Why is counter-flow usually more effective?

Counter-flow maintains a more even temperature difference along the length and can heat the cold outlet closer to the hot inlet than parallel-flow can.

What does Cmin mean physically?

C = m dot cp is the heat-capacity rate. The stream with smaller C changes temperature more for the same heat transfer, so it limits the maximum possible q.

Heat Exchanger ε-NTU

Parallel and counter-flow heat exchanger calculator: NTU = UA/Cmin, capacity ratio Cr, effectiveness, heat transfer, and outlet temperatures.

The model assumes steady operation, constant heat-capacity rates, no phase change, and no heat loss to the room. It is ideal for sizing intuition before detailed exchanger geometry.

Live graphs

About this model

The effectiveness-NTU method computes heat-exchanger performance without needing the outlet temperatures in advance. Given UA and heat-capacity rates C_h and C_c, the smaller capacity rate defines NTU = UA/C_min and C_r = C_min/C_max. Effectiveness ε relates actual heat transfer to the maximum possible heat transfer: q = ε C_min(Th,in - Tc,in). This simulator compares parallel-flow and counter-flow formulas, draws qualitative temperature paths, and plots ε(NTU) at the current C_r. It assumes steady state, constant properties, no phase change, no fouling variation, no heat loss to ambient, and ideal one-dimensional flow arrangements.

Who it's for: Thermal engineering, heat-transfer, HVAC, and process-equipment design introductions.

Key terms

Effectiveness-NTU
Heat exchanger
Capacity ratio
Counter-flow
Parallel-flow

How it works

Epsilon-NTU heat exchanger calculator for parallel and counter-flow arrangements: capacity rates, UA, effectiveness, heat transfer, and outlet temperatures.

Key equations

NTU = UA/Cmin, Cr = Cmin/Cmax, q = epsilon Cmin(Th,in - Tc,in)

Parallel: ε=(1-e^{-NTU(1+Cr)})/(1+Cr); Counter: ε=(1-e^{-NTU(1-Cr)})/(1-Cr e^{-NTU(1-Cr)})

Frequently asked questions

Why is counter-flow usually more effective?: Counter-flow maintains a more even temperature difference along the length and can heat the cold outlet closer to the hot inlet than parallel-flow can.
What does Cmin mean physically?: C = m dot cp is the heat-capacity rate. The stream with smaller C changes temperature more for the same heat transfer, so it limits the maximum possible q.

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Heat Exchanger ε-NTU

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About this model

How it works

Key equations

Frequently asked questions

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Frequently asked questions