Design double pipe exchangers with reliable thermal calculations. Review duties, coefficients, area, velocity, and losses. Make sizing decisions faster with organized engineering results today.
The form stays in one vertical page flow, while inputs rearrange into three columns on large screens, two on medium screens, and one on mobile.
Q = m × Cp × ΔT. The calculator evaluates heat duty on both hot and cold sides and then uses their average as the design duty.
LMTD = (ΔT1 − ΔT2) / ln(ΔT1 / ΔT2). Counterflow uses (Th,in − Tc,out) and (Th,out − Tc,in). Parallel flow uses (Th,in − Tc,in) and (Th,out − Tc,out).
The overall coefficient based on outer area uses convection inside the tube, wall conduction, and fouling on both sides: 1/Uo = do/(dihi) + doln(do/di)/(2kw) + Rf,ido/di + Rf,o + 1/ho.
A = Q / (U × LMTD). Required total tube length is A / (π × do).
Velocity = volumetric flow / flow area. Reynolds number = ρvD / μ. Pressure drop uses Darcy–Weisbach: ΔP = f(L/D)(ρv²/2), with laminar and Blasius friction estimates.
The calculator applies simple Nusselt correlations for internal flow. Laminar cases use constant-value estimates, while turbulent flow uses the Dittus–Boelter style relationship.
| Item | Sample value | Unit |
|---|---|---|
| Flow arrangement | Counterflow | — |
| Hot fluid location | Inner tube | — |
| Hot inlet / outlet temperature | 140 / 105 | °C |
| Cold inlet / outlet temperature | 30 / 60 | °C |
| Hot / cold mass flow | 2.00 / 1.20 | kg/s |
| Hot / cold specific heat | 2.10 / 4.18 | kJ/kg·K |
| Tube ID / OD | 38 / 48 | mm |
| Outer pipe ID | 82 | mm |
| Calculated LMTD | 77.473 | °C |
| Calculated overall coefficient | 381.126 | W/m²·K |
| Required area | 5.037 | m² |
| Required tube length | 33.405 | m |
It estimates heat duty, LMTD, overall coefficient, required area, tube length, velocities, Reynolds numbers, flow regimes, and straight-length pressure drops for a double pipe exchanger.
Both are shown to help you check energy balance. A large mismatch usually means one or more temperatures, flow rates, or specific heat values need review.
Enter a manual U value when you already have a plant standard, vendor estimate, or validated design coefficient. Leave it blank to calculate U from the supplied transport properties.
Yes. The terminal temperature differences and NTU effectiveness relation change automatically when you switch between counterflow and parallel flow modes.
No. They are useful for early sizing and comparison. Final design should include entrance losses, return bends, fittings, roughness effects, and manufacturer geometry details.
Use properties at a representative mean bulk temperature for each stream. That gives more realistic Reynolds, Prandtl, film coefficient, and pressure drop estimates.
An invalid LMTD appears when a terminal temperature difference becomes zero or negative. That usually indicates an impossible thermal target for the selected flow arrangement.
Yes. The calculator converts required tube length into estimated straight sections using your entered standard segment length, which is useful during preliminary layout planning.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.