Enter a compressor: rated point, coefficients or displacement

• –One capacity and power input at the datasheet's evaporating and condensing dew points, superheat and subcooling.
• –It's judged only when the design's evaporating and condensing temperatures match the rated ones. Otherwise it reads Not judged and asks for coefficients.
• –A different superheat or subcooling in the design is flagged, not corrected.

• –The ten-coefficient polynomial of AHRI 540, pasted from the manufacturer's selection software: capacity and power input, and optionally mass flow. Record the standard, the frequency, and the rating's suction condition and subcooling.
• –Enter the published operating envelope as a rectangle. A design point outside it isn't rated: Kelvin never extrapolates the coefficients.
• –Where the design's superheat or subcooling differs from the rating basis, mass flow is corrected by AHRI 540 Appendix D and capacity follows as mass flow × enthalpy difference, on Kelvin's refrigerant properties. That needs the mass-flow coefficients.
• –Enter one capacity read off the datasheet under Datasheet check point. The sheet compares the coefficients with it and warns when they're more than 2% apart, usually a coefficient pasted in the wrong box or order.

Swept volume at 50 Hz only. Capacity is estimated from the cycle's suction density, volumetric efficiency and refrigeration effect, so the ledger marks its source as an estimate.

• –Most suction groups are judged on their cooling load in kW. Three are judged on the mass flow the cycle puts through them, in kg/h: a transcritical booster's medium-temp pack, a two-stage system's high-pressure stage, and a parallel compressor on the flash gas (with an ejector, on all the receiver's vapour).
• –On those groups a rated point reads Not judged, because it gives only a capacity at its own conditions; enter the displacement instead. Coefficients are judged there only through their mass-flow set.
• –Each group's heading says what it carries and the suction state it draws.