Cooling within the data centre is a fundamental function of the smooth and efficient operation, however, the cooling equipment is a major share of the cost within the CAPEX outlay.
A combination a of energy efficiency measures and rising energy costs have resulted in companies searching for ways of lowering their PUE (Power Usage Effectiveness) and operating costs. It is especially crucial for the colocation data centres. In particular Big Data companies have been criticised for their inefficiency which is seeing their adoption of newer technologies.
Main types of precision cooling used in data centres
Following amendments in the ASHRAE 2011 (still need to identify that relaxed temperature and humidity requirements for the Data Centres, the cooling segment of the data centre market is undergoing some dramatic changes and opened opportunities for a range of technologies).
Traditional close control (CRAC and CRAH) is still fit for purpose in many countries, however, it is gradually losing its share to newer technologies, especially evaporative cooling.
Evaporative cooling capitalises on the feature of water as a natural coolant when warm and dry air is being humidified allowing for significant savings in operating costs. Evaporative cooling can either utilise the pressurised or compressed water mist (evaporative system) or wetted pads media (adiabatic system).
It is also divided into direct (direct external air is allowed into the data hall) and indirect (when external air does not mix with the internal air within the data hall).
Lone Hansen, WMI Manager – I.T. Cable Group, BSRIA, said: “One major downside with evaporative systems is that they consume water (which can itself be an issue if supplies are scarce) and the evaporative process can cause scaling of pipework and heat exchangers in high pressure systems. The products are more suitable for new build projects due to the space and height requirements, as they are mostly large units. The use of water also raises the issue of legionella, which needs to be given consideration in the design and operation of a facility.”
Close coupled solutions embrace a range of products, located close to the heat source: in-row, rack, rear door heat exchangers and overhead terminal units. These are intended to be more expensive and more suitable at higher densities racks.
Liquid (direct on-chip or immersion cooling) cooling is taking the water or other source of heat rejection (Novec 1230) directly to the server. Depending on application and the technology chosen the server equipment can be completely submersed into the coolant. However, there is still a certain stigma around liquids being at the heart of the IT equipment and it still remains a rather niche product, used only to deal with extremely high densities in HPC segment (>35kW per rack).
What are the geographical differences in the use of technology?
Both the UK and the US are major data centre users sharing a similar profile for the choice of cooling technology used, however, it is believed that as more applications move to off-site data centres, operators will increasingly be looking for locations in low cost countries, this will drive the use of different technology used in these newer application.
The US accounts for approximately 40 per cent of the worldwide precision cooling market. It is the market with the largest share of the evaporative cooling, representing 26 per cent of the total market.