GCAP Industrial Ammonia Refrigeration Training Practice Test

In a refrigeration system, the compression ratio is the ratio of the pressure of the refrigerant vapor leaving the compressor (discharge pressure) to the pressure of the refrigerant vapor entering the compressor (suction pressure). When the suction pressure drops, the compression ratio increases because you are still compressing the refrigerant from a lower suction pressure to the same discharge pressure.

An increased compression ratio can lead to several implications in the system, such as increased power consumption and higher discharge temperatures, requiring the compressor to work harder to achieve the same cooling effect. Essentially, as the suction pressure decreases, the system is compressing the same volume of refrigerant from a lower baseline, which results in a higher ratio of discharge pressure to suction pressure, thus increasing the compression ratio.