Parametric design of a low-profile, forced convection heat sink for high-power, high-density LED arrays

Abstract

Solid state light sources, such as light emitting diodes (LEDs), provide many inherent benefits and will dominate the lighting industry in the coming decades. While much of the industry is currently focused on packaging LED technology in standardized 19th century form factors to address the massive installed base of traditional fixtures, the unique characteristics of solid state devices can and will be exploited to produce new luminaire types and new paradigms in lighting design for the 21st century and beyond. Since operating temperatures directly impact energy efficiency, output spectrum, and product lifetime, thermal management is a key linkage in the interdependence of application requirements, design trade-offs, and performance characteristics. This paper details the design of a high-power, high-density LED-based light source for large-scale lighting applications. In particular, a low-profile folded-fin copper heat sink was designed for forced-convection cooling by an array of 38 mm × 38 mm fans. Heat sink dimensions, including fin thickness, fin spacing, heat sink length, and heat sink base thickness to fin height ratio, were varied within form factor constraints and manufacturing limits to produce a suitable thermal solution for a 60,000+ lumen, 50.8 mm × 50.8 mm LED array dissipating 600 W of heat. Results of numerical, analytical, and experimental investigations demonstrate that LED junction temperatures can be maintained below maximum operating limits in a 45°C ambient.