On the importance of radiation in natural convection cooling of plate-finned heat sinks: A review

Plate-finned heat sinks are essential components in natural convection-based thermal management systems, particularly in electronics, energy devices, and passive cooling technologies. While heat is transferred through conduction, convection, and radiation, the radiative component is frequently neglected in both experimental and numerical studies. This review compiles and evaluates over 60 published works to quantify the role of thermal radiation across different fin geometries, including rectangular, pin-fin, innovative, and microscale designs. In microscale systems using high-emissivity materials such as silicon, radiation may contribute up to 70 % of total heat dissipation due to weak convective transport. For conventional aluminum-based rectangular and pin-fin configurations, the radiative share typically ranges from 10 % to 50 %, depending on parameters such as surface emissivity, fin spacing, and thermal orientation. Enhanced geometries designed to improve convective performance may also increase view factors, thereby amplifying radiative transfer unintentionally. This review identifies key parameters influencing radiative contribution, including temperature gradients, input power, and surface treatment, and highlights the need for improved experimental methods to directly measure radiation. The compiled results offer practical guidance for optimizing passive cooling systems where accurate heat transfer prediction is essential. The review also emphasizes the importance of incorporating radiation in modeling and design to ensure thermal performance reliability, especially under low-convection or high-temperature conditions. In addition, the review highlights that the emissivity and temperature of surrounding walls play a non-negligible role in determining the net radiative heat transfer, particularly in confined or low-power systems. The survey also reveals that uncertainties related to emissivity measurement, view-factor estimation, and radiation–convection separation are rarely quantified, limiting the reliability of reported radiation fractions. Last but not least, a consistent correlation between geometrical parameters and thermal radiation that covers a considerable universal range seem to be still absent.