Which compressor does not require a crankcase heater to prevent refrigerant migration?

The scroll compressor does not typically require a crankcase heater to prevent refrigerant migration. This is largely due to its design and operational characteristics.

In a scroll compressor, the refrigerant is compressively trapped between the fixed and moving scrolls. This design enables efficient and smooth compression with a minimal amount of refrigerant remaining in the crankcase during operation. As a result, the risk of refrigerant migrating and causing liquid flooding upon startup is considerably lower, which eliminates the need for a crankcase heater that would otherwise be used to vaporize any liquid refrigerant in the crankcase.

In contrast, other types of compressors, such as reciprocating compressors or screw compressors, often have a more significant volume of refrigerant within the crankcase. These compressors can allow liquid refrigerant to accumulate, particularly during off periods. A crankcase heater is essential for these systems to ensure any accumulated refrigerant is vaporized and does not condense back into liquid, potentially causing hydraulic lock or damage when the compressor restarts. Similarly, while centrifugal compressors also operate differently, they typically accommodate large refrigerant volumes in their casings, further necessitating crankcase heating in specific applications.

This understanding underscores the unique operational advantages of scroll compressors within specific refrigeration and air conditioning applications