5 Commencing operation and control behavior
Rittal cooling unit assembly and operating instructions page
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Figure 5: Replacement of the filter mat
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Technical informations
The cooling unit (compressor refrigeration unit) con-
sists of four main components: the coolant compres-
sor, evaporator, condenser, and the capillary, which
are connected by suitable Pipe-work. This circuit is
filled with a readily boiling substance, the refrigerant.
The R134a (CH2FCF3) refrigerant is free from chlo-
rine. It has an ozone destroying potential (ODP) of 0
and is therefore environmentally friendly. A filter
dryer which is integrated in the hermetically sealed
cooling circuit, provides effective protection against
moisture, acid, dirt particles, and foreign bodies with-
in the cooling circuit.
7.1.1
Operation of the cooling unit
Figure 6: Operation of the cooling unit
The compressor takes the gaseous refrigerant from
the evaporator and compresses it to a higher pres-
sure in the condenser. During this process the tem-
perature of the refrigerant rises above the ambient
temperature and heat can be dissipated to the envi-
ronment via the surface of the condenser. Then the
refrigerant is liquefied and, by means of a thermos-
tatically controlled capillary, returned to the evapora-
tor, where it evaporates at low pressure. The heat
required for complete evaporation is drawn from the
enclosure interior causing it to cool down. The cool-
ing cycle is thus completed, the aforementioned
process of the heat transfer starts afresh.
7.1.2
Condensate discharge
A drain pipe fitted to the evaporator divider panel
ensures that any condensate which may form on the
evaporator (at high air humidity, low temperatures
inside the enclosure) is drained away from the bot-
tom of the unit. For this purpose, a length of hose
should be fitted to the condensate pipe connection
piece. The condensate must be able to run off freely.
If the condensate is to be drained off over a greater
distance, then care must be taken that the hose is
free from kinks and a check for correct drainage
made.
8
Handling instructions
8.1
Fitting the cooling unit
The enclosure cooling unit may optionally be exter-
nally mounted on the enclosure (1) or partially inter-
nally mounted (2).
