Compressor — R410A compressor — 24.4 kW cooling, 9.34 kW input, COP 2.61 at the AHRI 7.2/54.4 °C rating point.
A Danfoss listing, from the manufacturer's published data.
| Model | Danfoss VZH052CJ (R410A inverter scroll) |
| Refrigerant | R410A |
| Performance data | AHRI 540 / EN 12900 10-coefficient map |
| Reference superheat / subcool | 10.0 / 0.0 K |
| Cooling capacity @ 7.2/54.4 °C | 24.37 kW |
| Input power @ 7.2/54.4 °C | 9.34 kW |
| COP @ 7.2/54.4 °C | 2.61 |
AHRI 540 / EN 12900 ten-coefficient polynomials in evaporating and condensing temperature, rated at 10.0 K superheat and 0.0 K subcooling; the solver corrects them to the operating superheat and subcooling. Envelope: the manufacturer's 10-sided polygon. It publishes 18 part-load steps (AHRI 540 §5.3.3), which the solver interpolates between. The mass-flow coefficient set is published too, and the solver checks it against the capacity set.
| te / tc °C | Capacity kW | Power kW | COP |
|---|---|---|---|
| -20 / 10 | 14.46 | 3.84 | 3.77 |
| -20 / 30 | 10.93 | 5.71 | 1.91 |
| -10 / 10 | 21.80 | 3.66 | 5.95 |
| -10 / 30 | 17.86 | 5.78 | 3.09 |
| -10 / 60 | 8.98 | 10.74 | 0.84 |
| 0 / 10 | 31.37 | 2.99 | 10.49 |
| 0 / 30 | 26.72 | 5.73 | 4.66 |
| 0 / 60 | 15.60 | 10.47 | 1.49 |
| 20 / 30 | 51.68 | 4.26 | 12.13 |
| 20 / 60 | 34.69 | 10.27 | 3.38 |
Points on a 10 K grid inside the published envelope; the builder solves any point in it, and warns past it.
Open the builder and pick this listing from the catalog picker — the solver runs it with the catalog's own figures, at your design point or across a year of weather.
| Part-load interpolation between published compressor steps | the envelope between 16 steps | 0.04 % mean, 0.21 % worst between the knots |
| A data centre's cooling loop as a heat source: the water-source heat pump against the same machine on air | a full Seattle year and one winter week, both sources | the same 55.3 MWh into the radiators either way; 7.9 MWh of electricity on the loop against 19.5 on air (seasonal COP 7.0 against 2.8 — the inverter's published steps are what the loop-source machine spends most of the year on, at part speed near its best point), and the chiller 41.7 against 45.8 MWh for the 49.7 MWh the heat pump took off the loop — the site 91.3 against 107.0 MWh, 15 %. The ring conserves within 2 % (CRAH duty = heat pump take + chiller duty) with the one-hour lag, both plants converge every hour, and the north floor is held to 6 unmet hours where the air-source machine leaves it 13. Before the high-pressure cutout (the row below) the air-source variant failed 705 hours a year. What the guard cannot say: the paper reports no seasonal COP and no per-kilowatt figure, so the machine is the catalog map on both sides and only the arrangement is the anchor. (Until 4 Sep 2026 the plant was a Copeland ZP91KCE run as a flat-scaling inverter emulation and read 9.9 against 19.2 MWh, COP 5.6 / 2.9, the site 12 % down.) |
| A maker's inverter scroll read from its own selector: the Danfoss VZH052CJ | eighteen speeds; three selector readings at te −10 / tc 30 (1 002, 3 000, 6 000 rpm); four envelope points for the displacement; the rating point and a grid for the cycle closure | capacity and power at each of the three speeds within 0.3 % of the selector's own rows; the three parameter sets close the refrigeration cycle within 0.5 % at the rating point and 3 % across the grid, each step's own sets within 1 %; the implied volumetric efficiency sits inside the scroll band at every envelope point (the same band the VZH088 entry is held to). The map carries the maker's 65 °C condensing ceiling as a polygon, which is what the cutout rule below reads |
From the validation page; every row is held by a test.
Listed from published data; a listing's figures are the manufacturer's, the model that runs them is ours. Solver results never depend on who has claimed what.