Cooling capacity and electrical input are different
Industrial chiller cooling capacity is the amount of heat removed per unit of time. It can be expressed in kW or refrigeration tons. Electrical input, also often expressed in kW, is the power supplied to the equipment. The two figures describe different quantities; a cooling capacity of 17.58 kW does not mean an electrical input of 17.58 kW.
A refrigeration ton is a unit of cooling capacity, not the weight of the machine or the tonnage of plastic processed. In the U.S. convention, one refrigeration ton is 12000 BtuIT/h, equivalent to 3.516853 kW according to NIST's conversion factors. The rounded comparisons below are unit conversions, not ratings for RHONG models.
| Refrigeration tons | Cooling capacity, kW | Cooling capacity, BtuIT/h |
|---|---|---|
| 1 | 3.52 | 12000 |
| 3 | 10.55 | 36000 |
| 5 | 17.58 | 60000 |
| 10 | 35.17 | 120000 |
Changing units does not change the conditions at which a capacity was rated. Nor can 5 refrigeration tons be converted directly into a 5 hp compressor or used on its own to calculate electricity use. If a quotation uses hp, ask whether it identifies a motor or a series designation and request the actual capacity and input figures.
Put the rating conditions beside the number
Suppose two quotations each state 5 refrigeration tons, or about 17.58 kW. One gives that figure at warmer process supply water and a lower ambient temperature; the other uses different conditions. The matching numbers alone do not establish equal capacity at your site. Ask both suppliers for performance data or a curve at the same target conditions. A simple ton-to-kW conversion cannot adjust a rating from one set of conditions to another.
For a useful comparison in plastics process cooling, provide and check:
- Process supply and return water temperatures, flow rate, and the cooling medium and its concentration.
- For an air-cooled unit, the ambient condition; for a water-cooled unit, the condenser inlet water condition, together with the corresponding cooling performance data.
- Electrical input and what equipment it includes, separately from cooling capacity.
- Pump flow and pressure at the actual system working point, plus the system connection requirements.
The rated cooling kW does not establish that a pump or its connections match your system. Temperature, heat load, flow and pressure also form separate parts of the selection discussion, as described in PolyScience's chiller selection guide.
If you are also deciding how to reject heat, see the air-cooled and water-cooled comparison. You can review RHONG's air-cooled and water-cooled chiller pages, then send the process conditions for a quotation discussion.