Engineering
Heat Exchanger Effectiveness Calculator
Calculate hot and cold capacity rates, minimum and maximum capacity rates, maximum possible heat transfer, actual hot-side duty, effectiveness, calculated cold outlet, capacity ratio, and transferred period energy.
Hot capacity rate (kW/K)-
Cold capacity rate (kW/K)-
Minimum capacity rate (kW/K)-
Maximum possible heat transfer (kW)-
Heat transfer from entered hot outlet (kW)-
Heat-exchanger effectiveness-
Cold outlet from energy balance (°C)-
Minimum-to-maximum capacity rate-
Transferred energy over entered hours (kWh)-
Decision view
Counterflow temperature path and duty gauge
Counterflow temperature path and duty gaugeHot and cold stream temperatures share an energy-balance schematic while actual duty is compared with the capacity-rate maximum.
Exact scenario comparisonHot outlet temperature (°C) changes while all other entered assumptions remain constant.
| Hot outlet temperature (°C) | Hot capacity rate (kW/K) | Cold capacity rate (kW/K) | Minimum capacity rate (kW/K) | Maximum possible heat transfer (kW) | Heat transfer from entered hot outlet (kW) | Heat-exchanger effectiveness | Cold outlet from energy balance (°C) | Minimum-to-maximum capacity rate | Transferred energy over entered hours (kWh) |
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How to use Heat Exchanger Effectiveness Calculator
- Enter hot-side mass flow, heat capacity, inlet, and outlet temperature.
- Enter cold-side mass flow, heat capacity, and inlet temperature.
- Confirm which stream has the smaller capacity rate.
- Interpret effectiveness and the calculated cold outlet together.
Calculator guide
Understanding Heat Exchanger Effectiveness Calculator
Heat-exchanger effectiveness compares actual duty with the greatest duty allowed by the smaller stream capacity rate and inlet-temperature difference. This calculator also closes the cold-side energy balance.
Calculation method
How the calculation works
Calculate both stream capacity rates, the theoretical maximum heat transfer, and actual hot-side duty before deriving effectiveness and a cold-side outlet balance. Multiply mass flow by specific heat for each stream, use the smaller capacity rate with the inlet temperature difference for maximum duty, and use the hot-side temperature drop for actual duty.
Detailed calculation process
Establish the capacity-rate limit before evaluating actual duty
The defaults cool 2.2 kg/s of water-like fluid from 90 to 58 C while heating 2.8 kg/s from 20 C.
General formula: C_h = m_h cp_h; C_c = m_c cp_c; C_min = min(C_h,C_c); Q_max = C_min(T_hi-T_ci); Q = C_h(T_hi-T_ho); epsilon = Q/Q_max; T_co = T_ci + Q/C_c The smaller heat-capacity rate limits the maximum possible exchange. Actual hot-side duty is compared with that limit, then applied to the cold side to calculate an outlet that satisfies energy balance.
What each symbol means
Worked substitution with the default inputs
The default exchanger transfers 294.272 kW against a 643.720 kW maximum, for 45.714% effectiveness and a calculated cold outlet of 45.143 C.
Thermal pathway
Track both stream temperatures and the duty ceiling
A counterflow-style schematic and duty gauge separate temperature movement from effectiveness.
Worked situations
Practical examples
- The hot capacity rate is 9.196 kW/K.
- The cold capacity rate is 11.704 kW/K.
- The modeled cold outlet is 45.143 C.
Better inputs
Useful tips
- Use properties at representative mean temperatures.
- Check sensor consistency before interpreting effectiveness.
- Keep heat duty and transferred period energy on separate units.
Before relying on the result
Limitations and common mistakes
- The model assumes steady adiabatic operation and constant heat capacities.
- Phase change, fouling, leakage, pressure drop, and external heat loss are excluded.
- Configuration-specific NTU, LMTD correction, and equipment selection are outside this page.
Reference
Key terms
- Capacity rate
- Mass flow multiplied by specific heat, in kW/K.
- Effectiveness
- Actual heat duty divided by maximum possible duty.
- Energy balance
- Equality of hot-side heat loss and cold-side heat gain in the model.
Important note
Calculated from the entered values using the displayed engineering relationship. Confirm design values, load cases, safety factors, standards, and field conditions with a qualified professional.
Frequently asked questions
Why does Cmin control maximum duty?
The smaller capacity-rate stream reaches the opposing inlet-temperature limit first.
Can effectiveness exceed 100%?
A consistent passive exchanger model should not; values above 100% indicate incompatible inputs or assumptions.
Is the cold outlet entered?
No. It is calculated from the same actual duty used on the hot side.
Does effectiveness identify exchanger configuration?
No. Arrangement and NTU analysis require additional data.