Operating conditions
Application envelope
The discharge temperature depends mainly on
the combination of evaporating temperature,
condensing temperature and suction gas
superheat. Discharge gas temperature should
be controlled with an isolated thermocouple or
thermostat attached to the discharge line 15 cm
from the compressor shell. Maximum discharge
gas temperature must not exceed 140°C when
the compressor is running within the approved
operating envelope.
Maximum discharge gas
temperature
Discharge gas temperature
protection (DGT)
DGT protection is required if the high and low
pressure switch settings do not protect the
compressor against operations beyond its
specific application envelope. Please refer to
the examples below, which illustrate where DGT
protection is required (n°1) and where it is not
(n°2).
The compressor must not be allowed to cycle
on the discharge gas thermostat. Continuous
operations beyond the compressor’s operating
range will cause serious damage to the
compressor!
A DGT accessory is available from Danfoss: refer to
section "Spare parts and accessories".
The operating envelope for Danfoss Heat
Pump scroll compressors are given in the figure
below, where the condensing and evaporating
temperatures represent the range for steady-state
operation. Under transient conditions, such as
start-up and defrost for heat pump applications,
the compressor may operate outside this
envelope for short periods.
The operating limits serve to define the
envelope within which reliable operations of the
compressor are guaranteed:
•
Maximum discharge gas flow temperature:
140°C,
•
A suction superheat below 5 K is not
recommended due to the risk of liquid flood
back,
• Maximum superheat of 30 K as long as maximum
discharge gas temperature is not exceeded,
•
Minimum and maximum evaporating and
condensing temperatures as per the operating
envelopes.
R407C
10
20
30
40
50
60
70
-25
-20
-15
-10
-5
0
5
10
15
20
Continuous operation ranges - R407C dew
Evaporating temperature (°C)
C
o
n
d
en
si
n
g
t
em
p
er
at
u
re
(°C)
SH = 5 K
SH = 10 K
17
FRCC.PC.017.A2.02
Application Guidelines