Data centres    

COLT TELECOM SAVES £230,000 WITH TURBOMISER CHILLERS AT POWERGATE
 
Energy savings of 55 per cent have been achieved following replacement of existing chillers with new Turbomiser chillers at Colt Telecom’s Power­gate data centre facility.
Monitoring of power consumption by the client shows that the annual electricity bill for the existing plant before replacement was £321,200 a year. Following replacement with Turbomiser chillers, power consumption fell to £146,000 a year. This represents a saving of 55 per cent, amounting to a saving of£175,000 a year. According to Colt, adding in savings in break­down and servicing costs gives a total annual saving of £230,000.
 
Project details:
 
The project, carried out by Bristol-based Cool-Therm, demonstrates the exceptional performance and efficiency of Turbomiser chillers, running on virtually friction magnetic bearings.
The previous system comprised 3 x 1200kW chiller packages based on screw compressors, DX evaporators, copper tube/aluminium fin condens­ers and basic electro-mechanical controls. Two of the three chillers were to run with one as “standby”. The units had been in service for 10 years and were considered to be inefficient and expensive to maintain.
 
Problems with existing system
 
• Energy consumption: very high due to a relatively low EER of 2.5-3.0-1 (the ratio of power input to cooing output);
• Poor reliability: compressors kept failing resulting in concern over re­lated risks for continuity of cooling;
• High maintenance costs: in order to minimise the risk of compressor failures, engineers had to visit site many times to ensure oil filters and refrigerant filter driers were kept clean;
• High running costs: these were escalating as the air-cooled condensers became chocked with dirt, causing inefficiencies within the system and resulting in overheating condenser fan motors.
• Oil contamination: due to compressor burn-outs, reducing heat ex­changer efficiency.
 
The brief
 
The brief was to replace the existing three 1200kW chillers with new Tur­bomiser chillers as a turnkey package, matching the existing Data Centre cooling load and maintaining cooling to the centre at all times during the changeover.
 
 
         

  Before: The existing chiller before the arrival of the Turbomisers
 
 
       
After: A new Turbomiser chiller is lowered into position onsite
 
EQUIPMENT List
 
The three existing 1200kW chillers were replaced with six 600kW Turbomiser chill­ers, dramatically improving resilience.
All chillers are operated to­gether under inverter control, to gain maximum compres­sor efficiency and use all heat exchanger surfaces to reject heat.    

Key requirements of the project:
• New chillers to have an ESEER at least 25% better than the existing;
• New chillers should not require intensive maintenance to keep them op­erating at design conditions;
• New chillers must be reliable at all times;
• Overall performance of new chillers must be significantly better than those they replace.
 
System design and approach
 
After careful analysis of the requirements, the replacement system pro­posed consisted of six x 600kW Turbomiser chillers to replace the existing 3 x 1200kW onsite, thereby dramatically improving resilience.
 
It was decided to operate all six chillers together to gain maximum com­pressor efficiency under inverter control, at the same time achieving maxi­mum condenser efficiency due to the utilisation of all heat exchanger sur­faces to reject heat.
 
The same logic also applied to the chilled water evaporators. Increasing the chilled water temperatures into and out of the Data Centre was also examined and it was thought that it could be raised from 6/12 deg. C (origi­nal design) to 8/14 deg. C, improving efficiency even more.
The client wanted to prove the performance of the new chillers against the old. Therefore, a monitoring system was put in place to measure en­ergy consumption against the previous system
 
Results
 
Reduction in energy use: By the time all six Turbomiser chillers were oper­ational, energy consumption had gone down by 55%. This is supported by independent monitoring carried out by the end user. Annual energy con­sumption by the previous system was 4,015,000 kWH, costing £312,200; with the new system, annual energy consumption was 1,825,000kWH, costing £146,000 – representing an annual saving of £175,000 (55 per cent).
 
Improved reliability: To the energy savings must be added the reduction in breakdown costs, running at £50,000 a year.
 
Lower maintenance: Maintenance in the future will be significantly re­duced mainly as a result of the absence of oil in the refrigeration systems.
 
Overall savings: The client estimates that annual savings will be in the re­gion of £230,000 a year.
 
Future plans for Turbomiser
 
Colt has been highly impressed with the result of its first replacement proj­ect. The company is now evaluating the potential for application of Tur­bomiser chillers at its other Data Centres across Europe.
 
 
   
 
  Before: The old chillers had become inefficient and subject to breakdowns
 
   

     After: Six new Turbomisers provide 55%power savings for the end user