Ammonia Chiller Answers Legislative Challenge

Johnson Controls has been providing maintenance services for the existing refrigeration system for the ice rink at Dewars Centre in Perth. The ice rink’s refrigeration system had been operating on hydrochlorofluorocarbons (HCFCs). Due to European legislation, by Jan. 1, 2015 all HCFCs are banned for servicing and maintaining existing systems.

Mandate Requires Tailor-Made Solution

Live Active Leisure needed to replace its existing system due to the legally imposed phaseout of HCFCs. Overall, the solution needed to be environmentally friendly and LAL wanted an efficient system to replace the existing infrastructure. Johnson Controls proposed the installation of an air-cooled ammonia chiller complete with heat recovery and a very low ammonia charge due to the location being close to a pedestrians’ footpath.

Return on Investment Within Three Years

The implemented solution consists of several elements, all designed to answer the specific requirements of the customer.

• A low charge air-cooled ammonia chiller with variable speed drive screw compressors.

• Waste heat recovery from a desuperheater and oil coolers for ice pit snow melting.

• A supervisory control and data acquisition (SCADA) system for complete remote monitoring of the system.

• An efficient glycol pumping system using variable speed drives.

• New flow and return headers.

• The replacement of the flow and return individual loops for improved operation of the ice rink.

The skid-mounted chiller is a completely new solution, designed to match the client’s specifications. Since it works on ammonia, it necessitates more stringent controls due to the nature of the product. The chiller could therefore not be placed inside the existing plant room. Johnson Controls set up a new construction outside the building on the loading area. Because of the proximity to the nearby public areas and the intake of goods, the infrastructure had to be made safe and consideration was given to soundproofing the installation.

Extensive calculations were completed to ensure the noise was kept to a minimum, using variable speed drives for all the compressors and highly efficient EC fans for the air- cooled condenser. The fully enclosed off-site chiller was made weatherproof, and was equipped with acoustic removable panels and lockable access doors, allowing technicians to work safely inside the unit.

Achievements

Johnson Controls provided Live Active Leisure with a highly efficient system that delivers several advantages. For example, due to the compressors variable speed drives, the chiller is still efficient even at its minimum load of 10 percent. The EC fans and wet bulb controller on the condenser also facilitate closer capacity control, increasing the longevity of the unit and reducing the overall energy consumption.

To answer the environmental demands, Johnson Controls designed the air-cooled chiller to have zero ozone depletion potential (ODP) and global warning potential (GWP). The installation has a low ammonia charge at 0.3 kg per kW of the refrigeration capacity. The use of a new glycol system ensured the temperature of the cooling mat was brought down more rapidly, which resulted in quicker ice formation than the previous system. Consequently, the hours working on ice pad formation and running times of the chiller were greatly reduced. And when there is minimum load on the ice rink during off-peak hours, the chiller and pumps drop down in capacity to match site conditions.

And, last but not least, Johnson Controls acted as principal contractor, providing the client with a one-stop shop for all its demands, facilitating the execution and support of the project.

Publication date: 8/18/2014

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