Manitowoc QD0202A, Service Manual

Page: 113 / 175

Part No. 80-1100-3
7-1
Section 7
Refrigeration System
Sequence of Operation
SELF-CONTAINED AIR OR WATER -COOLED MODELS
Figure 7-1. Self-Contained Prechill and Freeze Cycle
(Models Q200/Q280/Q320/Q370/Q420/Q450/Q600/Q800/Q1000)
Prechill Refrigeration Sequence
No water flows over the evaporator during the prechill.
The refrigerant absorbs heat (picked up during the
harvest cycle) from the evaporator. The suction pressure
decreases during the prechill.
Freeze Cycle Refrigeration Sequence
The refrigerant absorbs heat from water running over the
evaporator surface. The suction pressure gradually
drops as ice forms.
H E A T
E X C H A N G E R
E V A P O R A T O R
C O N D E N S E R
C O M P R E S S O R
E X P A N S I O N V A L V E
H A R V E S T S O L E N O I D V A L V E
A I R O R W A T E R
D R I E R
S T R A I N E R
R E C E I V E R
( W A T E R C O O L E D O N L Y )
L O W P R E S S U R E V A P O R L O W P R E S S U R E L I Q U I D H I G H P R E S S U R E L I Q U I D H I G H P R E S S U R E V A P O R
X
SV1569