RLC-SVX19J_SHORT-GB
28
Operating Principles
Refrigerant Circuit
Each unit has two refrigerant circuits, with one or
two rotary screw per circuit. Each refrigerant circuit
includes a compressor suction and discharge service
valve, liquid line shutoff valve, removable core fi lter,
liquid line sight glass with moisture indicator, charging
port and electronic expansion valve. Fully modulating
compressors and electronic expansion valve provide
variable capacity modulation over the entire operating
range.
Refrigerant Cycle
Typical refrigerant cycle on the RTAF is represented
on the pressure enthalpy diagram shown in the fi gure
below. Key state points are indicated on the fi gure. The
cycle for the full load design point is represented in the
plot.
Figure 13 – Pressure enthalpy (P-h) diagram
The RTAF chiller uses a shell and tube evaporator design
with refrigerant evaporating on the shell side and water
fl owing inside tubes having enhanced surfaces (states
4 to 1). The suction lines are designed to minimize
pressure drop (states 1 to 1b) the compressor is a twin-
rotor helical rotary compressor designed similarly to the
compressors offered in other Trane screw compressor
based chiller (states 1b to 2). The discharge lines include
a highly effi cient oil separation system that removes
99,8% of the oil from the refrigerant stream going to
the heat exchangers (states 2 to 2b). De-superheating,
condensing and sub-cooling are accomplished in a
microchannel cooled heat exchanger where refrigerant
is condensed inside the microchannel (states 2b to 3b).
Refrigerant fl ow through the system is balanced by an
electronic expansion valve (states 3b to 4).
Refrigerant Cycle with Economizer
Liquid refrigerant either leaves the micro channel
condenser at point 5a and a part of it fl ows to the
secondary expansion valve and enters BPHE economizer
at point 6 and then the fl ow is vaporized to the
compressor economizer port at state 3a. Meanwhile
the major part fl ows to BPHE economizer acting as
an additive subcooler and refrigerant is cooled down
to state 5b then the major part of the liquid fl ow goes
through the main expansion valve and returns to the
evaporator at state 1.
Refrigerant and Oil
RTAF use R134a, R513A or R1234ze, Trane believes that
responsible refrigerant practices are important to the
environment, our customers, and the air conditioning
industry. All technicians who handle refrigerants must be
properly qualifi ed. All local and UE regulations in what
handling, reclaiming, recovering and recycling, must be
followed.
R134a/R513A/R1234ze is a medium pressure refrigerant.
It may not be used in any condition that would cause
the chiller to operate in vacuum without a purge system.
RTAF is not equipped with a purge system. Therefore
RTAF must not be operated in a condition that would
result in a saturated condition in the chiller of -26°C or
lower. R134a/R513A/R1234ze requires the use of specifi c
POE oils as designated on the unit nameplate.
Table 2 – Trane oil according to refrigerant
Refrigerant
Trane OIL
R134a & R513
fi
xed
speed compr
OIL0048E/OIL0023E
R513A
OIL0048E/OIL0023E
R134a+R513 with VFD
OIL00317/OIL00315
R1234ze
OIL00317/OIL00315
OIL066E/OIL067E possible if on
nameplate
