High Performance Pulsating Heat Pipe for Electronics Cooling

The purpose of this study was to explore the capabilities and limitations of additive manufacturing technology when it comes to printing a PHP system with an integrated water-cooled condenser. A flat plate PHP with an overall size of 80mm´38mm was designed to be heated on one side of the evaporator section by a resistor contacting a surface area of 899mm2. At the opposite end, a water-cooled condenser was integrated onto both faces with a surface area of 2280mm2. The PHP serpentine consisted of 48 rectangular channels with the following dimensions: 0.6mm wide and 1.7mm tall. Selective laser melting (SLM), a powder bed fusion technology, was used to manufacture the PHP. Some of the main challenges overcome in this study were powder evacuation from the serpentine, eliminating printing defects and respecting tolerances of the interface. An experimental investigation was then undertaken to analyze the performance characteristics of the printed PHPs by varying water inlet temperature, water flow rate, resistive power, and inclination angle. A leak-tight flat plate PHP was printed and successfully de-powdered and post-processed. An external wall thickness of 0.45mm and a channel spacing thickness of 0.15mm was achieved. The total thermal resistance of the device was about 0.15K/W in all orientations including inverted. The thermal resistance of the PHP was around 0.11K/W from a start-up power of 2W to a maximum of 440W. An overall heat flux of 49W/cm2 was achieved with a hot spot heat flux of 190W/cm2. The PHP demonstrated very good thermal performance to deal with high-power electronics and densely packed multi-core microprocessors.