Nanofluid Heat transfer in a Double Pipe Heat Exchanger: Paper Validation

Nanofluid Heat Transfer in Double Pipe Heat Exchanger, Paper Numerical Validation, ANSYS Fluent Training

Description

This project examines heat transfer inside a double pipe heat exchanger fitted with louvered strip inserts, based on the reference article "Heat transfer enhancement of nanofluids in a double pipe heat exchanger with louvered strip inserts." Results are validated against the paper's published data using ANSYS Fluent.

A louvered strip runs the length of the inner pipe, angled at 30 degrees with 60 mm spacing between successive strips. A nanofluid flows through the pipe at a Reynolds number of 30,000, which — using the outer tube's diameter as the characteristic length — corresponds to an inlet velocity of 1.537279 m/s, entering at 293 K.

The heat exchanger wall breaks into three functional zones: a central section where the outer tube carries a constant heat flux of 200,000 W/m², flanked by insulated entry and exit sections at either end. The louvered strip attached to the inner tube stays thermally insulated throughout. The goal is to determine the Nusselt number along the outer tube wall specifically within this heated central zone.

Geometry & Mesh

Built as a 2D model in Design Modeler, the double-pipe geometry sets the inner tube diameter at 0.001 m and the outer tube at 0.0196 m, with an outer tube length of 1.5 m and an inner tube length of 0.5 m. The louvered strips, angled at 30 degrees and spaced 0.06 m apart, run along the inner tube's body. ANSYS Meshing produced a structured grid of 296,880 elements.

Methodology

The simulation runs as steady-state with a pressure-based solver, gravity excluded. Turbulence uses the RNG k-epsilon model with standard wall functions, energy equation on. The inlet is a velocity inlet at 1.537972 m/s and 293 K; the outlet holds 0 Pa gauge pressure. The heated wall carries a fixed 200,000 W/m² flux, while the louvered strip walls stay at zero heat flux. SIMPLE handles pressure-velocity coupling, with second-order (upwind, where applicable) discretization across pressure, momentum, turbulence, and energy. Initialization follows the standard method, matching the inlet conditions.

Conclusion

The resulting Nusselt number along the heated outer wall — calculated using the outer tube diameter as the characteristic length and the 293 K bulk fluid temperature as reference — was checked against Figure 6-A of the reference article at Re = 30,000:

The close agreement between the two values confirms the simulation reproduces the paper's reported heat transfer enhancement. Additional 2D contours of pressure, temperature, and velocity, along with 2D pathlines, round out the results.