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SS-APG008H-EN
Microchannel Heat Exchanger Condensers (MCHE)
The microchannel heat exchanger (MCHE) condenser
design is quite similar to the design of an automobile
radiator. Refrigerant is distributed to very small channels in
a thin plate. There are any number of thin plates, one
above the other, separated by fins as shown in
Figure 6.
MCHE Condenser
Fins
Header (
top
rem oved)
This design improves heat transfer and the refrigerant that
enters the coil quickly turns to liquid. The MCHE tube
volume holds very little refrigerant, so the refrigerant
charge of the system is reduced. However, the tube volume
is so small that if the flow of refrigerant out of the MCHE
condenser is slowed much more than the flow of refrigerant
into the MCHE condenser, the condenser may quickly fill
with liquid and cause a high-pressure control trip. To avoid
this condition, the designer or servicer should not include
the following:
•
No pump-down: The storage capacity of the MCHE
won’t support pump-down.
•
No trim solenoid: The storage capacity of the MCHE
won’t support partial shut-off of the evaporator coil.
