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Heat Exchanger Effectiveness Calculator

Estimate effectiveness, heat rate, qmax, capacity-rate ratio, and outlet temperatures using basic epsilon-NTU relationships.

Effectiveness NTU inputs

Result section

warningcounterflow

Heat-exchanger effectiveness

0.660576

Secondary results

Heat-transfer rate: 92480.6 W
Maximum possible heat transfer: 140000 W
Estimated hot outlet temperature: 59.1731 °C
Estimated cold outlet temperature: 66.2403 °C
Capacity-rate ratio: 0.666667

Unit conversion summary

Unit-normalization summary: SI base units; counterflow

Warnings

Thermal properties can vary with temperature, pressure, composition, grade, direction, phase, surface condition, manufacturing process, and data source. Verify all values for the actual operating condition.

Assumptions

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.

Calculation steps

Calculate effectiveness and outlet temperatures from energy balance0.660576

Effectiveness-NTU heat exchanger

counterflow epsilon-NTU relationship

Technical visual

Calculate heat-exchanger effectiveness-NTU performance and outlet temperature estimates.

Engineering interpretation

Outlet temperatures are estimated from a basic energy balance using the calculated effectiveness.

What is the heat exchanger effectiveness calculator?

Use this calculator when inlet temperatures, capacity rates, and NTU or UA are known and a basic effectiveness-NTU model is suitable.

How to use the heat exchanger effectiveness calculator

Select parallel flow, counterflow, or one-side phase-change.
Enter capacity rates, inlet temperatures, and NTU.
Review effectiveness, heat rate, outlet temperatures, and energy-balance checks.

Input explanations

Capacity rates are entered directly as W/K or equivalent units.
Cr = Cmin/Cmax is calculated from the entered hot and cold capacity rates.
The phase-change mode uses epsilon = 1 - exp(-NTU).

Notation

Formula notation
Symbol	Meaning	Unit
epsilon	Heat-exchanger effectiveness	-
NTU	Number of transfer units	-
Cmin, Cmax	Capacity rates	W/K
qmax	Maximum possible heat transfer	W

Worked examples

For NTU = 1.5 and Cr = 2/3 in counterflow, effectiveness is about 0.637.

Cross-tool workflow

The effectiveness calculator supports parallel flow, counterflow including Cr = 1, and one-side phase-change Cr = 0 limiting cases.

Compare with LMTD

Common mistakes

Using mass flow rate without multiplying by specific heat.
Using counterflow formulas for parallel-flow hardware.
Expecting the tool to size a complete exchanger geometry.

Limitations

Thermal properties are treated as constant user-entered values.
The tool does not select material, fluid, steam, refrigerant, phase-change, or fouling data automatically.
Results are preliminary engineering estimates and do not certify code compliance or safety.
Multidimensional effects, transient storage, contact details, and property variation must be evaluated separately when important.
No crossflow, shell-and-tube correction charts, pressure drop, fouling design margins, or full heat-exchanger sizing package is included.

References

Fundamentals of Heat and Mass Transfer: Incropera, DeWitt, Bergman, and Lavine, Fundamentals of Heat and Mass Transfer.
Heat and Mass Transfer: Cengel and Ghajar, Heat and Mass Transfer: Fundamentals and Applications.
Heat Transfer: Holman, Heat Transfer.
Compact Heat Exchangers: Kays and London, Compact Heat Exchangers.
SI units: BIPM, The International System of Units (SI Brochure).
NIST unit guidance: NIST Special Publication 811, Guide for the Use of the International System of Units.

What assumptions does the heat-exchanger effectiveness calculator use?

It uses the stated steady or lumped formula with user-entered properties and does not infer hidden losses, standards factors, or temperature-dependent property data.

Are Celsius and Fahrenheit temperature differences handled as offsets?

No. Absolute temperature and temperature difference are separate quantities. Temperature differences use delta units without absolute-temperature offsets.

Can I use the result for final design approval?

No. Use the result for education, estimation, and preliminary review only. Critical work must be checked with standards, validated software, measured properties, and qualified engineering judgment.

Does the calculation run on a remote thermal-property API?

No. Calculations are performed locally in your browser and are not submitted to a third-party calculation API.

Engineering disclaimer

This tool is intended for educational, estimation, and preliminary engineering use. Always verify critical heat-transfer calculations with applicable standards, validated software, measured properties, and qualified professional judgment before using results in real design, manufacturing, construction, safety, or compliance decisions.

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Last reviewed: 2026-06-30

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Effectiveness NTU inputs

Result section

warningcounterflow

Heat-exchanger effectiveness

0.660576

Secondary results

Heat-transfer rate: 92480.6 W
Maximum possible heat transfer: 140000 W
Estimated hot outlet temperature: 59.1731 °C
Estimated cold outlet temperature: 66.2403 °C
Capacity-rate ratio: 0.666667

Unit conversion summary

Unit-normalization summary: SI base units; counterflow

Warnings

Thermal properties can vary with temperature, pressure, composition, grade, direction, phase, surface condition, manufacturing process, and data source. Verify all values for the actual operating condition.

Assumptions

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.

Calculation steps

Calculate effectiveness and outlet temperatures from energy balance0.660576

Effectiveness-NTU heat exchanger

counterflow epsilon-NTU relationship

Symbol

Meaning

Unit

epsilon

Heat-exchanger effectiveness

NTU

Number of transfer units

Cmin, Cmax

Capacity rates

W/K

qmax

Maximum possible heat transfer

Limitations

Thermal properties are treated as constant user-entered values.

The tool does not select material, fluid, steam, refrigerant, phase-change, or fouling data automatically.

Results are preliminary engineering estimates and do not certify code compliance or safety.

Multidimensional effects, transient storage, contact details, and property variation must be evaluated separately when important.

No crossflow, shell-and-tube correction charts, pressure drop, fouling design margins, or full heat-exchanger sizing package is included.

References

Fundamentals of Heat and Mass Transfer: Incropera, DeWitt, Bergman, and Lavine, Fundamentals of Heat and Mass Transfer.

Heat and Mass Transfer: Cengel and Ghajar, Heat and Mass Transfer: Fundamentals and Applications.

Heat Transfer: Holman, Heat Transfer.

Compact Heat Exchangers: Kays and London, Compact Heat Exchangers.

SI units: BIPM, The International System of Units (SI Brochure).

NIST unit guidance: NIST Special Publication 811, Guide for the Use of the International System of Units.

Engineering disclaimer

Effectiveness NTU inputs

Calculation mode

Effectiveness NTU inputs

Result section

Secondary results

Unit conversion summary

Warnings

Assumptions

Calculation steps

Effectiveness-NTU heat exchanger

Technical visual

Engineering interpretation

What is the heat exchanger effectiveness calculator?

How to use the heat exchanger effectiveness calculator

Input explanations

Notation

Worked examples

Cross-tool workflow

Common mistakes

Limitations

References

Related tools

Print summary

Engineering disclaimer

Need Professional Support?

Effectiveness NTU inputs

Calculation mode

Effectiveness NTU inputs

Result section

Secondary results

Unit conversion summary

Warnings

Assumptions

Calculation steps

Effectiveness-NTU heat exchanger

Technical visual

Engineering interpretation

What is the heat exchanger effectiveness calculator?

How to use the heat exchanger effectiveness calculator

Input explanations

Notation

Worked examples

Cross-tool workflow

Common mistakes

Limitations

References

Related tools

Print summary

Engineering disclaimer

Need Professional Support?