Heat Exchanger Temperature Profile Calculator
Model hot and cold stream temperatures, calculate heat duty, and size exchangers using thermal engineering methods.
Calculation Results
Temperature profile
Position is measured from the hot-fluid inlet. Counterflow cold fluid travels in the opposite direction.
Local temperature difference
Comparison: parallel versus counterflow
Segment-by-segment results
| Position (%) | Hot (°C) | Cold (°C) | Local ΔT (K) |
|---|
Inputs and Options
Formula Used
C = ṁ cₚ | Cᵣ = Cmin/Cmax | NTU = UA/Cmin
Qmax = Cmin (Tₕ,in − T꜀,in) | ε = Q/Qmax
Q = U A F ΔTlm | ΔTlm = (ΔT₁ − ΔT₂)/ln(ΔT₁/ΔT₂)
For equal positive terminal differences, LMTD equals either difference. LMTD for crossflow or multipass designs requires appropriate correction factors. Temperature-profile equations are exact for constant-property ideal parallel/counterflow; other layouts display a clearly labeled illustrative reconstruction.
How to Use This Calculator
- Select the exchanger configuration and mode.
- Enter fluid properties, inlet temperatures, and flow rates.
- Supply U and exchanger area, or specify a target duty.
- Click Calculate and inspect the performance warnings.
- Review temperature charts and export CSV or PDF.
Understanding Heat Exchanger Temperature Profiles
What a temperature profile shows
Heat exchangers transfer energy between fluids without intentional mixing. Temperature profiles show how both streams change along the equipment. Engineers use profiles to identify poor thermal approaches. Profiles also reveal whether outlet targets are physically achievable. The horizontal axis represents position along the exchanger. The vertical axis displays hot and cold temperatures.
Parallel and counterflow arrangements
Parallel flow sends both fluids in one direction. Their temperatures approach each other near the outlet. Counterflow sends fluids in opposite physical directions. This arrangement often provides stronger average driving differences. Counterflow can also support larger cold outlet temperatures. Actual performance depends on capacity rates and geometry. Crossflow exchangers require separate effectiveness correlations and assumptions. Shell exchangers often need multipass correction factors.
Calculating heat transfer performance
Mass flow and specific heat determine thermal capacity rates. The smaller capacity rate limits maximum possible duty. Effectiveness compares actual transfer against that theoretical maximum. NTU compares heat transfer conductance with thermal capacity. Greater NTU typically improves effectiveness until practical limits arise. LMTD summarizes the exchanger's thermal driving temperature difference. Engineers combine LMTD with area and overall conductance. Variable properties require additional numerical modeling for reliable predictions.
Practical checks and design limits
Check units before comparing temperatures or thermal power. Always confirm energy conservation between the two streams. Fouling increases resistance and reduces effective heat transfer. Excessive pressure losses increase pumping energy and expenses. Boiling and condensation need phase-appropriate material properties. An isothermal phase-change approximation has important validity limits. Real equipment may also exhibit leakage and maldistribution. Verify mechanical constraints, pressure ratings, and material compatibility. Use manufacturer data before selecting critical industrial equipment. Treat preliminary estimates as screening results, not certification. Profile charts make thermal limitations easier to explain. Compare candidate designs under consistent boundary conditions and assumptions. Recorded assumptions improve repeatability during engineering design reviews.
Example Data
| Parameter | Sample value | Unit |
|---|---|---|
| Hot inlet temperature | 120 | °C |
| Cold inlet temperature | 20 | °C |
| Hot mass flow | 1.2 | kg/s |
| Cold mass flow | 1.5 | kg/s |
| Specific heat (each stream) | 4.18 | kJ/kg·K |
| Overall U | 650 | W/m²·K |
| Exchanger area | 18 | m² |
Frequently Asked Questions
It shows how hot and cold fluid temperatures vary along the exchanger.
The rating mode uses effectiveness–NTU and an energy balance.
Counterflow generally achieves higher effectiveness for equal NTU and capacity ratio.
It represents the effective mean temperature driving force for heat transfer.
Effectiveness is actual heat duty divided by the maximum thermodynamically possible duty.
It changes capacity rates, outlet temperatures, pressure losses, and sometimes convection coefficients.
Fouling adds thermal resistance, reducing overall U and attainable duty.
A simplified isothermal stream is supported. Detailed phase-change design requires property correlations and pressure-dependent enthalpy.