Effectiveness-NTU Calculator

What Is the Effectiveness-NTU Method?

The Effectiveness-NTU method is a standard technique in thermal engineering for evaluating heat exchanger performance, especially when outlet temperatures are unknown.

The Formula

NTU = UA / Cmin, and for a parallel-flow heat exchanger, effectiveness ε = (1 − e^(−NTU(1+Cr))) / (1+Cr) or more generally for the case shown here, ε = (1 − e^(−NTU(1−Cr))) / (1 − Cr·e^(−NTU(1−Cr))), where Cr = Cmin/Cmax is the capacity rate ratio. When Cr = 1, ε simplifies to NTU/(1+NTU).

For general educational and planning purposes; real exchanger performance also depends on flow arrangement (counterflow, crossflow, etc.).