Free-cooling chillers

Naturally chilled, cost effective

Free-cooling is the latest environmentally friendly technique for cooling your datacentre. Datacentre UK is expert in the installation of low-cost, low-energy, free-cooling systems which can be adapted to suit most facilities.

Free-cooling systems make use of low outside air temperatures for chilling water in your air conditioning, rather than traditional energy intensive refrigeration systems. Operation is simple. When the ambient air drops to a set temperature, a valve allows all or part of the cooling water to bypass the powered chiller and run through the free-cooling system instead, immediately reducing your energy requirements.

More on the Free Cooling operation system_in more depth on the next page

Free Cooling operation system in more depth

When all year long water cooling is required, a free cooling chiller is certainly the right choice as the efficiency of this system is, on average, much higher than a traditional water chiller. The cost of this system is easily recouped in a short time, with big environmental benefits. Obviously the best application of a free cooling chiller is on a cooling system where the required chilled water temperature is higher than usual for air conditioning applications. It is particularly suited for industrial process cooling and computer suite/ data centre air conditioning.

The operation of the free cooling system consists of finned pack heat exchangers placed in front of the condensing coils. Air flows through the water coils before crossing the condensing coils. When the outdoor temperature is lower than the returning water temperature, the free cooling system can operate. The free cooling efficiency (EER) depends on the temperature difference between the ambient and desired chilled water temperature (EER is higher than the water/air delta temperature increase).The chiller can operate under three main conditions: Mechanical cooling_Ambient temperature is higher than the returning water temperature. Partial free cooling_Ambient temperature is lower than the returning water temperature.Total free cooling_Ambient temperature is lower than the returning water temperature at least 6°c.

More about energy saving (next page).

Energy saving

The aim of the graphs is to show the energy saving thanks to the performance
of the free-cooling chiller compared to the performance of a standard one.

Graph A
Curve no. 1 refers to the operation of a standard chiller and shows the power
input at different ambient temperatures.
Curve no. 2 refers to the power inputs of a free-cooling chiller at different
ambient temperatures and is divided into three basic parts:
a) full free-cooling (only the fans are working);
b) partial free-cooling;
c) mechanical operation (fans and compressors are working).
The difference in power input between a standard chiller and a free-cooling
chiller is quite obvious in this graph.
Energy saving starts from an ambient temperature of 15°C.

Graph B
The curve in this graph shows the duration, in hours, of ambient temperature
measured in the sample city of Munich in one year.
For example: for 328 hours out of one year the temperature was 5°C.

Graph C
Graph C shows the amount of energy absorbed during one year by the two
chillers being compared. Using the information provided by the previous graphs
we can estimate the annual energy saving between a free-cooling chiller and
a standard one which, in this case, is approximately 50%.
Reference conditions:
Sample city: Munich.
Chiller operating 24 hours a day.
Chilled water in/out: 16/10 °C.