14. Correction Factor for LMTD - F for 1-2 Exchanger

$F$ for 1-2 Exchanger:



  • Generally \(F\) is less than unity for cross-flow and multipass arrangements; it is unity for true countercurrent flow heat exchanger.

  • \(F\) represents the degree of departure of the true mean temperature difference from the LMTD for the counterflow.

  • It should be noted that in case of condensation or evaporation the correction factor becomes unity (\(F =1\)).

  • While designing a heat exchanger, the rule of thumb is that the \(F\) should not be less than 0.8.