Case studies

Asda Distribution Centre / UK

Planning / Implementation / Main components: Star Refrigeration Ltd
Refrigerant: Ammonia (NH3)
System start-up: 2007

Beginning in 2002, the British supermarket chain Asda has had Star Refrigeration replace all refrigeration units which use the hydrochlorofluorocarbon (HCFC) R22 at its distribution centres, as part of a long-term modernisation programme. Star Refrigeration implemented an ammonia and carbon dioxide cascade facility for the refrigerated warehouse at one of its major distribution centres in Lutterworth, UK.


A system to provide efficient refrigeration for the 270,000m³ premises. Areas requiring refrigeration were: a frozen food cold store at -25°C and several chill rooms at temperatures between 1°C and 13°C.

Solution: Star Refrigeration designed a central refrigeration system which supplies liquid carbon dioxide at -31°C to six air coolers in the cold store. It also supplies carbon dioxide as a volatile secondary refrigerant at -5°C to 20 air coolers in three chill rooms. The cascade facility’s low temperature circuit yields a refrigerating capacity of 820 kW, while the high temperature circuit produces 2,700 kW.
Technical data:
Type of facility cascade facility
Refrigerant NH3
Refrigerant volume approx. 2,000 kg NH3
Refrigerant CO2
Refrigerant volume approx. 8,000 kg CO2
Refrigerating capacity 3.5 MW
Refrigerating temperature CO2 low-temperature circuit: -31 ºC
CO2 high-temperature circuit: -5 ºC

Main components

2 CO2 and 4 NH3 screw compressors made by Grasso,
26 air coolers,
1 CO2 surge drum and pump set,
2 plate and shell heat exchangers
2 NH3 evaporative condensers,
1 NH3 high pressure receiver
Special features / Comments Computerised control system, ammonia and carbon dioxide detectors for early leak detection

Star Refrigeration Ltd
David Blackhurst
Thornliebank Industrial Estate
Glasgow G46 8JW
United Kingdom

Phone: +44 (0)141 638 7916
Fax: +44 (0)141 638 8111