Data centres using high density blade racks can require cooling up to 35kw per cabinet, equivalent to an enormous load of 18,200 watts/m².

TROX Advanced IT Cooling Systems (TROX AITCS) is reacting to this challenge with the development of a high cooling output and a high intrinsically resilient CO₂ based cooling system.

Guy Hutchins, Sales Director of TROX AITCS,  explains that intrinsic resilience (IR) is the inherent ability of the system to cope with various potential disasters.  To make the point and the importance of a high IR rating, Guy says that if there were two aeroplanes that both went through the same rigorous testing routine but one could glide to safety if the engines failed – which one would you choose?”

Guy explains:  “Within our R & D programme for a cooling system for data centres there were three main challenges to satisfy, namely, 1. Design a system that has a high intrinsic resilience (IR) rating, 2. Meet the ever increasing cooling loads required by blade servers, 3. Develop a system that has very low energy consumption and carbon emissions.

The high heat loads and low energy consumption challenges were met by using CO₂ as a refrigerant directly removing heat in the cabinets by way of a partial phase change with this eco friendly natural refrigerant.

The third challenge, a high IR rating came about through the careful design of the system.”

Guy goes on to explain: “Server cooling systems need a level of redundancy in the event of parts of the system failing and this is simply achieved by duplicating plant components wiring, piping, etc., and is down to the M & E services consultant who has to find a balance between cost and satisfying his client’s redundancy requirements.

But a cooling system with a high IR means that the risk of cooling failure and an overheated server crash is very much reduced.

The TROX AITCS CO₂OLrac^TM doesn’t have to use a sealed cabinet, generally the case  with water based systems. The CO₂OLrac^TM is simply attached to the cabinet permitting open architecture of the racks so that the whole room air volume can be exposed to the blade load in the case of cooling failure.”

This intrinsic resilience (IR) can bring about very important benefits.

Failure Mode – Individual Cabinet cooling

Despite a system being designed with a high level of redundancy, what if a cabinet loses its cooling?  With water based sealed cabinets temperatures would rise very quickly by up to 20 degrees in just 10 seconds.  This would undoubtedly cause servers to crash!   However, with CO₂ because of the open architecture design the heat from the blades is dissipated into the room with a minimal rise in local ambient temperature of just 1 or 2 degrees.  The adjacent cabinets and their servers are more than happy with exposure to such a modest temperature increase which causes zero performance problems.  The surrounding CO₂OLrac^TM units, designed with a high IR, are able to fully absorb and neutralise the heat of their failed neighbour.

Failure Mode – Complete System

If the complete cooling system failed with water based sealed cabinets the entire data suite could be exposed to a dramatic shutdown due to overheating, possibly in a matter of seconds.

With the CO₂OLrac^TM open architecture and its high IR means the blades do not reach critical temperatures for a minimum of 3 minutes and in some cases up to 20, which is sufficient time to activate a controlled shutdown without loss of data.

Recovery Mode

Following a failure and when the cooling is fully operational the CO₂ absorbs heat seven times greater than water. The open architecture using the whole mass of room air ensures no thermal shock to the blades can occur as the space is gently brought down to design conditions and the data centre is fully operational very much quicker using  CO₂ cooling.

The data centre market is already conditioned  to a robust redundancy regime and a high Intrinsic Resilience (IR) of a system is set to become a major factor in choice of equipment.

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