Refrigeration (Cooling) Cycle - Trane RTWD Installation Operation & Maintenance

Refrigeration (Cooling) Cycle

Overview
The refrigeration cycle of the Series R chiller is
conceptually similar to that of other Trane chiller
products. It makes use of a shell-and-tube evaporator
design with refrigerant evaporating on the shell side and
water fl owing inside tubes having enhanced surfaces.
The compressor is a twin-rotor helical rotary type. It
uses a suction gas-cooled motor that operates at lower
motor temperatures under continuous full and part
load operating conditions. An oil management system
provides an almost oil-free refrigerant to the shells to
maximize heat transfer performance, while providing
lubrication and rotor sealing to the compressor. The
lubrication system ensures long compressor life and
contributes to quiet operation.
For RTWD units, condensing is accomplished in a shell-
and-tube heat exchanger where refrigerant is condensed
on the shell side and water fl ows internally in the tubes.
For RTUD units, condensing is accomplished in a remote
air-cooled condenser unit. The refrigerant fl ows through
the tubes in the condenser. Air fl ows over the coils in
the condenser, removing the heat and condensing the
refrigerant.
Figure 15 - Pressure/Enthalpy Curve
L= Liquid
G = Gas
P = Pressure
E = Enthalpy
RLC-SVX14H-GB
A unit-mounted starter (Wye delta on SE, HE, PE
Versions or AFD on HSE versions) and control panel is
provided on every chiller. Microprocessor-based unit
control modules (Tracer CH530) provide for accurate
chilled water control as well as monitoring, protection
and adaptive limit functions. The "adaptive" nature
of the controls intelligently prevents the chiller from
operating outside of its limits, or compensates for
unusual operating conditions, while keeping the chiller
running rather than simply tripping due to a safety
concern. When problems do occur, diagnostic messages
assist the operator in troubleshooting.
Cycle Description
The refrigeration cycle for the RTWD/RTUD chiller can be
described using the pressure-enthalpy diagram shown
in Figure 15. Key State Points are indicated on the fi gure
and are referenced in the discussion following.
Operating Principles
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