Use of hydrocarbons as drop-in replacements for HCFC-22 in on-farm milk cooling equipment

Many refrigeration systems on New Zealand dairy farms use HCFC-22 which is being phased out by 2015. Both laboratory and on-farm trials were undertaken to investigate hydrocarbons as drop-in replacements to HCFC-22 in milk silo refrigeration systems. A mixture of propane and ethane (Care-50) reduced energy use by 6–8%, and had similar system cooling capacity relative to HCFC-22. With propane (Care-40), energy use decreased by 5% but cooling capacity was 9% lower. The retrofits were simple and low cost because no alterations to the systems other than change in refrigerant and appropriate safety labelling and documentation were made. For most farms, the outside refrigeration system location and small charge mean that hydrocarbons could meet NZ standards for safe use of refrigerants. The low retrofit cost, improved energy efficiency, low environmental impact, mineral oil compatibility, similar cooling capacity and controllable flammability risks mean that the propane–ethane mixture is an attractive replacement for HCFC-22 on NZ dairy farms.