This case study session will give you an inside view of a world-class energy efficient data centre. Chris Flanagan, will provide an inside look into a Fujitsu facility. The session will focus on the innovations, trends and technologies that have led to the success and acclaim of Fujitsu facilities.

Measurement methodologies used to track efficiency

Deduplication techniques in the data centre

Operational insights and strategies

• Unique exhibitor showcase allowing each sponsor to pitch their product on a strict 7 minute clock
• Fun and exciting way to get the information you need while avoiding the hard pitch
• Get acquainted with the exhibitors and choose who to connect with for project and product development

This presentation will examine indirect evaporative air cooling (IEAC) systems options for new and legacy data centres virtually eliminating the need for conventional mechanical refrigeration to meet the specific requirements of any facility desired cooling conditions using significantly less energy than standard air conditioning. The presentation will cover the design, energy modelling and operational benefits, with practical installation examples of PUE’s achieved of 1.2 or less.

The energy efficient process of IEAC is explained, including system design and other factors that affect the operation of cold aisle supply temperatures between 23oC and 35oC allowing the latest IEAC’s to all but remove the need for conventional cooling to just a small number of hours per year.

Historically data centre equipment was cooled with standard HVAC air conditioning delivering air at 10oC. As the cool air passed through the computer equipment it returned to the HVAC unit at 24oC to 27oC where it cooled to 10oC to be redelivered.

Modern day servers and storage equipment can operate at considerably higher temperatures than legacy equipment. Most medium to large sized data centres require 0.5 to 50 MW. The recommended supply air temperature for computer rooms is 27ºC (ASHREA Thermal Guidelines for data processing environments 2009a) which makes demand for Indirect Evaporative Air Cooler (IEAC) the preferred choice. Market research point towards these temperatures will increase to even higher levels… as decreased temperatures mean added cooling costs.

The indirect air-side economizer (IASE) cycle uses outdoor air to reject heat, but the outdoor air never enters the process or space. The IASE uses an air-to-air heat exchanger (HX) to transfer data centre heat to a separate outdoor airstream (“fresh air”). The example to be presented uses horizontal polymer-tube heat exchangers.

With this design, outdoor fresh air is drawn across the exterior of elliptical tubes, which are wetted by a recirculation water pump. The elliptical shape of the heat exchanger tubes maximizes the allowable surface area for heat rejection and is sufficiently elastic such that its subtle expansion and contractions, resulting from normal operation, aid the shedding of residual solids that are a by-product of evaporation.

With fresh air flowing over the wet exterior tube surfaces, evaporative heat transfer efficiently cools the data centre hot aisle air flowing through the inside of the tubes. The HX is 45% to 50% effective when operating dry, when the outside of the polymer-tube HX is wetted, the HX is able to provide 70% to 80% wet-bulb depression effectiveness (WBDE), as an indirect evaporative cooler. WBDE is a measure of the approach of the hot-aisle dry-bulb temperature to the outdoor air wet-bulb temperature.

Using a 75% WBDE HX design, 100% of data centre heat may be rejected solely using indirect evaporative cooling (IEC) whenever the ambient wet-bulb temperature is 19°C or lower, based on a hot aisle temperature, after recirculation fan heat, of 38.6°C cooling to a target cold-aisle temperature of 23.9°C.

Modulating mixed air dampers and relief fans/dampers are not required as part of the heat rejection cycle. IASE systems achieve supply temperature control by varying fresh air fan flow and staging/modulating DX or modulating chilled water valves.

IASEs require one-third of the water flow rate of conventional water-side economizer systems, and operate with less pump head, resulting in significant annual pump power savings. IASE systems require no pump energy during cooler ambient conditions.

Contrast this with an open water-side economizer (direct tower to coil), providing 13.9°C of air-side sensible cooling, taking a water-side temperature rise of 5.6°C . Such a water-side economizer requires approximately 0.35 L/s, 471.9 L/s at sea level and may require 30.5 m of pump head, or more, depending on the installation. Water-side economizers with HXs and solids separators require additional pump power.

When integrated with indirect evaporative cooling, refrigeration capacity can be significantly reduced on IASE systems in virtually all climates, which is not true of conventional direct air-side economizers or wet-bulb economizer installations that require supply air dew point to be maintained below the current recommended value for Class I environments of 17.2°C.

Data centre operators are rapidly moving towards Indirect Evaporative Air Coolers which incorporate heat exchangers with outdoor air, to give minimal air filtration and enhanced supply temperatures resulting in data centre PUE’s of less than 1.2

For more information contact airtreatment@munters.co.uk or go to www.munters.com/datacentre