Low-charge NH₃ chillers deliver energy savings at Snozone

After installing two Star Refrigeration’s low-charge ammonia Azanechiller 2.0 unit in 2017, Snozone Milton Keynes – an indoor skiing and snowboarding venue that ranks among the UK’s top indoor leisure attractions – is celebrating multiple savings on electricity and CO₂ emissions.

Two ammonia-based Star AA415MTE-1 Azanechiller 2.0 units replaced the original chillers based on R404A, an HFC blend being phased down under the EU’s F-Gas Regulation. The Azanechiller 2.0 boasts a capacity of 360kW and chills ethylene glycol from -10°C to -13°C.

Vahterus plate and shell heat exchangers help to minimise the ammonia charge to only 85 kg per chiller. Acoustic enclosures around the compressor/motor assembly combined with EC condenser fans present the lowest noise outlay possible for the retrofit installation.

Hulley & Kirkwood, consulting engineers, came up with a strategy for improving the cooling plant at Snozone Milton Keynes, while maintaining business continuity. Star Refrigeration provided the ammonia chillers at the heart of the new plant’s system.

In only four months, Snozone saved 56% on electricity bills and reduced CO₂e emissions thanks to the efficiency of the Azanechiller 2.0, which exceeds Europe’s Eco-Design Minimum Energy Performance Standards (MEPS) requirements by 80%.

The Snozone facility contains 1,500 tons of snow and ice, which has to be maintained at -4˚C air temperature for optimal operation, and the new refrigeration plant uses less energy to produce better skiing conditions.

Star Refrigeration and Hulley & Kirkwood worked together to overcome challenges including the setback of the existing plant room being unsuitable for an ammonia plant. To identify all the safety measures required to install the new outdoor packaged ammonia chillers, specialist refrigeration consultants Star Technical Solutions carried out an Ammonia Hazard Assessment.

The location of two 9.7m long chillers on the paved area outside the plant room required careful surveying to ensure that they did not obstruct any underground services or impact traffic movement or parking adjacent on the site access road. A louvered perimeter wall was specified to screen the chillers from public access that also allowed adequate airflow onto the air-cooled condenser coils.

The new ammonia installation has been transformational for the Milton Keynes venue. Alan Walkinshaw, sales manager, special projects at Star Refrigeration, says, “the new equipment has been easily able to maintain -13°C glycol temperatures in the ski slope even on warmer days, whereas the previous equipment was struggling to achieve -8°C at peak times”.

“The plant isn’t necessarily working harder than the previous system, it is just more efficient. Energy savings have been dramatic, with a 56% saving on electricity in the first four months of operation – from 1,511,062 kWh to 661,255 kWh for the same period in 2016,” Walkinshaw said.