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EVAPORATIVE COOLING APPLICATIONS - DATA CENTRES
We can now offer evaporative cooling systems (CRECS) for data centres, UPS rooms, IT rooms and server rooms. Conventional Computer Room Air Conditioners (CRAC’s) are high users of electricity. An EcoCooling evaporative cooling system can significantly decrease these costs by over 90% giving potential pay backs of under a year and creating massive carbon savings. Read the independent article by Modern Building Services.
PUE (Power Utilisation Effectiveness) = the ratio between the total data centre power and that used by the IT equipment.
DCiE (Data Centre infrastructure Efficiency) = the proportion of power that goes to the IT equipment in a Data Centre
Here are just a few of our projects using evaporative cooling to efficiently and economically cool data centres...
What has changed to make all this possible?
Modern IT is equipment is far more robust than older equipment. For example most manufactures specify a 10°C to 35°C operating temperature. Relative Humidity is not so critical now tape to tape and paper systems are no longer used. This has been exploited to a limited degree with the use of air economizers or free air cooling systems. Until now these still required a back-up of refrigeration system to accommodate the times of the year when ambient temperatures exceed 25°C. EcoCooling evaporative cooling systems (CRECS) remove the need for refrigeration completely by providing a constant flow of cooled air under 22°C – even during the warmest periods.
What can EcoCooling provide?
EcoCooling have been working with data centres and server room equipment manufacturers to develop a modular system for retrofitting to existing facilities. Comprehensive process controls maintain compliant temperatures together with all of the connectivity required for the secure and safe operation of the total package.
Evaporative Cooling vs Computer Room Air Conditioning for cooling Data centres
Traditional Data Centre Cooling
Computer Room Air Conditioners (CRACs) use a refrigeration system to cool air and pass it to the void under the raised floor.
Evaporative Cooling Free Air System
An EcoCooler takes external air and passes it to the void under the raised floor. Below 18°C ambient air is taken and mixed with air re-circulated from the hot aisle. Above 21°C the EcoCooler uses evaporative cooling to provide air which never exceeds 22°C.
How are the savings achieved?
An EcoCooling free air system provides a constant flow of attemperated air between 18°C and 22°C. No refrigeration is used – the air is cooled by evaporative cooling when ambient temperatures are high and is heated by recirculation of air from the server exhaust when the ambient temperature is low. No refrigeration is used as all of the cooling is achieved using evaporative cooling. This results in energy saving in excess of 90% compared with traditional Computer Room Air Conditioners (CRAC’s)
1 – Fresh air is brought into the system though primary filtration and wetted filter pads
2 – Evaporative cooling operates during warm periods
3 – Low energy axial fan air distribution
4 – Patented control system controls air supply temperature
5 – Air flow is matched to density of cooling required
6 – Hot and cold aisle arrangement of racks is preferred
7 – Room is kept at a positive pressure
8 –Ceiling void can be used for exhaust path.
9 - No exhaust fans are used to reduce complexity and energy use
10 - Hot air is exhausted to atmosphere
System Design
The air flow required of the system is dependent upon the total IT load and the server design. Using a typical ΔT of 10C a single EcoCooler CREC can support a load of 35kW. The systems can be either fixed or variable flow.
The low energy air distribution system uses axial fans which can accommodate most applications. Where raised floors are used, the overall design, in particular the floor grill numbers and position, should reflect the pressure drops and rack cooling load density.
Most systems are controlled centrally. This allows fully automatic control and identification of any fault conditions.
Server and IT operating conditions
The following must be taken into account when providing a cooling solution:
Temperature: In Europe an EcoCooler can provide 100% compliance against the latest ASHRAE[1] standards and meet all manufacturer environmental specifications. Some early main frame systems require close control and evaporative cooling is not suitable.
Relative Humidity: In Europe an EcoCooler can provide 99% compliance against ASRAE allowable conditions. Older equipment such as paper tape and magnetic tape systems are less tolerant and evaporative cooling is not suitable.
Dust: The filter pads provide an adequate level of filtration for modern IT equipment with sealed bearings and closed drives.
Redundancy – The required redundancy is met using the modular system.
BENEFITS
The key benefits of using EcoCoolers compared with conventional refrigeration based air conditioning are:
Cost- Over 90% reduction in electricity usage
- Lower capital costs
- Lower maintenance costs
- EcoCoolers qualify for Interest free loans from the Carbon Trust and Salix schemes.
Engineering
- Low energy ventilation system
- Low cost spare parts holding
- No F gas compliance costs
- Simple technology
- Ability to cope with very hot days
- Allows release of available power for other activities
Operational
- External access for maintenance.
- No internal space used
- Modular system achieves required redundancy
- Simple expansion through modular design
Environmental Benefits
- No refrigerants
- Less than 10% of the carbon footprint of conventional air conditioning
- Can fit into Carbon Reduction Commitment energy reduction scheme
[1] - 2008 ASHRAE Environmental Guidelines for Datacom Equipment
Where can EcoCooling be used?
EcoCoolers require ducting from an outside wall or roof. Modern data centres and server rooms can easily accommodate both data rack cooling and UPS room cooling.
1 – EcoCooling evaporative coolers are externally fixed
2 – Modular systems provide simple compliance with tiered redundancy levels
3 – Existing CRAC systems can be retained
4 – Air is supplied to the underside of the raised floor.
5 – Standby generators only have to support 10% of the electricity consumption of the CRAC systems.
6 – UPS rooms are cooled with simple ventilation systems utilising evaporative cooling
7 - EcoCoolers are linked to all fire systems for controlled shut-downs.
8 – Typical roof mounted EcoCooler.
Useful links about new approaches to cooling of data centres and server rooms.
Intel’s proof of concept of fresh air cooling in New Mexico.
Note the following:
- Very little control compared with EcoCooling
- No significant filtration compared with EcoCooling
- No increased failure!
- Recognition of changing standards of environmental standards for modern equipment.
- Hot and cold aisles being important