RLC-SVX19J_SHORT-GB
16
Optional Free-Cooling
Chiller integrated free-cooling
operation mode
The power of chiller integrated free-cooling relies on
the chiller control to maximize the use of free-cooling
when outdoor temperatures are favorable. The choice
between compressor refrigeration and Free-Cooling
refrigeration will be made and activated depending on
three temperature measurements:
• The ambient air temperature
• The evaporator entering and leaving temperature
• The chilled water set point
Free-cooling coils are fi t in series with the evaporator,
and a set of water regulation valves allows the coils
to be by-passed when they are no longer needed due
to outdoor temperatures which are favorable for free-
cooling.
Three operating modes can be differentiated:
1. Summer operation or Compressor refrigeration
mode
In this operation mode, ambient temperature is higher
than the temperature of the fl uid entering the evaporator.
Free-cooling is not activated, compressors are running,
and control is done in function of the fan/compressor
logic of operation.
2. Mid-season operation or combined refrigeration +
Free-cooling mode
In this operation mode, free-cooling will be enabled
whenever the outdoor temperature is below the
evaporator entering water temperature. The operating
logic is described below. The free-cooling system
operates combined with the mechanical compressor
refrigeration. Most of the time, free-cooling will only
partially cover the required cooling duty. In other words,
mechanical refrigeration will complete what has already
been delivered by free-cooling.
3. Winter operation or Full free-cooling mode
Below a certain ambient temperature, and depending
on the chilled water set point requested, the entire
cooling duty is delivered by the free-cooling system.
Compressors do not operate, since the free-cooling
coils will be able to deliver the requested chilled water
temperature. The regulation of the capacity is described
in the next section. In this mode, only fans are running.
General information
The chiller integrated free-cooling system fl uid based
consist in a set of “Macro-channels” or “Radiators” coils,
fi t in the same frame than the MCHE condenser coils
of the chiller refrigerant circuit. Free-cooling coils will
be full aluminum, fl at radiator design type, with low air
pressure drop to avoid fan performances degradation.
Free-cooling coils are fi t in series with the evaporator,
and a set of water regulation valves ensures the system
to reach the required free-cooling capacity.
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