Session: 05-04 Phase change cooling technologies

Paper Number: 94910

94910 - Measurements and Parametric Study of Phase Change Material Integrated Transient Cooling 

Thermal management of power electronics is facing growing challenges as power densification intensifies continued electronic devices miniaturization. While many conventional thermal management approaches focus on steady-state operation, many electronic devices operate in transient conditions. These conditions include pulsed power input or cycling power load conditions, where the thermal capacitance of the cooling system and device plays an important role in the device's thermal response. Thermal management systems are typically designed according to limit the maximum device temperature by minimizing the device-to-coolant thermal resistance. This thermal resistance minimization creates a trade-off between thermal capacitance and cooling efficiency because both depend upon the properties of the material between the heat source and heat sink. Phase change materials (PCMs) represent an opportunity for efficient transient cooling, due to their highly effective thermal capacitance arising from the large latent heat of fusion and relatively small volume. In this work, we measure the transient heat transfer performance of PCMs integrated with power electronic devices. Starting with a circuit board-mounted gallium nitride (GaN) power transistor (4.6 mm*2.6 mm*0.5 mm), we attach a composite PCM and study the direct cooling thermal response of the device. The composite PCM is a Field’s metal impregnated copper foam composite (7 mm*6 mm with varying thickness). We also tested the response of a copper heat spreader instead of the PCM, to create a reference case. The measurements tested PCM cooling performance was performed for PCM thickness of 1.3 mm, 3 mm, and 4.5 mm. The cooling conditions were air natural convection, air forced convection, or liquid immersion in pure ethylene glycol with device power between 0.6 W and 7.0 W. The heating time is between 10 s and 250 s, and the duty cycle ranges from 10% to 75%. We find that the optimal PCM design significantly depends upon the operating conditions, and in some cases the copper heat sink outperforms PCMs. We show how these measurements can lead to the development of design heuristics for PCM integration in transient cooling applications.

Presenting Author: Soonwook Kim University of Illinois at Urbana-Champaign