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AC-SVX002C-EN
Operating Principles
This section contains an overview of the operation of
Ascend
™
Model ACS air-cooled liquid chiller equipped
with microcomputer-based control system.
N
No
otte
e:: To ensure proper diagnosis and repair, contact a
qualified service organization if a problem could
occur.
General
Ascend
™
Model ACS units are scroll compressor, dual
circuit, air-cooled liquid chillers. These units are
equipped with unit-mounted starter/control panels and
operate with R–410A refrigerant.
The basic components are:
•
Unit-mounted panel containing starter and Tracer
®
UC800 controller and Input/Output LLIDs
•
Scroll compressors
•
Brazed-plate evaporator
•
Air-cooled Microchannel (MCHE) condenser with
subcooler
•
Electronic Expansion Valve (EXV)
•
Relating interconnecting piping
Refrigerant Cycle
The refrigeration cycle of the ACS chiller is
conceptually similar to other Trane air-cooled chiller
products. The chiller uses a brazed plate evaporator
and an air-cooled MCHE condenser. The compressors
use suction gas cooled motors and an oil management
system to provide almost oil-free refrigerant to the
condenser and evaporator for maximum heat transfer
while lubricating and sealing compressor rotors and
bearings. The lubrication system helps to assure long
compressor life and contributes to quiet operation.
Refrigerant condenses in the MCHE air-cooled heat
exchanger. Liquid refrigerant is metered into the
brazed plate evaporator using an electronic expansion
valve to maximize chiller efficiency at full and part load
operation.
The chiller is equipped with a unit-mounted starter and
control panel. Microprocessor based unit control
modules (Trane Tracer
™
UC800) provide accurate
chilled water control and providing monitoring,
protection and adaptive limit functions. The adaptive
nature of the controls intelligently prevent the chiller
from operating outside of its limits, or compensates for
unusual operating conditions while keeping the chiller
running rather than simply shutting off the chiller. If
problems do occur, the UC800 controls provide
diagnostic messages to help the operator in
troubleshooting.
Oil System
The oil is efficiently separated inside the scroll
compressor and will remain in the scroll compressor
during all run cycles. Between 1-2% of the oil circulates
around with the refrigerant.
See compressor section for oil level information.
Condenser and Fans
The air-cooled microchannel condenser coils use all
aluminum brazed fin construction. The coil is
composed of three components: the flat microchannel
tube, the fins located between the microchannel tubes,
and two refrigerant manifolds. Coils can be cleaned
with high pressure water. (See Maintenance chapter for
instructions.) The condenser coil has an integral
subcooling circuit. Condensers are factory proof and
leak tested at 650 psig. Direct-drive vertical-discharge
airfoil condenser fans are dynamically balanced.
