Ammonia Compressor Sizing & Swept Volume Calculator
Model industrial ammonia (R-717) screw and reciprocating compressor swept volume, suction CFM, mass flow, compression ratio, and shaft horsepower.
Refrigeration Load & Temperatures
Volumetric Efficiency Setting
Displacement & Power Summary
Thermodynamic Operating State
Engineering Staging Recommendation
Recommended Tools & Equipment
Tested hardware and components for high reliability
Frequently Asked Questions
Why does ammonia (R-717) have a much higher refrigerating effect than synthetic refrigerants?
Ammonia has a very low molecular weight (17.03 g/mol) and powerful hydrogen bonding, giving it a latent heat of vaporization of approximately 550 to 570 BTU/lb. By comparison, synthetic halocarbons like R-404A or R-507 have latent heats around 70 to 90 BTU/lb. Consequently, ammonia requires roughly one-sixth the mass flow rate to deliver the same tons of refrigeration.
What is compressor swept volume displacement and why does it differ from actual suction CFM?
Swept volume displacement is the geometric volume physically swept by the compressor rotors or pistons per unit time. Because of gas re-expansion in clearance pockets, internal rotor slip leakage, and valve throttling, the actual volume of suction gas drawn in is lower. The ratio of actual CFM to swept CFM is the volumetric efficiency (typically 80% to 88% in screw compressors).
When should an industrial ammonia system transition from single-stage to two-stage compression?
When the compression ratio exceeds approximately 7.5:1 to 8:1 (typically evaporating temperatures below -10°F to -15°F condensing at 95°F), two-stage compression becomes necessary. Single-stage operation at high ratios causes dangerously high adiabatic discharge temperatures, rapid lubricating oil degradation, and severe power inefficiency.
What is the role of an economizer on an ammonia screw compressor?
An economizer injects intermediate-pressure flash vapor into a port partway along the screw rotor compression process. This provides liquid subcooling to the main liquid feed line, boosting refrigeration capacity by 10% to 20% with only a modest increase in compressor shaft power.