Inputs
Enter operating conditions and select arrangement
Tip: Use consistent units; converters handle common selections.
Example data table
These examples illustrate typical ranges and expected trends.
| Case | Arrangement | Th,in (°C) | Tc,in (°C) | ṁh (kg/s) | ṁc (kg/s) | UA (W/K) | NTU | Cr | ε |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Counterflow | 120 | 25 | 1.2 | 1.5 | 2500 | ~0.50 | ~0.80 | ~0.35 |
| 2 | Parallel flow | 90 | 30 | 0.8 | 0.6 | 1800 | ~0.75 | ~0.75 | ~0.38 |
| 3 | Crossflow (one mixed) | 150 | 20 | 2.0 | 1.0 | 6000 | ~0.72 | ~0.50 | ~0.46 |
Formula used
The method uses heat-capacity rates and the effectiveness definition:
- Ch = ṁh cp,h, Cc = ṁc cp,c
- Cmin = min(Ch, Cc), Cmax = max(Ch, Cc)
- Cr = Cmin/Cmax
- NTU = UA / Cmin (when using UA mode)
- Qmax = Cmin(Th,in − Tc,in)
- ε = Q / Qmax so Q = ε Qmax
Effectiveness relations depend on flow arrangement:
- Parallel flow: ε = [1 − exp(−NTU(1 + Cr))]/(1 + Cr)
- Counterflow: ε = [1 − exp(−NTU(1 − Cr))]/[1 − Cr exp(−NTU(1 − Cr))]
- Crossflow: the calculator provides mixed/unmixed options (including a series form for both-unmixed).
- Special limit: when Cr → 0, ε = 1 − exp(−NTU).
Outlet temperatures are computed from energy balances:
- Th,out = Th,in − Q/Ch
- Tc,out = Tc,in + Q/Cc
How to use this calculator
- Select a calculation mode: compute NTU from UA, or enter NTU directly.
- Choose the flow arrangement that matches your exchanger geometry.
- Enter inlet temperatures and pick the desired output temperature unit.
- Provide mass flow rates and specific heats to compute capacity rates.
- Click Calculate to view effectiveness, duty, and outlet temperatures.
- Use Download CSV or Download PDF for reporting.