In a system with a -34ºF evaporator and 89ºF condensing, which compressor would be running based on the compression ratio?

The correct answer indicates that a screw compressor, which has a maximum compression ratio of 20:1, would be the type of compressor running in a system with a -34ºF evaporator and an 89ºF condenser.

To understand this better, it’s important to analyze the concept of compression ratio in relation to evaporator and condenser temperatures. The compression ratio is a crucial factor in determining the suitability of a compressor type for a specific refrigeration system. It is calculated based on the absolute pressures corresponding to the evaporator and condenser temperatures.

In this scenario, the evaporating temperature of -34ºF (which translates to a low pressure) and the condensing temperature of 89ºF (which corresponds to a higher pressure) creates a significant difference that results in a high compression ratio. Since the screw compressor can handle a maximum compression ratio of 20:1, it is well-suited for this application, as it can efficiently compress the refrigerant from the low pressure in the evaporator to the high pressure in the condenser.

Other compressor types, such as rotary vane and reciprocating compressors, have lower maximum compression ratios (4:1 and 8:1, respectively). These limitations mean that they would not be able to