Read the passage below:
Commercial refrigeration systems utilize crankcase heaters to prevent liquid refrigerant from accumulating in the compressor oil during off-cycles. When the compressor shuts down, the temperature inside the crankcase decreases, allowing vaporized refrigerant to migrate toward the cooler crankcase and dissolve into the lubricating oil. Upon compressor startup, the sudden drop in crankcase pressure causes dissolved refrigerant to rapidly boil off, creating severe oil foaming that deprives mechanical bearings of adequate lubrication and risks hydraulic cylinder damage. By maintaining crankcase oil at a temperature higher than the coldest part of the refrigeration circuit, electric resistance heaters ensure refrigerant vapor remains in a gaseous state outside the oil sump.
Based on the passage, match each technical condition or mechanism on the left with its accurate paraphrased description on the right.
- Primary function of crankcase electric resistance heatersKeeping lubricant temperatures above system cold points so working fluid stays in a gaseous state.
- Refrigerant behavior during compressor off-cyclesCooling sump conditions attract gaseous refrigerant to migrate and blend into the lubricating oil.
- Physical trigger for rapid refrigerant boil-offA sharp reduction in internal crankcase pressure occurring immediately upon equipment startup.
- Direct hazard resulting from severe oil foamingStarving rotating bearings of necessary lubrication film and risking mechanical cylinder damage.