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I Sainsbury's Horsham store inSussex, Britain, goes green byadopting secondary refrigerationfor storing both chilled and frozenfoods. Ammonia is used as the mainrefrigerant while the secondarycooling agent is a combination ofglycol and silicon oil (TechnologyPartnership Initiative, issue 7).
Each of the nine compressorscontain 140 kg of ammonia, whilethe secondary system uses 3,960 kgof propylene glycol. Serving 41chilled use sections, the system canrecover heat. The likelihood of leakshas been minimised by operatingthe unit at low pressure and maintaining a constant flow in the secondary circuits.