COMMERCIAL REFRIGERATION CH. 4
EXAM 2025/2026 QUESTIONS AND
ANSWERS 100% PASS
The discharged vapor picks up which of the following two more additional sources of sensible
heat as the suction vapor is processed through the compressor? - ANS Motor heat and the
heat of compression
What is "clearance volume" and how can it affect compressor efficiency? - ANS The area of
high pressure gas between the top of the piston and the bottom of the valve plate.
What is "volumetric efficiency"? - ANS How well a compressor is operating compared with its
design capacity
If an R404A commercial freezer has design conditions of -20° evaporator and +125° condensing,
what is the compression ratio? - ANS 10.5 to 1
In the example above what is the compression ratio if the customer lowers the box temperature
so that the evaporator is operating at -30° with the same head pressure? - ANS 14.1 to 1
Assume the above freezer evaporator temperature remains at -20°, but the condenser is
designed for a 25° condenser split and the condensing temperature drops to 120°. What is the
compression ratio? - ANS 10.5 to 1
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
EXAM 2025/2026 QUESTIONS AND
ANSWERS 100% PASS
The discharged vapor picks up which of the following two more additional sources of sensible
heat as the suction vapor is processed through the compressor? - ANS Motor heat and the
heat of compression
What is "clearance volume" and how can it affect compressor efficiency? - ANS The area of
high pressure gas between the top of the piston and the bottom of the valve plate.
What is "volumetric efficiency"? - ANS How well a compressor is operating compared with its
design capacity
If an R404A commercial freezer has design conditions of -20° evaporator and +125° condensing,
what is the compression ratio? - ANS 10.5 to 1
In the example above what is the compression ratio if the customer lowers the box temperature
so that the evaporator is operating at -30° with the same head pressure? - ANS 14.1 to 1
Assume the above freezer evaporator temperature remains at -20°, but the condenser is
designed for a 25° condenser split and the condensing temperature drops to 120°. What is the
compression ratio? - ANS 10.5 to 1
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
