fraisasghar/CAD-and-Simulation-of-Baffled-Shell-and-Tube-Heat-Exchanger

CAD, CFD Simulation, and Independently Verified Thermal Design of a Baffled Shell and Tube Heat Exchanger

Overview

Baffled Shell & Tube Heat Exchanger is a complete thermal fluid engineering study of a seven tube, six baffle shell and tube heat exchanger, carried out end to end in COMSOL Multiphysics. A hot water stream sweeps across a baffled tube bundle while a cold water stream flows through the tubes, and the two exchange heat through conjugate wall conduction rather than an assumed heat transfer coefficient.

Every simulated result is independently cross checked by hand. Energy balance, LMTD, effectiveness NTU, and Reynolds number calculations are carried out from first principles using only the port averaged CFD outputs, closing to within a fraction of a percent of the simulation itself.

CAD Model	CAD Inner View
Mesh	Mesh Inner View
Temperature	Temperature Inner View
Velocity	Velocity Streamline
Pressure	Pressure Inner View

How It Works

Every downstream panel, the field plots, the derived value tables, and the hand calculations, reads from the same converged solution, so the report and the presentation can never drift out of sync with the model.

Physics Setup

Turbulence: k epsilon RANS with wall functions, justified by Reynolds numbers above 10,000 on both streams Heat Transfer: Conjugate coupling through the tube walls via Nonisothermal Flow multiphysics, no assumed coefficient Mesh: Free tetrahedral with five layer boundary inflation, locally refined at every curved wall Materials: Aluminium solid domain, temperature dependent water properties on both streams

Results and Manual Validation

Every quantity below tagged Hand Calculated is derived from the port averaged CFD values using first principles heat exchanger theory, energy balance, LMTD, effectiveness NTU, and Reynolds analysis, not read directly from COMSOL.

Port Conditions (source: CFD)

Port	Temperature	Gauge Pressure
Hot Inlet, Shell	70.09 °C	194.29 Pa
Hot Outlet, Shell	48.08 °C	−3.76 Pa
Cold Inlet, Tube	25.29 °C	79.10 Pa
Cold Outlet, Tube	47.45 °C	−2.07 Pa

Energy Balance (Hand Calculated)

Quantity	Value
Heat duty, hot side, Q hot	46.00 kW
Heat duty, cold side, Q cold	46.31 kW
Average heat duty, Q	46.16 kW
Balance closure	0.68%

LMTD and Overall Heat Transfer Coefficient (Hand Calculated)

Quantity	Value
ΔT₁ (hot in − cold out)	22.64 K
ΔT₂ (hot out − cold in)	22.79 K
Log mean temperature difference, LMTD	22.72 K
Heat transfer area, A	0.1338 m²
Overall U, LMTD method	15,180 W/(m²·K)

Effectiveness NTU Cross Check (Hand Calculated)

Quantity	Value
Capacity rate, C min = C max	2090 W/K
Maximum possible heat transfer, Q max	93.63 kW
Effectiveness, ε	49.3%
Number of transfer units, NTU	0.972
Overall U, effectiveness NTU method	15,190 W/(m²·K)
Agreement between the two U methods	within 0.1%

Reynolds Number Check (Hand Calculated)

Stream	Reynolds Number	Regime
Tube side	≈ 13,000	Turbulent
Shell side, local at baffle window	≈ 11,500	Turbulent
Shell side, bulk average	≈ 700	Laminar, bulk only

Pressure Drop (source: CFD)

Stream	Pressure Drop
Shell side, hot	198.0 Pa
Tube side, cold	81.2 Pa

Roadmap

Phases 1 through 5 are complete. Phase 6 opens the geometry to a parametric sweep, more baffles, tighter pitch, longer shell, to push effectiveness past the current 49.3% without a meaningful pressure drop penalty.

Tech Stack

COMSOL Multiphysics, CFD Module and Heat Transfer Module, for geometry, meshing, and the coupled Nonisothermal Flow solve. Results are packaged into a fully formatted Word report and a PowerPoint deck, both generated programmatically from the converged solution to keep every figure and number traceable to the model.

Reproducing This Study

1. Open the model in COMSOL Multiphysics (CFD Module and Heat Transfer Module required).
2. Rebuild the geometry sequence to regenerate the parametric shell, tube bundle, and baffles.
3. Run the predefined free tetrahedral mesh sequence, including boundary layers.
4. Solve the Stationary study coupling Turbulent Flow, k epsilon with Heat Transfer in Fluids.
5. Regenerate derived values and field plots, or open the included report and slides directly.

Contributing

1. Fork the repo
2. Create a branch: git checkout -b feature/your-feature
3. Commit your changes
4. Open a pull request

References

Cengel, Y. A., and Ghajar, A. J. Heat and Mass Transfer: Fundamentals and Applications. McGraw Hill. Incropera, F. P., DeWitt, D. P., Bergman, T. L., and Lavine, A. S. Fundamentals of Heat and Mass Transfer. Wiley. COMSOL AB. CFD Module and Heat Transfer Module User's Guide. COMSOL Multiphysics.

License

Distributed under the MIT License. See LICENSE for details.