Managing The Problem
Air Conditioning and Refrigeration Systems Oil Fouling
The oil that finds its way into the refrigeration circulation system must somehow be managed.* The obvious question then becomes how to manage this troublesome oil fouling. Some of the techniques used by manufacturers to control migrating oil include the use of mechanical devices such as separators, skimmers, drums, heat sources, suction risers, traps and pumps. According to ASHRAE's Handbook*, these high-tech designs are not efficient enough to remove all of the unwanted oil.
Coalescing separators are far better than separators using only mist pads or baffles; however, even they are not 100% effective; and so oil fouling forms anyway. Although the mechanical solutions may reduce the problems of restricted or plugged capillary tubes or sticky expansion valves, they do not resolve the boundary layer oil fouling over time.
* 1998 ASHRAE Handbook, Refrigeration, Chap. 2.9
