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AB243586442172en-001401
System design recommendations
To obtain optimum efficiency of the complete
refrigerant system, optimised R410A heat
exchangers must be used. R410A refrigerant has
good heat transfer properties: it is worthwhile
designing specific heat exchangers to gain in size
and efficiency.
An evaporator with optimised R410A distributor
and circuit will give correct superheat at outlet
and optimal use of the exchange surface. This is
critical for plate evaporators that have generally a
shorter circuit and a lower volume than shell and
tubes and air cooled coils.
For all evaporator types a special care is required
for superheat control leaving the evaporator and
oil return.
A sub-cooler circuit in the condenser that creates
high sub cooling will increase efficiency at high
condensing pressure. In R410A systems the
positive effect of sub cooling on system efficiency
will be significantly larger than in R22/R407C
systems.
Furthermore, for good operation of the
expansion device and to maintain good
efficiency in the evaporator it is important
to have an appropriate sub cooling. Without
adequate sub cooling, flash gas will be formed at
the expansion device resulting in a high degree
of vapour at the expansion device inlet leading to
low efficiency.
Heat exchangers
Refrigerant charge limit
Danfoss SH compressors can tolerate liquid
refrigerant up to a certain extent without major
problems. However, excessive liquid refrigerant in
the compressor is always unfavourable for service
life. Besides, the installation cooling capacity may
be reduced because of the evaporation taking
place in the compressor and/or the suction line
instead of the evaporator. System design must be
such that the amount of liquid refrigerant in the
compressor is limited. In this respect, follow the
guidelines given in the section “Essential piping
design recommendations” in priority.
Use the tables below to quickly evaluate the
required compressor protection in relation with
the system charge and the application.
When the condenser is mounted at a higher
position than the compressor, a suitably sized
“U”-shaped trap close to the compressor is
necessary to prevent oil leaving the compressor
from draining back to the discharge side of the
compressor during off cycle. The upper loop also
helps avoid condensed liquid refrigerant from
draining back to the compressor when stopped.
Discharge lines
HP
LP
Condenser
3D exibility
U Trap
Upper loop
Model
Refrigerant charge limit
(kg)
SH090
5.9
SH105-120-140-161-184
7.9
SH180-240-295
13.5
SH380
14.5
SH485
17
Application Guidelines
Summary of Contents for SH485
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