Effectiveness-NTU Calculator
Calculate ε from NTU and Cr for a counter-flow heat exchanger.
How to Use This Calculator
1
Enter NTU
Number of transfer units based on UA/Cmin.
2
Enter Cr
Capacity rate ratio Cmin/Cmax between 0 and 1.
3
Calculate ε
Click Calculate to get effectiveness for counter-flow configuration.
Formula
ε = (1 − exp(−NTU·(1 − Cr))) / (1 − Cr·exp(−NTU·(1 − Cr)))
Example: NTU=2, Cr=0.5 → ε ≈ 0.775
About Effectiveness-NTU Method
The effectiveness-NTU method estimates heat exchanger performance from geometry (UA) and flow capacity rates without knowing outlet temperatures.
- Designing and sizing heat exchangers
- Estimating maximum possible heat transfer
Frequently Asked Questions
Which configuration is used?
This tool uses the counter-flow formula. Other configurations have different relations.
What range can ε take?
Effectiveness ranges from 0 to 1.