Thermal Performance Characterization of Pulsating Heat Pipe Based Electronics Heat Spreaders

The thermal performance characterization of an additively manufactured Pulsating Heat Pipe (PHP) heat spreader for electronics cooling is investigated experimentally and discussed in this work. Performance testing was conducted in both ambient and vacuum environments, the latter being relevant for space applications. The PHP heat spreader was additively manufactured using AlSi10Mg alloy for 3U form factor electronics cards with dimensions of 160 mm × 100 mm × 3.38 mm. The PHP fluid channels, with a diameter of 1.52 mm, were embedded within the heat spreader, and ammonia was used as the working fluid for thermal performance characterization in ambient pressure and vacuum environments. Testing was performed across varying condenser temperatures from -10°C to +30°C using a central 1-inch × 1-inch heater block with cartridge heater inserts. The results showed that the PHP could transfer up to 340 W or more (heat flux ~52.7 W/cm²) without experiencing dry-out. The thermal performance improvement was approximately two-times compared to a conduction plate. Additionally, the mechanical shock and vibration testing performed in accordance with VITA 47 specifications showed a mechanically fail-proof PHP heat spreader. This work is supported by the ongoing NASA SBIR Phase II program #80NSSC22CA205.