Heat Exchanger Effectiveness NTU Calculator
Calculate counterflow/parallel-flow effectiveness, heat transfer and both outlet temperatures from entered UA and fluid capacity rates.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Form capacity-rate ratio and NTU, evaluate the ideal arrangement relation and apply the same energy flow to both streams.
NTU=UA/Cmin; heat=effectiveness×Cmin×(hot inlet−cold inlet)
Worked example
UA=1000 W/K and both capacity rates 1000 W/K give NTU=1, Cr=1. In counterflow effectiveness is 0.5, heat 30 kW and both outlets 50°C for 80/20°C inlets.
Assumptions and input details
Single pass with constant positive mass flow/cp, no phase change and hot inlet above cold inlet. The counterflow Cr=1 limiting relation is evaluated explicitly. UA is entered, not inferred from nominal equipment size. Pressure drops, axial conduction, variable properties, fouling growth, ambient loss and equipment suitability are excluded. This predicts ideal outlet temperatures rather than inferring UA from four measured temperatures.
References: MathWorks: effectiveness-NTU heat-exchanger relations
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
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The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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