Process Manufacturing worked example

Heat Exchanger Duty with process fluid mass flow rate of 45,000 lb / hr: a worked example

This scenario runs the heat exchanger duty calculation on the strong side: process fluid mass flow rate of 45,000 lb / hr, with every other input held at its documented default. checking heating or cooling duty for a process fluid or utility loop

The inputs for this scenario

  • Process fluid mass flow rate: 45,000 lb / hr (raised for this scenario; the documented default is 18,000)
  • Fluid specific heat capacity: 0.92 Btu / lb F (unchanged)
  • Inlet-to-outlet temperature change: 45 F (unchanged)
  • Fouling and design margin: 1.15 x (unchanged)

Working through the calculation

  • Applying the documented formula (Heat exchanger duty = flow rate × heat capacity factor × temperature change × margin) to the inputs above produces each figure below.
  • At this operating point the engine returns 2,142,450 Btu / hr for required heat exchanger duty, the number this scenario is built around.
  • At this operating point the engine returns 1,863,000 value for clean calculated duty.
  • At this operating point the engine returns 1.15 x for fouling and design margin.
  • At this operating point the engine returns 41,400 value for flow heat capacity product.

How this compares with the baseline

  • Against the tool's baseline example, where process fluid mass flow rate sits at 18,000 lb / hr and the headline result is 856,980 Btu / hr, this scenario comes in 150% above the baseline at 2,142,450 Btu / hr.
  • Use it when sizing or rating a heat exchanger, specifying utility loads, or checking an existing unit against a new service. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.

Results at a glance

  • required heat exchanger duty: 2,142,450 Btu / hr (headline result)
  • clean calculated duty: 1,863,000 value
  • fouling and design margin: 1.15 x
  • flow heat capacity product: 41,400 value

Run it with your numbers

  • Every input above is editable in the live Heat Exchanger Duty calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.