Energy Efficiency Reference/Refrigeration/Recommendations/Install Economizer

Refrigeration Recommendation: Summary edit

Summary Install an economizer in a simple refrigeration cycle to increase the cycle efficiency by increasing the refrigeration effect at a given suction temperature. Economizers only apply to screw compressors with an unused secondary suction port.

When to Apply: When a secondary section port is available on screw compressor and suction temperature is <-15 degrees F.

Key Engineering Concepts:

  • Refrigeration system is determined by the mass flow rate of the refrigerant and the refrigeration effect at a given suction temperature.
  • The refrigeration effect is the enthalpy change between the expansion device exit and the compressor inlet (suction).
  • During the isenthalpic expansion process, refrigerant evaporates to cool the liquid-gas mixture to the saturation temperature at lower pressure. The remaining vaporization is the refrigeration effect.
  • An economizer vessel at an intermediate pressure is used to separate the saturated liquid and gas after the refrigerant is partially expanded to lower temperature.
  • Less refrigerant mass flows through the evaporator for the same load or system capacity is higher at full flow.