GPSA Ch. 14
| Parameter | Range |
|---|---|
| Propane Evaporator | −40 to +40°F |
| Ethylene Evaporator | −150 to −50°F |
| Methane Evaporator | −260 to −150°F |
| Cascade Approach | 5–10°F |
| COP (2-stage cascade) | 1.5–3.0 |
Coefficient of Performance (COP):
Where QL = cooling duty at the evaporator, Wnet = total compressor power input across all stages.
Optimal Interstage Temperature:
Geometric mean of absolute condenser and evaporator temperatures minimizes total compressor work for equal compression ratios per stage.
Cascade Advantage: By splitting the total temperature lift across multiple refrigerants, each compressor operates at a lower compression ratio. This reduces discharge temperatures, improves volumetric efficiency, and significantly reduces total power consumption compared to single-stage operation.
Power Savings: A 2-stage cascade typically saves 20–35% compressor power vs single-stage over the same temperature range.
Understand cascaded refrigeration design, refrigerant selection, and cryogenic process optimization
Cascaded refrigeration uses multiple refrigeration stages with different refrigerants to achieve progressively lower temperatures. This calculator sizes multi-stage systems and calculates COP improvement and power savings vs. single-stage per GPSA Ch. 14.
Cascaded systems typically use propane for the high-temperature stage, ethylene or ethane for intermediate cooling, and methane for cryogenic temperatures. Each refrigerant operates in its efficient boiling range per GPSA Ch. 14.
Cascading reduces the compression ratio per stage, lowering compressor discharge temperatures and improving the coefficient of performance (COP). The calculator compares multi-stage power consumption against equivalent single-stage operation.
Cascaded systems can reach cryogenic temperatures below -150°F (-100°C) for deep NGL recovery. The calculator supports up to three stages with user-defined temperature levels for each cascade stage.