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12 | PROCESS | November 2019 | Climalife contact #16 Improving the performance of a refrigeration system by simply changing the lubricant A low-GWP refrigerant is not the only factor that affects a system’s energy efficiency; replacing the system’s refrigeration oil is also beneficial. When doing so, two characteristics have to be taken into account: the compatibility of the refrigerant / oil and maintaining or improving the system’s performance. Esso SAF, a subsidiary of the ExxonMobil Group, works on this challenge on a daily basis with Climalife and other refrigeration professionals. In this article we examine two procedures that are representative of the food production industry. 1. Procedure for converting a subcritical or transcritical CO2 installation (R-744) with POE oil to a new technology POE oil, Mobil SHCTM Gargoyle Arctic 80 POE. Aim: to save energy The challenge posed by this type of system is to ensure optimal lubrication in hot and cold conditions. For highly soluble refrigerants, such as R-744 or R-1234ze, Mobil has developed an advanced technology polyolester oil, Mobil SHCTM Gargoyle Arctic 80 POE, which has a higher viscosity index than conventional POEs to ensure optimal lubrication and a low traction coefficient (friction of molecules together), which is syno- nymous with a possible reduction in energy use. The first stage of the conversion procedure is to check that the system’s current oil and the new Mobil oil are compatible on a physical-chemical level. PROCESS Assessment of the system and recording of its operating parameters Drainage of the conventional POE oil and filling with advanced technology POE oil Run the installation for one hour to bring the oil and the compressor up to the operating temperature Shutdown of the system to drain the POE oil Non-compatible POE oils Compatible POE oils Refilling with advanced technology POE oil Running of the system for one hour Shutdown of the system to drain the POE oil Replacement of the coalescing filter, drying cartridges, oil filters Filling with advanced technology POE oil Assessment of the system and recording of its operating parameters Implementation of analytical monitoring at 100, 500 and then every 1,000 hours PROOF OF PERFORMANCE The SAS Abera plant, located in Saint-Brice-en- Coglès (France), is an abattoir that produces fresh and frozen meat. Using a conventional polyolester oil, Abera had problems with four reciprocating CO2 compressors caused by insufficient lubrication. Using ExxonMobil’s new POE oil in Abera’s refrigeration compressors brought about several benefits: • Viscosity index: 28% higher. • Brookfield viscosity at -30°C: 68% lower. • Traction coefficient: lower, measured on a mini-traction machine (MTM). • Greater protection of sensitive parts from wear. • Longer inspection and maintenance intervals. • Lower temperatures in the oil sump and pistons. • Fall in energy consumption.