British manufacturer of cooling solutions, Airedale International Air Conditioning, is releasing an indirect fresh air free cooling adiabatic airhandling unit (AHU). The company advises this new unit offers remarkable free cooling potential and, being an indirect system, can considerably reduce the risk of contaminated air entering the data centre.

With production launch set for spring 2014, the company’s AireFlow AHU is designed to use fresh air as the predominant cooling source, which has the potential to significantly reduce operational costs. In contrast with direct air handling units, indirect cooling solutions are also able to reduce the dependency on back-up mechanical cooling required to prevent contaminated ambient air permeating the data centre.

The solution will be available in five footprints between 100 and 300kW, each with two separate case sizes depending on whether roof or wall mounted connection is required.

From a technical perspective, high efficiency is achieved through electronically commutated (EC) centrifugal backward-curved fans that draw return air from the data centre through the heat exchanger. Cooler air from the outside ambient is drawn through a separate air path within the heat exchanger, also by EC plug fans. This temperature difference drives heat exchange, with the supply temperature being managed through modulation of the ambient air flow rate.

At any point in the year, as climatic conditions dictate, moisture is added to the warm outdoor air which has the effect of lowering the dry bulb temperature. A typical UK peak summer day for example may have a dry bulb of 35°C with a wet bulb temperature of 21°C. By fully saturating the air, the dry bulb temperature can be reduced to 21°C. This lower air temperature is then used as a cooling medium and, based on London ambient temperatures, can achieve AHSRAE recommended conditions using 100 percent free cooling.

In more challenging environments, an optional mechanical cooling module will ‘top-up’ the cooling capacity with a partial DX supplementary cooling section.

The company advises, an optional integrated fresh air inlet unit provides added installation benefits and reduced footprint compared with other makes of air handling unit. Air flow and pressure monitoring also allows filter and fan performance to be managed.

Other features include: G3/G4 air filtration, N+1 redundancy on EC fans and an intuitive touchscreen colour user display.

In addition the company has also launched a range of dedicated chilled water systems.

Available in capacities from 11 to 233kW, the company’s SmartCool SD, SN & SR range has been designed to maximise the use of the internal heat exchange area in addition to other energy efficient enhancements.

The new frame design on the SmartCoolSD (60kW–233kW) facilitates a larger coil area and improved airflow path. The systems includes a slab coil arrangement, with filters located on the face of the coil, this is claimed to provide up to 15 percent more surface area for air flow and allows for low air-side pressure drop, increasing efficiency by lowering fan power. Energy efficiency in the SD model is further increased by locating the fans in the floor void.

The solution is also designed with two fully modulating, two-way actuated ball valves in place of a single three-way valve. In addition to improved efficiency, this brings further benefits as the two-way valve method of controlling the chilled water can be used as an auto-commissioning tool saving commissioning time.

Models in this range include the SN/SR (11kW–60kW) which are designed with V-frame heatexchangers, that improve air flow through the unit reducing pressure.

All the units in this range incorporate the latest release in fan technology. The backward-curved centrifugal EC fans are claimed to be up to 50 percent more efficient than their AC equivalents and allow units to be configured to customer needs according to whether they require high airflow/high capacity or low airflow/ high efficiency.

According to the company the aerodynamic design of the fans also helps reduce noise.

This product range is available in a number of different configurations to suit a wide range of specifications including compact applications where space is a limiting factor.

One of the first orders received for the new range by the British manufacturer will see 20 of the chilled water units delivered to its eastern European customer in December 2013.

The company advises a third new product release will make it the first company to launch a production range of high performance free cooling chillers using the low global warming potential (GWP) refrigerant R1234ze.

R1234ze is a hydro-fluoro olefin (HFO) based refrigerant with a low GWP of six compared with GWPs approaching 1,300 for more traditional refrigerants such as R134a which are expected to be phased out by 2030. One of the so-called ‘fourth generation’ refrigerants, HFOs are olefins or ‘unsaturated’ hydrocarbons, which readily break down in the atmosphere within a very short lifetime of just a few days in comparison with 13 years for their previous generation counterparts.

In recognition of its low global warming impact, the TurboChill free cooling chiller (TCF) with R1234ze automatically receives two BREEAM points. In contrast, R134a TurboChill  TCC and TCF variants receive one point for their Direct Effect Life Cycle (DELC) CO2 equivalent emissions of =1000 kgCO2e/kW cooling capacity and a further point for leak detection and automatic shutdown and pump-down of refrigerant.

Energy efficiency is a key design criterion across Airedale’s entire range of chillers, precision air conditioning and IT cooling systems which offer part-load performance and energy efficiency for footprint. All models in the TurboChill range have been designed to meet the criteria established by the Energy Technology List and selected models* qualify for a 100 percent first year capital allowance under the Government’s Enhanced Capital Allowance (ECA) scheme. (*Accreditation of remaining models is pending).

The FreeCool (TCF) is claimed to offer twice as much free cooling as a thermosiphon free cooling system and can deliver free cooling for up to 95 percent of the year1. By constant monitoring of temperature differences,

The company’s control software permits concurrent free cooling – a mixture of free cooling and mechanical cooling– switching on the mechanically-driven compressor only when extra cooling is required.

The free cooling (TCF) range will be released at the end of 2013 alongside a 1,600kW dual circuit TurboChill incorporating R134a, delivering redundancy back-up and quicker compressor start-up to full load capacity in a 500kW higher capacity model.

1 Based on a 24/7 data centre with a typical room temperature of 24°C, London, UK

Airedale International