Case studies

Dual Temperature Cooling System, Hertfordshire (UK)

Planning / Implementation:

Star Refrigeration Ltd.


Ammonia (NH3)

Refrigerant Capacity:

2,224 kW

System start-up:

May 2012

In 2012, a logistics provider was looking to convert an existing empty warehouse at its site in Hertfordshire into a temperature controlled food and beverage storage and distribution facility. Star Refrigeration was charged with the development of an energy efficient cooling system for cold and chill stores within the building, using environmentally friendly natural refrigerants.


Working on behalf of the building contractor, Star Refrigeration supplied a bespoke ammonia refrigeration plant to meet both frozen and chill requirements within the new facility. The fast track project has to be completed in less than six months from order placement.

Star Refrigeration Ltd. Designed, built, installed and commissioned a two-stage pumped circulation ammonia refrigeration plant.


Located in a plant room adjacent to the warehouse building, the system has an overall capacity of 2,224 kW including cooling for the cold store, chill store and loading bay areas. The existing ambient warehouse was fitted out with a 9,000 sq m frozen chamber operating at minus 25 degrees and a 5,000 sq m chill chamber operating at plus two degrees centigrade. Cooling is delivered to the chambers via evaporators located along one wall of the facility. These discharge air 120 metres across the store towards the vehicle loading docks.

Technical data:

Type of facility:

Storage and distribution centre


Ammonia (NH3)

Refrigerant volume:


Refrigerant capacity:

Total 2,224 kW; Frozen  = 1,200kW; Chill = 1024kW

Evaporation temperature:

-25 °C Frozen ; -6°C Chill

Condensation temperature:


Main components:

Two low stage, two high stage and one “swing” screw compressor, low temperature and high temperature surge drums and two evaporative condensers.

Special features/comments:

The centre is equipped with a computerised control system with HMI touch screen interface.

Star Refrigeration Ltd.

Mr. Rob Lamb

Phone: +44(0)1332/756041

Fax: +44(0)1332/757289