Heat-Sink Calculator

Under development

A design tool built on my research into conjugate heat transfer in longitudinal-fin heat sinks: the performance below is evaluated from explicit asymptotic formulas (no simulation, no iteration) for laminar, pressure-driven flow through a fully shrouded fin array on an isothermal base. Set the overall dimensions, driving pressure drop and materials, then explore the fin spacing and thickness, or let the tool find the geometry that minimises the thermal resistance.

Heat sink

Width W (mm)

Fin height H (mm)

Flow length L (mm)

Pressure drop Δp (Pa)

Materials

Fin material

Fluid

Fin geometry

Fin spacing s (mm)

Fin thickness t (mm)

Minimises R_t over spacing and thickness at fixed dimensions, pressure drop and materials.

– Mean Nusselt number Nu

–K/W Thermal resistance R_t

ε = s/H: –
Ω (conductance): –
Fin efficiency η_f: –
Mean velocity: – m/s
Gap Reynolds: –
Flow rate: – L/min

Fin temperature T_f(y)

Fin Nusselt number Nu_f(y)

Thermal resistance R_t(ε, Ω) ● current design · × minimum

Model. Fully developed laminar flow between fins that span the full duct height (no tip clearance), an isothermal base (e.g. a vapour chamber), and thermally developing conditions along the flow length. The thermal eigenvalue is evaluated from the composite asymptotic correlation with a Churchill–Usagi closed form (exponent n = 1.0335); fin profiles use the high-conductivity asymptotic solution, plotted against the dimensionless fin coordinate y (0 = base, 1 = tip), and T_f is the fin temperature excess over the local bulk fluid, scaled by the base–fluid difference. Fluid properties are taken at 25 °C. Results are reliable for laminar flow (gap Reynolds number < ~2000) and slender channels (s/H ≲ 0.5); the tool warns when a design leaves this window.