Plant Utilities worked example

Process Cooling Capacity at 66% system uptime: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop system uptime to 66%, then walk the calculation through step by step. Estimate usable process cooling capacity from circuit capacity, available circuits, uptime, and heat exchanger effectiveness.

The inputs for this scenario

  • Cooling capacity per circuit: 45 tons / circuit (held at the documented default)
  • Available cooling circuits: 6 circuits (held at the documented default)
  • System uptime: 66 % (the input this scenario stresses; the baseline uses 92)
  • Heat exchanger effectiveness: 88 % (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Gross cooling capacity = cooling capacity per circuit × available cooling circuits.
  • Good output capacity works out to 157 tons at these inputs, and this is the headline figure for the scenario.
  • Gross process cooling capacity works out to 270 tons at these inputs.
  • Capacity lost to downtime works out to 91.8 tons at these inputs.
  • Capacity lost to exchanger effectiveness works out to 21.38 tons at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where system uptime sits at 92% and the headline result is 219 tons, this scenario comes in 28.26% below the baseline at 157 tons.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to system uptime, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It applies uptime and effectiveness as flat multipliers; real capacity also varies with ambient wet-bulb, fouling, and load profile, so treat the result as a design-point estimate.

Results at a glance

  • Good output capacity: 157 tons (headline result)
  • Gross process cooling capacity: 270 tons
  • Capacity lost to downtime: 91.8 tons
  • Capacity lost to exchanger effectiveness: 21.38 tons

Run it with your numbers

  • To rerun this with your own numbers, open the live Process Cooling Capacity calculator, set system uptime to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.