Heat Exchanger Performance Calculator

Example Data Table

Parameter	Example Value	Unit
Flow arrangement	Counter Flow	-
Hot inlet temperature	150	°C
Hot outlet temperature	110	°C
Cold inlet temperature	30	°C
Cold outlet temperature	70	°C
Hot mass flow rate	2.20	kg/s
Hot specific heat	4.00	kJ/kg·K
Cold mass flow rate	2.40	kg/s
Cold specific heat	4.18	kJ/kg·K
Overall U-value	0.30	kW/m²·K
Heat transfer area	18	m²

Use these values to test the form and review the exported report structure.

Formula Used

Heat duty from hot side: Q_hot = m_h × C_p,h × (T_h,in − T_h,out)

Heat duty from cold side: Q_cold = m_c × C_p,c × (T_c,out − T_c,in)

Capacity rates: C_h = m_h × C_p,h, C_c = m_c × C_p,c

Maximum possible duty: Q_max = C_min × (T_h,in − T_c,in)

Measured effectiveness: ε = Q_avg / Q_max

UA value: UA = U × A

NTU: NTU = UA / C_min

LMTD: LMTD = (ΔT₁ − ΔT₂) / ln(ΔT₁ / ΔT₂)

Duty from area method: Q = UA × LMTD

Keep units consistent. This page uses kg/s, kJ/kg·K, kW/m²·K, m², and °C. That keeps calculated heat duty in kW.

How to Use This Calculator

Select the exchanger flow arrangement.
Enter hot-side inlet and outlet temperatures.
Enter cold-side inlet and outlet temperatures.
Provide both mass flow rates and specific heats.
Enter the overall heat transfer coefficient and area.
Click Calculate Performance.
Review duty, effectiveness, NTU, LMTD, and balance error.
Download the report in CSV or PDF format.

Frequently Asked Questions

1. What does this calculator measure?

It estimates exchanger heat duty, capacity rates, NTU, LMTD, effectiveness, UA-based duty, and thermal balance error from entered operating data.

2. Why are both hot-side and cold-side duties shown?

Field data often contains measurement differences. Showing both sides helps identify imbalance, heat loss, sensor error, or inconsistent properties.

3. What is LMTD used for?

LMTD represents the effective average temperature driving force across the exchanger. It is used with UA to estimate transferable heat duty.

4. What does NTU mean?

NTU measures exchanger size relative to the weaker heat-capacity stream. Higher NTU usually indicates greater potential heat transfer performance.

5. Why can effectiveness exceed one here?

That usually signals inconsistent inputs, wrong units, or unrealistic outlet temperatures. Real exchangers should not exceed maximum possible duty.

6. Which flow pattern should I choose?

Choose counter flow when fluids move opposite each other. Choose parallel flow when both streams travel in the same direction.

7. What units should I use?

Use kg/s for mass flow, kJ/kg·K for specific heat, kW/m²·K for U-value, m² for area, and °C for temperature.

8. Can I use this for design and troubleshooting?

Yes. It works well for quick screening, comparison studies, report preparation, and identifying where measured performance differs from expected behavior.