Heat Sink & Fin Array Thermal Calculator

ThermoFluidCalc

https://thermofluidcalc.com

Engineering Calculation Report

Date: 2026-06-04 20:20

Interactive Design Preview

Observe the dynamic physical layout of the heat sink array above. Adjust the sliders in the Configurator to recalculate:

Plate Fins: Continuous parallel sheets running in the flow direction.
Pin Fins: A grid arrangement of cylindrical posts providing high surface area.
Clearance/Spacing: Spacing dynamically updates based on the plate width and fin counts.

Configurator

Heat Sink Configuration

Heat sink type:

Base Plate Dimensions

Base Width ($W$) [mm]:

Base Depth ($D$ - flow direction) [mm]:

Base Plate Thickness ($t_{base}$) [mm]:

Fin/Pin Array Parameters

Number of Fins/Pins ($N$):

Fin Height ($H$) [mm]:

Fin Thickness ($t$) [mm]:

Base Material:

Custom Conductivity ($k$) [W/m·K]:

Convection & Operating Mode

Convection Mode:

Inlet Air Velocity ($V_{in}$) [m/s]:

Thermal Power to Dissipate ($Q$) [W]:

Ambient Temperature ($T_\infty$) [°C]:

Max Allowable Base Temperature ($T_{max}$) [°C]:

Convection Coefficient ($h$):

Override Convection ($h$) [W/m²·K]:

Results & Optimization

Results and optimization curves will be displayed here upon completion of the calculation.

Calculation Methodology

Mathematical Model & Heat Sink Layout

Heat sinks are the standard mechanism for thermal dissipation in electronics. This calculator solves the conjugated thermal resistance network through the base plate and fin array:

$$R_{hs} = R_{base} + \frac{1}{\eta_o h A_{tot}}, \quad R_{base} = \frac{t_{base}}{k W D}$$ $$T_{base} = T_\infty + Q \cdot R_{hs}$$

Overall surface efficiency $\eta_o$ accounts for individual fin wetted area $A_f$ and efficiency $\eta_f$:

$$\eta_o = 1 - \frac{N A_f}{A_{tot}} (1 - \eta_f)$$ $$\eta_f = \frac{\tanh(m H_c)}{m H_c}, \quad H_c \approx H + \text{correction}$$

For plate fins, $H_c = H + t/2$. For pin fins, $H_c = H + d/4$.

Convective Correlations & Spacing Limit

For vertical plates in **Natural Convection**, the optimal fin spacing $S_{opt}$ balancing buoyancy airflow vs wetted area is derived by Bar-Cohen & Rohsenow (1984):

$$S_{opt} = 2.714 \frac{H}{Ra_H^{1/4}}, \quad Ra_H = \frac{g \beta (T_{base} - T_\infty) H^3}{\nu \alpha}$$

For **Forced Convection**, plate-fin heat transfer coefficients use the composite correlation from **Teertstra et al. (1999)**. Pin-fin arrays use **Zukauskas (1972)** cross-flow correlations over cylinder bundles.

Academic References:

Bar-Cohen, A. and Rohsenow, W. M. (1984). Thermally Optimum Spacing of Vertical, Natural Convection Cooled, Parallel Plates. J. Heat Transfer.
Teertstra, P., Yovanovich, M. M., and Culham, J. R. (1999). Analytical Forced Convection Modeling of Plate Fin Heat Sinks. ASME Proceedings.

Heat Sink & Fin Array Calculator