Bitzer support for low-charge ammonia chiller

UK: A new compact ultra-low-charge ammonia chiller has been developed by Gateshead-based KGM Refrigeration with support from Bitzer UK.

The charge reduction in the AMChill packaged chiller, achieved by doing away with the traditional flooded evaporator, is seen as key to the chiller’s innovative design. 

This approach, coupled with minimised pipework, is said to reduce the ammonia charge by around 75%. For example, for a duty of 150kW, the charge on a traditional ammonia chiller with flooded evaporator could be around 40kg, compared to just 10kg on the AMChill.

Based on open-drive Bitzer W-series compressors optimised for use with ammonia, the chiller is designed for roof-top mounting. Safety is further enhanced by the use of integrated ATEX-rated leak detection with system shutdown, and an ATEX-rated fan for enclosure ventilation.

The Bitzer compressors are supported by Bitzer AWA valves and coalescing oil separator to minimise oil carry-over.

The chiller’s light weight and compact dimensions – 1m wide x 1.6m long x 1.9m high – enable it to be easily transported onto rooftops via a standard lift. Its packaged design means it only requires water and electrical connections on site.

The chiller is available in three sizes, spanning capacities from 100kW to 150kW, based on an outlet temperature of +6°C.

Energy efficiency

Said to deliver a significant improvement in energy efficiency against conventional HFC/HFO chillers, The AMChill has a COP/EER of 5.43 for a cooling output of 150kW at a typical duty point of +12°C/+6°C evaporator and +30°C/+35°C on the condenser. Bitzer UK says that this compares with 4.95 for a similar unit running on R513A. 

Key to the unit’s efficiency is the use of a variable speed drive linked to a synchronous reluctance IE5 motor, believed to be the first refrigeration application in the UK of this technology.

A heat pump version of the chiller is also available to enable recovery of waste heat.

KGM says it is now working on further reducing the ammonia charge by refining the design and minimising pipe lengths, which it believes could yield an additional 20% reduction – to around 8kg for a 150kW unit.

Pilot project

A UK pilot project at a major pharmaceutical manufacturing site in Cramlington is said to have proved the chiller’s performance and reliability. 

Sterling Pharma Solutions installed a 150kW AMChill to provide supplementary cooling for existing process refrigeration plant.

“The cooling load at the test site is highly variable, and provided excellent validation of the chiller’s ability to respond rapidly to changes in demand,” said Amar Marwaha, KGM Refrigeration’s engineering director. “To date, the unit has over 5,000 run hours, and has performed to design since being commissioned.”

On the basis of the successful trial, the company is installing further AMChill chillers at the site, and extending the roll-out to other production facilities.