Down Flow Cooling Solutions
Down flow cooling systems are the most common design of data centre cooling systems, and are named as such due to the way the CRAC units handle the air, with hot exhaust air entering through the top, passing over the internal cooling systems within, before being ejected out of the bottom of the unit. CRAC units, or computer room air conditioning units, are configured as either Down Flow Plenum or Down Flow Front Displacement.
Down Flow Cooling Solutions
The overall design of your data centre cooling systems should be sized to the I.T. load, with the ability to expand without disruption to critical services which avoids energy wastage due to system losses. It is vital to build redundancy into your data centre cooling systems, as CRAC units require frequent servicing every 3 months as a minimum. Redundant systems provide additional resilience and facilitate repairs during maintenance checks.
It's paramount that down flow CRAC units are efficient and have a high sensible heat ratio (SHR), EC rated fans and electronic expansion values. Selecting the right cooling system will also have a significant effect on the PUE or DCiE.
Down Flow Plenum Data Centre Cooling Solutions
CRAC units positioned around the perimeter of the data centre provide cooling down into and through a raised access flooring system. The colder air then flows through floor grilles situated at the front of hardware cabinets. The hot exhaust air is then return back into the top of the CRAC units. These can be set up using either:
DX or Direct Expansion
Using external condensers with copper pipe work, DX systems are considered the least efficient but offer the best resilience as every CRAC unit has its own pipe work and condenser. These data centre cooling solutions are most effective in smaller data centres and server rooms.
Air Cooled Condensers or Dry Air Coolers
Using external dry air coolers with steel pipework, they are a very efficient but a more costly cooling solution than DX. They are however, ideal for Hybrid DX or Chilled Water CRAC units combined with chillers. Their deployment is generally more suited to medium and large sized data centres.
Chillers & Free Cooling Chillers
External chilled water units with steel pipework, these cooling solutions are very efficient and excellent for chilled water CRAC units. Free cooling chillers come combined with a dry air cooler and so are ideal when external space is restricted. Chilled water data centre cooling systems are most suited to medium and large data centres.
Down Flow Front Displacement Data Centre Cooling Solutions
CRAC units positioned around the perimeter of the data centre provide cooling through a grille on the front of the CRAC or mounted on a plinth with air grilles. Hot exhaust air from the hardware cabinets is then return back into the top of the CRAC units. Front displacement systems are ideal cooling solutions for a data centre with height constraints. These can be set up using either:
DX or Direct Expansion
Using external condensers with copper pipe work, DX systems are considered the least efficient but offer the best resilience as every CRAC unit has its own pipe work and condenser. These data centre cooling solutions are most effective in smaller data centres and server rooms.
Air Cooled Condensers or Dry Air Coolers
Using external dry air coolers with steel pipework, they are a very efficient but a more costly cooling solution than DX. They are however, ideal for Hybrid DX or Chilled Water CRAC units combined with chillers. Their deployment is generally more suited to medium and large sized data centres.
Chillers & Free Cooling Chillers
External chilled water units with steel pipework, these cooling solutions are very efficient and excellent for chilled water CRAC units. Free cooling chillers come combined with a dry air cooler and so are ideal when external space is restricted. Chilled water data centre cooling systems are most suited to medium and large data centres.
