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Heat Exchanger NTU Calculator — Effectiveness, Duty & Outlets
Solve NTU-effectiveness for counterflow or parallel flow from hot/cold capacity rates, UA and inlet temperatures; report effectiveness, duty and outlet temperatures.
Last updated: September 17, 2026
Results
Reverse-size UA from target effectiveness
Enter capacity rates and a target between 0 and 100%.
Formula, example and assumptions
NTU=UA/Cmin; Cr=Cmin/Cmax; Q=εCmin(Thi−Tci).
For NTU=2 and Cr=0.5, counterflow effectiveness is about 77.5%.
- Single-phase constant-property sensible heat transfer is assumed.
- Flow arrangement must match the selected effectiveness relation.
Frequently asked questions
What does the Heat Exchanger NTU Calculator calculate?
Solve NTU-effectiveness for counterflow or parallel flow from hot/cold capacity rates, UA and inlet temperatures; report effectiveness, duty and outlet temperatures.
Which units should I use?
The input labels show the required SI units. Keep properties and geometry consistent before using the result in another engineering calculation.
Can I use this result for design?
Use it for transparent engineering estimates and checks. Validate property data, geometry, correlations and applicable codes for safety-critical design.