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Flooded type water cooled screw chiller (MIC)
MCAC-CTSM-2018-1
112
a.
Waterbox shall have standard victaulic grooves.
Unit manufacturer shall insulate the cooler shell, compressor suction elbow, motor shell and
motor cooling lines. Insulation shall be
3
/
4
in. (19 mm) thick with a thermal conductivity not
exceeding 0.28 (Btu in.)/hr ft
2
F [(0.0404 • W)/(m • °C)]
2. Condenser shall be of shell and tube type construction. Units shall be fabricated with
high-performance tubing, minimum 10 mm steel shell and tube sheets with fabricated steel
waterboxes.
a.Waterbox shall have standard victaulic grooves.
3. Waterboxes shall have vents, drains, and covers to permit tube cleaning.
A thermistor type temperature sensor with quick connects shall be factory installed in each water
nozzle.
4. Tubes shall be individually replaceable from either end of the heat exchanger without affecting
the strength and durability of the tube sheet and without causing leakage in adjacent tubes.
5. Tubing shall be copper, high-efficiency type, with integral internal and external enhancement
unless otherwise noted. Tubes shall be nominal 3/4-in. or 1 in.
6. Cooler shall be designed to prevent liquid refrigerant from entering the compressor.
7. The condenser shell shall include a flash sub-cooler which cools the condensed liquid refrigerant
to a reduced temperature, thereby increasing the refrigeration cycle efficiency.
8. A reseating type pressure relief valve shall be installed on each heat exchanger.
G. Refrigerant Flow Control:
1. To maintain optimal part load efficiency, the refrigerant expansion device to the cooler shall use a
EXV
H. Controls, Safeties, and Diagnostics:
Controls:
a. The chiller shall be provided with a factory installed and wired microprocessor control center.
The microprocessor can be configured for either English or SI units.
b. All chiller and starter monitoring shall be displayed at the chiller control panel.
c. The controls shall make use of non-volatile memory.
d. The chiller control system shall have the ability to interface and communicate directly to the
building control system.
e. The default standard display screen shall simultaneously indicate the following minimum
information:
1) date and time of day
2) 24-character primary system status message
3) 24-character secondary status message
4) chiller operating hours
5) entering chilled water temperature
6) leaving chilled water temperature
7) evaporator refrigerant temperature
8) entering condenser water temperature
9) leaving condenser water temperature
10) condenser refrigerant temperature
11) oil supply pressure
12) oil sump temperature
13) percent motor rated load amps (RLA)
f. In addition to the default screen, status screens shall be accessible to view the status of
every point monitored by the control center including:
1) evaporator pressure
2) condenser pressure
3) bearing oil supply temperature
4) compressor discharge temperature
5) motor winding temperature
6) number of compressor starts