RAACT_S5_U21 Flashcards
In a dry-type evaporator, what is the usual range for superheat values?
8° to 12° F
To ensure a dry-type evaporator has enough liquid refrigerant during operation, what must be done?
Superhet must be calculated
How is superheat calculated for a dry-type evaporator coil?
Compare the boiling temperature of the refrigerant inside the coil (suction pressure) with the temperature of the line leaving the coil (suction line)
What is superheat?
Sensible heat added to the vapor refrigerant after the change of state.
In a starved evaporator event, does superheat go up or down?
Superheat goes up.
True or false; A starved evaporator coil is likely to freeze up.
True
True or False; Evaporator superheat will stay in the usual range during a hot pulldown event.
False.
During a hot pulldown event, will superheat tend to run high or low?
It will tend to run high?
True or false; Many modern TXVs have wide temperature ranges, some controlling evaporator superheat from +20°F to -20°F.
True.
What part of a system can be damaged by evaporator flooding?
The compressor.
How does evaporator flooding damage the compressor?
Liquid refrigerant may make its way into the compressor.
True or false; a malfunctioning TXV can cause compressor failure.
True.
How full of liquid refrigerant should an evaporator coil be to operate efficiently?
As full as possible.
