User's Manual

49
CTV-PRC007-EN
Condenser/Heat Recovery
Condenser
Shell and Waterboxes
The condenser shell is formed of carbon
steel plate designed and constructed in
accordance with ANSI/ASHRAE 15
Safety Code. For all units, all pass
arrangements are available at 150 psig or
300 psig water side working pressures
with grooved connections. Flanged
connections are also available. Marine-
type waterboxes are available.
Tube Sheets
A thick carbon steel tube sheet is welded
to each end of the shell and is drilled and
reamed to accommodate the tubes.
Three annular grooves are machined into
each tube hole to provide a positive
liquid and vapor seal between the
refrigerant and water sides of the shell
after tube rolling. Intermediate tube
support sheets are positioned along the
length of the shell to avoid contact and
relative motion between adjacent tubes.
Tubes
Individually replaceable externally finned
seamless copper tubing, either internally
enhanced (one-inch nominal diameter)
or (three-quarter inch nominal diameter),
is utilized as the condenser heat transfer
surface.
Refrigerant Gas Distribution
A baffle between the tube bundle and the
condenser shell distributes the hot gas
longitudinally throughout the condenser
downward over the tube bundle
preventing direct impingement of high
velocity compressor discharge gas upon
the tubes.
Shell Tests
The refrigerant side of the condenser
shell with tubes, but without waterbox
covers, is proof-tested at 45 psig, vacuum
leak-tested and pressure leak- tested. The
water side of the shell with waterboxes in
place is hydrostatically tested at one and
a half times the design working pressure,
but not less than 225 psig. (These tests
are not to be repeated at installation).
Economizer
The CVHE/CVHG style CenTraVac
™
two-
stage economizer (single-stage
economizer on CVHF style units) is a
series of interstage pressure chambers
which utilize a multiple orifice system to
maintain the correct pressure differential
between the condenser, economizer and
evaporator over the entire range of
loading. This patented system contains
no moving parts.
Purge System
The CenTraVac chiller utilizes a purge
system operating with a 120/60/1 or 120/
50/1 power supply. The purge system,
using an air-cooled condensing unit,
operates automatically to remove any
noncondensables and water vapor
which may be present in the refrigerant
system. Normal operating efficiency
does not exceed 0.002 lbs. of refrigerant
lost per pound of dry air removed.
Noncondensable discharge and
refrigerant return are automatic
functions of the purge. The purge can be
operated at any time independent of
chiller operation. ASHRAE GUIDELINE 3
recommends that the purge should be
able to run even while the chiller is idle.
Purge unit includes lights to indicate
condenser running, fault indication and
service operation. An elapsed time meter
is included as standard to monitor any
amount of leak rate and running time.
Unit Control Panel
The microcomputer control panel is
factory installed and tested on the
CenTraVac
™
unit. All controls necessary
for the safe and reliable operation of the
chiller are provided including oil
management, purge operation, and
interface to the starter. The control
system is powered by a control power
transformer included in the starter panel.
The microcomputer control system
processes the leaving evaporator fluid
temperature sensor signal to satisfy the
system requirements across the entire
load range.
Mechanical
Specification
The microprocessor controller is
compatible with reduced voltage or full
voltage electromechanical starters,
variable speed drives, or solid state
starters. Depending on the applicability,
the drives may be factory-mounted or
remote mounted.
The controller will load and unload the
chiller via control of the stepper- motor/
actuator which drives the inlet guide
vanes open or closed. The load range
can be limited either by a current limiter
or by an inlet guide vane limit (whichever
controls the lower limit). It will also
control the evaporator and condenser
pumps to insure proper chiller operation.
The panel features machine protection
shutdown requiring manual reset for:
•
low evaporator refrigerant temperature
•
high condenser refrigerant pressure
•
low evaporator/condenser differential
pressure
•
low differential oil pressure
•
low oil flow
•
high oil temperature
•
critical sensor or detection circuit faults
•
motor overload
•
high motor winding temperature
•
high compressor discharge
temperature (option)
•
starter contactor fault
•
starter transition failure
•
compressor failure to accelerate
•
external and local emergency stop
•
electrical distribution faults: phase loss,
phase unbalance, phase reversal
•
inter-processor communications lost
•
high bearing temperature (optional)
•
free-cooling valve closure failure (free-
cooling applications only)
•
extended compressor surge
•
actuator drive circuit fault
Over 100 diagnostic checks are made
and displayed when a fault is detected.
The display indicates the fault, the type of
reset required, the time and date the
diagnostic occurred, the mode in which
the machine was operating at the time of
the diagnostic, and a help message. A
diagnostic history will display the last 10
diagnostics with the time and date of
their occurrence.