Patent Pending 0421232.0 CO 2 OLrac Blade Server Cooling
Cooling with CO 2 Carbon dioxide (CO 2 ) is an ideal refrigerant, particularly when considered against ecological and safety criteria. It is natural, non-flammable, oil-free, chemically inactive and has zero potential for ozone depletion. It is electrically benign and does not present a danger to servers or power and data cabling. Performance As CO 2 evaporates it is able to absorb over seven times more heat than chilled water per kg. In comparison with conventional air cooling systems, the use of CO 2 High Density Cooling achieves a spatial saving of up to 75% in the server room. 150kW conventional air cooling The High Density Cooling solution facilitates the deployment of high density servers e.g. Blades. Advantages: High cooling capacity of 30kW+ per rack High density server racks reduce floor areas by up to 75% Energy-efficient, with up to 30% savings in comparison with chilled water (CHW) CO 2 OLrac is compatible with all server racks Maximum safety due to a gas detection and isolation system Suitable for new and existing data centres 150kW high density CO 2 cooling The latent heat capacity of carbon dioxide is 182 kj/kg per degree Kelvin. The specific heat capacity of water amounts to 4.2 kj/kg per degree Kelvin. This means that evaporation of 1kg carbon dioxide absorbs the same amount of heat as 7kg water that heats up by 6K (e.g. from 6 C to 12 C). 03
Heat absorption The CO 2 OLrac units are fitted to the rear of the racks to absorb the heat that is rejected from the server equipment. Additional High Density Cooling in the server room is not necessary as the entire heat load is absorbed within the individual CO 2 OLrac units. The solution benefits from an open architecture design. The rack air inlet and CO 2 OLrac exhaust are open to the server room which enhances the system s resilience. The combined effect of the open architecture design and heat absorption provides further resilience. When a rack is accessed, the adjacent units absorb the heat that escapes from the open rack; this maintains the server room at design condition. The CO 2 OLrac unit is designed to fit to the server rack door and the dual-layer CO 2 flexible hose provides access to the servers. The low level castors safely transfer the unit's weight to the floor and ease the door opening. 22 C +/- 24 C +/- 35/40 C 22 C 24 C +/- 22 C e-chain - power and cooling track Plan view - normal operation Plan view - rack access 04
CO 2 OLrac units are designed to accept single or dual power supplies. It is recommended that they are powered from a UPS supply. Fan selection is designed to provide N+1 redundancy. Simple fixings and plug and socket connections enable the fans to be replaced while the unit and server are running - hot swapable. The fan operating status is displayed by LED s on the user control pad along with the discharge air temperature and coil healthy status. The fan condition and temperature can be monitored remotely via the building management system (BMS). User control pad 05
Resilience and redundancy With a wide range of plant, pipework and coil arrangements to choose from, any level of redundancy can be achieved. System uptime can be enhanced by the specification of standby plant and components (N+1, N+N). Imperial College, London Distribution pipework is made of high-grade stainless steel. For new projects, fully welded pipework is generally used. In existing operational data centres that are not suitable for welding, prefabricated welded sections and cold formed joints are the norm. ~ 30o C + /- ~ 24o C + / - ~ 24 o C + / - CO 2 sensors in the racks and in the server room ensure occupant safety. The detection system will automatically isolate the CO 2 supply to the individual CO 2 OLrac unit and send an alarm signal to the maintenance team via the BMS. The intrinsic resilience of a high-performance server rack is guaranteed through the combination of open architecture and heat absorption provided by CO 2 OLrac. An off-line CO 2 OLrac continues to reject the heat of the server into the room raising the local ambient temperature by a few degrees. The surrounding CO 2 OLrac units compensate for the failure by absorbing the additional load. The servers continue to operate within their recommended limits as the room remains at its design condition. Intrinsic resilience example ~ 22o C + / - Normal operation - CO 2 OLrac x 10 at 20kW Intrinsic resilience - CO 2 OLrac x 8 at 25kW 07