York R-407C Optimized, Руководство пользователя, Страница: 4 / 120

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YORK INTERNATIONAL
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YORK INTERNATIONAL
FORM 201.19-EG4
Specifications
These YORK air cooled chillers are shipped as a
complete factory package. Each unit is completely as-
sembled with all interconnecting refrigerant piping and
internal wiring, ready for field installation, including:
HFC REFRIGERANT R-407C:
• R-407C has outstanding properties which make it the
superior HFC refrigerant for air cooled chillers.
• R-407C is an HFC (hydrofluorocarbon). HFCs have
zero ODP (ozone depletion potential) because they
contain no chlorine to damage the ozone layer.
• R-407C achieves low total global warming impact in
YORK ’s eco
2
air cooled chillers. Direct effect GWP
(Global Warming Potential) assumes refrigerant is al-
lowed to leak into the atmosphere. Refrigerants suit-
able for air cooled chillers have similar GWPs, and the
slight differences are not significant when evaluating
TEWI (Total Equivalent Warming Impact). Instead, the
CO
2
and rejection heat from utilities generating elec-
tricity to run the machines account for 98% to 99% of
TEWI over the typical life of a chiller. Therefore, the
critical issue is energy efficiency. The YORK eco
2
air
cooled chillers have excellent energy efficiency.
• R-407C is safe and chemically stable. R-407C is
listed in ASHRAE Standard-34 Number Designation
and Safety Classification for Refrigerants as an “A-1”
refrigerant; lowest toxicity, non-flammable.
• R-407C is similar to R-22. Though there are many
refrigerants, HFC R-407C retains many of the fine
properties of HCFC R-22, the venerable ‘work-horse’
refrigerant of air-cooled DX chillers for decades, but
with no chlorine. In fact, the pressures, temperatures,
and heat transfer characteristics of R-407C are so
similar to R-22, it has been applied for years as a
‘drop-in’ alternative in machines originally designed
for R-22.
• R-407C has “Glide,” which benefits performance. Glide
describes the property of a refrigerant boiling across a
temperature range at a given pressure (it is zeotropic ),
rather than at a single temperature ( azeotropic ). R-
407C is a blend of three constituents (23% R-32, 25%
R-125, and 52% R-134a) and is zeotropic. At typical
water chiller evaporator pressures, R-407C has about
8°F (4.4C°) of glide. While placing a refrigerant with
glide into a machine designed for an azeotropic refrig-
erant (no glide, like R-22) typically diminishes chiller
performance, the YORK eco
2
machine exploits glide
to achieve exceptional energy efficiency.
• R-407C is a good “DX” refrigerant, well suited to air
cooled chillers. DX, or Direct Expansion (refrigerant
evaporated in the tubes, and water flowing over the
tubes inside the shell), and Flooded (refrigerant boil-
ing in a ‘pool’ in the shell, and water inside the tubes)
are terms used to describe typical chiller evaporator
heat exchangers. While flooded designs are easily
employed on indoor equipment, DX is preferred on
air-cooled equipment for better refrigerant and oil
management across the broad range of ambient
conditions, resulting in greater application flexibility
and system reliability.
EVAPORATOR:
• YORK
’s special eco
2
‘Counter-Flow’ heat exchanger
design takes advantage of the “Glide” characteristic
intrinsic to HFC R-407C. It employs technologically
advanced (patented) high efficiency tube assemblies
which make possible a single refrigerant pass, DX type
cooler that is better than a flooded cooler; delivering
refrigerant suction gas warmer than the leaving chilled
water at full load.
• Independent circuits provided for each compressor.
• Design working pressure of the shell waterside is 150
PSIG (10.3 Bar), and 350 PSIG (23.8 Bar) for the
refrigerant side. Constructed and tested in accordance
with applicable sections of ASME Pressure Vessel
�
Water
HFC-407C
Water In Refrigerant Out
Water Out Refrigerant In
13.0
11.0
9.0
7.0
5.0
3.0
1.0
Temperature ° F
LD04906
Code, Section VIII, Division (1). Water side exempt
per paragraph U-1, (c), (6).
• Water baffles fabricated from galvanized steel to
resist corrosion. Removable heads allow access to
internally-enhanced, seamless, copper tubes. Water
vent and drain connections included.
• Cooler equipped with thermostat controlled heater
for protection to -20°F (-29°C) ambient, and insu-
lated with 3/4" (19 mm) flexible, closed-cell foam
(k = 0.25).
SEMI-HERMETIC YORK SCREW COMPRESSORS:
• Continuous function, microprocessor controlled,
3-way proportional Capacity Control Valve provides
regulated output pressure independent of valve input
pressure for a stable, smooth, and precise match of
compressor capacity to cooling load to 10% of chiller