Experimental investigation on Three-Dimensional pulsating heat pipe embedded electronics heat spreader & enclosure

• A three-dimensional metal embedded pulsating heat pipe (PHP) electronics cooling system was fabricated. • PHP devices lowered thermal resistance by more than 45% compared to the conduction alternative. • PHP heat spreader showed gravity insensitive operational characteristics. • PHP heat spreader was capable of operating in non-central (biased) heat load modes. • PHP embedded electronics cooling result in up to 5% reduction in component mass. Pulsating heat pipe (PHP)–embedded heat spreaders and modular enclosure units (MEU) are presented as high-performance alternatives to conventional conduction-based solutions for electronics cooling. The PHP devices were fabricated by additive manufacturing using AlSi 10 Mg alloy in a 3U form-factor design. Following a working-fluid down-selection, ammonia was tested in the heat spreader for high heat load dissipation, while propylene was tested in the MEU for faster start-up and stable operation at relatively lower heat fluxes. The PHP heat spreader achieved a thermal resistance below 0.5°C/W, about 45% lower than the conduction plate, and transferred up to 300 W (> 46.5 W/cm 2 ) without dry-out. In contrast, the thermal resistance of the conduction-based heat spreader was 0.87°C/W. The PHP heat spreader demonstrated consistent performance with similar thermal resistance in both horizontal and vertical orientations, indicating gravity insensitivity. The PHP heat spreader also demonstrated effective operation under an unconventional biased heat load method. The PHP heat spreader exhibited thermal performance comparable to a commercial scale embedded heat pipe heat spreader. However, the PHP heat spreader can operate in cold environments, overcoming freeze–thaw thermal control requirements of the former. Similarly, the PHP based MEU demonstrated more than 45% reduction in thermal resistance compared to the conduction-based alternative. Furthermore, it was deduced that the PHP based solutions reduced the component mass by 5%, a critical benefit which for weight sensitive applications such as space systems.