Calculate sensible or latent heat exchanger duty, outlet temperature, or required flow with SI and imperial units, capacity rate, and detailed energy-balance steps.

Constant specific heat over the entered temperature range; heating or cooling.

Heat Exchanger Duty Formula

For a single-phase stream, sensible duty is Qฬ‡ = แน ร— Cp ร— |Tout โˆ’ Tin| with constant Cp. For phase change, the separate latent-duty equation below applies to the mass flow actually undergoing the transition.

HED = M ร— LH

Variables:

  • HED is the Heat Exchanger Duty (kW)
  • M is the fluid mass flow rate through the exchanger (kg/s) 
  • LH is the latent heat (kJ/kg) 

For phase-change duty, multiply the phase-changing mass flow by the applicable latent heat. This excludes sensible heating before or after the transition. Use the separate sensible, outlet-temperature or mass-flow modes for single-phase energy balances.

How to Calculate Heat Exchanger Duty?

The following steps describe Phase-change duty mode. Select the relevant solve mode rather than leaving an arbitrary input blank.

  1. First, determine the fluid mass flow rate through the exchanger (kg/s). 
  2. Next, determine the latent heat (kJ/kg). 
  3. Next, gather the formula from above = HED = M * LH.
  4. Finally, calculate the Heat Exchanger Duty.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

fluid mass flow rate through the exchanger (kg/s) = 75

latent heat (kJ/kg) = 100

HED = M * LH = 75 ร— 100 = 7,500 kW