryogenic manufacturing facility has
to choose a new refrigerant to replace R-12 used in its refrigeration
systems. Refrigerant R-134a is one choice which satisfies the
energy requirement. To further evaluate this new refrigerant, the entropy changes need to be determined.
What is known:
- Refrigerant R-134a enters the evaporator of the refrigeration system
as a saturated liquid-vapor mixture at a pressure of 200 kPa.
- Refrigerant R-134a leaves the evaporator as saturated vapor at a
pressure of 200 kPa.
- Refrigerant R-134a absorbs 150 kJ of heat from the cooled space.
- The cooled space of the refrigeration system is maintained at -4oC.