Heat Exchanger NTU-Effectiveness Calculator
Evaluate the thermal effectiveness of a counterflow heat exchanger given overall heat transfer coefficient, area, and stream capacity rates.
Examples
- U = 550 W/m²·K, A = 24 m², Cₕ = 12,000 W/K, C𝚌 = 9,500 W/K ⇒ Result: 72.02% effectiveness
- U = 380 W/m²·K, A = 18 m², Cₕ = 8,200 W/K, C𝚌 = 6,000 W/K ⇒ Result: 63.11% effectiveness
FAQ
Can I use this for fluids with varying Cp?
Use average specific heats over the expected temperature range or segment the exchanger into smaller sections for higher accuracy.
What if my exchanger is cross-flow?
Cross-flow requires correction factors (F). Apply the correction to NTU or use manufacturer charts for the exact configuration.
How do I get the capacity rates?
Multiply mass flow (kg/s) by specific heat (J/kg·K). Convert to W/K by dividing by seconds if your data is in kJ/h·K.
Additional Information
- Effectiveness is returned as a percentage for a counterflow configuration.
- NTU equals UA divided by the minimum capacity rate.
- Capacity rate is mass flow rate multiplied by specific heat at average temperature.
- For parallel flow exchangers, use the corresponding formula: ε = (1 − e^{−NTU (1 + Cr)}) / (1 + Cr).