Aircon Services were recently approached to find a more efficient cooling solution for the Main Data Room at ‘Travelport’ Head Office, Langley, Berkshire.
Their data room was being cooled using 3No. Liebert L99UA down flow close control computer room units and their corresponding Leibert HBE99 air cooled condensing units offering a combined Sensible cooling capacity of 255kW spread over 6No refrigerant circuits. The condensing units were located within a purpose built compound at ground level but across a service road. With the interconnecting refrigeration pipe work running through a trench below this service road. Over time the condensing units had become badly corroded resulting in inefficiency through lack of heat transfer. A new solution was required.
We needed to look at the current design conditions and evaluate the actual amount of cooling being utilised. By interrogating the existing UPS systems we opted for a Heat Load for the room of Circa ‘no more than’ 100kW. So adding potential growth we chose 120kW. It was decided that 50% redundancy (N+1) should be built into the operating system therefore we opted for 3No. 60kW systems strategically positioned within the room as opposed to the 3No. inefficient 90kW systems currently being used.
With the assistance of GEA Denco and after a fact finding visit to their Herefordshire factory with our client we proposed to supply, install and commission 3No GEA Multi Denco DMA065D downflow Close Control Air Conditioning Units coupled to 3No. GEA DMOUC075E air cooled condensing units Each system is capable of 60kW Nett Sensible culminating in a combined total Nett Sensible cooling capacity of 180.00kW
Due to the location of the site (Adjacent to the M4 & M25 motorways) and the condition of the existing condensing units it was decided that the new condensing units would be ‘Blygold’ treated to protect against environmental corrosion.
Our next problem was to keep the Data Room operational during our installation. So it was decided to locate the new condensing units upon the roof mounted on a ‘Big Foot System’ to evenly distribute their weight. This enabled us to undertake the new installation with no disruption to the existing systems thus allowing the Data Room to operate as normal.
After pressure testing each new refrigeration circuit with Oxygen Free Nitrogen to ensure integrity each system was evacuated and charged with R410a refrigerant and commissioned.
The 3No. systems were finally linked together via their Microprossesor controls so as to allow 2No. units taking control of the rooms heat load evenly between them and allowing 1No. unit to be in standby mode. The 3No. units were then sequenced so as to place a different system into standby mode each week.
Our final task was to strategically relocate the supply grilles in the raised floor in order to evenly distribute the conditioned air to where it was best needed. Holes in floors and cable entries were then sealed up to prevent air loss and the return air routes were cleared to ensure maximum heat transfer was achieved.
When all this was complete a check was undertaken via the systems controls and it was determined that the peak load on the 2No. operational systems was 40kW each culminating in an approximate annual energy saving of £35,000
Multi-DENCO Energy Saving Benefits @ 40Kw Nett sensible load
GEA Multi Denco System
Fan power + Compressor power + outdoor unit power = 1.2 kW + 5.2 + 0.3 = 6.7Kw x 3 units = 20.1kW
Existing units (estimated) (this is based upon all fans running on all three units, and 4 from 6 circuits running)
Fan power + Compressor power + outdoor unit power = 6 kW + 11.6 + 2.2 = 19.8Kw x 3 units = 59.4kW
Estimated annual cooling running costs difference
Difference in power kW (59.4-20.1) x 8760 hrs/annum x £0.10 kW/hr
= £35k per annum